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Planetary Camera for Dob

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#1 Leibowitz

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Posted 25 January 2013 - 10:11 AM

I've got an Orion XT10i and I would like to begin doing some planetary imaging. I've read through many threads and I'm still having trouble pinpointing a good camera to image planets with. It's not a Goto so I'd simply be taking video of the object drifting through the FOV and stacking. I realize my imaging capabilities are limited almost exclusively to planetary/lunar objects so I don't think I need to spend a lot of money. I'm wondering if I should go with one of the cheaper cameras that Orion and Celestron offers or should I modify a webcam? If I was to modify a webcam, does anyone have any current suggestions? Seems all the threads I come across reference models no longer made.

#2 pippo

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Posted 25 January 2013 - 03:18 PM

You need to use a short shutter time (between 10 or 15 ms depending on the focal length) to avoid that the planet drift results in a blurred image.

A good choice is to by a BW camera.

This is a great value:

http://www.ebay.com/...a-/290845851...

Even if they just increased the price!
Follow this tread:

http://www.cloudynig...5316325/page...

#3 Mirzam

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Posted 25 January 2013 - 03:18 PM

I think you are going to need an equatorial platform to provide some level of tracking. Without it you will have only a few seconds at best before a planetary image drifts off your camera chip.

JimC

#4 ToxMan

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Posted 25 January 2013 - 04:09 PM

Even alt-az mounting is better than none. There will be some field rotation after a couple minutes.

#5 Jeff2011

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Posted 25 January 2013 - 09:28 PM

+1 on the EQ platform. I built my own but there is at least one company that will build one for you. Just google equatorial platforms.

#6 jgraham

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Posted 26 January 2013 - 08:34 AM

You might find this thread interesting...

http://stargazerslou...ing-with-a-dob/

I wonder how well the 5x movie mode of a Canon DSLR would work. The idea being that you can use the super wide field of the full frame mode for locating and focusing, then the movie mode for imaging. Backyard EOS makes this fairly easy to do. I've done lunar imaging with my Lightbridge 16, but I haven't tried the planets yet. It'll be interesting to try.

#7 Leibowitz

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Posted 28 January 2013 - 10:39 AM

ToxMan, I don't understand what you mean about field rotation. I know what it is but I won't be able to capture more than about 8-10 seconds before any planet passes completely through my FOV. I realize I'm very limited with no tracking at all but I've seen some decent results with people using Dobs and a webcam. I may be in the wrong location here. I was hoping to get some answers from someone who has some experience with my very crude set up. My understanding is that I should be able to get a decent final product by stacking several AVI's with Registax. Lunar should be fairly straight forward. I'm needing some help with Mars/Jupiter/Saturn. All the help I can get. There's limited info on my setup, I'm afraid.

#8 bunyon

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Posted 28 January 2013 - 12:37 PM

You can let the planet drift through the field but that will still limit you to very short avis. The only undriven images I'm aware of ever seeing are from folks who "hand-guide" the scope. That is, let the planet drift onto the chip and then try to track it as best you can manually (by moving the scope as you normally would). I'd think it very hard to pull of but have seem some decent results.

I just don't think letting the planet drift through the FOV will get you far. It will drift through in a few seconds, allowing you to get a few hundred frames. You need more.

#9 pippo

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Posted 28 January 2013 - 12:38 PM

I have a LB Dobson (12") and a Intes mak (7") on a manual alt-az mount. I am able to obtain reasonable images using a spc900nc and a firefly MC cam and letting the planet to drift during the movie.

The problems are
1)field rotation (it is stronger the higher the planet is in the sky) that limits the total acquisition time to 2-4 minutes and
2) the drift speed of the planet.

The drift speed depends on the focal length. With a focal length of 4860mm and a pixel size of 6micron, you should limit the total exposition time below 1/50, 1/60 sec.


Here is a example with the firefly the mak 7" with an average turbulence.

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#10 bunyon

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Posted 28 January 2013 - 12:40 PM

Also, a good camera to use would be the best ones. There won't be any difference with a Dob than any other scope. The two "leading" cams seem to be the Flea3 and the ZWO ASI120. The DMK21-618 is also very good.

#11 bunyon

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Posted 28 January 2013 - 01:00 PM

pippo, how long does the planet stay on the chip as it drifts across? How many frames do you get?

#12 pippo

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Posted 28 January 2013 - 02:04 PM

I take 60 fps for 120 seconds: 7200 frames.

5000/6000 contains a full jupiter.

#13 bunyon

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Posted 28 January 2013 - 02:11 PM

So do you "guide by hand"?

#14 pippo

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Posted 28 January 2013 - 02:25 PM

no I let jupiter drift and when it is out of the sensor I reput jupiter on the other side of the sensor, it let it drift again,...,...,

#15 mikewirths

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Posted 28 January 2013 - 02:26 PM

Leibowitz-- I image using a dob, but of course it is driven. I think you will be very frustrated trying to do it by hand, check out this link for a very reasonable eq platform:

http://www.faintfuzz...ervingAids.html

Its near the bottom of the page. This is far cheaper than a Tom O platform, and with it given good seeing you could get superb results!

cheers

Mike

#16 Leibowitz

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Posted 28 January 2013 - 02:44 PM

Yes, I'm wondering how many frames you processed to get that image. Can I not let the object pass through the FOV, re-aling the scope to catch it again, and stack multiple AVI's together? Let's say for Jupiter and Saturn?

#17 pippo

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Posted 28 January 2013 - 03:03 PM

> Can I not let the object pass through the FOV, re-aling the scope to catch it again, and stack multiple AVI's together

It is what I do.

For the image, I staked 2000 frames selected among 5000 by pipp
https://sites.google...site/astropipp/

stacked with registax.

Obviously an equatorial platform is much more practical and allows for longer focal length than 4800mm and longer shutter time than 1/50 s. However you can also play without it in the beginning...

#18 Leibowitz

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Posted 29 January 2013 - 12:38 AM

How do you get 120 seconds of video? If you get maybe 10 seconds before Jupiter passes through the FOV, are you repositioning 12 times to get that many frames?

#19 pippo

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Posted 29 January 2013 - 03:27 AM

Yes more or less:
it takes about 10 sec, and I reposition about 10 times (some seconds are lost in repositioning Jupiter at the correct place).

#20 Leibowitz

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Posted 29 January 2013 - 12:26 PM

I won't be frustrated if I get images like that. I'm wondering if I can get similar results with a modified webcam rather than spending $300-$500 on one of the above mentioned cameras. I'm not sure I can justify spending that kind of money when all I can do is solar system imaging. I'd love to have it but surely there's a webcam out there that can get me close? I wonder if this would be a waste of time or not.

http://www.telescope...s/Orion-Star...

#21 bunyon

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Posted 29 January 2013 - 12:28 PM

The Microsoft life cam hd5000 goes for $35 or so and worked well for me.

#22 Leibowitz

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Posted 30 January 2013 - 03:53 PM

The reviews are mixed on the Orion, I'm not sure. Anyone know of any other webcams from recent history? I'm just looking for options. I'm going to make a purchase soon.

#23 pippo

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Posted 31 January 2013 - 02:08 AM

without drive you need a fast camera like the camera on ebay that I suggested you in my first post. It is cheap and fast.

#24 pippo

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Posted 01 February 2013 - 02:22 AM

Here is an other image of Jupiter + Europa taken on the 30th without drive on a alt-az manual mount a mak 7" and a firefly MV camera an IR filter and with a fair turbulence (pickering scale 5)
http://www.damianpea...m/pickering.htm

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#25 Leibowitz

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Posted 01 February 2013 - 04:34 PM

So, I guess that Orion camera is not nearly fast enough for unguided planetary imaging. I've re-read through your link about the camera in your OP. You've got me 98% sold. My only concern is the modifications that need to be done to it. I know absolutely nothing about photography. Your step by step instructions seem fair I guess. I've got to start somewhere.






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