Bird Photography with Astro scopes?

[Chris Brennan]

(Moderators: please move to the appropriate forum if this is in the wrong place)

It is quite unlikely that I'll ever able to afford one of Canon's super tele "L's" like a 600mm or an 800mm. The investment I made in a 400mm f4 DO a year ago will have to do for a while, I'm afraid...

In the continuing search for getting closer to subjects than my DO + converters will currently allow, I've "discovered" a whole group of (quite talented) photographers who are using astro telescopes modified for use with DSLRs. Most of the scopes I've seen come from manufacturers such as TeleVue, Skywatcher or Stellarvue and they seem fairly reasonably priced (under $2K). I know that manual focus is the norm with these, and BIF won't be possible most of the time, but I've seen some stunningly beautiful and very sharp images made from these scopes, and am wondering whether anyone here at BPN currently uses these scopes for bird photography.

[John Chardine]

Hi Chris- The closest I ever came to one of these was a Canon 500mm f8 mirror lens which was of similar design to many of these astro scopes. The Questar is a famous brand which I have used as a spotting scope and it's quality is superb. There are a few inherent problems with these cassagrain designs- inability to change the aperture, slow (f8, f11), lower constrast than a refracting lens, and donut shaped highlights in the bokeh.

[Chris Brennan]

John -

The scopes you're referring to are catadioptric reflectors or mirror style scopes: Schmidt-Cassegrains or Maksutov-Cassegrains. The Questar is probably the best known of these designs, and you're right, it's a gorgeous precision instrument. I did try one of them and was quite disappointed in the results: the donut highlights were annoying but the worst was the inherently low contrast and incredibly slow aperture... and the quality was terrible.

However, the scopes I'm referring to are straight-line OTA (Optical Tube Assembly) refractor scopes.

[Roger Clark]

Chris,

Yes, there are many telescopes that will do great at bird photography, at least bird portraits so not moving toward or away from you. Astronomical telescopes are corrected for infinity and not close range, so you may find that as the bird gets closer, the image could go soft, but that would probably be at a very close distance--so close you would need extension tubes.

In refractors, look for apochromatic designs (the lens has three elements for better corrections).

A fast Newtonian can also do well. You can get an f/4 class telescope in large aperture, 6, 8, even 10 inches, giving 610 mm, 813 mm, and 1016 mm f/4 telephoto! In the larger aperture (6-inches and greater), the secondary is not as big a factor in reducing contrast. A field flatener/coma corrector at the camera end can deliver sharp images over a the camera's large field. The disadvantages of the Newtonian are the camera is pointed to the side and the out-of-focus doughnuts. You can probably repair the out-of-focus holes with photoshop.

Roger

[John Chardine]

John -

The scopes you're referring to are catadioptric reflectors or mirror style scopes: Schmidt-Cassegrains or Maksutov-Cassegrains. The Questar is probably the best known of these designs, and you're right, it's a gorgeous precision instrument. I did try one of them and was quite disappointed in the results: the donut highlights were annoying but the worst was the inherently low contrast and incredibly slow aperture... and the quality was terrible.

However, the scopes I'm referring to are straight-line OTA (Optical Tube Assembly) refractor scopes.

Interesting Chris. I've never heard of this. Could you post a link to examples of images made with these lenses, and also the lenses themselves. Thanks.

[Chris Brennan]

John -

IMHO, there's a very gifted photographer in the UK, Paul Corfield, who uses an "Astro" scope with excellent success. He is a regular on www.birdforum.net in, coincidently, a subforum called "Photography using Astro telscopes" . I've kept his Digiscope Gallery in my "favorites" list to be a constant reminder that it really can be done if you set your mind to it: http://homepage.ntlworld.com/paulcorfield/canon.htm. Obviously, the very first picture is of his "astro" rig. Enjoy... I certainly have!

[Chris Brennan]

Chris,

Yes, there are many telescopes that will do great at bird photography, at least bird portraits so not moving toward or away from you. Astronomical telescopes are corrected for infinity and not close range, so you may find that as the bird gets closer, the image could go soft, but that would probably be at a very close distance--so close you would need extension tubes.

In refractors, look for apochromatic designs (the lens has three elements for better corrections).

A fast Newtonian can also do well. You can get an f/4 class telescope in large aperture, 6, 8, even 10 inches, giving 610 mm, 813 mm, and 1016 mm f/4 telephoto! In the larger aperture (6-inches and greater), the secondary is not as big a factor in reducing contrast. A field flatener/coma corrector at the camera end can deliver sharp images over a the camera's large field. The disadvantages of the Newtonian are the camera is pointed to the side and the out-of-focus doughnuts. You can probably repair the out-of-focus holes with photoshop.

Roger

Thanks, Roger! All very helpful information to have...

[Chris Ober]

moving to the photography gear forum