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Equipment Discussions >> Cats & Casses

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andysea
Pooh-Bah
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Reged: 09/03/10

Loc: Seattle, WA
Baker-Schmidt camera new
      #5595989 - 12/30/12 11:52 AM

I was looking for a catadioptric forum but I just realized that it doesn't exist so I'm posting here.
I just found this italian telescope maker
http://lnx.costruzioniottichezen.com/joomla/index.php?view=article&catid=...
They have a series of Baker-Schmidt cameras that look very interesting and inexpensive. I corresponded with the owner (I speak the language) and he confirmed that they design and produce all their optics. Their scopes are made to order, delivery time is 4-8 months.
Does anyone know anything about them? Their prices look extremely interesting.

Andy


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: Baker-Schmidt camera new [Re: andysea]
      #5596029 - 12/30/12 12:11 PM

Quote:

I was looking for a catadioptric forum but I just realized that it doesn't exist



Look under "Cats and Casses", or click here:
http://www.cloudynights.com/ubbthreads/postlist.php/Cat/0/Board/cat

Mod, you may want to move this thread.


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andysea
Pooh-Bah
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Reged: 09/03/10

Loc: Seattle, WA
Re: Baker-Schmidt camera new [Re: hottr6]
      #5596066 - 12/30/12 12:29 PM

Oops you're right! My bad.
Mod can you please move this thread to the Cat and Mak's forum? Thanks!!


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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Baker-Schmidt camera new [Re: andysea]
      #5596830 - 12/30/12 07:49 PM

The schematic on the linked-to page suggests a possibly undersized primary if the angular field is large.

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andysea
Pooh-Bah
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Reged: 09/03/10

Loc: Seattle, WA
Re: Baker-Schmidt camera new [Re: GlennLeDrew]
      #5597230 - 12/31/12 12:28 AM

I asked the manufacturer to provide the size of the fully corrected/fully illuminated field. That will be crucial information I would want to be able to use my Canon 5d2 or other 35mm sensors.
How would you determine whether or not the primary is undersized? Is there specific information/specs that you need?


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psandelle
professor emeritus


Reged: 06/18/08

Loc: Los Angeles
Re: Baker-Schmidt camera new [Re: andysea]
      #5597250 - 12/31/12 12:48 AM

Wow, wish I spoke Italian. Please post more info as you find out. Very curious....

Paul


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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Baker-Schmidt camera new [Re: psandelle]
      #5597283 - 12/31/12 01:24 AM

If the entrance pupil is not the primary mirror, then the primary should have a diameter sufficient to field the full light bundle for an edge-of-field target. I'm not certain regarding the Baker variant, but the Schmidt camera has its entrance pupil at the corrector, thus requiring the primary mirror to have a larger aperture.

The amount of 'over-sizing' depends on the desired circle of full illumination, which in turn is driven by the designed-for sensor size.


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andysea
Pooh-Bah
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Reged: 09/03/10

Loc: Seattle, WA
Re: Baker-Schmidt camera new [Re: GlennLeDrew]
      #5597570 - 12/31/12 09:20 AM

I think I understand. I might have to do more reading about Schmidt cameras.
I will post the reply from the manufacturer as soon as I hear back.
I also asked for the weight of the scope. I wish they had more info on their website.
Similarly fast scopes from the more well known manufacturers cost 2~3 times as much!


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TxStars
Pooh-Bah
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Reged: 10/01/05

Loc: Lost In Space
Re: Baker-Schmidt camera new [Re: andysea]
      #5597789 - 12/31/12 11:35 AM

I'm guessing the optics price is in Euros?
LASTRA 400 SPECCHIO 400 FOCALE 1200 € 5.735,00

I did not see what the optics made of Pyrex/Quartz ?


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andysea
Pooh-Bah
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Reged: 09/03/10

Loc: Seattle, WA
Re: Baker-Schmidt camera new [Re: TxStars]
      #5598552 - 12/31/12 06:44 PM

Yes the price is in Euros for sure.
I believe what that means is that the corrector plate is 400mm, the mirror is 400mm and the focal length is 1200 so that would make it an f3.

Mirror material is a very good question! I will ask that too.


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ed_turco
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Reged: 08/29/09

Loc: Lincoln, RI
Re: Baker-Schmidt camera new [Re: GlennLeDrew]
      #5601098 - 01/02/13 11:34 AM

I believe that a rule of thumb is that the primary diameter must be increased by twice the diameter of the of the photographic plate, or sensor, (excuse me!), as we call it these days.

Memories


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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Baker-Schmidt camera [Re: ed_turco]
      #5601640 - 01/02/13 05:40 PM

Ed,
Certainly true for the 'classic' Scmidt camera, where the detector lies at the focus of the primary. But when a secondary is installed which has some amplifying power (as is the case here, in order to place the image at an accessible location beyond the back end), the amount of oversizing of the primary mirror is reduced.

For example, on an f/10 SCT (with f/2 primary), for a 25mm image circle the primary most certainly need not be oversized by 50mm. But for a similar aperture f/2 primary working as a (classic) Schmidt camera, the primary would indeed have to be 2" larger.


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