Digiscoping with a G1 and Pentax spotting scopes

Started Mar 6, 2009 | Discussions thread
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Jim Scarff
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Digiscoping with a G1 and Pentax spotting scopes
Mar 6, 2009

I was intrigued by a prior post ( http://forums.dpreview.com/forums/readflat.asp?forum=1033&message=31010659&q=g1+digiscop&qf=m ) in which Neil 11 describes his success in digiscoping with a G1 using a Swarovski spotting scope & adapter. I had assumed that like the FZ50, the G1 would not be work for digiscoping because the lens diameter was too large. Well, I was wrong.

Pentax spotting scopes are a tremendous bargain and superb scopes. At one point Better View Desired, the birding optics website, declared the Pentax PF-80ED the reference standard for high quality scopes, and later gave glowing reviews to the smaller Pentax PF-65ED. These Pentax scopes are very, very close to the optical quality of the very best scopes from Swarovski, Leica, Zeiss and Kowa, but only about half the price (around $1,000 rather than $2,000+). A key element in scope quality is the eyepiece. Pentax had a "stellar" reputation for eyepiece quality which were used in many astronomical telescopes. Eventually, they got around to building spotting scope bodies to work with those eyepieces.

To define what I did clearly -- there are two optical ways to connect a camera to a spotting scope, only one of which interests me.
(1) the camera with its lens is placed behind the scope's eyepiece, or
(2) the scope's eyepiece is replaced with an adapter to connect to the camera.

Method (1) is the principal method used by digiscopers and what I was interested in. This method gives enormous magnification since you get the full power of the magnification from the scope's eyepiece plus potentially the magnification from the camera's zoom. Method (2) is the older method which basically turns the scope barrel into a moderately long telephoto lens with much lower magnification, and usually renders the scope unusable for regular viewing.

My experiments involved Pentax PF -80ED-A and PF-65ED-A scopes with both the 20-60mm Pentax SMC eyepiece (8-24mm) and the Pentax SMC XW14 wide-angle eyepiece.

1) The G1 using the 14-45 kit lens works well with the SMC XW14 eyepiece. From the 18-50mm range, there is no vignetting. Zoom more than that, and vignetting becomes a problem.

2) The G1 does NOT work well with 20-60X eyepiece. The vignetting is terrible at all focal lengths.

3) The G1 works with the SMC XW14 eyepiece because the latter has a huge diameter, approximately the same size as the G1 lens. The G1 would probably NOT work on scopes with much smaller diameter eyepieces, e.g. Nikon Fieldscopes.

4) The choice between the two models of Pentax scopes is a matter of personal preference. The 80ED lets in more light, but also significantly increases the magnification making "camera shake" much more of a problem to deal with. The 65ED lets in slightly less light, but has so much to commend it in lower price, much smaller size, and less motion to stabilize. NOTE that the 65ED comes standard with smaller diameter and lower quality XF eyepieces, which I am confident will NOT work with the G1. The XW series of eyepieces are options and are the ones you want.

5) Attaching the G1 to the telescope. The quality of any digiscoped photos is a direct function of (a) how closely aligned and square you can get the camera to the scope eyepiece, and (b) how well you are able to eliminate camera movement. Swarovski, Zeiss, and Leica have great adaptors to quickly mount and unmount a digiscoping camera to the scope. Pentax only recently released a swing-arm adapter that seems too flimsy for a camera as heavy as the G1. For testing, I simply hand-held the camera to the eyepiece. This worked far better than expected, because the rubber eyepiece rim fits nicely up against the black border around the G1 lens. A fear I usually have that the eyepiece will scratch the camera lens is dealt with beautifully -- it is nearly impossible if you are careful. I even left the lens hood on. Because I was pressing the lens up against the eyepiece rubber guard, it was easy to establish the correct distance from the scope and square the camera to the scope.

MOTION - hand-holding the camera against the eyepiece imposes undesirable motion on the whole setup, and remember in digiscoping all motion is vastly magnified compared to what the camera's IS can deal with. In an ideal world, the camera would be held there by a hands-free adapter and the shutter triggered by a remote release to minimize motion, but my world is less than ideal. My "solution" was to set the shutter on rapid fire and shoot off a burst of photos. Any motion caused by my pressing the shutter would have ended before the 2d or 3rd shot. You shoot a LOT of shots, but I find one has to do that always in digiscoping since the keeper percentage is always going to be low.

I left the camera on autofocus. I would focus on the subject in the scope with the scope focusing, then hold the G1 up to the lens and let AF work. I found it nearly impossible to use manual focus in this setup.

Later this morning I'll post some of my photos in this thread. They are hardly brilliant, but I was very pleasantly surprised by the results.

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