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Old Jun 18, 2008, 7:28 PM   #1
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Good evening folks. Just joined yesterday or I would have back to you sooner. I am hoping to answer some questions for three earlier posts, so stay with me. Feel free to get back to me if you want.

General:
I have had good success digiscoping. I find I get sharper images from my scopes digiscoping than from a prime or direct focus image to my dSLR. See my attached Bluebird image. An enlarged section at http://www.ohiobirds.org/forum/attac...amp;download=1 represents an 18 x 23 inch enlargement.

Scopes:
Hey, you guys have some first class scopes. My scope is a home made 3 x 24 inch achromat lens. The lens is a Jaegers surplus of typical $75. worth. It does test to near the resolution limit for a 3 inch lens, so it is OK. Lens diameter usually trumps quality and cost for resolution.

My second scope, my big gun, is a Celestron f-5 10 in. dia. Dob. mount. See my Forum post of the Male Cardinal taken from 135 feet. http://www.ohiobirds.org/forum/attac...amp;download=1

Camera:
The most important part of digiscoping. A camera will take no sharper digiscope image than it will take on its own. I have searched the images on Steves-Digicams and have found the sharpest image is from the small Canon A-650, 12 meg camera. In fact, it is sharper than nearly all of the Nikon dSLR cameras and also the Canon 20D dSLR!!! I have an 8 meg Canon A-720 that is almost as sharp, and should be available used or out of date for about $100.

Remember that 2 years is about the useful evolving life of a point and shoot digital camera if you want the best quality. The Canon A series cameras have a small lens system are easier to use with more eyepieces. The two Canons have bayonet body mounts for attaching an adapter that I use to mount a 2 inch dia. steel tube that fits my 2 inch focusing mounts on both scopes. The eyepiece is accurately mounted inside the steel tube. After an approximate manual focus the camera auto focus does the fine focus as the shutter is depressed and shows the green indicator confirmation.

Eyepieces:
My favorite and the one I keep using is an Orion Expanse 20mm 1 1/4 mount. It has an eye-relief of 17mm and an eye lens of 23mm diameter. I find the Orion Epic 12.5 mm 1 1/4 mount also works fine with my f-5 scope, but only fair with my f-8 scope.

Magnification:
The theoretical magnification is not straight forward for me to calculate, so I measured it directly. With my 24 inch focal length scope and 20mm eyepiece, no zoom on the camera, I measure a 35mm equivalent of 1950mm. Of course that would be a bit over 6 times the magnification you would get with a 300mm 35mm equivalent lens. I just about fill the frame with a bluebird at 30 feet. You should be able to scale up or down with different scope focal lengths and eyepieces.
I use a sturdy pod and a 2 sec. time delay to get the hands off the camera at exposure.

NOTE: For some unknow reason the bluebird print only posted about half of the image areaI submitted and so is not as sharp as it would have been.
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Old Jul 5, 2008, 1:38 AM   #2
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[align=left]The spider in the bluebird pix is interesting in that you can see it to be a wolf spider at 30 feet. It is further interesting in that the bird has it clamped across the pedicel with its beak. This shuts off blood flow from the heart behind to the muscles and nerves up front leaving the arachnid hanging limp as you can see but probably still alive and tasty.

How does this pose compare with simply using the A650 without additiional lensing. With the excellent lighting and the 12 mp, I think it should be comparable. Am I wrong. Are you happy with this camera otherwise. I haven't found a comprehensive review and see considerable evidence of picture flaws in the limited reviews, but not in the bluebird shot.
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[align=left]I am searching desparately for the best way to get critically sharp pictures of small spider details for publication. I have decided the 100mm Canon macro lens isn't enough. The much higher power 60mm looks promising although not going smaller than !:! on the sensor; I can't get enough hands-on time with it to be sure. I have a nice 6-45x leica zoom stereo scope, but am not happy with a camera setup. You can't focus the point-and-shoot cameras well enough and the SLR's are too massive to mount on the eyepiece. I think the digi-cams are the way to go, but still haven't seen one in operation that is convincing.
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redrichard
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Old Jul 5, 2008, 6:35 PM   #3
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Thank you for your comments. Perhaps the bluebird is better at delivering fresh meat than the supermarket chains!

First, some general comments. Yes, I am glad to send additional information and sample pictures that may be of more direct interest to you. I do not have the Canon A-650, but a prior model the A-720. My recommendations for the A-650 are from the sharp sample pictures presented on Steve's-Digicams, such as the brick school building. I also examined an A-650 with my favorite astro eyepiece and believe it is compatible for digiscoping. It has the same bayonet mounting for a two inch adapter as the A-720, and of course has a 12 Meg sensor.

You had questioned how the magnification at full zoom (6X) would compare with the digiscoped shots. I calculate that the digiscoped shots are 8 times the size of a full zoom shot.

You mentioned trouble focusing. My A-720 auto-focus does work with digiscoping, either with a telescope or the microscope objective. However, the manual focus must be pre-positioned close to sharp for it to work properly, then it will auto-focus and give the green in-focus indication.

For microscopic photography I found it more convenient to attach an objective to my 2 inch tube than try to adapt the camera to a microscope. It seems important to use an astro eyepiece, such as the Expanse 20mm, rather than a microscope eyepiece with such a small eye-lens and perhaps short eye relief. It should be easy to attach a rack and pinion height adjustment to the 2 inch tube.

I was quite pleased with the compatibility of the camera, eyepiece and the Lomo 4X objective. I got a nice flat field, but of course a narrow depth of focus. The area pictured was only about 3 mm. Perhaps this is too small for your purposes. I also have a Nikon 2.5X Plan objective I will try. It has a field of about 4.5mm by 6 mm. I will go spider-hunting and do some portraits with the 4X and the 2.5X microscope objectives. These may be more interesting to you than the microscopic shots of the snowflakes on the site.

You may contact me directly at Smithhill1@Embarqmail.com Gene Smith
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Old Jul 10, 2008, 1:22 PM   #4
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Hi Red,

1:1 on the Canon 100mm F2.8 can get you all the sharpness you need on small spider macros - what you are likely missing is depth of field.

There are several ways to get depth of field which may be of interest to you. First you can use small apertures and to the extent that diffraction doesn't become an issue you can usually get decent macro depth of field. Another way is as you see in Gene's image, using a telescope and digiscoping which allows you to shoot from a greater distance with depth of field accordingly because the focal length of most telescopes coupled with the normal small apertures (F14 or so) help a great deal. Also being further from the subject tends to decrease the probability of frightening it. You may want to look at an inexpensive scope such as the Meade ETX-90 which has a native 1250mm focal length but will focus as close as about 7 feet.

I frequently shoot with my Canon dSLR's using the Meade and have been able to get frames of tiny butterflies such as the Painted Lady which I simply can't do with my macro lenses. It's just not possible to get close enough without spooking them into flight.

Perhaps the very best way to get incredible depth of field for tiny insects such as spiders is to set up your tripod and go ahead and use your 100mm F2.8 macro. Instead of relying on a single frame, quickly take several shots each focused manually at a different focus point. Shoot the head, then the body, then the legs without moving the camera just by focusing on different areas of the insect. Next combine the frames using a product such as Helicon Focus which will make a single infinite focus image from numerous frame captures taken at different focus points. The results are fantastic this way. Of course this requires you to have a rock-solid tripod, remote release, and be able to quickly manually change focus points but it's being done all the time so it's entirely possible to get what you want using several different approaches.

Here's a sample taken through my Meade ETX-90 at a 35mm equivalency of 2000mm (1.6x crop plus 1250mm). You can judge the size of this tiny butterfly by the dandelion she's resting on:



Lin


redrichard wrote:
Quote:
[align=left]The spider in the bluebird pix is interesting in that you can see it to be a wolf spider at 30 feet. It is further interesting in that the bird has it clamped across the pedicel with its beak. This shuts off blood flow from the heart behind to the muscles and nerves up front leaving the arachnid hanging limp as you can see but probably still alive and tasty.

How does this pose compare with simply using the A650 without additiional lensing. With the excellent lighting and the 12 mp, I think it should be comparable. Am I wrong. Are you happy with this camera otherwise. I haven't found a comprehensive review and see considerable evidence of picture flaws in the limited reviews, but not in the bluebird shot.
[/align]
[align=left]I am searching desparately for the best way to get critically sharp pictures of small spider details for publication. I have decided the 100mm Canon macro lens isn't enough. The much higher power 60mm looks promising although not going smaller than !:! on the sensor; I can't get enough hands-on time with it to be sure. I have a nice 6-45x leica zoom stereo scope, but am not happy with a camera setup. You can't focus the point-and-shoot cameras well enough and the SLR's are too massive to mount on the eyepiece. I think the digi-cams are the way to go, but still haven't seen one in operation that is convincing.
[/align][align=left]

redrichard
[/align]
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Old Aug 5, 2008, 10:22 AM   #5
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Richard, here is a post of the 3mm spider I also sent you privately. Used my Canon A720 digiscope style with an Orion Expanse 20mm eyepiece and a Nikon Plan 2.5 X microscope lens. Depth of field is narrow so not all is in focus. Used a LED for lighting (not the best for color).

Am fabricating a semi-telescopic set-up to get the same magnification at about 7 inches distance from the subject. Have the Jaeger brand coated objective achromatic lens ordered. Since the photo angle is very small the dual element lens should do a fine job. Complex lenses are only needed for larger angle shots such as a typical camera 60 or 80 degree subject, or, of course fast f numbers.

That is a "Dandy" shot Lin. Very nice fly also.
Gene Smith
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