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ASTRO PHOTOGRAPHY


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I have a 10" auto tracking Dob. no goto. What is the best I can hope to achieve photographically with this scope and how? I have a Canon Eos 50D but not quite sure how to hook it up yet with all the various adaptors on the market. I see quite a few of you have similar scopes so I thought I would get a far better answer here. :mad:

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Your scope is supposed to have a direct DSLR connection (you would still need a Canon T-Ring). Being Alt-Az, you will be limited on exposure length, perhaps to 30s depending on the quality of the gears, but with an aperture that big it will be enough to get some good images by stacking several exposures together.

Head to the imaging section of the forum for help and tutorials!

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This type of scope is screaming for a high-frame-rate, small chip, short exposure camera like a webcam (Philips ToUCam) or a DMK to image small bright objects like the planets and lunar surface.

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depending on the drives, you should be able to manage at least 30 second exposures, longer if you're low in the east or west. Even with 30 second exposures, get enough of them and you'll be surprised at what you can pick up. I do agree with Themos though, a small sensor, high frame rate camera on the moon and planets...

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This type of scope is screaming for a high-frame-rate, small chip, short exposure camera like a webcam (Philips ToUCam) or a DMK to image small bright objects like the planets and lunar surface.

would that be better than using my dslr?

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I really want to image DSOs more than planets as they are so beautiful and will make fine album covers too. so should I go dslr or others as mentioned above?

As usual you guys are quick with very useful replies thank you so much :mad:

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I really want to image DSOs more than planets

Then your DSLR would be the option of choice over webcams. So all you'll need should be the Canon T-ring. I'd also recommend a bahtinov mask for focusing.

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Before you blow money on adaptors, can't you get somebody local to lend you the bits so that you can see if the tracking is good enough at that focal length? You should need just the Canon-to-T-thread adaptor as it looks like your scope has a T-thread on it already. Whereabout's are you?

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....small chip....

Why a small chip? Im a very keen amateur photographer and I have always extolled the virtues of a large chip as they reduce noise.

Is a small chip acceptable because for AP we stack multiple shots together to the SNR down?

Its an interesting point, i think anyway :mad:

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Small chip allows the frame rate to go up which is what you want for planets (which are so small that can't cover a large chip anyway at non-ridiculous focal lengths).

Besides, noise is related to pixel size, not chip size.

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Thanks for the input themos, didnt think about it that way. However a the pixel size will inevitably affect the chip size :mad:

Well, consider that digital compacts can have pixels which are about 3 square microns and DSLRs have pixels bigger than 25 square microns and some CCDs go near 100 square microns. Webcams like the ToUCam and the DMK have pixels that are big like a DSLR's but the overall size of the sensor is smaller than a compact's.

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Your scope is supposed to have a direct DSLR connection (you would still need a Canon T-Ring). Being Alt-Az, you will be limited on exposure length, perhaps to 30s depending on the quality of the gears, but with an aperture that big it will be enough to get some good images by stacking several exposures together.

Head to the imaging section of the forum for help and tutorials!

Just a word on aperture. How big your aperture is has nothing whatever to do with how much light you will get onto your chip in a given time. That depends entirely on focal ratio. If your Dob is f4 you will have a chance of getting at least something in a short Deep Sky shot. You don't say what its f-ratio is. The slower it is the worse are your chances. If you are hoping to get results such as those in the Deep Sky imaging section then it would be best to say straight out that you won't. The fast frame rate cameras on the planets will give you a real result, though.

Olly

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Well, consider that digital compacts can have pixels which are about 3 square microns and DSLRs have pixels bigger than 25 square microns and some CCDs go near 100 square microns. Webcams like the ToUCam and the DMK have pixels that are big like a DSLR's but the overall size of the sensor is smaller than a compact's.

Ah ok that makes sense 'cos webcams have a lower megapixel count as a result - which is something I gotta get my head round, that is: they have a lower megapixel count but Ive seen some stunning images. I presume as they are taking an imaging through a small 'aperture' i.e. a 2" or 1.25" tube the there is some correlation between FOV and megapixels that make this work.

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Since they have DSLR-sized pixels, if you can get them to do long-exposure (by modifying the electronics) you can get very low noise images. The downside is that the images are quite small in megapixels but then again they are quite cheap.

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I had a quick blast lastnight with my 10" dob mounted on an motorized eq6 unguided.

Im not really sure on how long i can push exposures unguided. So ended up doing 10sec exp @800 iso.

This is one shot, no processing and some nasty light pollution to the right side, thankfully my home made blocker mangaged to stop most the light shining on the telescope...

Also a quick Moon 1/250 @iso 200

post-20440-133877465722_thumb.jpg

post-20440-13387746573_thumb.jpg

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I think you need longer exposures for dso and a tracking system, but, at least you had some clear skies, it's pea soup down here for days! Must be the first lay of astronomy kicking in that must surely state. "When a new eyepiece is bought there will be clouds for days"

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Yup, need much more with regards to exposures, mount does not need to be tracking but a properly polar aligned EQ mount should do the job, a bonus with motor drives which my EQ6 has.

I already have another 30 or so shots to mount, but that was just an example of my first quick test of my 10" dob on the eq6 without guiding.

Also, just to add.... Light pollution is a nightmare around here, there are 3 hps lights right outside my house, and as this was a test i didn't bother with longer exposures and iso 1600 here is not an issue!

Edited by Starblazer
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