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06-19-2008, 02:42 AM   #1
Pentaxian




Join Date: Jun 2008
Location: Flyover America
Posts: 4,475
For the folks over at POTW from Wildman by request

First let me say this setup is not for everyone. It's specialized for
capturing shy fast moving woodland birds in their native habitat. This
is not a grab and go setup where you pick up your camera and wander
through the woods taking snap shots of whatever happens to show up.

Second I'm very much old school when it comes to photography. I cut my
teeth on a gorgeous Rolliflex twin lens reflex with a Zeiss 2.8 planar
way back in the late 1950s. Think Ansel Adams not photojournalism.

Third I am primarily a birder not a photographer. I say this because
after 40 years of birding I have developed a sense of where to find
birds which is a big advantage considering my photographic setup.

OK. heres the basic facts:

Camera:
Pentax *ist DL soon to be replaced by a K20D

Scopes:
Astro Tech 80mm f/7/560mm APO triplet
Pentax 100mm ED spotter f/6.2/620mm with Pentax CA-35 DSLR camera adapter
Celestron 102mm f/5/500mm "Wide View" achro
Orion 120mm f/8.3/1000mm achro

All mounted on Bogen 3246 tripod and a Bogen 3421 fork mount.

Plus a mess of extension tubes, remotes releases, barlows etc.

Instead of trying to explain everything I'll include some pics of the
various setups and will be happy to answer any specific questions in
detail.


Last edited by wildman; 06-28-2008 at 11:55 PM.
06-19-2008, 03:21 AM   #2
Pentaxian
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Join Date: May 2007
Location: Edmonton Alberta, Canada
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Posts: 10,648
Thanks for the great info. I'm sure I'll have some other questions after doing some research but just a few for now. Is the barlow the tube shown in Pic 2 and the last one between the camera body and the scope? This is the unit here correct? How a Barlow Lens works

When fitting an extension tube set to a scope (as in the last image above), it simply increases the magnification? Any issues with infinity focus? Why use an extension tube instead of a Barlow?

What is your most used and favourite scope from the group above? Would you mind listing the lenses in the shot above from left to right? (the picture with all 4 on a table pic 3).

Is a T mount used to mount the scope or Barlow to the camera body? Any other parts needed?

BTW great images with these in the latest POTW. If you don't mind, it would be great to know what scope setup and approx focal length was used with some of your future picture posts.

Last edited by Peter Zack; 06-19-2008 at 03:38 AM.
06-19-2008, 08:10 AM   #3
Pentaxian




Join Date: Jun 2008
Location: Flyover America
Posts: 4,475
Original Poster
Thanks for the great info. I'm sure I'll have some other questions after doing some research but just a few for now. Is the barlow the tube shown in Pic 2 and the last one between the camera body and the scope? This is the unit here correct? How a Barlow Lens works

Wildman:
Essentially yes. However there is no barlow tube just the barlow element that fits inside the extension. If you leave it out you are shooting at prime focus. See pic.

When fitting an extension tube set to a scope (as in the last image above), it simply increases the magnification? Any issues with infinity focus? Why use an extension tube instead of a Barlow?

Wildman:
These are astro scopes. So they assume you will be adding a prism or a diagonal and then a ep or camera to that. This typically adds about 50-60mm of physical length to the scope. Thus the prime focus point of the objective actually lies outside the physical end of the scope without any extension. So when you add a camera to the scope you need to make up for the lost 50mm when not using a prism or diagonal. Because your camera is at the proper focal point with the extension tube there is no issue with focus or magnification.

In my pictures you will typically see much more than the standard 50mm extension but this is because I want to lose focus at infinity and move the focus much closer - typically down to the 20-60 foot range for the close-ups you see in my pictures. There is only a very marginal increase in magnification because magnification is a function of focal length and adding 100mm to a 600mm scope don't make all that much difference.

What is your most used and favourite scope from the group above? Would you mind listing the lenses in the shot above from left to right? (the picture with all 4 on a table pic 3).

Wildman:
No favorite. Depends upon what I want to do.
Going from left to right in the pic of all the scopes on the table -

1000mm. Use this only for very special situations. It pretty much at the limits to what my tripod-head will handle as to weight and magnification. It's a killer glass if I must stay far away and not disturb the wildlife like taking pictures of nesting birds. But it is my least used scope.

Pentax 100mm ED spotter. My most versatile scope. With the camera adapter it works as a 1920mm f/12 scope at 38x. And I can always pop a eyepiece in for magnification up to about 90x visually. The camera adapter is not just a passive mechanical adapter but a high quality 5 element APO glass that acts somewhat like a x2 barlow. Very high quality results and it is hard to tell when a picture is taken with and without it. That is the extra glass does not seem to introduce any additional abberations.

Celestron 100mm/500mm fl f/5. This is only a 100 buck scope new. It gives astounding results. Being an achromat you have to be careful about lighting conditions or you will get CA fringing but most often it's no big deal. Bright with a wide field of view. Perfect for chasing wood warblers through the bush if I can get close enough. If you question how good a 100 buck glass can be some of the posts I made on the other forum were taken with this scope and I bet you can't tell the difference from any of the others.

Astro Tech 80mm APO triplet.
Technically my "best" scope. High contrast and sharp as a tack with no CA. Barlows well. This one is as close as I get to a grab and go scope. Very well made mechanically as well with a butter smooth two speed 11 to 1 focuser.

Is a T mount used to mount the scope or Barlow to the camera body? Any other parts needed?

Wildman:
No just a T-ring and that's all.

BTW great images with these in the latest POTW. If you don't mind, it would be great to know what scope setup and approx focal length was used with some of your future picture posts.

Wildman:
OK will keep that in mind.

My best,
Wildman

Pic:
Barlow installation...
06-19-2008, 08:26 AM   #4
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What's the "thing" between the Celestron and your camera body? I thought the Celestron had a T-mount, and you can mount the camera body directly to that.

06-19-2008, 08:34 AM   #5
Pentaxian




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Original Poster
QuoteOriginally posted by volosong Quote
What's the "thing" between the Celestron and your camera body? I thought the Celestron had a T-mount, and you can mount the camera body directly to that.
A drawtube extension so you can vary the length exactly.

The Celestron does have t thread ont the end of the 2" to 1.25" adapter and you can physically mount a camera directly on to that with an appropriate t-ring of course.

The problem is a camera will not come to focus without that extra 50mm of extension or so. Other things like a binoviewer will work this way but not a camera.

Last edited by wildman; 06-19-2008 at 08:49 AM.
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