CHDK for Astrophotography - page 2 - Creative Uses of CHDK - CHDK Forum

CHDK for Astrophotography

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Offline eteny

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Re: CHDK for Astrophotography
« Reply #10 on: 07 / January / 2011, 23:21:37 »
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Hi morel! There is a technique called afocal imaging. No fancy equipment required, any decent telescope or binoculars and a point-and-shoot camera will do (better if you use CHDK-enabled cameras so that you'll have access to more camera settings). You just need to hold the camera steady in close proximity to the binoculars' or telescopes eyepiece (you can just use masking tape, but not very elegant though :)). I have posted a few do-it-yourself adapter I built last year that you can fabricate yourself. Just set the camera's focus to infinity, then adjust the focus instead using the telescope's/binoculars' focusing knob. The moon is a good target to start with. You might need to play with the camera's setting like exposure, etc.

Clear skies!

Eteny


Could you give us some clues, how to set camera and telescope (or binocular etc) wihout using commercial adaptors? Is it possible? How to set focus? How to calibrate ameras lenses and telescope lenses?

Re: CHDK for Astrophotography
« Reply #11 on: 08 / January / 2011, 05:11:10 »
better if you use CHDK-enabled cameras so that you'll have access to more camera settings


What settings do you require that cannot be set without CHDK ?

Re: CHDK for Astrophotography
« Reply #12 on: 08 / January / 2011, 10:05:59 »
The main CHDK setting I use is a simple script to choose how many shots I take (past ten). For most of my moon images I try to get between 30-50 shots to use for stacking. Having to re-press the shutter button (after ten) would likely shift the image and/or cause slight change in focus.

I did also experiment with tethering camera to laptop for live-view (with PTP interface) which helped a little with focusing but it's just easier not having to plug into laptop (i.e. quicker to set up at night)!

I imagine using RAW images might improve deep sky work but haven't given that a go yet.

Cheers,

Nick
a710is

Re: CHDK for Astrophotography
« Reply #13 on: 08 / January / 2011, 10:34:52 »
The main CHDK setting I use is a simple script to choose how many shots I take (past ten).

Thanks, Nick, that tells me what I want to know.

Do you use any other CHDK features for regular photography ?


David


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Offline eteny

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Re: CHDK for Astrophotography
« Reply #14 on: 08 / January / 2011, 11:17:10 »
Hi Microfunguy, I'm using s3is, and it is only capable of taking up to a maximum of 15 seconds exposure. Such a short duration is not enough to capture faint deep-sky objects. For instance, the Great Orion Nebula we have just posted requires exposure of at least 60 seconds.

Sensitivity can also be improved using CHDK. I normally use ISO 16000. Before I learned about CHDK, I was seriously considering buying a DSLR, because of its bulb setting, and its high sensitivity. But now with my CHDK-enabled camera, I can now take exposures up to 10000 seconds, more than enough to capture the milky way, some galaxies, and a few deep-sky objects. :)

I am currently experimenting with the possibility of capturing the International Space Station while it crosses the sun's disc (an event that lasts only for less than a second or so) with the help of a script (which I still have to find since I'm just new in this forum) that will allow the camera to take hi-speed bursts while the satellite crosses the disc. Thanks!


Eteny

Re: CHDK for Astrophotography
« Reply #15 on: 08 / January / 2011, 12:03:26 »
I normally use ISO 16000...
I can now take exposures up to 10000 seconds ...

Well, if you say it is satisfactory then I guess it must be   :)

Do you have any images that show that as compared with the camera's normal maximum settings ?

(I do have an old 8" Meade Schmidt Cassegrain that I have not used for over a decade, maybe I should).

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Offline eteny

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Re: CHDK for Astrophotography
« Reply #16 on: 08 / January / 2011, 12:52:06 »
Hi! This is the best image I could come up with if not using CHDK (ISO 800, exposure 15 seconds as compared to ISO 16000, exposure 120 seconds with CHDK). Kindly compare it with my previously posted nebula picture. Both images were taken on the same night, using exactly the same equipment. This is image was taken just to check if my camera is properly focused.

Wow! Your 8-inch telescope is much more powerful than what I am currently using!  :) With such a large aperture, it is capable of resolving more details.

Eteny

Re: CHDK for Astrophotography
« Reply #17 on: 08 / January / 2011, 13:31:25 »
Thanks, but you really have to compare the full-size originals to check for noise, etc (even after stacking).

One problem I noticed with the scope when I gave it a brief check two years ago was that it misted-up from the inside.

I am reluctant tp remove the corrector plate but I believe it can be done.


David


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Offline eteny

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Re: CHDK for Astrophotography
« Reply #18 on: 08 / January / 2011, 13:39:22 »
I agree, each aspect must be checked in order to give a conclusive comparison. Well, in any case, I am very much pleased and satisfied with the new/enhanced capabilities of my camera, which wouldn't have been possible without CHDK :)

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Offline reyalp

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Re: CHDK for Astrophotography
« Reply #19 on: 08 / January / 2011, 16:00:31 »
Sensitivity can also be improved using CHDK. I normally use ISO 16000.
I think you will find if you do controlled test, CHDK override does not increase sensitivity over the maximum canon setting.

Set your camera to maximum canon ISO
take one shot at without CHDK override
take one shot with CHDK override at 16000
keep all exposure and illumination the same.
compare the levels of the raw files.

If your camera behaves differently, this would be unusual compared to other cameras that have been tested.

Note that the last stop of ISO in canon settings on many camera isn't actually sensor gain, it's done in the jpeg process. (e.g. if the camera goes to 800, raws for 400 and 800 are identical.) "High ISO" mode on newer cameras is also different, more like binning.
Don't forget what the H stands for.

 

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