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11-12-2009, 11:48 AM   #16
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QuoteOriginally posted by jbinpg Quote

I think one of the benefits of the K-x's clean 12800 ISO is that it will allow shorter exposures for astrophotography such that you don't have to worry about as much sensor noise showing up in the frame. I would like to see the combo of K-x 12800ISO and PhotoAcute in action. The results could be spectacular.

Jack
I wouldn't quite call it a "clean" ISO 12800, just cleaner. That said, I really need to look up this photoacute program you mention...

11-12-2009, 02:07 PM   #17
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Nice image! Stars are crisp right to the edge.
11-13-2009, 07:53 AM   #18
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what do you guys use to stack?

I'm new to the idea of astrophotography, but I've always wanted to try. Now that I've taken the plunge and gotten a DSLR (kx) I'd like to get into it a little.

What methods or software (I'm probably going to try this photoacute, sounds cool) do you use to stack images and subtract dark frames? Can this be done easy enough with the standard fare of photo programs like GIMP or photoshop?
11-13-2009, 08:46 AM   #19
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QuoteOriginally posted by youareme7 Quote
I'm new to the idea of astrophotography, but I've always wanted to try. Now that I've taken the plunge and gotten a DSLR (kx) I'd like to get into it a little.

What methods or software (I'm probably going to try this photoacute, sounds cool) do you use to stack images and subtract dark frames? Can this be done easy enough with the standard fare of photo programs like GIMP or photoshop?
Try RegiStax or K3CCDTools, both free, or RegiStar (not free). I like 'em all but probably would go with RegiStax. Note this is not a point and click endeavor, there is a bit of a learning curve with all these programs. In fact every time I dive back in I have to re-remember things.

11-13-2009, 08:59 AM   #20
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I used Deep Sky Stacker for the shot I posted above.
11-13-2009, 09:03 AM   #21
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QuoteOriginally posted by pingflood Quote
I used Deep Sky Stacker for the shot I posted above.
Good. I forgot about that one, it's good too. Maybe try it first, a bit more friendly.
11-13-2009, 10:26 AM   #22
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For the uniformed like me, could you plaese explain in 1-2 sentences what stacking images is and if it is stacking one image or several differnt images? thanks.
11-13-2009, 10:41 AM   #23
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QuoteOriginally posted by mrpackerguy Quote
For the uniformed like me, could you plaese explain in 1-2 sentences what stacking images is and if it is stacking one image or several differnt images? thanks.
See my explanation here k7-long-exposure thread

11-13-2009, 07:46 PM   #24
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QuoteOriginally posted by LeoTaylor Quote
I gather the K-x lacks an external 6.5 vdc power jack? How could they drop such a simple and needed feature? Does that accessory require removing the batteries to insert the adaptor? It would seem even a brief loss of power (tripping on a cord in the dark) would abort the session. With my K110D running on external power it will last about 10 minutes on internal batteries, plenty of time for me to discover the power plug fell out and get the external power back on line. I'd say it happens about twice a year!

I'm a die hard Pentax lover but must admit Canon makes better cameras for astro without even trying. The one astro camera they did make (20Da I think it was called) simply had a better red response for nebulas.
Yes, there is no power jack on the K-x but I find it is not as needed as it is on the K200D. With eneloops I recently got hours of combined exposure time and still had battery life in the green. It looks like the movie and live view drains it much faster than just plain exposure time. I don't have the accessory yet because I can't find it anywhere. In the manual it shows that it inserts in the place of the AA batteries. This being the case, you don't want to loose power as you pointed out, although I have all of my power cords terminate under the mount and then one supply cord to the car outlet so it is not in the way.

I agree about the Canon being better a while back but the gap has narrowed and now with the K-x I believe we have a real contender. I'm finishing my stacking of last weekends astro outing and will post the results in a bit so you can see just how good the K-x really is.

QuoteOriginally posted by pingflood Quote
Not really, but it's something I would like to get into. It seems like you really need to get a tracking mount if you want to do any longer glass or longer than ~30 second exposures though, isn't that true? The "barn door" mounts look interesting and it seems that with some care in the design you can make a "manual tracking" version that might be ok for some longer exposures. Any advice on doing something fun on the cheap would be appreciated! I do have some stellar (hah!) long glass but I bet I'd get streaks/elongation pretty damn quick at 300/400mm.
Yes, a tracking mount is necessary to see any deep sky objects. The only thing you can do without a motor drive is wide field Milky Way shots although some of those come out pretty good expecially if you can combine it with a good forground subject. Orion telescope has some cheap manual rotate mounts for doing this with short lenses for around $50. Going as high as 400mm really requires the extra step of guiding unless you have a really expensive mount and absolutely perfect polar alignment.

QuoteOriginally posted by youareme7 Quote
I'm new to the idea of astrophotography, but I've always wanted to try. Now that I've taken the plunge and gotten a DSLR (kx) I'd like to get into it a little.

What methods or software (I'm probably going to try this photoacute, sounds cool) do you use to stack images and subtract dark frames? Can this be done easy enough with the standard fare of photo programs like GIMP or photoshop?
I use RegiStax but this is a very difficult program to use and requires a lot of time and practice. Some of the others that were mentioned above will be better for first timmers.
11-13-2009, 08:08 PM   #25
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according to the manual, though, you can buy a wall power adapter for the K-x
11-13-2009, 08:40 PM - 2 Likes   #26
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Here's the results, with the K-x

Ok, I finally got around to stacking these images from last week. The location is in Missouri outside of St. Louis. The seeing conditions were not very good. I cold barely see the Milky Way due to light pollution from a nearby town and lots of upper atmosphere hummidity.

The Andromeda galaxy below is a stack of 55 30s exposures half are at ISO 800 and the other at 1600. NR was turned off for both photos and I did not bother with dark frames because I knew there would be a better night but just wanted to get some photos. It turns out that the K-x really doesn't need DFS nearly as much as any previous Pentax DSLR.

The Lens was a 400mm F4 M* 67 with K adapter. All photos were manually guided with a seperate guide scope so the stacks would be as accurate as possible.

Processing was just simply applying contrast curves in PS and a touch of NR at the end. Color balance is a little off due to trying to clip the heavy red/brown light fog thus the green fringe due to inconsistent color curves but I just wanted to get these up here and get more particular once I get better night conditions.

These pictures are a good representation of what anyone can do with the K-x even with some light polution. If you can see the Milky Way at all these are possible. My results with previous Pentax DSLRs including the K200D are not nearly this good and require clipping the noise much more aggressively loosing much of the blue fringe areas but not so with the K-x!

Considering the conditions I think these photos prove that the K-x is a serious low light performer and I really look forward to doing some more serious work with it.
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11-13-2009, 09:37 PM   #27
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pti-andy:

Really nice. You got the reflection gas in the Pleiades what are the stacking specs. If you got the gas with 30sec exposures I'm very impressed. For all those out there that haven't tried hand guiding let me tell you pti-andy's eyes are watering even now. Very impressive.
11-13-2009, 09:39 PM   #28
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amazing!

wow
11-13-2009, 10:31 PM   #29
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I would be proud of either of these images Andy!
11-13-2009, 10:49 PM   #30
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QuoteOriginally posted by JackBak Quote
pti-andy:

Really nice. You got the reflection gas in the Pleiades what are the stacking specs. If you got the gas with 30sec exposures I'm very impressed. For all those out there that haven't tried hand guiding let me tell you pti-andy's eyes are watering even now. Very impressive.
Thanks for the kind remarks. The Pleiades was not very high in thy sky and was very washed out so I'm really looking forward to redoing it with better conditions. Even so, I'm surprised that so much of the reflection nebula pulled through the murk.

This shot is just 30 - 30s exposures for a total of 15 minutes of exposure time. There was no NR on the camera and I just stacked the jpegs and applied curves. I've never gotten results like this with such sky conditions and lack of processing attention.

I'm chuckling about the eyes watering. You must be a true night owl or you wouldn't have such sympathy. But yes, you're right... after a while I was seeing spots or rather red crosshairs. The drive home was interesting trying to see the road. At least breaking up the exposure time into 30s increments allows me to look away now and then. When I use to do this with film I'd be stuck for hours looking through the eyepiece. It's worse when it is freezing cold out and the eyepiece gets frosted up due to the proximity to a warm eyeball socket. That's the true definition of torture or maybe mental illness for doing it.

Last edited by pti-andy; 11-13-2009 at 10:56 PM.
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