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Does Anyone Own and use the Meade 12" Schimdt Camera w/film From The 1990's?

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#1 RalphMeisterTigerMan

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Posted 26 November 2020 - 01:03 AM

I'm not sure how many of you still remember the limited 12" Schmidt Camera that Meade built and sold back in the 1990's. I remember seeing a picture of one that David Levy had in his home observatory. This camera was quite the "animal". The tube was quite long with a 12" corrector plate in the front. About half way down the tube was then attached to a larger diameter tube in order to accomodate the 16" primary mirror located at the bottom of the tube. The idea being that the 12" corrector plate was designed in such a way to not only correct the primary's spherical abberation but also bend the incoming light to increase the diameter of the light cone to 16-inches, the primary then reflects the light back up the tube to a spider assembly which accomodates a film holder for specially sized pieces of the old style "silver hallide" film which then needed to be developed in a "dark room". Very, very old school. When you see a picture of one of these beasts you can actually see the specially designed "hatch" that can be open and closed in order at attach the film holder onto the spider assembly, presumably held on by a magnet.

 

Last I heard, David was contemplating replacing the film holder with a CCD camera. I'm not sure if he was successful or not. I would love to hear from anyone still has one of these unique instruments.

 

Clear skies!

RalphMeisterTigerMan


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#2 jgraham

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Posted 26 November 2020 - 12:42 PM

I have never seen Meade’s 12” Schmidt camera, but I do have Celestron’s 8” and 5.5” Schmidt cameras (converted to digital). The tube is long because the corrector is placed at the center of the radius of curvature of the primary (twice the focal length). If I recall right it doesn’t expand the incoming rays, but the wider primary is used to provide full illumination across the field. The incoming rays cover a cylinder that is 12” wide, but since the corrector is at the center of the radius of curvature and the primary is spherical different parts of the field are collecting light from different 12” diameter regions of the primary that are peering through the corrector at different angles. This the the same way a camera lens works with an iris located within the lens stack.

 

Neat stuff, I have to see if I can find anything on the Meade 16”.

 

P.S.

 

I couldn’t find anything specific to David Levy’s Schmidt camera, but I did find references that describe the divergence of the incoming rays. The same thing happens with Schmidt-Cassegrains.

 

Ed Jones in the ATM forum was working on restoring a Celestron 8” Schmidt camera for use with film. You might check there.


Edited by jgraham, 26 November 2020 - 12:58 PM.

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#3 Don W

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Posted 26 November 2020 - 01:01 PM

I would suspect that there were not that many sold. It was a big, heavy beast that required a substantial mount. Not sure about the stuff about the silver/halide film. You could use any type of film that you were able to cut into the required size/shape. It could be B&W or color. I'm sure people also used hypered film which was soaked in hydrogen gas which increased sensitivity.


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#4 davidc135

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Posted 26 November 2020 - 03:15 PM

The primary could be the same diameter as the cp but there'd be considerable light loss at the edge of the field. Is this the case in the 5.5'' and 8'' Celestron Schmidts? IIRC the primary diameter would need to be greater by twice the diameter of the film for completely even illumination but in practice limiting the extra size to the film diameter width is fine.

 

The 12''/16'' could potentially cover a 4'' film circle, or more which would be something. I think they were difficult to keep in focus. These days the difficulty is flattening the curved field over a sensor of any size.

 

David


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#5 Justin Fuller

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Posted 26 November 2020 - 04:30 PM

I'm not sure how many of you still remember the limited 12" Schmidt Camera that Meade built and sold back in the 1990's. I remember seeing a picture of one that David Levy had in his home observatory. This camera was quite the "animal". The tube was quite long with a 12" corrector plate in the front. About half way down the tube was then attached to a larger diameter tube in order to accomodate the 16" primary mirror located at the bottom of the tube. The idea being that the 12" corrector plate was designed in such a way to not only correct the primary's spherical abberation but also bend the incoming light to increase the diameter of the light cone to 16-inches, the primary then reflects the light back up the tube to a spider assembly which accomodates a film holder for specially sized pieces of the old style "silver hallide" film which then needed to be developed in a "dark room". Very, very old school. When you see a picture of one of these beasts you can actually see the specially designed "hatch" that can be open and closed in order at attach the film holder onto the spider assembly, presumably held on by a magnet.

 

Last I heard, David was contemplating replacing the film holder with a CCD camera. I'm not sure if he was successful or not. I would love to hear from anyone still has one of these unique instruments.

 

Clear skies!

RalphMeisterTigerMan

I followed this thread hoping someone with actual first hand experience would chime in about these scopes as I've always been interested in them as well, since I first saw them in the late 90's Meade catalog (Their glory days). Company 7 has a cool repository of old Meade catalog PDFs http://www.company7....eade/notes.html including the sections for the Schmidt camera. 

 

Interestingly the comet Hale-Bopp image in the ad is credited to Steve Padilla, who I volunteer with at the Mt. Wilson Observatory. He's been a long time solar observer at the observatory, and it appears he got to have a go using the 12" Schmidt on Mt. Wilson. I'll ask around and see what happened to the scope, though as far as I know it's no longer at Mt. Wilson.

 

David Levy does have one (named Obadiah), and there are a couple pictures of it to be found on the web. I remember a brief article in S&T over a decade ago I think, of him having it converted to a CCD at the focal plane (and a field flattening lens I would think). I'm rummaging through my old S&Ts trying to find it to share.

 

I could be wrong (hopefully someone with experience responds to your thread), but I believe David Levy has the one example, likely the prototype they took up to Mt. Wilson at one point, and then let astrophotography maven's like Jason Ware use to highlight it's abilities. I'm under the impression these did not go into full production as it came out right at the time film astrophotography was starting to die.

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Edited by Justin Fuller, 26 November 2020 - 04:38 PM.

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#6 junomike

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Posted 26 November 2020 - 07:03 PM

Never even knew that existed.  So basically a modified 12" SCT?



#7 carolinaskies

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Posted 26 November 2020 - 08:30 PM

Never even knew that existed.  So basically a modified 12" SCT?

No, it's a modified 16" with the corrector removed and the 12" extension corrector added.   Photographically specialized. 

I remember seeing them in the catalog and I think one write-up in S&T.   Such a specialized system it creates a small but flat field.  



#8 jgraham

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Posted 26 November 2020 - 09:30 PM

Wow, it’s incredible that they’d use a 7” ED as a guide scope. If I recall right Celestron made a similar monster based on the orange tube C14.

 

Neat stuff.



#9 junomike

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Posted 26 November 2020 - 09:33 PM

No, it's a modified 16" with the corrector removed and the 12" extension corrector added.   Photographically specialized. 

I remember seeing them in the catalog and I think one write-up in S&T.   Such a specialized system it creates a small but flat field.  

Thanks for the info.   Quite interesting, anyone recall the cost?   $$$$$



#10 PowerM3

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Posted 26 November 2020 - 09:57 PM

WOW, never even heard of that! And they advertise the 178ed as a guide scope???? Awsome!!! Thanks for posting, this just made my day!



#11 davidc135

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Posted 27 November 2020 - 04:46 AM

This original Schmidt camera was invented around 1930 as an astrograph. It has a huge field virtually free of aberrations at this F ratio and slower but suffers from a curved field whose radius of curvature is equal to the camera's focal length. So, as was said, flat over a small field if there's no flattener.

Scts and other designs were later developed.

 

In the film astrophotography forum there is a collection of around 100 12'' Schmidt photos taken by Aldo Radrizzani in Italy. I wonder if the library of both hemispheres of the entire sky taken by the 48'' Palomar Schmidt and it's southern counterpart have been digitized?

 

David


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#12 luxo II

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Posted 27 November 2020 - 05:42 AM

The southern sky survey plates were digitised at MSSO way back in the late 70s using a plate measuring machine - I had a bit to do with it as a postgrad.

But not digitised in the modern sense of an image format such as FITS.

I’d be very surprised if the Palomar plates were not done the same way.

Edited by luxo II, 27 November 2020 - 05:46 AM.

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#13 RalphMeisterTigerMan

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Posted 27 November 2020 - 12:10 PM

If memory serves, the film holder was actually curved and so with the film when installed onto the film holder. This was supposed to correct for any of the abberations which would occur with these types of scopes. I believe that Lumicon was still in business when the 16" Schmidt cameras came out so that one could make use of their gas film hypering kits. What I do not know is where you would get the right sized film pieces or would you have to custom size them yourself. I could see many problems with that solution including accidentally exposing the film before it was placed into the camera.

 

Can you imagine using "glass" plates for a big Schmidt camera such as the 48" Oschwin camera on Mt. Palomar like they used to do back in the day? I'm certain at some point that the 48" was somehow converted to accomodate a CCD camera.

 

I would love to talk to David Levy about his experiences in using this beast and how the pictures turned out.

 

Clear skies!

RalphMeisterTigerMan



#14 Astrojensen

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Posted 27 November 2020 - 12:30 PM

 I wonder if the library of both hemispheres of the entire sky taken by the 48'' Palomar Schmidt and it's southern counterpart have been digitized?

 

The southern sky survey plates were digitised at MSSO way back in the late 70s using a plate measuring machine - I had a bit to do with it as a postgrad.

But not digitised in the modern sense of an image format such as FITS.

I’d be very surprised if the Palomar plates were not done the same way.

 

They've been digitized decades ago. I am completely flabbergasted that you guys have never heard of this before: http://archive.stsci...i-bin/dss_form 

 

 

Clear skies!

Thomas, Denmark


Edited by Astrojensen, 27 November 2020 - 12:31 PM.

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#15 kbastro

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Posted 27 November 2020 - 03:44 PM

Jason Ware from texas had one for awhile,, or still does?,,  in reality I can't see this old 12" sct camera beating a modern 11 or 14" RASA,,, rasa's have better coatings, newer tech. etc...

this photo is from his site,,, www.galaxyphoto.com

 

 

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#16 jgraham

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Posted 27 November 2020 - 05:51 PM

We had a brief discussion a while back in the ATM forum about how to make a simple field flattener to help with using a large digital sensor with these old Schmidt cameras. I use a small chip camera in mine so the flattening lens isn't needed.
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#17 ANM

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Posted 28 November 2020 - 10:02 AM

IIRC in the Celestrons the film holder was a ring that fit over the circular piece of film and over then the convex piece that maintained the focal plane. The film was forced to fit the convex focal plane. I believe Celestron supplied a cutting guide to the film and any film could be used as long as it was large enough.


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#18 jgraham

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Posted 28 November 2020 - 10:40 AM

That is correct. The Celestron film holder was ground to the same radius of curvature as the primary. The holder was attached to a kinematic mount with magnets in the base of a ring held by the spider.


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#19 Justin Fuller

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Posted 28 November 2020 - 04:37 PM

Found one article: In David Levy's Star Trails article from S&T March 2006 issue, there's a picture of his Meade 12" Schmidt Camera captioned that it was modified to use a SBIG STL-1100M. It looks as though they replaced the film holder with a turning flat and then there is likely some flattening lenses before the CCD.

 

Perhaps I'm imagining it, but I remember an article specifically about converting the 12" Schmidt from film to digital.

 

Threads on CN about the Meade Schmidt camera have popped up periodically and seem to offer just as much info ( or lack there of ). One user quoted a price of $26,000 , another said maybe 4 or 5 were ever made, which sounds about right. Apparently a CN user had / has one, but no user name was mentioned or reference to a thread.

 

At any rate, it's fun looking through old S&Ts in my free time.

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Edited by Justin Fuller, 28 November 2020 - 04:43 PM.



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