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re: Tech Pan pinholes w/ D-19 but not w/ MWP-2 ...

I find this interesting ...  are you processing the same Tech Pan ( i.e.
same emulsion number, same film batch )  ???

The MWP-2 is probably giving you ~ 1/2 the true speed ( measured ) of D-19
so it is to your advantage to process in D-19 ...  suggestions:   try cutting
your stop bath to < 1% strength acetic acid ... not sure how you mix your stop
bath ...
so if you do not mix from 'raw' glacial acetic acid I'd suggest cutting your
stop bath
by a factor of about 10 to be really safe and then trying the D-19 ...

If you r Tech Pan is old ... been frozen for awhile ... I'd suggest trying a NEW
batch of Tech Pan ... older emulsions generally show pinholes ...

MWP-2 worked well on 103a emulsions but it yields slower speed and much higher
contrast than D-19 .... you might also try HC-110 B for about 16 mins and see
what you
find .. HC-110B will give you about 80% of the speed of D-19 but with
substantially lower
contrast ...

do feed back on this ... it is an interesting problem ...

Brad Wallis

Astro_Images and Astro_Imaging hints:
    http://voltaire.csun.edu/wallis_provin.html

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      When processing hypered Tech Pan in D-19 (10min @ 68 D F), I
      continually get what I call emulsion "drop outs".  That is, tiny areas
      of the emulsion that appear to have flaked off of the film base. It
      doesn't seem to matter if the film is 35mm, 120, or 4x5.   However,
      when using MWP-2 chemestry, (12min @ 68 D F) the problem vanishes.
      Does anyone know the reason for this?

      jg

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>...  do lower you MAK-SHIELDS and discuss a

The good Captain had to pursuade Mr. Worf to power down phasers never mind
the shileds :-).


>bit the comparison of a MAK-CASS and a CONCNETRIC SCHMIDT CASS system
>with both running at f/4 ...   image size ( oops .. i forgot that is a bad
>topic here <G> ) and color ...

Brad, you need to be a little more flexible, I really do not understand your
fixation with the Concentric Schmidt Cass. I said it before, but I guess
I'll have to say it again:

I believe the Newtonian configuration is superior to the Cassegrain because
faster speed systems can be achieved covering a wider field and format with
less vignetting.

Brad, a while ago I posted this to the list--did you see it?

>I compared the performace of the 8" f/4 concentric Schmidt Cass design with
an 8" f/4 Mak astrograph design >described above. The spot sizes are the
same at the edge of a 60mm field, but the Mak design, with the same
>obstruction, has extended coverage, out to an 86mm dia field (6 deg), with
an RMS spot size of only 12 microns >(the airy disk is 6 microns across) at
the extreeme edge.

Peter

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Just a quick round up of results so far on the problem of matching the
density of colour film material (with orange base) against the neutral grey
of the step tablet....  with thanks to Jerry and Brad for the excellent
suggestions....

I've not had a chance to try Brad's suggestion yet, however I've tried
Jerry's suggestion, and it works surprisingly well!  His idea is to mask the
entire light box with card in which two small adjacent holes are punched -
one to view the step tablet, and the other to view the film under test.

I made a masking device from a large sheet of thin opaque card (large
enough to cover the entire light box) which I cut horizontally into two
equal halves. Near the top of the lower half I punched two 5mm holes 1-1/4
inch apart (a standard paper punch makes holes exactly the right size). I
glued the two halves together with a thin overlap, but skipped a 1" wide
section above one of the holes - this enables the step tablet to slide
through the gap and cover one of the holes.

I found that it helped further to place a Cokin 4x neutral density filter
over both holes. The colour difference between the two materials is still
apparent, but it's MUCH easier to match the density this way.

This gave some interesting results on my hypered film - the PJM-2 is
probably way overhypered, whereas the PPF-2 is probably about right. There's
still a lot of uncertainty because the test is only subjective, but the
biggest limitation to accuracy is the big step sizes between the densities.
A step size of 0.15 is simply too big when one is looking for a density
difference of only 0.10. This kind of application needs 0.05 steps, and they
only need go up to about 1.00 (for color negative material, at least).

So, some mixed feelings about the step tablet - it's certainly better than
nothing, but way short on the sort of accuracy needed, and $95.74 (converted
UK cost) is one helluva price for a 5.5" piece of uncalibrated film! :-)  For
anyone serious about hypering, that cost might be better invested towards a
densitometer...

Thanks again for the help...

Philip Perkins -- 51 27'N - 1 36'W
(philip.perkins@...)

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Will, when shopping for a Meade, you will not find a big break
goind mail order. So I would first consider a local vendor that
will promise support. Find someone that will let you exchange it
for another if you find the optics aren't up to snuff or who is
willing to send it back to Meade if there is a problem on their
own nickle. I went through a place called Nurnburg Sci. who is
local. They sent my 12" back to have the optics tweeked and now I'm
VERY happy with it. I have also HEARD that The Nature Company has a
wonderful exchange policy and warrenty that goes beyond Meade's, though
you will probably not find any skilled advice there on how to use it.
As I said, I've gotten some nice shots and am happy with mine but I've
heard others that have had problems. Be sure you are dealing with a
seller that can help you if you have problems too.

Glenn Graham

>
> Hi all,
>
> I am new to astrophotography and think I am ready to move up to a 10" SCT.  I
> am thinking of the Meade LX50 10".  I know that they have there draw backs,
> but find that this is the most I can get for my money and also offers the
> best all around applications.  My question is, where should I make my
> purchase?  I have been hearing alot of negative things about certain
> companies and don't want to regret where I make my purchase.
> Also, I would like to thank all of you for providing useful information.  I
> find the discussions here very interesting, even though the refractor
> discussion is getting kind of long winded.
> In general, what is everyones favorite company to deal with?
>
> Sincerely,
>
> Will
>

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Hi all,

I am new to astrophotography and think I am ready to move up to a 10" SCT.  I
am thinking of the Meade LX50 10".  I know that they have there draw backs,
but find that this is the most I can get for my money and also offers the
best all around applications.  My question is, where should I make my
purchase?  I have been hearing alot of negative things about certain
companies and don't want to regret where I make my purchase.
Also, I would like to thank all of you for providing useful information.  I
find the discussions here very interesting, even though the refractor
discussion is getting kind of long winded.
In general, what is everyones favorite company to deal with?

Sincerely,

Will

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Is Jack really off his rocker? Lets see, I just spent 2 minutes playing with
Zemax (a powerfull optical design software package) checking on Jacks sanity
and found that Jack may not be quite the crack pot some of you think he
is---at least in my humble opinion.

I modeled a 6" f/6 Newtonian telescope with a perfect paraboloidal primary
and determined that the RMS spot size is zero on axis but ballons to about
75 microns at the corner of a 35mm frame. Please note that I have not made
allowances for the inevitable vignetting caused by the diagonal or 35mm
camera body.

I then messed around with the figure of the primary until there was about 1
wave of spherical aberration **on the wavefront** at best focus on axis. The
axial spot size is now about 20 microns but the extreme off axis spots are
relatively unchanged.

It is interesting to note that the 1 wave, 20 micron, axial RMS spot size in
the "Schmidling Primary" is roughly equal to the perfect paraboloid spot
size about .25" off axis.

What does this mean?

Well, in this case, I believe the 1 wave wavefront primary will form
reasonable photographic images on color film. It will be handicapped for CCD
imaging in good seeing though with a Kodak 9 micron pixel array, but it will
be ok with an ST6 with the big 25ish micorn pixels. I am told that the
smallest number of pixels a real image can cover (ie not a cosmic ray hit)
is 4 pixels. So the ST6 will undersample even this 1 wave primary's images.

I do not advocate lousy optics, however not everyone can afford the high end
scopes some on this list use and to suggest that any thing less than optimum
will not perform well is simply wrong. Few people realize that when the
images move off-axis the wavefront aberration can be horendous. Also, too
many of us have this "axial wavefront quality" fixation and fail to consider
the crap that happens off axis in photographic systems.

Peter

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DECEMBER 29. After awakening at 5:45, I walked the hundred yards south along
the well trodden path to the observatory under a brilliant waning gibbous Moon
high in the southwest that gave so much light off the two foot deep snow cover
that a flashlight was not needed. Even though the temperature was a bracing
-24o (-31oC), it seemed warmer, perhaps because the air was dead calm, or
perhaps because I've finally become acclimated to another northern prairie
winter. I did not, however, spent any time getting into the warmth of the
observatory office. After placing Comet Hale-Bopp's 7 o'clock coordinates
(18hr38.9min RA and 04o12' DEC) into the SkyGlobe v.3.6 planetarium software,
it appeared the comet would rise at 6:24 at 83.7o azimuth. After positioning
the tripod mounted 8x56 binoculars facing the office east window, I began a
search for the comet about 6:45. Ten minutes later its glimmering form popped
into sight due east (89.5o azimuth) and 5.3o altitude. At 7:25 Altair slipped
into view at 1.9o altitude along the east northeastern horizon (78.6o in
azimuth). I decided to get a less distorted view of Hale-Bopp and thus I
grabbed the binoculars and moved outside onto the observatory deck for a brief
look, noting afterwards that its stubby broad tail was conspicuous even though
the moonlight and first signs of approaching dawn did nothing for the view. At
that time the Moon was 30.6o altitude (244.8o azimuth) and 4o south southwest
of Regulus, Mars was 40.0o altitude (210.2o azimuth) in Virgo, and Venus was
low in the east southeast at only 5.7o altitude (132.9o azimuth), while the
comet was than 10.2o (95.2o azimuth). I continued to follow Hale-Bopp from the
much appreciated warmth in doors until losing sight of it at 7:33 as it reached
an altitude of 11.6o (96.7o azimuth), an hour since the start of a rather
colorless dawn (old Sol was then only 8.6o below the southeastern horizon) and
nearly an hour before this morning's half past 8 o'clock sunrise. After
consulting the Sun's calendar, I see we will finally reach our latest sunrise
the last morning of this year when it rises at 8:31; seems only fitting that we
start the new year feeling optimistic.

Yesterday's mail brought three images of the comet using Royal Gold ISO 1000
film. The first frame taken at the SCT's prime focus on November 01 included
the fine globular M14, and the other two were taken on December 21 with the
camera and 210 mm lens riding piggyback on the telescope. The first was marred
by poor hand guiding, thus producing blotted stars, while the latter two
displayed some drift as well (I couldn't locate a guide star because of the
bright fading twilight and the poor choices Ophiuchus offered that evening)
since I let the drive do its thing without my guidance. Still, they are at
least mediocre records of Hale-Bopp's closing days as an evening object this
year.

John Leppert Deneb Observatory 48o56'07"N 99o09'40"W: 29 Dec 1996 09:30 CST


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how about making an agreement to stop kicking a dead horse

this has been about as inane a conversation as any i have heard.

jamie

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Brad Wallis wrote:

> JS is  100% PLUS in the WRONG ... If anyone is following his advice or
> words of 'wisdom' they are heading down the road to disaster...

I offered no advice and simply predicted what Steve is likely to find
out when he gets his refigured mirror back.  I have no interest in a
spitting contest with you guys and am content to wait to hear from
Steve.

> and you can be *really* certain that none of us will just send off a prime neg
to someone who refuses to believe that they exist

First of all I never asked for a prime negative.  I would presume that
with the hundreds (thousands?) of negs folks have taken, there must be
one less than prime that one could spare.  After all, if so many people
have so little difficulty attaining such images, they should not
have to dig into their stock of trophies.

I never said anyone was lying or even exagerating but my experience
and from what I have seen of the negatives people have sent to me,
there is a measurement problem out there and not a "crummy" scope
here.  In all cases, it was agreed that my measurement system and
technique was more accurate and objective than what they had used.

I also suggested reading the section in Tex's book to get a feel for
the problem.  Believe it or not, measuring the size of the fuzzball
objectively is harder than taking the picture in the first place.  The
biggest problem is deciding where the fuzzball ends and the background
grain begins.  I humbly suggest that there is almost a 10 micron
uncertainty in making that decision, so claims of 10 micron image size
really do need to be taken with a grain of salt.

> ( and believes that the 'classics' of the 1940s are still primesources of
information ! )...

No.  I said there are pictures there that folks can look at that do
not have access to a microscope to get a feel for the problem.  I
allowed as how Techpan probably is variable here but that is another
issure.

> If you look at the CCD iamges at our web site you can find star iages that are
18 microns across ( 2 pixels ) ..

The discussion is about film photography.

js

--
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> Now .. I think we need to find an optics crackpot to join into this
> discussion to make it *really* 'interesting ....    ;-)

> Brad Wallis



seems to me you have a crackpot, all we have to do is put glasses on him
and, PRESTO, an optics crackpot :]]] would a miopic crackpot do??? :]]]

jamie

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I *really* hate to get into this .. but there is an issue here that is
important ... and a loud voice that is sending out info that is completely
incorrect and based on lack of facts and lack of information and lack
of evidence ....

JS is  100% PLUS in the WRONG ... If anyone is following his advice or
words of 'wisdom' they are heading down the road to disaster... and they
can consider that both Jerry Lodrigus and I have warned them that JS
is totally wrong and that his statements here are completely and totally
wrong.

You can look at images from Jerry, from George Greaney, Tony Hallas, and
Jason Ware ( as well as from Robert and I ) ... with a scope of about 50 inches
FL we are all able to record images that are well under 20 microns... I have
negs that hit 12 microns .. Tony says he hits < 10 microns now and then..
and you can be *really* certain that none of us will just send off a prime
neg to someone who refuses to believe that they exist ( and believes that the
'classics' of the 1940s are still prime sources of information ! )...
If you look at the CCD iamges at our web site you can find star iages that are
18 microns across ( 2 pixels ) .. but due to the undersampling with 9 micron
pixels you see stars of all shapes so have to look for the best star images
in the frame ...

THe INTERNET has a lot of plusses ... but it also has a bundle of minuses...
one MINSU that we all need to keep alert of is that there are a lot of
bad sources of information about and we all need to weigh what we read
on the internet ....

In this issue of star image sizes, the matrter of FL must be considered.
If some of the best imagers in the country are getting 10-12 micron
images with 50 inches of FL ( this is something near 2 arc seconds )
we are seeing limited.... If one does the same image in the same place
with 2 arc second seeing and 100 inches of FL then it will be quite
probable <G> that the star images will be twice the linear size of those
obtained with 50 inches of FL ...  unless one uses AO on the system <G>...

and ... JS was tossed off of this list once for resorting to personal
insults on several people ... Jason Ware LEFT this list because of JS's
continual tirades and BS ... and JS then took his tirade of personal
insults and denegrations out into S.A.A. and continued to insult
the people who he had started attacking her on the APML ...

be careful of what information you absorb from the internet ...

ENjoy !!

Brad Wallis

Astro_Images and Astro_Imaging hints:
    http://voltaire.csun.edu/wallis_provin.html

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and  while you are at it ...  do lower you MAK-SHIELDS and discuss a
bit the comparison of a MAK-CASS and a CONCNETRIC SCHMIDT CASS system
with both running at f/4 ...   image size ( oops .. i forgot that is a bad
topic here <G> ) and color ...

since I can NOT get a refractor ED APO to run at f/4 ( yet ! ) I have
to consider other options .. and the Concentric Schmidt Cass would be my
weapon of choice in this arena <G> ... and ... if the f/4 MAK-CASS is
such a wonderful toy .. how come it is not in the Ceravolo product line
( yet ) ...

Now .. I think we need to find an optics crackpot to join into this
discussion to make it *really* 'interesting ....    ;-)

Brad Wallis

Astro_Images and Astro_Imaging hints:
    http://voltaire.csun.edu/wallis_provin.html

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> Is any of this stuff of interest to any one other than Brad and myself? I
> mean this high end instrumentation stuff, how it works, why it doesn't etc.

Yes!  I'm continuing to learn by reading books, participating in this
e-mail forum, pushing glass, etc.

For me it may help me with my second astrograph project (summer '97?)
since my first one is coming sort of close to completion:  six inch
f/3.75 hyperboloid (eccentricity 1.34), Lumicon 2" coma corrector.
I'm done figuring the mirror (a star test in the tube assembly
will be the final test of that!) and hope to try it out soon.  I know
it will have field curvature and vignetting, but this is a first
effort to prepare me for a larger version - probably with a different
corrector design.

The hard part for me is to decide:
  - what design for the corrector?
  - can I make it myself or can I find someone to make if for me
without it being too expensive?  (OK, I can make/figure a single
mirror, but several lenses?!? and anti-reflection coatings?)

Hmmmm, I know out there lurks a "perfect" astrograph design for me!  ;-)
(Yikes!  Here come the flames!)

Tom Krajci

Capt Tom Krajci
B-52 Intelligence Officer
"Military Intelligence - an oxymoron!"
http://spur.barksdale.af.mil

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On Sat, 28 Dec 1996, Peter Ceravolo wrote:

> Hi All,
>
> Is any of this stuff of interest to any one other than Brad and myself? I
> mean this high end instrumentation stuff, how it works, why it doesn't etc.
>
> If so I'd be glad to share what I've learned. If not I've got a hell of a
> lot of work to do :-).

beats the drivel that goes on here . . . . what right have you to keep
all the information to yourself ???? :]]]] knowledge is to be shared, or
am i in the wrong part of the world ?

jamie

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I've posted a new picture to my web site at:

http://www.astropix.com/sag_scorp.html

to remind you of summer as we get into the meat of the winter.

Jerry

email: jml@...
Astrophotography Techniques and
Digital Enhancement in Photoshop Tips:
http://www.astropix.com

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>Is any of this stuff of interest to any one other than Brad and myself? I
>mean this high end instrumentation stuff, how it works, why it doesn't etc.
>
>If so I'd be glad to share what I've learned. If not I've got a hell of a
>lot of work to do :-).


Peter, yes, I am definitely interested. I always listen VERY carefully when
someone who actually knows what they are talking about is speaking. -)

Jerry
email: jml@...
Astrophotography Techniques and
Digital Enhancement in Photoshop Tips:
http://www.astropix.com

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>Not sure who elected you to inform the world on what books I
>choose to read.  Fact is, I have read the book cover to cover and
>get tired of your repeating this mantra on a regular basis.

Well, the last time we talked, you hadn't read it, refused to read it, and
were proud of your ignorance. Now I feel my mission in life is accomplished! :-)


>If you have or can get a copy of Jean Texereau's excellent classic on
>telescope making, there is a section devoted to this subject.  Including
>photos of microscope views of images on film.  It is very eyeopening to
>anyone in this field without access to a microscope.  It is based on
>yesterday's emulsions but from my experience, these photos look pretty
>much like what I see on Techpan.

I borrowed Texereau's book from a friend tonight, where is the specific
reference you are siting?

I haven't looked at it yet, but just the fact that his photos are based on
yesterdays emulsions and in your photos on techpan look like his tells me
something. Either you don't have the optics, or you don't have the seeing,
or your don't have the tracking.  Previously you blamed your inability to
record smaller than 20 micron stars on "The image of a point of light on a
high-speed photographic emulsion has a minimum diameter of 20 to 25 microns
as a result of difusion of light in the film."  Surely with techpan this
must be better, it's finer grained, higher resolution, higher contrast, and
thin emulsion.


>Seems like Jean Texereau is another clutz like me.  The difference is
>he has published his best and all the "others" just talk about them.
>

>And I own the Brookly Bridge.  Just don't happen to want to sell it
>right now.  Read Tex's book and argue with him.


So you read a book and it says he hasn't broken 20 microns, and you haven't
either so when someone else says they have you just don't believe it, yet
why would these other people have reason to lie?

You think I am going to send YOU one of my best original negs just to prove
it to YOU? Ha!  I guess you don't believe man has gone to the moon either
just because you haven't.




>And most people severely overestimate the importance of high quality
>optics for prime focus photography.


So your argument is that on film at prime focus, you will not see the
difference between a scope with good optics that normally produces small
spot sizes and one with bad optics that produces what, anything under 20
micron spot sizes because 20 microns is the best the film can ever resolve?
The actual numbers are not important here, it is the LOGIC that I am attacking.

I have a 130mm aperture refractor that can and does resolve 0.87 arc sec,
lets round it off to 1 arc sec. That equals 5 microns at my film plane.  Now
I KNOW the scope can produce this because I have observed it visually, so
when it produces 20 micron stars on film it's NOT because of the optics,
right?

Lets say the optics were bad and it could only produce 10 micron stars at
prime focus. YOU are saying that it would still produce 20 micron stars on
film because 10 micron stars still fit in your arbitrary 20 microns-on-film
definition.

SO, you say that even though 5 micron stars go to 20 microns on film (a 4x
degradation factor, and NOT because of the optics), 10 micron stars won't
get any worse than 20 microns? This might be true if the film's resolution
was the ONLY other factor involved (and IF the film's resolution was
limited, in fact, to 20 microns), but you have to factor in the seeing and
the guiding too.




>I was removed once before from this list for defending myself
>against your sleeze and have played punching bag long enough.

No, you've got it wrong again Jack.  You were removed from the list for
calling reputable people names, and I have kept the messages that document
this to prove it if you have rationalized it and forgotten the facts.


>Get off my case.

Stop posting mis-information and I will.


Jerry

email: jml@...
Astrophotography Techniques and
Digital Enhancement in Photoshop Tips:
http://www.astropix.com

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Lt. Worf:
"Captain.. We are being hailed".

>Refractor believer to MAK believer:
>  Hold your fire and continue the dialogue.....     ;-)   ;-)

Picard:
"Clearly this a reasonable being. Stand down Mr. Worf and open a channel."


Hi All,

Is any of this stuff of interest to any one other than Brad and myself? I
mean this high end instrumentation stuff, how it works, why it doesn't etc.

If so I'd be glad to share what I've learned. If not I've got a hell of a
lot of work to do :-).

Peter

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Jerry Lodriguss wrote:

>  The optical quality of the photographic image is based on several things,....

Thanks for the nice review but it does not negate my point that the
least important link in the chain is the quality of the optics, beyond
a certain point.  What we can disagree on is just what that point is
and I propose one wave SA as a point to start from.

> As usual, all of this is covered in detail in Brad Wallis
> and Robert Provin's fine book "A Manual of Advanced CelestialPhotography",
which I don't believe Jack has read.

Not sure who elected you to inform the world on what books I
choose to read.  Fact is, I have read the book cover to cover and
get tired of your repeating this mantra on a regular basis.

More to the point is that I referred the readers to a book by
Texerau with photos and a discussion in support of my position but
it seems that you did not read that book or chose to ignore what is
relevant to the topic.

>Jack's saying 1 wave optics are sufficient for photography and using theexample
"If ALL of the energy from a star was in the defraction
  [SIC] rings, it (they) [SIC] would still be well within the 20 micron
image and it would look no different than if it had been formed by a
point source", is as ridiculous as saying you can obtain 20 micron
stars even if you have atrocious 6 arc-second seeing (this based on
Jack's example of Steve's 16 inch f/4.5 having 3 micron spot sizes.)

6 second seeing on Steve's scope equates to roughly 60 microns at
the film plane.  I fail to see the logic in you anology. But I do
see how important my careless spelling is to this discussion.

> With logic and arguments like these, it's no wonder Jack has never broken the
20 micron barrier while others have.

Seems like Jean Texereau is another clutz like me.  The difference is
he has published his best and all the "others" just talk about them.

> As far as Jack's "challenge" goes, I personally have negatives and
> transparencies that have stars with FWFM diameters of less than 20 microns and
if Jack doesn't take my word for it, I couldn't care less.

And I own the Brookly Bridge.  Just don't happen to want to sell it
right now.  Read Tex's book and argue with him.

I would rather wait for Steve's report than argue with you.

> Most people severely underestimate the importance of factors 2 and 3 listed
above.

And most people severely overestimate the importance of high quality
optics for prime focus photography.

> Perhaps that is why Jack has never broken it.  Then again, maybe he just has a
crummy telescope optically.

I suspect that you are well aware that the scopes I use for photography
have all been of my own design and making. To call them "crummy" just to
put frosting on your "argument" is just another bit of your constant
barrage of ad hominam attacks against me and I am getting a bit tired
of them.  I was removed once before from this list for defending myself
against your sleeze and have played punching bag long enough.

Get off my case.


js

--
Visit our WEB pages:
Beer Stuff:  http://dezines.com/@your.service/jsp/
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Dear APML member,

      Through hastiness, I accidentally sent a message intended for one
member to the entire list.  For this oversight, I apologize.

Paul Rybski

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Dear John,

      I would like your permission to post your Hale-Bopp observation to
ASTRO, my netlist run out of Atlanta on Mindspring.com.  The list is
encountering a seasonal hiatus, and your excellent report might jump-start
some more observing reports. Please let me know your response as soon as
possible.

      Thanks in advance for your help.

Paul Rybski, listowner of ASTRO and ASTRO-DIGEST
Assoc. Prof., Physics, Univ. of Wisconsin-Whitewater, USA

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26 DECEMBER. I slept here at the observatory last night in order to rise early
and perhaps locate Comet Hale-Bopp from the comfort of the office. After
awakening at 6 o'clock, I attached 8x56 binoculars to an old tripod (using a
binocular mount) and faced them due east through the office window. Although I
was looking through a thin sheet of insulating plastic covering the single
pane of glass, I was able to resolve fairly decent images of the stars in
Ophiuchus and Serpens Cauda. Although it appeared that it would rise just
north of due east around 6:35, I was not able to locate it until 7:10 because
of the brilliant waning gibbous Moon, then 18o above the western horizon, and
the attendant moonlight reflecting off our deep snow cover. At 7:20 I decided
that if I were to confirm the suspected object as that of the comet I needed
to do so out-of-doors, and so I donned insulated snowmobile coveralls, boots,
and jacket, stocking cap, and seal mittens and transferred the binoculars out
onto the observatory deck in the -28o (-33oC) pale orange dawn (astronomical
twilight having begun at 6:34, sunrise to follow at 8:30). Indeed, I could
then its characteristic stubby tail and nebulous coma near its predicted
position of 18hr36.1min RA and 03o45' DEC, some 6.0o above the eastern horizon
(using SkyGlobe v.3.6 and DeepSpace v.5.21 software). Venus lay just northwest
of Antares, some 6.5o above the southeastern horizon, while Mars was very high
(41.7o altitude) in the south southwest near the Leo-Virgo border; the latter
has brightened considerably over the last month as it approaches opposition in
three months. After confirming HaleBopp's position, I continued to follow the
comet from the warmth of the office until I lost sight of it at 7:30 as it
reached an altitude of 9.3o in the deep orange twilight.


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I had a some time on my hands over the Christmas holidays because even
though it was clear, it was full moon, naturally!

So I made up a little JAVA page, it's at:

http://www.astropix.com/java/java.html

You'll need either Netscape v3.0 or Internet Explorer v.3.0 to view it. It
may take a minute or so to download so be patient!

Best wishes for the holiday season!

Jerry
email: jml@...
Astrophotography Techniques and
Digital Enhancement in Photoshop Tips:
http://www.astropix.com

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STEVE BELL WROTE:
>
>> Imagine if it turns out that 1 wave optics don't perform any better
photographically than better figured optics (an estimate that I believe
>Jack Schmidling has given) - one would then be better off spending
>his/her money on gasoline to travel to dark sites with good seeing than
>buying that precisely figured scope.
>


JACK SCHMIDLING WROTE:

>I will stick with that position with a few qualifications.
>
>The first being that you never put an eyepiece in and try to see
>anything very elusive.
>
>The second being that we were only talking about prime focus
>photography.
>
>It also depends on what is wrong with the optics and we usually refer
>to spherical aberration or deviation from a parabaloid (SIC) when we talk
>wavelength specs.  The spot size of a smooth 1 wave "parabaloid" (SIC) is
>still smaller than the smallest image possible on the photographic
>negative.  The better parabaloid [SIC] would be smaller, of course but you
>can't see the difference on the film.
>
>I am still waiting for someone to take me up on the Sub 20 Micron
>Challenge.  A shiny new EASYTESTER is dying to find a home.  All I get
>are promises, promises.


JACK SCHMIDLING WROTE:

>I don't wish to beat a dead horse but...
>
>The theoretical minimum spot size for your 16" F 4.5 is about 3 microns.
>
>The image of a point of light on a high-speed photographic emulsion
>has a minimum diameter of 20 to 25 microns as a result of difusion [SIC] of
>light in the film.
>
>If ALL of the energy from a star was in the defraction [SIC] rings, it
(they) [SIC]
>would still be well within the 20 micron image and it would look no
>different than if it had been formed by a point source.
>
>Add to that the fact that we display photographs, not negatives, so we
>can add another step of loss through diffusion in the printing.  We
>also make only nominal enlargements, not microscopic scrutiny, and
>consequently, the advantage of better optics is lost with prime focus
>photography.



PREVIOUSLY JACK SCHMIDLING HAS WRITTEN:

>I again present my offer to send a free EASYTESTER to anyone who sends
>me a negative with star images less than 20 microns in diameter.
>
>The only stipulaton [SIC] is that it must be unfiltered on Techpan.
>I don't care how long the exposure or how it was guided or what
>kind of camera it was taken with as long as it is done by an amateur
>on amateur type equipment.
>
>I am not trying to stir up trouble just trying to learn why after
>trying for several years on several different optics, I can't even
>get close.




  The optical quality of the photographic image is based on several things,
each like the links in a chain, and as we know, the chain is only as strong
as it's weakest link.

1. The total quality of the photographic instrument. This includes the
quality of the curve of the primary, the smoothness of the surface, the size
of any secondary obstruction, the rigidity of the tube assembly, mirror
cell, secondary holder, focuser, mirror flop, etc etc.

2. The quality of the guiding. This includes any flexure that may take place
between the main photographic instrument and the guidescope if the main
scope is not off-axis guided. It also includes the ability of mount to
accurately track, and the accuracy of the gearing and the stepping rate of
the stepper motor if one is used.  It goes without saying that manually
guided photos, CANNOT approach the quality of guiding obtained with an
autoguider. The quality of the seeing is also incredibly important to the
guiding.

3. The quality of the seeing. I know many amateurs in New Jersey who think
the seeing is pretty good, when I consider it mediocre at best, because at
our observing site, we almost NEVER get really good seeing, and some people
just don't know what excellent seeing is, because they've never seen it.
This applies to final photographic quality also.

4. The quality of the photographic emulsion. Technical Pan film is the king
here, but some of the newer E6 emulsions like Provia are remarkably good.

5. The quality of the focus, and the ability of the camera body to hold the
film flat exactly IN the focal plane during the entire exposure. No
vibration or movement should be introduced by the shutter or shutter release
when the camera body is opened or closed if the hat trick method is not used.

When ALL of these factors are at an optimum, ONLY then can the maximum
resolution of the TOTAL package be achieved.  And if the maximum quality is
compromised in ANY of these factors, then the final outcome will be
compromised too.  As usual, all of this is covered in detail in Brad Wallis
and Robert Provin's fine book "A Manual of Advanced Celestial Photography",
which I don't believe Jack has read.

Jack's saying 1 wave optics are sufficient for photography and using the
example  "If ALL of the energy from a star was in the defraction [SIC]
rings, it (they) [SIC] would still be well within the 20 micron image and it
would look no different than if it had been formed by a point source", is as
ridiculous as saying you can obtain 20 micron stars even if you have
atrocious 6 arc-second seeing (this based on Jack's example of Steve's 16
inch f/4.5 having 3 micron spot sizes.)

With logic and arguments like these, it's no wonder Jack has never broken
the 20 micron barrier while others have. Most people severely underestimate
the importance of factors 2 and 3 listed above.  Perhaps that is why Jack
has never broken it.  Then again, maybe he just has a crummy telescope
optically.

As far as Jack's "challenge" goes, I personally have negatives and
transparencies that have stars with FWFM diameters of less than 20 microns
and if Jack doesn't take my word for it, I couldn't care less.

Jerry



email: jml@...
Astrophotography Techniques and
Digital Enhancement in Photoshop Tips:
http://www.astropix.com

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  Hello!

I wish to all astrophotographers merry Christmas and Happy New Year!!!

Also many clear, moonless nights!



  Valery Deryuzhin
  ARIES INSTRUMENTS Co.,
  Kherson, Ukraine.

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And to you!!!


>Dear Everybody out there at ASTROPHOTO:
>
>        MERRY CHRISTMAS AND A HAPPY NEW YEAR !!!
>
>James Kevin Ty
>Philippine Astronomical Society
>Binondo , Manila 1006
>PHILIPPINES
>14.5 N , 121 E





Mike Regish

>>>>>No matter where you go...there you are.<<<<<

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Dear Everybody out there at ASTROPHOTO:

         MERRY CHRISTMAS AND A HAPPY NEW YEAR !!!

James Kevin Ty
Philippine Astronomical Society
Binondo , Manila 1006
PHILIPPINES
14.5 N , 121 E

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Steve Bell wrote:


> I know your statements are true if you only consider the spot size
> (which I presume you mean the size of the Airy disk), but I'm hoping
> that another effect will come into play. The farther off a mirror is
> from perfect, the more light is taken out of the Airy disk and
> redistributed out into the diffraction rings.

I don't wish to beat a dead horse but...

The theoretical minimum spot size for your 16" F 4.5 is about 3 microns.

The image of a point of light on a high-speed photographic emulsion
has a minimum diameter of 20 to 25 microns as a result of difusion of
light in the film.

If ALL of the energy from a star was in the defraction rings, it (they)
would still be well within the 20 micron image and it would look no
different than if it had been formed by a point source.

Add to that the fact that we display photographs, not negatives, so we
can add another step of loss through diffusion in the printing.  We
also make only nominal enlargements, not microscopic scrutiny, and
consequently, the advantage of better optics is lost with prime focus
photography.

> I view an image at the  film plane as, in a loose sense, a "mosaic" of a
gazillion Airy disks, each of a different intensity and each with their
attendent diffraction rings. If the mirror is bad, all of these bright,
wide diffraction rings degrade the resolution of the image (ie, fuzz it
up)....

That's a good anology but the problem is that the film fuzzes it up on
a much larger scale.  Imagine a bunch of donuts and a bunch of Munchkins
or whatever Dunkin Donuts calls the holes.

Lay a hulla hoop on the floor and fill it with either than get back
and look at it.  If you get back far enough you could not tell the
difference between donuts and holes.



> Now, it maybe that the diameter across the outer diffraction ring
> produced by even a 1 wave mirror is still smaller than the ability of
> film to record, but maybe the cumulative effect I've just described is
> noticable on a large scale. But then again, everything that I just said
> might be a bunch of hooey, but a guy can hope, can't he?

Nothing based on reasoned thought is hooey and the proof of the pudding
is in the eating.  Nothing would please me more (and you even more yet)
than to be proven wrong.

Keep in mind also that the brighter a star is, the larger the image
for equal exposure time and what we are discussing only applies to
stars at the very margin of detectability because they are the only
ones that can approach the theoretical minimum size.  So the name
of the game and the proof of the pudding is going to be the limiting
magnitude of your photographs and this is going to be a tough thing
to prove unless the improvement is drastic.  You won't be able to
make comparison photos under exactly the same conditions for obvious
reasons.

> I hope that my refigured mirror gives me both better high powered views
> and low powered views. And I'm optimistically thinking that if my low
> powered views are substantially increased in quality, that means I'll
> also see improvement in my photographic resolution at prime focus.

They are one and the same and my arguments above apply to both.

If you have or can get a copy of Jean Texereau's excellent classic on
telescope making, there is a section devoted to this subject.  Including
photos of microscope views of images on film.  It is very eyeopening to
anyone in this field without access to a microscope.  It is based on
yesterday's emulsions but from my experience, these photos look pretty
much like what I see on Techpan.

> My 16" Meade mirror also had gross astigmatism, that I originally
> attributed to my own eye.

It can be a real killer and depending on how bad it is, it could
effect prime focus photography but it would really have to be bad.

> Hence, we see that Orion's mirrors don't even meet the Rayleigh criteria all
by themselves, let alone if you put a diagonal in
front of them.

Considering the price, I don't see how thay could make a profit
if they just supplied a Pyrex blank.  It's an awful lot of stuff
for the money.  Unfortunately, I didn't want stuff and what they
sent was worse than nothing at any price.  I never expected to get
a defraction limited optic and would not have sent it back if it
were not for the astigmatism.

Doesn't matter anyway, seems we have entered into an era of
permanant cloud cover.

js


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On Tue, 24 Dec 1996 18:45:58 -0500 Mike Regish <mregish@...> writes:
>The Astro-Photography Mailing List
>------------------------------------
>
>
>>This counter is great to put you within the "ball park" of focusing,
>but
>>remember
>>5-10 degree's of a tempature change will effect your collimation,
>thus
>>you'll have
>>a new focus position.   With any ccd device, its always nice to know
>>roughly where
>>your focus position are, using & noting your last setup positions, as
>a
>>benchmark.
>>This is why I have always used & still do, a digital caliper, on
>other
>>types
>>of instruments prior to the availability of  these digital focus
>counter
>>for SCT's, as
>>the mirror had to be in a fixed position.     Now the mirror can be
>>benchmarked.
>>No problems so far.....and also NEVER think this device will replace
>fine
>>focusing
>>for astrophotography, always check it the hard way!         Carl
>Faulkner
>>
>
>
>I use a Pentax K1000 and it does not have interchangeable focus
>screens. The
>one it comes with is not very bright. As a result I have to do my
>focussing
>on relatively bright stars. If I get the camera focussed on a bright
>star,
>record the setting on the dial, return to the object I want to
>photograph
>and center it with an eyepiece (with its different focus point) and
>then
>replace the camera and reset the focus counter, will that be
>accurately
>focussed? I figure it should be since the counter measures 1/1000th of
>a
>turn, which translates to a fraction of that on the mirror movement. I
>don't
>know what the pitch of the thread on the focusser is, it's probably
>fairly
>fine. I don't think temerature shifts would be a factor in the short
>timespans involved, but I don't really need this thing if it won't do
>what I
>just outlined.
>
>TIA and Happy Holidays!!!
>
>
>
>Mike Regish
>
>>>>>>No matter where you go...there you are.<<<<<
>
>
Your outline using a bright star will work, however just about every
SCT's focus screw general act in it own special way, being loose,
too tight, ect.      Understanding your system by testing repeatedly from
a
bright star, to other bright stars.    This will give you some idea on
how
accurately your mirror & focus adjustment knob is holding its position
during all the different movement through the sky during the test.
Furthermore by using some simple type of indexing on your focus knob,
(a couple of marks), will give you even more accuracy.
As I stated earlier, by doing this, you will most likely notice
some changes in your fine focus within the course of the entire night.
Obviously your first focus "setting" will NOT work all night.
A good test on  you focus abilities using this system, is by  using
some  hypered 2415.    If the star's don't turn into "donuts," your doing
it right......   good luck,       HAPPY   HOLIDAYS!        Carl Faulkner