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Old Oct 11, 2011, 9:57 PM   #1
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Default Digiscope with larger cameras

I have some questions that I couldn't find answers that were dumbed down enough for me so hopefully you folks can set me straight...

I tried putting my Nikon P100 26x lens up to a set of 12x50 binoculars but apparently the eyeglass hole is too small because my photo ended up being about 80% black with a small round peep hole of the photo. When I tried putting a really small P&S camera up to it the result was a much bigger picture and less vignetting. Do you guys use a certain size spotting scope? I know a lot of people use SLRs so my big Nikon should still be able to work, as it's about a 35mm size. Is there a formula to determine what size model scope to get??

Lastly, I need to figure out the total magnification I'll get when combining my 26x camera with a scope. If I used a 60x scope would my total zoom be 86x (26 + 60) or do they multiply eachother (26x60)? I'm trying to determine what goals are realistic for space photos.

I'll keep researching in the mean time but hopefully you are all very smart and can help me get started. Thanks in advance!
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Old Oct 16, 2011, 5:28 PM   #2
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In the case of SLRs to telescopes, one usually uses an adapter on the scope to a T-mount, and a T-mount adapter for the camera type. The focal distances are built in to the adapters, so the image will fill the frame. Essentially, what you are doing then, is using the telescope as a camera lens, and the magnification is figured from the focal length.
The exit pupil of your binoculars is quite small, less than 5mm, so if the camera is very close, you get just the small image you observed. In order to fill the frame, you have to move the camera further away from the binocular eyepiece. Alignment then becomes a problem, so an adapter tube is in order. For many telescopes, these adapter tubes are available from the maker.
The further you move your camera lens from the eyepiece of the scope, the dimmer the image is (you are spreading the same amount of light over a larger area), so you may wind up with very slow shutter speeds. The larger the objective lens of the scope you use, the more light it gathers (and the more expensive it gets) to give you a brighter image.
I am not sure how to figure magnification in the situation you describe, as I haven't attempted this and have no experience. The magnification of a telescope is figured differently than your camera, though, so it may not be doable in a straightforward manner.

brian
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Old Oct 17, 2011, 10:00 AM   #3
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I got a deal so I broke down and bought a Celestron 90mm telescope. It has a 45* and straight occular eye piece. It comes with a threaded adapter and t-mount for an SLR. That won't fit my P100 but I may be able to fabricate an attachment with a slip fit. Worst case scenario my older Canon 720 has a threaded adapter and it takes great pictures for a small P&S.

What I found was the T-mounts have another lens inside that changes the magnification properly for the focal point of the SLRs. Once I get the t-mount I can take some measurements and figure out what spacing and magnification would be needed for the specs on my super zoom. Won't be easy but I certainly can't afford an SLR at this point.

Thanks for all that info Brian, it's appreciated!
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Old Oct 23, 2011, 3:49 PM   #4
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I got a deal so I broke down and bought a Celestron 90mm telescope. It has a 45* and straight occular eye piece. It comes with a threaded adapter and t-mount for an SLR. That won't fit my P100 but I may be able to fabricate an attachment with a slip fit. Worst case scenario my older Canon 720 has a threaded adapter and it takes great pictures for a small P&S.

What I found was the T-mounts have another lens inside that changes the magnification properly for the focal point of the SLRs. Once I get the t-mount I can take some measurements and figure out what spacing and magnification would be needed for the specs on my super zoom. Won't be easy but I certainly can't afford an SLR at this point.

Thanks for all that info Brian, it's appreciated!
This link can supply you with any kind of adapter you need...
http://www.scopetronix.com/

Dave
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Old Oct 30, 2011, 6:42 PM   #5
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Default Digiscoping

Sorry you are having problems. First of all, I suggest you ask for digiscoping advice on the Digiscoping Birds forum at:
http://tech.groups.yahoo.com/group/d...birds/messages

Join and you can read the extensive archives.

The Canon A720 is a good digiscoping camera, and it will be much better than a DSLR for a several reasons, including the lens extension adapter that fits the body. It is a fraction of the weight and will not put such a distorting force on your scope and eyepiece. It has a smaller sensor which is a MAJOR advantage for digiscoping, giving you a number of stops faster speed. You have a misunderstanding about a T adapter, it is not used for digiscoping. The camera lens must be in place behind the scope eyepiece or you are not digisoping.

The scope eyepiece is important also. It should be a fixed focus piece of about 30 power. Zoom eyepieces many times do not give enough eye relief. If there is a problem I LOVE the Astro type Baader Hyperion 17mm eyepiece, digiscopes great. I think the Celestron scope will take the 1 1/4 astro type eyepiece. It has a thread on top that can be adapted to the A720 extension.

You may have to custom fit the distance from the eyepiece to the camera lens. The spacing that happens to occur when you attach the camera to the eyepiece may not be satisfactory to preventing vignetting of the image. Hand holding the camera is perhaps the best way to investigate the spacing, and then alter the adapters to fit. There are threaded filter ring extensions and always a hack saw and epoxy. Get back to me if you have problems Gene
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Old Nov 5, 2011, 3:06 PM   #6
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Sorry you are having problems. First of all, I suggest you ask for digiscoping advice on the Digiscoping Birds forum at:
http://tech.groups.yahoo.com/group/d...birds/messages

Join and you can read the extensive archives.

The Canon A720 is a good digiscoping camera, and it will be much better than a DSLR for a several reasons, including the lens extension adapter that fits the body. It is a fraction of the weight and will not put such a distorting force on your scope and eyepiece. It has a smaller sensor which is a MAJOR advantage for digiscoping, giving you a number of stops faster speed. You have a misunderstanding about a T adapter, it is not used for digiscoping. The camera lens must be in place behind the scope eyepiece or you are not digisoping.
The Canon may or may not be a good camera for digiscoping. I have no idea - But NO P&S is as good as an SLR. The T-adapter for an SLR turns your 'scope into a lens. The attachment is direct to the camera, and is completely solid. I've been using such a rig for ten years, and swing the camera around with no thought or worry about "strain."

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The scope eyepiece is important also. It should be a fixed focus piece of about 30 power. Zoom eyepieces many times do not give enough eye relief. If there is a problem I LOVE the Astro type Baader Hyperion 17mm eyepiece, digiscopes great. I think the Celestron scope will take the 1 1/4 astro type eyepiece. It has a thread on top that can be adapted to the A720 extension.

You may have to custom fit the distance from the eyepiece to the camera lens. The spacing that happens to occur when you attach the camera to the eyepiece may not be satisfactory to preventing vignetting of the image. Hand holding the camera is perhaps the best way to investigate the spacing, and then alter the adapters to fit. There are threaded filter ring extensions and always a hack saw and epoxy. Get back to me if you have problems Gene
Camera adapters for SLR's replace the eye piece. It's a special piece of glass, usually sold separately. These adapter are "rated." So, for example, I have two different adapters for my Swarovski, one is rated at 800mm, the other at 1100mm, f10 and f13 respectively. When you connect a scope to a digicam, you are basically using a work around adapter, and the F numbers will be much higher (f20?) depending on the magnification setting of the eye piece.

Now many of these adapters, despite my use of the words, "Workaround" are quite solid, although certainly not as solid as the direct connection of camera adapter to t-mount - camera body.

Dave
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Old Nov 5, 2011, 10:39 PM   #7
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Dave,

The question at hand wasn't whether an SLR body camera does better or not. We all know it's better because you have more shutter and aperture options but I don't own one. I'd love to BUT the funds aren't there. After a bit of testing the P100 gets MUCH better quality images. But all I can do is hold the cameras up to the lens trying to get focus set properly so w/out an adapter it's tough.

Which is why I broke down and just bought an Orion SteadyPix universal adapter on Amazon. I figure $40 was worth the man hours I'd waste building an adapter that still wouldn't have a swing mount. Someday way in the future when I can afford an SLR I'll get the Celestron T-adapter.
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Old Nov 6, 2011, 1:29 PM   #8
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Dave,

The question at hand wasn't whether an SLR body camera does better or not. We all know it's better because you have more shutter and aperture options but I don't own one. I'd love to BUT the funds aren't there. After a bit of testing the P100 gets MUCH better quality images. But all I can do is hold the cameras up to the lens trying to get focus set properly so w/out an adapter it's tough.

Which is why I broke down and just bought an Orion SteadyPix universal adapter on Amazon. I figure $40 was worth the man hours I'd waste building an adapter that still wouldn't have a swing mount. Someday way in the future when I can afford an SLR I'll get the Celestron T-adapter.
I was responding to Gene's statement that connecting to an SLR puts "strain" on the adapter. The link I posted in a previous post shows a number of different types of adapters. Some of them look quite good to me.

Good luck with your digiscoping! I've been doing it for years, and while there are many disadvantages, often enough a 'scope has better optics then most lenses.

Dave
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Old Jan 6, 2012, 7:10 PM   #9
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A general rule of thumb in digiscoping is to ensure that the diameter of the glass on the camera is smaller than the diameter of the glass on the eyepiece you are using on the scope. Most DSLR lenses do not meet this criterium. Most P&S cameras having 10X focal length ranges or less generally work. Eyepieces with focal lengths of 25mm and greater are good candidates for digiscoping as are some of the very expensive ones with shorter focal lengths.
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Old Jan 6, 2012, 7:28 PM   #10
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For those of you who think that a point and shoot camera is not up to the task of digiscoping, I submit a shot of the moon I made using a Sony H70, homemade adapter, A Meade 8-24mm zoom eyepiece, and a Russian 1000mm lens. I also include a photo of my setup.
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Sony A57 with 18-55 kit lens, Sony A200 and Sony H70
50mm f3.5 Minolta Maxxum macro
24mm f2.8 Minolta Maxxum
100-300mm Minolta Maxxum APO Zoom
70-300 Sony apo G SSM Zoom
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