[netuser]

Hi, is it possible to do this kind of pictures with k20d and only using lenses and/or adapter/extention tubes ??

PENTAX Photo Gallery

Thanks

[Lowell Goudge]

you need a telescope with an astronomical clock mount but yes

[Wheatfield]

you need a telescope with an astronomical clock mount but yes

Well, not necessarily the telescope, but the clock driven equatorial mount for sure.

[WerTicus]

where can one get a star tracking mount device... and what's their proper name?

[netuser]

Can someone speak/write english ?

Feel free to educate and show some pictures of the stuff needed

[Wheatfield]

where can one get a star tracking mount device... and what's their proper name?

They are called equatorial mounts, and I'd be checking the telescope suppliers out.

[Marc Sabatella]

Lots of info out there is you google astrophotography. See, for example, this site:

Catching the Light: Astrophotography by Jerry Lodriguss

The picture you linked to was taken by attaching a very ordinary film camera to a telescope. Any decent camera, including the K20D, could have taken the same picture - if it was attached to that same telescope. It's possible to take pictures like that without a telescope, if you've got a good long telephoto lens that provides similar magnification. But the picture in question was taken with a 28mm lens, so it must have been attached to a telescope to get that kind of magnification.

EDIT: Actually, I take that back. I see now this is a section of the Milky Way, not a nebula as I first assumed. Still looks cropped from what I'd expect of a 28mm field of view on film, but it's not the sort of high magnification I thought it was at first.

Either way, you're talking about exposures that might be several minutes long, so you need a device designed to keep the camera pointed directly at the thing you are taking a picture of even while the earth turns. Stars rise in the east and set in the west just like the sun, after all, and in the several minutes it took to take that picture, the things it would have moved ut of the frame the camera and telescope hadn't been attached to a device that kept the camera moving at the same rate as the earth's rotation.

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Last edited by Marc Sabatella; 04-21-2009 at 03:34 PM.

[netuser]

Without a telescope what kind of mm in a telephoto is needed ?

[Marc Sabatella]

Without a telescope what kind of mm in a telephoto is needed ?

See the edit I just made to my post above. I may have been wrong about that picture needing a long telephoto lens - it's actually a bigger chunk of the sky than I thought it was at first.

As for what how long a lens you need, that depends on what you are taking pictures. Focal length means the same thing in that kind of astrophotography that it means in regular photography. Want a picture of the whole Big Dipper, you need a lens hat shows the whole thing. Want a picture of the nebula in the belt of Orion, you need something pretty long to magnify it enough to come close to filling the frame - "hundreds" of mm, let's say.

So if you don't already know what the various things in the sky are that might be worth photographing, that's the place to start. Otherwise, it's like asking about the best lenses for shooting birds, but then asking, "now, what does a bird look like, again?"

[netuser]

So, where can I start a thread "Marc Sabatella to forum moderator" ?

Thanks for the education :P
(again lol)

[Raybo]

You can build a "barn door"

Low-tech barndoor drive

[nanok]

one small pitfall might be that the k20d does not allow you to disable dark fram substraction, actually, it might become outright infuriating.

do check out tethered shooting, it will help probably. (pentax remote something for windows, pkremote for linux)

keep in mind astrophotography is not exactly a cheap hobby

[Raybo]

one small pitfall might be that the k20d does not allow you to disable dark fram substraction, actually, it might become outright infuriating.

do check out tethered shooting, it will help probably. (pentax remote something for windows, pkremote for linux)

keep in mind astrophotography is not exactly a cheap hobby

I would not assume that taking good astro images is expensive, it CAN be done on the cheap.
I would recommend using something other than a K20 (maybe a K100)

[MPrince]

where can one get a star tracking mount device... and what's their proper name?

Here's one source

Telescopes & Accessories at Factory-Direct Prices! - Telescope.com

[netuser]

The things we can learn in this forum