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01-14-2009, 07:27 AM   #1
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K20 with astronomical telescope

Hi, sorry if this has already been addressed.

I am trying to convince a work mate to get a K20D so that he can mate it to his telescope using a 'T' mount; like on a mirror lens.

I have see threads here form people who are using mirror lenses but does anyone use it with a 'proper' telescope and if so, how?

Any advice / pointers would be appreciated.

Bill

01-14-2009, 08:15 AM   #2
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I use a t mount adapter to connect my DS to my refractor scopes. I made a special t mount X 2" adapter for my 8" reflector scope.
Use the camera in manual mode, and practice a lot.
01-14-2009, 08:26 AM   #3
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Here is a photo of the snout I made, and mounted on my 8" scope. The photo was taken with this setup.

Last edited by wildlifephotog; 09-27-2013 at 07:22 AM.
01-14-2009, 03:17 PM   #4
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I have a similar arrangement as shown above by "Wildman", but mine is more for the purpose of "digiscoping". I have my K10D attached to my Swarovski Spotting Scope, the AT-80-HD with a 20X to 60X eyepiece. The camera has the Pentax 40mm pancake lens mounted onto the eyepiece, via an adapter that I and a friend made in his machine shop. This arrangement avoids the use of a T adapter, and allows considerably higher overall magnification. The 40 mm lens, which has an equivalent focal length of 60 mm, which when multiplied by the scope's 20X gives a minimum focal length of 1200 mm equiv. If the higher eyepiece settings are used, just multiply the setting by the 60 to get the equiv. focal length. However, this combo is sharpest at 30X and below.

If someone wants to see it, I'll be glad to post a picture of this arrangement, but first you will have to tell me how to add such a photo - I've never tried before in all my previous posts.

Olin

01-14-2009, 03:30 PM   #5
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Actually when doing the math. You should use the offical lens length. The 60mm is only a reference length pertaining to apparent field of view for the smaller sensor.
The lens doesn't actually become 60mm.
01-14-2009, 06:26 PM   #6
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QuoteOriginally posted by wildlifephotog Quote
Actually when doing the math. You should use the offical lens length. The 60mm is only a reference length pertaining to apparent field of view for the smaller sensor.
The lens doesn't actually become 60mm.
I know it doesn't actually become 60mm, but when the word "equivalent" is used, that refers to what field of view it obtains relative or equivalent to a 60mm lens if used on a 35mm camera. The word "equivalent" is common, but still confusing to lots of people, especially those new to the digital camera standards.

If a 35mm film camera with a 60mm lens were attached to the spotting scope at 20X it would be total focal length of 1200mm. The same thing applies, as far as the field of view, in this case - at least in my judgment. Do you disagree with this logic?
01-14-2009, 06:35 PM   #7
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Is that a red-dot gunsight for a finder? Pretty good call.
01-14-2009, 07:08 PM   #8
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The camera lens jargon doesn't enter into the mix. You have to figure your FOV for the final setup. Let's say 1200mm. The moon is about .5 degree wide when full. At 1200mm you will be very lucky to get a full 1 degree FOV.

01-15-2009, 05:21 AM   #9
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Thanks for all the input guys, I have passed it all onto Simon.
01-20-2009, 05:07 PM   #10
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I want one of those adaptors!!!
01-20-2009, 10:48 PM   #11
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QuoteOriginally posted by Billgscott Quote
Hi, sorry if this has already been addressed.

I am trying to convince a work mate to get a K20D so that he can mate it to his telescope using a 'T' mount; like on a mirror lens.

I have see threads here form people who are using mirror lenses but does anyone use it with a 'proper' telescope and if so, how?

Any advice / pointers would be appreciated.

Bill
I'm going to get into trouble for this.... but here goes....

Unless you plan to only photograph solar system bodies, such as the Sun, Moon, and planets... I would seriously consider the closest camera to the K20D; that being the Canon D50... or save a lot of money and purchase one of the Canon 20D - 40D models.

These Canon models are the preferred choice among Astrophotographers because of the low light/low noise advantage they have over all other DSLRs in this price range.

In regards to purchasing a t-mount (and other accessories), I highly recommend Scopetronics (out of Florida) ScopeTronix Quality Astronomy Products - I have purchased a LOT from them since about 2004, great service, amazing prices, and you get top notch quality parts. Another great alternative is Adorama camera. Everyone knows about them, I am sure!
01-20-2009, 10:50 PM   #12
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QuoteOriginally posted by Sodbuster Quote
I want one of those adaptors!!!
If you don't want a do-it-yourself-er, see ScopeTronix Quality Astronomy Products for a large variety of t-mounts and other telescope accessories.
01-21-2009, 02:39 PM   #13
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My wife and I have many Scopetronix adapters and eyepieces for our Nikon Coolpixs. The DigiCams do not have removeable lenses so need special adapters to connect AFOCAL (lens to eyepiece). If you can avoid it, it is better to not have all that extra glass (over 10 elements) in the light path.

The only reason I can think of to use AFOCAL with a DSLR is with a spotting scope that does not have removable eyepieces.

My Pentax connects PRIME FOCUS (no glass) via a T-Ring - no need for custom made parts from Scopetronix. Many telescopes include T-Ring threads, for those that don't you can use a variety of T-ring to EP holder adapters. I prefer a threaded connection so the camera won't slide out during a image!

I thought Scopetronix went out of business a couple of years ago? Has anyone actually ordered something from the web site recently? I'd be delighted to find they are back in business.
01-21-2009, 02:45 PM   #14
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One more note:

As mentioned recently in another thread the K20 is the only Pentax DSLR that can not turn off Noise Reduction on long exposures. It can still be used for astrophotography but this increases the time to image faint objects. I use my modified K110D both with and without NR depending on circumstances.

Last edited by LeoTaylor; 01-21-2009 at 02:45 PM. Reason: Typo
01-21-2009, 03:57 PM   #15
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Well, I've never had my adapter slide out. Even when I use it on a refractor almost straight up. But one should have a safety strap on the camera just in case.
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