Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Seemingly Nice Alternative To Schmidt Camera

  • Please log in to reply
9 replies to this topic

#1 Todd N

Todd N

    Ranger 4

  • *****
  • topic starter
  • Posts: 316
  • Joined: 07 Dec 2007

Posted 23 December 2019 - 11:23 PM

I just stumbled upon this: 6" f/2.8 Hypergraph newtonian. I haven't seen it anywhere else. I would jump on it but where I image the atmosphere is too turbulent even for f.l. 420mm. Corrected field 44mm.

 

https://agenaastro.c...5028hnt-gd.html


  • telesonic and j.gardavsky like this

#2 Nightfly

Nightfly

    Apollo

  • -----
  • Posts: 1,285
  • Joined: 20 Jun 2007
  • Loc: Dark Skies, Maine

Posted 24 December 2019 - 08:43 AM

That would be a great kit for 35mm.  At f/2.8 you could employ many good films such as Provia, Gold 400, Acros, and the new Ektachrome.   Perhaps others.  Fully illuminated fields at a 150mm aperture would be most excellent.   I'd most certainly pick this over a Schmidt camera! 


  • Todd N and j.gardavsky like this

#3 Alen K

Alen K

    Apollo

  • *****
  • Posts: 1,214
  • Joined: 25 Nov 2009

Posted 25 December 2019 - 08:40 PM

Looks very promising. If I had an extra $2k USD kicking around, I would buy one. 



#4 TxStars

TxStars

    Surveyor 1

  • *****
  • Posts: 1,957
  • Joined: 01 Oct 2005
  • Loc: Lost In Space

Posted 26 December 2019 - 02:11 AM

If your looking for a bit more image scale they also have a 200mm f/4.2 scope.

https://agenaastro.c...0032pnt-gd.html


Edited by TxStars, 26 December 2019 - 02:12 AM.


#5 MikeMiller

MikeMiller

    Viking 1

  • -----
  • Posts: 804
  • Joined: 22 Jul 2014
  • Loc: Pittsburgh, PA, USA

Posted 08 January 2020 - 02:25 PM

Here is a link to the rather lengthy topic about this scope, including reviews:

 

https://www.cloudyni...ar#entry9892930

 

I am considering the 8" f/3.2 version.


Edited by MikeMiller, 08 January 2020 - 02:25 PM.


#6 Michal1

Michal1

    Viking 1

  • -----
  • Posts: 595
  • Joined: 25 Jul 2010
  • Loc: Czech Republic, Central Europe

Posted 08 January 2020 - 03:35 PM

I have heard that people are having problems with collimating these fast telescopes. Perhaps film would be more forgiving to collimation errors than the digital sensors.



#7 Todd N

Todd N

    Ranger 4

  • *****
  • topic starter
  • Posts: 316
  • Joined: 07 Dec 2007

Posted 08 January 2020 - 07:32 PM

I have heard that people are having problems with collimating these fast telescopes. Perhaps film would be more forgiving to collimation errors than the digital sensors.

I suppose we shouldn't be surprised. The tolerances for such systems becomes ever smaller. The spider looks real solid though. Perhaps there needs to be a new generation of more precise laser collimators?



#8 Michal1

Michal1

    Viking 1

  • -----
  • Posts: 595
  • Joined: 25 Jul 2010
  • Loc: Czech Republic, Central Europe

Posted 08 January 2020 - 07:48 PM

Perhaps the standard collimation would give acceptable results. I don't know. But if not, I don't know how I would improve the collimation without seeing the image immediately like with a CCD. Maybe I am too pessimistic. People had to focus the fast Schmidt cameras on film somehow, too.



#9 Todd N

Todd N

    Ranger 4

  • *****
  • topic starter
  • Posts: 316
  • Joined: 07 Dec 2007

Posted 09 January 2020 - 04:50 AM

Perhaps the standard collimation would give acceptable results. I don't know. But if not, I don't know how I would improve the collimation without seeing the image immediately like with a CCD. Maybe I am too pessimistic. People had to focus the fast Schmidt cameras on film somehow, too.

Collimation is easier than ever. It only takes a few minutes to collimate a typical newtonian with a modern laser collimator with a center marked mirror which is typical for newt mirrors these days. Video CCTV cameras work great for collimating SCTs or any other scope with a fixed primary. I use my Stellacam II for this. I imagine the schmidt camera was a tedious process of trial, error and refinement. As with the case for super fast schmidt cameras, temperature changes can change focus due to thermal expansion/contraction. Perhaps the root of the problem is in that.



#10 TxStars

TxStars

    Surveyor 1

  • *****
  • Posts: 1,957
  • Joined: 01 Oct 2005
  • Loc: Lost In Space

Posted 09 January 2020 - 07:36 PM

This type of scope like the Takahashi Epsilon series, when built properly hold collimation well and are not any more difficult that a standard newt to collimate.

 

These are not the same animal as a Schmidt camera, in that a schmidt camera has a preset focus from the factory that you do not adjust and can not be used visually.

A lot of issues with schmidt cameras were from transport to the customer by shipping companies like "OoPS" and "Fed-AHhX" dropping them.

Being the owner of an early 8" celestron schmidt camera I can say it has not had any of the issues some others have reported about them.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics