Who Does Both DSLR and Digiscoping? (1 Viewer)

I recently bought a Canon 30D. I tried the Canon 30D with the 17-55 Kitlens on mij Leica Televid (77 mm, 20W oculair, handheld, directly on the oculair) and after postprocessing the RAW-image (there is still some vignetting), I got this result (left picture). For a comparison I also include a picture made with my Sony W15 on the same telescope (Griturn adapter). Same day, same place.

I think that the result is not bad for a first try. It combines the best of two worlds.

Marcel van der Tol

Marcel,
Nice comparison. Did you AF or manual Focus for the DSLR image?
Neil

Neil said:

Marcel,
Nice comparison. Did you AF or manual Focus for the DSLR image?
Neil

Click to expand...

Manual focus, Aperture priority, f/5, 1/250s, iso 400, hi speed burst

Marcel

SLR Camera Quality Vs. Digicams for Scope Pictures

I wanted to take the sharpest telescopic pictures possible, so I choose to use a SLR camera with direct focus from my scopes. First I tried a SLR film camera, and had poor results. So I bought an Eos D-300 digital SLR and did considerable work with three different scopes. I had poor results. So, I resolution tested the scopes, and found them good. My suspicion was that the mechanical shutter in the SLR was jarring the camera, even though the mirror was locked up and a 6 second time delay was used. Of course this has been a decades old contention even with conventional lenses.

At last I was able to confirm this disruption from a contribution on Birdforum that published pictures showing unsharpness with SLR telescopic photographs. What a paradox that a cheap digicam can produce superior telescopic photographs compared to the brick sized SLR while sending the image through perhaps an additional dozen lens elements!

It has been my contention that you should be able to take a photograph showing almost the same sharpness detail that could be see through the scope directly. I noticed I could do this with a digicam, but not with a SLR. An important contribution has been the recent availability of digicams with sharp lenses yet compact enough to work inside the optical image cone of the telescope eyepiece. High pixel counts, good controls, and quality image processing in these digicams also helps.

I hope to publish side by side test photographs showing the best effort shots with a SLR and a Digicam using the same scope, target, and environmental conditions.
Gene Smith

Added: The problems are with the longer focal length lenses, 800mm and 1200 mm telescopes. These are 4 inch and a 10 inch dia. Dob. type mount.

I would be interested to see any comparison shots. I believe you are right about this, I once did some test shots in the house under artificial light and easily got sharp pics with the digiscoping gear (exposure around 1/2 a sec)but shots with my DSLR and 500 lens (similar exposure)were soft, due to mirror bounce this was remeded with mirror lock up but I think they may have been some shutter vibration in there as as well.

I also think that just down to the gear we use, results in digiscoping require much slower shutter speeds than we need with SLR gear. When we digiscope the objective lens is fixed more or less still by the tripod and even if we are hand holding the camera there is probably only a maximum of about 1mm of travel which might cause blurr. Even at a slow shutter speed (c.1/30s) it sometimes possible to get a sharp pic especially if we take a burst. This is because in at least one of the shots the camera and scope may be perfectly still. This is not true of hand holding DSLR gear unless we have Image Stabilisation where the end of a 4 or 500mm lens is waving around all over the place dictating a faster shutter speed is needed.

example

I'm not sure if this is a valid example. One is taken with a Coolpix4500 at f2.6 and camera 3sec self timer. The other one with a sony alpha and minolta 24mm using 2sec mirror lock and remote. Both pics with camera attached to a Pentax XW20mm eyepiece and digiscoped with a Pentax PF80A. White balance and color rendition will probably give away which is what but sharpness looks fairly similar to me. Jose

Smithhill said:

My suspicion was that the mechanical shutter in the SLR was jarring the camera, even though the mirror was locked up and a 6 second time delay was used. Of course this has been a decades old contention even with conventional lenses.

I hope to publish side by side test photographs showing the best effort shots with a SLR and a Digicam using the same scope, target, and environmental conditions.
Gene Smith

Added: The problems are with the longer focal length lenses, 800mm and 1200 mm telescopes. These are 4 inch and a 10 inch dia. Dob. type mount.

Click to expand...

As someone who uses a DSLR on long spotters and astro scopes I agree.
The movement from the mirror can be a real problem. In fact on certain
mounts I can release the shutter remotely while sighting down the barrel
of the scope and watch the objective end shake from mirror slap.

It can be minimized however. I found that once I changed to a gimbal
fork mount, a Manfrotto 393 (Bogen 3421), most of these issues just went
away. Set up this way I can typically shot at 1/100 of a sec with no
problem. I think it's an issue of balance. Although you can achieve
perfect balance on any mount with a sliding dovetail plate on the
horizontal the center of gravity shifts when you shift the scope up or
down (tilt). On a fork mount this is not an issue. Balance the scope
perfectly on the horizontal and then tilt the scope up or down and let
go and it just stops moving - rock solid.

Speaking only for myself, I tried the conventional PS digiscoping method
and gave up on that. For me it's just too slow, clumsy, awkward and with
poor uncertain results. I like to concentrate on fast moving passerines
and found the PS method just does not cut it for my purposes. Perhaps I
have a unusually low frustration level but a PS camera is just too klutzy
and slow and the results poor for what I want to do.

But different strokes for different folks I guess.

SF

Taken with a gigantic 1000mm FL astro scope in prime focus. This scope
is over 50 inches long with camera and extension tubes hanging off the
back end and mirror slap is not a big issues on my setup. Not a
practical setup for most but an example of what a proper mount can do.

1/125 sec. No shutter delay, mirror lock up nor remote release just normal manual shutter release. ISO 200

I have just changed from shooting with a Nikon 8400 and Swarovski ATS 80HD scope to using a Canon EOS 400D with the same scope.

Attached is a shot from the 1st days outing with the new setup

Bob Thompson
Hong Kong
www.flickr.com/jingbar