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09-16-2008, 12:25 PM   #1
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Does a 8in telescope count as a "lens?"

Last night I took the k20d out and connected it to an 8in SC telescope to take some moon shots. I know a full moon is not the best for photos, because contrast is so low, but it was such a beautiful night, I had to go out. For an 8in Schmidt Cassegrain, focal length is 2000mm, and the aperture is f/10. Live view was helpful for focusing because you can "zoom" the lcd display. Here is one of the pictures:



09-16-2008, 12:31 PM   #2
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damn right it does! I almost bought an old Asahi Pentax telescope and T mount adapter on the bay once... price got higher than my wallet could afford. great looking beast it was, wooden tripod and all.

Great photo though. seems strange at f10 that the right side would be sharper than the left.. cause the right side looks stunning then gets to hard to look at as I look to the left. either way great photo, im a bit envious... and now I long for that telescope I couldn't afford...
09-16-2008, 12:40 PM   #3
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I really think that the lighting of the moon is what caused the left side to look "flat." Notice that on the far left side of the moon, there are no 3D features visible at all. That was the way it looked to the naked eye as well. Contrast of full moons is terrible, and it makes the image look "soft." As the moon starts to wane in the month, better lighting will make the other features more visible and sharper. Here is a picture I took of the moon with my 18-250 some time ago. It is heavily cropped, but it still looks pretty good because of the lighting. Notice it is not a full moon, so features start to "pop" out, now on the left side, and the right is soft. When I took the same picture last night with the 250 the whole moon looked soft because of the lighting of the full moon.
09-16-2008, 12:58 PM   #4
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QuoteOriginally posted by séamuis Quote
damn right it does! I almost bought an old Asahi Pentax telescope and T mount adapter on the bay once... price got higher than my wallet could afford. great looking beast it was, wooden tripod and all.

Great photo though. seems strange at f10 that the right side would be sharper than the left.. cause the right side looks stunning then gets to hard to look at as I look to the left. either way great photo, im a bit envious... and now I long for that telescope I couldn't afford...
Séamus, at the moon's distance the depth of field has no influence whatsoever. Whether you use f/10 or f/2 makes no difference in that regards at all.

Before you buy a scope like that, try it at your next astronomy club. MOst of them have a C8 or the equivalent modell from Meade. This is a superb image and you won't get this quality on your first try, especially not, without some help from exprienced astrophotographers.

And if you ever buy a Pentax scope: congrats, they are wonderful, I have a small one myself and it easily outperforms some of much bigger scopes in terms of sharpness and contrast.

Ben

09-16-2008, 02:27 PM   #5
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I have used a celestron C90 spotting scope, and Peter Zack has I believe a meade that he uses.

The biggest issue I have found with scopes is stability of the tripod mount. I found mine needed to be reworked to make it vibration proof.
09-16-2008, 03:44 PM   #6
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QuoteOriginally posted by Ben_Edict Quote
...at the moon's distance the depth of field has no influence whatsoever. Whether you use f/10 or f/2 makes no difference in that regards at all.
This has me pondering what absurdly small theoretical aperture you would need in order to have depth of field effects visible in a photo of the moon...
09-16-2008, 04:33 PM   #7
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I only have 500mm/f8 telescope. I also enjoy shooting the moon!
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09-16-2008, 08:48 PM   #8
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Beautiful shot PentaxPoke! 8" sct definetly counts as a camera lens. A big one. Well done.
Nice job jianshi on the 500 shot!
thanks
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09-16-2008, 09:17 PM   #9
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I only have fa400mm telescope : )

09-17-2008, 12:52 AM   #10
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that's a beautiful shot ibbe.
09-17-2008, 05:29 AM   #11
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My 2 cents...
I took some moon shots yesterday. K10D, DA*200mm & TC Kiron MC7 2X.
100% crop

09-17-2008, 10:53 PM   #12
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QuoteOriginally posted by séamuis Quote
Great photo though. seems strange at f10 that the right side would be sharper than the left.. cause the right side looks stunning then gets to hard to look at as I look to the left. ...
Seamuis, I went out and shot the moon again tonight for comparison since the moon is now waning. Notice how you can start to see a lot more detail and the moon looks sharper because there are now shadows.

Also, you may notice that the entire moon is in the field of view. Since the f2000mm gets so close, I had to do a "pano" and stitch two images together:
09-18-2008, 12:46 AM   #13
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WOW! The last shot is superb.
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