Night Sky with A810 - page 3 - Creative Uses of CHDK - CHDK Forum

Night Sky with A810

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Offline blackhole

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Re: Night Sky with A810
« Reply #20 on: 04 / March / 2013, 02:43:01 »
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it would be awesome if I could get some shots if the milky way using only this A810.
Sure you can, but the question is will you get what you wanted. At wide angle (5mm or 28mm eq) you can go with the exposure of about 17 seconds without tracking. The problem is that in such a short exposure you have to use a high ISO, which will on cheap cameras make a lot of noise.
The attached image was taken with the A590 and probably with this camera can't do much better picture.
I believe that would similar result  was also with A810.
« Last Edit: 04 / March / 2013, 02:47:45 by blackhole »

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Offline Davo

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Re: Night Sky with A810
« Reply #21 on: 04 / March / 2013, 07:52:05 »
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Please tell me, can you capture the milky way with it without using a tracker?

I reckon you could do this easily with the A810. CHDK lets you shoot in RAW for durations up to 2048s with a built in intervalometer. You need to shoot several images to allow image stacking which reduces image noise. There is a good article here which describes what you are trying to do

http://bf-astro.com/widedslr.pdf

I would start by using ISO 1600, infinity focus and shoot a few shots to see how long you can shoot before star trails become a problem. Then shoot a bunch with the intervalometer at this shutter speed. Stack this bunch to see what you get.

Once you get hooked you can spend a few dollars on building a Scotch mount like this to eliminate trails and allow longer exposures.

http://www.astropix.com/BGDA/SAMPLE2/SAMPLE2.HTM

good luck

Re: Night Sky with A810
« Reply #22 on: 04 / March / 2013, 08:59:29 »
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Night Sky with A810
« Reply #23 on: 04 / March / 2013, 09:08:47 »
@backhole
If I could get images similar to that then it's good enough for me, at least for now. I just want to experience and learn the basics of astrophotography while I'm still a student then probably upgrade the tools to something more decent once i graduate. Thanks for posting an image, now I have an idea at least of what to expect in trying to get the milky way in an A810.

@Davo
Those are nice resources. I would love to try out stacking. And that simple DIY tracker is really cool! Looking forward to building one in the future. Thanks for sharing them!  :D


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Offline blackhole

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Re: Night Sky with A810
« Reply #24 on: 04 / March / 2013, 09:30:48 »
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I just want to experience and learn the basics of astrophotography

Astrophotography is a very nice hobby, but unfortunately very expensive if you want top performance.
If you encounter any problems with processing astrophotography, just ask. ;)

Re: Night Sky with A810 (part 2)
« Reply #25 on: 15 / March / 2013, 14:08:57 »
There is some ground glow in the image due to the fact that I live in town at 57N and there is plenty of light pollution. Orion doesn't get really high at my location.

Stumbled upon this thread, and I love that shot, including the glow! Wonderful work :)
G11, g11-100L-1.1.0-2634-full_BETA

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Offline Davo

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Re: Night Sky with A810
« Reply #26 on: 16 / March / 2013, 12:35:27 »
Glad you like it. I really bought my A810 for high speed bird photography so its ability for astro work is an unexpected bonus. The fact it has a CCD rather than a CMOS sensor makes it more suitable for multi-second star exposures.

One thing I noticed is that my stacking proessing has removed all the color from the stars and nebula. I am going to tweak the settings for my next shots to try and keep the colors.

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Offline lapser

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Re: Night Sky with A810
« Reply #27 on: 16 / March / 2013, 17:25:16 »
The fact it has a CCD rather than a CMOS sensor makes it more suitable for multi-second star exposures.
I think that's only true for the big CCD cameras designed for telescopes where the sensor is cooled to a very low temperature. They're pretty hard to fit in your pocket.

I've been really happy with the G1X with low light. The best thing about it is that it doesn't seem to generate hot pixels when you turn dark frames off. It also has a large, 14 bit sensor, which produces much better pictures than the other Powershot models.

I've been obsessed with day to night time lapses lately, so I haven't tried the G1X in full darkness much. Here's an experiment I did awhile back, right after I got the G1X:
http://www.youtube.com/watch?v=x2Ajd1GHrIg#ws

I also like the SX50 that we just got working with CHDK. But I think I need a better mounting platform at full zoom. There's was a bit of wind last night, which I think was shaking the camera a little during this time lapse:
http://www.youtube.com/watch?v=xFPNoiwaWsQ#ws
EOS-M3_120f / SX50_100b / SX260_101a / G1X_100g / D20_100b
https://www.youtube.com/user/DrLapser/videos


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Offline Davo

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Re: Night Sky with A810
« Reply #28 on: 18 / March / 2013, 10:35:03 »
Very cool videos. I like the way the camera AGC picks up the earthglow on the dark side of the moon near the end.

You should try digiscoping the moon to get lunar details. All you need is a telescope and a digiscoping bracket.

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Offline lapser

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Re: Night Sky with A810
« Reply #29 on: 18 / March / 2013, 11:47:43 »
Very cool videos. I like the way the camera AGC picks up the earthglow on the dark side of the moon near the end.
Actually, the exposure change is calculated using a new post shot metering function I'm working on. It reads the raw buffer after the shot and calculates a brightness that the script uses to set the exposure for the next shot. It works better than the camera meter, especially at low light levels.
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You should try digiscoping the moon to get lunar details. All you need is a telescope and a digiscoping bracket.
I have a Celestron spotting scope from the last century with a Pentax SLR camera mount. I'd love to connect the G1X to it, but the eyepieces are really small. The G1X only has 5X zoom, but a great sensor, so if I could get it to work with a scope, that would be really nice.

This is about what my scope looks like:
http://www.amazon.com/Celestron-52238-Mini-Spotting-Scope/dp/B00150XFLU/

Do you know of a scope and bracket that would fit the G1X and SX50?

The SX50 has a 50X zoom, which shows pretty good detail on the moon with the right exposure and without the camera shake. The G1X and SX50 have native raw capability, when I get serious about night shots, I'll try raw. This is a time lapse I did of the moon through light fog, without any wind shaking the camera:

http://www.youtube.com/watch?v=HXffHEPv7UM#ws
EOS-M3_120f / SX50_100b / SX260_101a / G1X_100g / D20_100b
https://www.youtube.com/user/DrLapser/videos

 

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