Pages: [1]   Go Down

Author Topic: A very long lens (well mirror :-)  (Read 2226 times)

ErikKaffehr

  • Sr. Member
  • ****
  • Online Online
  • Posts: 11310
    • Echophoto
A very long lens (well mirror :-)
« on: May 13, 2009, 12:21:07 am »

Hi,

I bought a Celestron Mak C90 spotting scope essentially for birds. Here are my first real world pictures. I forgot to shut down "Anti Shake" which may make sharpness a little worse. The images are shot on full frame and slightly cropped. Capture sharpening is rather strong.

The "lens" is hard to use, but a cheap way to have a very long lens (around 300 USD). Focal length is said to be 1250 mm but it seems more than that to me, more like 1500-1700.

The lens is also quite soft. On the positive side it can be used as a spotting scope. Weight is about 2.1 kg (assembled) size like my 400/4.5 APO (from Minolta) with 1.4x converter.

This type of lens is used for photography using a "photo adapter" screwed into the end of the optical tube and "T2" adapter between the camera and that tube. The original Celestron T2 adapter was a bad design I throw it away (after trying to fix it) and bought one from Soligor instead, that one is OK.

http://www.pbase.com/ekr/celestron_mak_c90

Makers info: http://www.celestron.com/c3/product.php?Ca...&ProdID=203

The enclosed picture may give an impression of the resolution. Celestron to the left Minolta 400/4.5 APO + 1.4X extender to the right (3:1)
[attachment=13642:560_vs_Mak90.jpg]

Best regards
Erik
« Last Edit: May 13, 2009, 02:01:21 pm by ErikKaffehr »
Logged
Erik Kaffehr
 

roskav

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 254
    • http://www.roskavanagh.com
A very long lens (well mirror :-)
« Reply #1 on: May 13, 2009, 06:09:56 am »

V interesting!... Your first battle is with sharpness?  I'd be interested in knowing what shutter speed you were using.

Ros

PS Bokeh is also rough but it has character!

 
Logged

cmox

  • Newbie
  • *
  • Offline Offline
  • Posts: 26
A very long lens (well mirror :-)
« Reply #2 on: May 13, 2009, 06:44:42 am »

We are actually discussing about those long focal lengths here:

http://luminous-landscape.com/forum/index....showtopic=33425

Yesterday I uploaded some examples from a Noflexar and a Leitz Telyt with converters.
Logged

francois

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 11678
A very long lens (well mirror :-)
« Reply #3 on: May 13, 2009, 08:21:45 am »

Quote from: Roskav
V interesting!... Your first battle is with sharpness?  I'd be interested in knowing what shutter speed you were using.

Ros
From the images posted on PBase, shutter speed is 1/100 of sec.

Quote from: Roskav
PS Bokeh is also rough but it has character!

 
I agree with you, the bokeh is far from excellent…
« Last Edit: May 13, 2009, 08:22:52 am by francois »
Logged
Francois

ErikKaffehr

  • Sr. Member
  • ****
  • Online Online
  • Posts: 11310
    • Echophoto
A very long lens (well mirror :-)
« Reply #4 on: May 13, 2009, 01:46:16 pm »

Hi!

Yes of course, but I regard both the Noflexar and the Telyt to be a different kind of animal. This is a very cheap and very long lens, not primarily intended for photographic usage.

Best regards
Erik


Quote from: cmox
We are actually discussing about those long focal lengths here:

http://luminous-landscape.com/forum/index....showtopic=33425

Yesterday I uploaded some examples from a Noflexar and a Leitz Telyt with converters.
Logged
Erik Kaffehr
 

ErikKaffehr

  • Sr. Member
  • ****
  • Online Online
  • Posts: 11310
    • Echophoto
A very long lens (well mirror :-)
« Reply #5 on: May 13, 2009, 01:50:54 pm »

Hi,

I don't really understand your comment on sharpness. Exposure time was around 1/100 s at ISO 400.

Aside from battling with sharpness other problems are:

- Hard to find the subject, there is actually a small telescope on the barrel that may be used for aiming. I would really prefer a gunsight.
- Most tripods I have flex so it is hard to maintain composition. My new Gitzo GT3541LS is better, probably because it lacks center column.
- Viewfinder image is hard to see
- Focus is very narrow

I'll post more images on PBase

Best regards
Erik


Quote from: Roskav
V interesting!... Your first battle is with sharpness?  I'd be interested in knowing what shutter speed you were using.

Ros

PS Bokeh is also rough but it has character!

 
« Last Edit: May 13, 2009, 02:13:12 pm by ErikKaffehr »
Logged
Erik Kaffehr
 

Plekto

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 551
A very long lens (well mirror :-)
« Reply #6 on: May 13, 2009, 04:05:44 pm »

Still, that first shot of the bird is very nice.  Yes, it's soft, but what does a 1500mm+ lens run by comparison?  

ie - getting an OK shot is better than none at all...    

And, this is a spotting scope.  A small high quality telescope would provide razor shard images by comparison(though weigh 15-20lbs including tripod and camera...)

http://luminous-landscape.com/forum/index....st&p=277838
The examples in post #68 are the difference between a good telescope and spotting scope.  Stunning, really.  

« Last Edit: May 13, 2009, 04:17:47 pm by Plekto »
Logged
Pages: [1]   Go Up