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02-10-2013, 02:50 PM   #496
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QuoteOriginally posted by smigol Quote
Here's my most recent effort. It's not complete yet.

Witch Head Nebula (IC 2118) is a reflection nebula near Rigel.
This is from 24 subs of 1200 seconds long at 100 ISO over two nights with my K10D. Camera cooled to 0-4C. Taken at a nearby dark site.
I want to get back there for another two nights of data if possible this coming week.
Amazing. Truly impressive and fantastic what you achieve with your modified K10D.

This makes me wonder: How much better is- or rather what class would you need of - a dedicated CCD astrocamera to achieve similar results in the same amount of time?

02-10-2013, 11:08 PM   #497
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OK, I have a few dumb utterly newbish questions here.

I took the K-30 out with the astrotracker just to see what I could do with it, and wound up completely blowing everything out due to overexposure.

Is there a chart anywhere that might have a rough guide as to how long and what aperture to use depending on conditions?

I'm not heading out again tonight (its 14 degrees out there!) but I'd like to go armed for my next stab at this when I can with at least a rough idea of what the heck I should be doing.

Gear was a 200mm f/3.5 prime and my 10-20mm f/3.5 Sigma. The Sigma shot came out better than the 200mm, but I forgot to turn the autofocus off and wound up with a nice out of focus mess.

Mind you, I'm just practicing for now, so if the answer is 'it depends' I'm cool with that as well.
02-10-2013, 11:15 PM   #498
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QuoteOriginally posted by Sagitta Quote
OK, I have a few dumb utterly newbish questions here.
Is there a chart anywhere that might have a rough guide as to how long and what aperture to use depending on conditions?
It's often a trial and error method, and it really depends on how bright your target is, and how bright the light pollution is.

Below is a example I did for Andromeda Galaxy

02-10-2013, 11:57 PM   #499
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QuoteOriginally posted by Stone G. Quote
Amazing. Truly impressive and fantastic what you achieve with your modified K10D.

This makes me wonder: How much better is- or rather what class would you need of - a dedicated CCD astrocamera to achieve similar results in the same amount of time?
I've done some research and the QHY-10 and Starlight Xpress M26C use the same sensor chip as the K10D (Sony ICX493AQA SuperHAD CCD).

If I were to switch, using either would still have the same requirements for sub duration since it's the same chip. I might be able to get away with some gain boost because of the greater headroom of the 16 bit vs 12 bit.

What this would provide as an advantage would be no amp glow, better thermal control,16 bit raws, reduction in weight, as well as a major reduction in power requirements.

The challenge with finding a similar comparison to the K10D in the astro CCD world is that the combination of APS-C, 6 um pixels, and CCD vs CMOS isn't met. The closest is the Kodak 8300 series, but that's a 4/3 size chip so wide fields are harder to produce.

Opening the whole one-shot color vs monochrome with filters is another can of worms. For my interests, I'm staying with OSC.

I'm also staying with the K10D as now that I've broken the seal from Spencers, I'm playing around with the inside and trying to get better contact with the cold finger. I'm reluctant to disassemble the camera further than just the base because I do not have the skills to de/resolder small wires.

02-11-2013, 03:01 AM   #500
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QuoteOriginally posted by Sagitta Quote
OK, I have a few dumb utterly newbish questions here.

I took the K-30 out with the astrotracker just to see what I could do with it, and wound up completely blowing everything out due to overexposure.

Is there a chart anywhere that might have a rough guide as to how long and what aperture to use depending on conditions?

I'm not heading out again tonight (its 14 degrees out there!) but I'd like to go armed for my next stab at this when I can with at least a rough idea of what the heck I should be doing.

Gear was a 200mm f/3.5 prime and my 10-20mm f/3.5 Sigma. The Sigma shot came out better than the 200mm, but I forgot to turn the autofocus off and wound up with a nice out of focus mess.

Mind you, I'm just practicing for now, so if the answer is 'it depends' I'm cool with that as well.
It would be helpful if you could show us one of your images. I would like to see one of your 200mm f/3.5 shots as I use an old Tamron Adaptall-2 lens (Model 04B) with those specs very much. Anyway in supplement to Dr_who's response:

1. Stopping down your lens is generally speaking not a good idea. Stars are point-like sources of ligt and your ability to record the fainter stars depend directly on the absolute physical aperture - not the f-number - of the lens. Further, due to diffraction the light from stars will be spread over a tiny disk which' size grows proportional to the f-number. You should rather work with your ISO and exposure time settings.

2. For us who have to shoot under a light polluted sky, washed-out images is the rule and there is no way around some post-processing. Just to give a very primitive example: The image of Hercules below was shot with a 55mm f/1.8 Takumar, exposed for 15 seconds at ISO 1600. (Just my K200D camera on tripod - long before I got my O-GPS1). Using ONLY curves and levels, you can get a fairly decent result as shown below again.

Of course, there is no real substitute for a dark sky. Still,I'm sure that you will soon discover the benefits stacking and post-processing.
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02-11-2013, 08:48 AM   #501
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QuoteOriginally posted by Stone G. Quote
It would be helpful if you could show us one of your images. I would like to see one of your 200mm f/3.5 shots as I use an old Tamron Adaptall-2 lens (Model 04B) with those specs very much. Anyway in supplement to Dr_who's response:

1. Stopping down your lens is generally speaking not a good idea. Stars are point-like sources of ligt and your ability to record the fainter stars depend directly on the absolute physical aperture - not the f-number - of the lens. Further, due to diffraction the light from stars will be spread over a tiny disk which' size grows proportional to the f-number. You should rather work with your ISO and exposure time settings.

2. For us who have to shoot under a light polluted sky, washed-out images is the rule and there is no way around some post-processing. Just to give a very primitive example: The image of Hercules below was shot with a 55mm f/1.8 Takumar, exposed for 15 seconds at ISO 1600. (Just my K200D camera on tripod - long before I got my O-GPS1). Using ONLY curves and levels, you can get a fairly decent result as shown below again.

Of course, there is no real substitute for a dark sky. Still,I'm sure that you will soon discover the benefits stacking and post-processing.

I think my big issue is I was spoiled in that my old haunts had magnificent dark skies.

Now I live in town - last nights test shots (more just to try to get the stars to be points then going for actual quality) were literally shot in a parking lot with a sodium light at my back, towards Jupiter which was sitting just over another sodium light.

In Freedom (old haunt) I could simply point the camera at the sky, take an X amount of an exposure, and have a nice dark result, I didn't have to factor light pollution at all. Here, well...

I've gone from THIS







To THIS. I was aiming at Jupiter - the bright blob above the arc light.







Obviously the 'just point skyward and expose' tactic is no longer valid for me.

First shot was with the Sigma 10-20mm, I forgot to shut of AF so it went blurry on me, second was with the 200mm. Less concerned about the streakiness (I can work on that) as I am with the fact things are washed out due to the light. Once the weather isn't bone-shatteringly cold I can walk down near the river (one block away) and shoot there - the lights aren't as bad if I locate myself properly.

Come decent weather, THIS is going to become my prime shooting location unless I drive back out to the place in Freedom. Considering I used the point and shoot for this one, I think I can deal with the light there a lot better than in the parking lot next door.


02-14-2013, 12:17 PM   #502
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QuoteOriginally posted by Sagitta Quote
Obviously the 'just point skyward and expose' tactic is no longer valid for me.
Well, I can see the difference. I would give a lot to have a sky and scene like in your first image. Still, light pollution or not, you can actually train and learn a lot from home as long as you point your lens towards the sky and forget about foreground objects. Judging from you 200mm test shot you and I have about the same degree of pollution to cope with, and some stacking and post processing will be a must.

And your last shot is indeed very pleasant! A good start, and cogratulations once again with your O-GPS1.

PS: Here's my night sky:
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02-14-2013, 02:38 PM   #503
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I also found out that my 200mm lens is worthless for use this way - its a Canon (I think) that someone played 'swap the mount' with before it made it way to me which is why my infinity shots were off - it can't reach it. I found I love that focal length enough I'll be keeping my eye out for a replacement, and will just press my zooms into service for mucking about for now.

It should prove a blast to learn this gizmo, and once nicer wether hits I should have (more) fun.


Last edited by Sagitta; 02-14-2013 at 04:32 PM.
02-14-2013, 05:43 PM   #504
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I finally managed a shot that is decent.

This was shot out the bedroom window using a 50mm f/1.7 stopped down a few pegs. Oddly, the lens size didn't show in the EXIF. Hardware bug or something?

Anyway, its Orion, and I'm happy to see a bit of the nebula going on considering the condiions it was shot under.


02-14-2013, 05:58 PM   #505
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QuoteOriginally posted by Sagitta Quote
I finally managed a shot that is decent.

This was shot out the bedroom window using a 50mm f/1.7 stopped down a few pegs. Oddly, the lens size didn't show in the EXIF. Hardware bug or something?

Anyway, its Orion, and I'm happy to see a bit of the nebula going on considering the condiions it was shot under.


That turned out good.
02-15-2013, 10:31 AM   #506
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QuoteOriginally posted by Ex Finn. Quote
That turned out good.
Thanks.

I've come to realize the GPS unit is very persnickity as far as getting it calibrated correctly, but when it its amazing. I'm going to attempt a moon shot later tonight I think - the moon rises directly in view of the windows along the eastern side of the apartment so I can cheat again while my wife is working her night shift by going out a window again.
02-15-2013, 02:43 PM   #507
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Open that window!

QuoteOriginally posted by Sagitta Quote
Thanks.

I've come to realize the GPS unit is very persnickity as far as getting it calibrated correctly, but when it its amazing. I'm going to attempt a moon shot later tonight I think - the moon rises directly in view of the windows along the eastern side of the apartment so I can cheat again while my wife is working her night shift by going out a window again.
Just be sure to open the window. Every pane of glass will degrade the image that much more. It's amazing what house glass will do to a star photo.
02-15-2013, 04:55 PM   #508
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I did. I'm prett sure the diffraction from the heat flying out of the apartment isn't helping matters any either.
02-17-2013, 01:35 AM   #509
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Learning my way around PixInsight a little more and more I went back to my data of M42 I did a week ago and here's the result.
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02-17-2013, 02:06 AM   #510
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Absolutely stunning. I love the images in this thread, so inspiring. Although it does make me price up some astro gear at times!
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