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Going back to film

astrophotography ATM Celestron
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#1 Ed Jones

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Posted 21 April 2018 - 11:38 AM

  Not going back far though, I have a couple of Canon DSLRs but can't say I've done of lot of AP with them.  Anyway I picked up a vintage Celestron Schmidt camera 8 inch F/1.5 and it is really best suited for film.  The original film holders were missing however but I would not have used them because I wouldn't like messing with cut film requiring that I develope it.  Celestron had a cassette film holder (which I also didn't get) but was large and obstructed a lot I think.  Instead I hope to use this cassette film holder that I made for another project with a flat field and modify it for a curved image plane.  It measures 2.25 X 2.5 inches, a lot smaller profile.  In this pic there is a curved film back that floats free between 2 rollers.  There is a wire lever next to the white (temporary) film wind knob that pushes this curved plate against the rectangular film frame when I rotate it 90 degrees to press the film for the curved image.  After each exposure I will need to release the pressure to advance the film.  This curved plate is black plastic and was sanded and polished against a 11.95 inch radius glass curve.  I'll now need to figure out how to modify the camera and mount this cassette.

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#2 TxStars

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Posted 22 April 2018 - 12:46 PM

You will need to make a new spider to hold this in place..

It will take time as you will need to measure the position of the focal plane.

Then you will have to place your holder in the same position.



#3 Ed Jones

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Posted 23 April 2018 - 07:38 AM

  The spider is mounted on a ring and looks pretty sturdy.  It has invar rods that space it from the mirror with a short length of threaded rod to hold the spider ring.  I need to use longer threaded rods to move this ring farther away from the mirror to get enough room for my film holder.   I have a microscope with a long throw which I will use to look at a white card for focusing the film holder, I just need to make a holder to hold the microscope and add a mirror diagonal for it.  

   I have a gear on the film winder with one tooth missing.  I can tell when I advance the film one revolution by a spring against the gear.


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#4 davidc135

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Posted 23 April 2018 - 03:25 PM

Looking forward to progress.  David



#5 highfnum

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Posted 24 April 2018 - 06:52 PM

waiting for this one also 



#6 Ed Jones

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Posted 25 April 2018 - 06:28 PM

Here's a shot of the Celestron Schmidt;

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#7 Ed Jones

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Posted 25 April 2018 - 06:30 PM

Here's the spider, ring and invar rods:

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#8 jgraham

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Posted 25 April 2018 - 07:31 PM

That is a neat piece of kit! Have fun with it. :)



#9 TxStars

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Posted 28 April 2018 - 10:35 AM

Ed,

  In the center piece is a magnet used to hold the original film holders for quick easy swap out.



#10 Ed Jones

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Posted 28 April 2018 - 06:10 PM

  is a magnet used to hold the original film holders for quick easy swap out.

Yes it has a magnet that looks like it fits tapered part.  I don't know what the original film holders looked like.  

 

 

 

No I just checked and it doesn't take a tapered part, the magnet just holds a flat part which locates on two pins.


Edited by Ed Jones, 28 April 2018 - 07:37 PM.


#11 Alen K

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Posted 03 May 2018 - 01:00 PM

Not going back far though... 

Not going back far??  That thing hails from the mid 70's. What would "far" be, then? The brownie? smile.gif

 

I remember the president of our astronomy club buying one new around 1975. I saw some of the photos he took with it, including some on color film. They were for the time astounding. I think they would be considered pretty good even today, although you can certainly get similar results with f/2.8 lenses and DSLRs. (A topic for another forum.)

 

 

Yes it has a magnet that looks like it fits tapered part.  I don't know what the original film holders looked like.  

Does this photo I found help? https://www.astromar...398/246007A.jpg  

 

PS. I found a better photo of the roll-film holder: http://www.astrosurf...film-holder.jpg

 

PPS. Are you the same Ed Jones referenced here? If so, nice to (sort of) meet you. laugh.gif


Edited by Alen K, 04 May 2018 - 09:53 AM.


#12 Ed Jones

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Posted 05 May 2018 - 07:37 AM

Alen,

   < Not going back far>   Meaning I never got very far in digital astrophotography, yes the Celestron Schmidt goes way back.

 

  Notice how much larger that cassette holder is than mine,with more obstruction.  I'm sure neither is available and no way did I want to mess with cut film and developing color myself.

 

  Yes I'm that Ed Jones. LOL



#13 Nightfly

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Posted 05 May 2018 - 09:48 AM

Ed,  it's nice to see you on the forum .  I'm sure we would love to see that Schmidt of yours see starlight again.  Let me know if you need some film for it.  I've got some frozen 35mm stock I'm not using.  Short of that, I'd recommend Provia 100F.  It is still available.  Your system is plenty fast so exposures would be in the 4 to 8 minute range.  

 

Hopefully, you'll get your roll adapter figured out.

 

Jim



#14 jgraham

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Posted 05 May 2018 - 07:00 PM

I was able to find several examples of images taken with the 5.5" and 8" Celestron Schmidt cameras. It is neat how fast you get used to the unique shape of the field. The image quality of the fields taken on curved film is excellent.




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