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07-31-2009, 09:08 AM   #16
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QuoteOriginally posted by pentaxmz Quote
When the K7 was first announced, I was excited as a 10 year old on Christmas eve, but now that reality has sunk in, I am extremely disappointed and I have no plans to purchase the K7.

The K7 suffers from the same fatal flaw that ruined the K20D for astrophotography and that is the forced DFS.

The 2009 Perseids meteor shower is approaching and I borrowing a Canon to take out as my primary camera. Last year's I missed a very bright fireball (within the field of view of my K20D) because the K20D was doing a 10 minute DFS!! %^$@ was I pissed! I missed many other potentially great photos for the same reason.... but the fireball loss really annoyed me! I still get angry thinking about that!

Sorry to tell you but if you plan to do a lot of long exposures, don't bother with the K20D or the K7.

i have a k2000. does the k2000 automatically do dark frame subtraction?
btw, when is the perseids this year?

thanks

jordan

07-31-2009, 09:26 AM   #17
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We have just entered the debris field. It will peak the 12 & 13th of August.

http://science.nasa.gov/headlines/y2009/31jul_perseids2009.htm
07-31-2009, 04:57 PM   #18
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QuoteOriginally posted by pentaxmz Quote
The 2009 Perseids meteor shower is approaching and I borrowing a Canon to take out as my primary camera. Last year's I missed a very bright fireball (within the field of view of my K20D) because the K20D was doing a 10 minute DFS!! %^$@ was I pissed! I missed many other potentially great photos for the same reason.... but the fireball loss really annoyed me! I still get angry thinking about that!
Sorry to tell you but if you plan to do a lot of long exposures, don't bother with the K20D or the K7.
Why are you still using very long exposures for astrophotography? That's so "film era" isn't it? Many DSLR astrophotographers prefer to use "stacking." It has so many advantages. Some of the best DSLR photographs I have seen use stacking instead of long exposure. If you use the right software, you can even take into account the earth rotation without using a tracking mount. There is even free software to do stacking so you don't have to do it manually:
DeepSkyStacker - Free

Here is a beautiful shot of M42 from Andy Weeks website. It was done with 14, 30-second exposures. That is approximately equivalent to a 7min single exposure:



That was done with an XTi at 800 iso. Imagine how much better it could be with a higher resolution camera with better high iso performance like the k20d or the k-7. There are so many great examples you can find. That is just a quick one I knew about. I haven't had a chance to try it out myself with the K-7 yet, but I intend to when I have a good clear night.

Stacking should work very nicely for meteor showers as well since each meteor event is relatively short. I have seen some nice images of shorter-exposed meteor showers using stacking. You may not have missed the shot you indicated had you been stacking instead of using very long exposures. It may have been better to do 20, 30-second exposures instead of a single 10-min exposure.

See, no need to get angry or borrow a different camera, just open your mind to new methods.

Last edited by PentaxPoke; 07-31-2009 at 05:23 PM.
07-31-2009, 05:05 PM   #19
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Amazing content...any possibilities with camera + telescope mount?

08-01-2009, 07:42 PM   #20
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nice shot of orion.
now to dust off that trusty celestar 8.

yep. stacking is the way to go. also helps when your scope's motor isn't very accurate to have shorter exposures and stack them up.

thanks for the link to the deepskystacker!
11-19-2009, 01:05 PM   #21
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Sorry to revive an old thread, but I was hoping someone could explain the process of stacking. Is it done with multi-exposure mode, or in post-processing?

I'm just a drive away from picking up a K-7, but the forced DFS is stopping me. If stacking can compensate for this, then I will most definitely pick one up....
11-19-2009, 01:16 PM   #22
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If you are wanting to stack a bunch of 30 second shots. The there are several choices.
Registax
DeepSkyStacker
Startrails

The programs take your shots, let's say 100. Then it matches them up per your settings into one photo.
I sometimes start a series and go to bed. In the morning it's done.
11-19-2009, 01:21 PM   #23
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Another way to do Orion. Is to do several shots exposed to bring out the center properly. Then do a series exposing for the rest of the nebula. They can the be stacked to give an overall clear exposed photo.

11-19-2009, 01:32 PM   #24
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So, if a shot requires a 2-minute exposure, I could instead take four 30-second exposures, and stack them with one of these programs? And this would yield a perfectly-exposed result?
11-19-2009, 01:36 PM   #25
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Each 30 second exposure has to be properly exposed, give or take a little.
11-19-2009, 01:44 PM   #26
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I quite fancy trying this but the K-7 is limited to 99 exposures, right?
11-19-2009, 01:51 PM   #27
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You don't stack in camera.
Use software stacker program.

I've sat and taken 378 shots in one session, then stacked with Registax.
11-19-2009, 02:04 PM   #28
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QuoteOriginally posted by wildlifephotog Quote
Each 30 second exposure has to be properly exposed, give or take a little.
Hmmm. I thought stacking was a way to avoid long exposures, and therefore avoid the time-loss due to the forced DFS. But this does not seem to be the case.

Sorry if I'm being dense here... Am I missing something?
11-19-2009, 02:10 PM   #29
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You avoid the DFS by staying at 30 seconds and under. The stacking greatly improves signal to noise ratio.
I had set my camera to continous, 30 second exposure. After 63.5 minutes I was done. I then stacked and tweaked the photo.

Last edited by wildlifephotog; 09-27-2013 at 07:21 AM.
11-19-2009, 02:34 PM   #30
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QuoteOriginally posted by wildlifephotog Quote
.......I then stacked and tweaked the photo.
What did you use to stack images ?
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