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Old 02-09-2008, 12:45 PM
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kosh (Goran)
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New imaging equipment advice



Hiya all,

I was wondering if anyone can chip in with some advice.

I am looking to sink into astro-imaging (same old story) and I want to start with a DSLR and a GOTO mount such as a Skywatcher EQ6.
I'm not new to Astronomy, i owned a LX-90 with wedge and other bits and bobs, but just didn't get a camera suitable for imaging.

Is it possible via an adaptor or something, to mount a DSLR directly to a GEM mount with the lens on to take some nice 30sec plus exposure wide angle pics?
Also, what would be a good DSLR to get going with? I have looked at the 450D and 1000D, i don't know that much about SLR's , or would a 300/350D do the trick?
I would like to control it via a laptop if possible.

Any help appreciated.
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Old 02-09-2008, 01:34 PM
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RB (Andrew)
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Hi Kosh,

You can mount a DSLR directly to an GEM mount by using a dovetail type bar and a suitable bolt to hold it in place.
You would, as you know, first have to polar align the mount using a scope.
Also you can buy rings that would fit your scope and piggyback your camera/lens on top instead which would later enable you to guide your camera/lens using the scope and a cheap guide camera.

If you choose one of the new Canon models, (450D/1000D) you'll be able to use the live view mode for focusing which will be a big help.
Also these new models have 14 bit image processor over the other older models.
I'd probably recommend the 450D over the 1000D, since it has slightly better specs.

The 300D/350D are good but don't have the live focus capability but they are relatively cheap now as you can only buy them second hand and you can use software like DSLRFocus to control them (up to XP SP2) or you can use ImagesPlus as well which supports Vista.

If these were my choices I'd go for the 450D and some good lenses.
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Old 02-09-2008, 02:28 PM
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kosh (Goran)
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thanks Andrew.

So i definately need a small scope to do a polar alignment? I can't use a polarscope built in to the mount? If i Had to maybe an ED80 or something.

Do you happen to know the maximum exposure time for the 450D and how do you control that camera? Does it have included software for remote control or via the programs you mentioned below?

To begin with, i just want to do rough alignments and experiment with whatever results i get, then upgrade as i can afford to but i don't want to have to rush out and buy another camera anytime soon. That's also why i want the SW EQ6 GT mount.
Can i get some nice pics just using the lens and maybe a small refractor?

I hope i doesn't sound like i'm bombarding you with questions!
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Old 02-09-2008, 03:02 PM
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Quote:
Originally Posted by kosh View Post
So i definately need a small scope to do a polar alignment? I can't use a polarscope built in to the mount? If i Had to maybe an ED80 or something.
You can use the polarscope and it will get you fairly close but for accurate alignment you're best off drift aligning using a scope.
An ED80 is perfect and later you'll be able to use it to image through as well.
But to start with certainly just using the polarscope to align will do for widefield shots through your DSLR and lens.
Quote:
Originally Posted by kosh View Post
Do you happen to know the maximum exposure time for the 450D and how do you control that camera? Does it have included software for remote control or via the programs you mentioned below?
On it's own the camera can do 30 sec max.
If you put it in Bulb/Manual mode it will expose as long as the cable release is held down. This is a cable you connect to the camera to operate the shutter for long exposures.
The new cameras have software included which allows you to focus and control the camera exposure.
The camera is conected to your laptop via USB.

The older models don't so you'll need third party software like the ones I linked to, for control and/or focus.

Quote:
Originally Posted by kosh View Post
To begin with, i just want to do rough alignments and experiment with whatever results i get, then upgrade as i can afford to but i don't want to have to rush out and buy another camera anytime soon. That's also why i want the SW EQ6 GT mount.
Can i get some nice pics just using the lens and maybe a small refractor?

I hope i doesn't sound like i'm bombarding you with questions!
You certainly can get very nice images with this sort of setup and it's highly recommended you start off this way and then add equipment as your skills progress.

Feel free to ask anything you need advice on imaging, there's a lot of people on here that have gone through the same learning experience.

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Old 02-09-2008, 10:53 PM
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Quote:
Originally Posted by RB View Post

On it's own the camera can do 30 sec max.
If you put it in Bulb/Manual mode it will expose as long as the cable release is held down. This is a cable you connect to the camera to operate the shutter for long exposures.
The new cameras have software included which allows you to focus and control the camera exposure.
The camera is conected to your laptop via USB.
So does this mean that even the newer cameras that ship with software like the 450D are still limited to 30sec exposures when controlled through a laptop without a cable release or is this meant more for the older models?

Also Nikon D40's are going cheap. Any ideas on this camera with astro-imaging?
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Old 03-09-2008, 03:04 AM
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Quote:
Originally Posted by kosh View Post
So does this mean that even the newer cameras that ship with software like the 450D are still limited to 30sec exposures when controlled through a laptop without a cable release or is this meant more for the older models?

Also Nikon D40's are going cheap. Any ideas on this camera with astro-imaging?
I haven't had hands on experience with the 450D's software but I believe you can control it via laptop USB in Bulb mode to go longer than 30 sec without the need of a cable release.
It's the older models that need the cable release and 3rd party software.

There's an IIS member, Matty_P, that has a 450D, perhaps you can send him a private message and ask him about the 450D.

As for the Nikon D40's, they are a good camera for terrestrial but I've not seen many use it for astro and from memory I recall they weren't as popular as the earlier Canons for astro type work.
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Old 04-09-2008, 05:02 AM
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If you are going to use the polar scope, get an inclinometer and compass and you should be within 1/2 degree to start with.

I don't know how accurate or easy the EQ6 polar scope is to use but even the best ones are limited by the faintness of Sigma Octans (if they sight on it).
If they don't use Sigma then they are not going to be very accurate.

At 1/2 deg polar misalignment and 30sec exposures you shouldn't see field rotation and you could probably get usable data with up to 100mm focal length lenses.
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Old 04-09-2008, 12:47 PM
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kosh (Goran)
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cool thanks guys. I think i might send matty a message.

yeah i suppose i don't know how good the skywatcher EQ6 polar finder is either but it's only temporary and as you say, short exposures only.

Well i'll keep hunting around. A friend of mine knows a fair bit about photography and SLR's and he says that i probably wouln't know the difference between 10mp and 12mp. He only does terrestrial photography though.
Would I notice a difference when astro-imaging between say the 400D and 450D? i'm not sure how all this works. Is it more sensitive or just a larger image?

Cheers.
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Old 04-09-2008, 02:04 PM
DeanoNZL (Adrian)
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Kosh,
The 450d uses the DIGIC III image processor & can be USB controlled for longer than 30s.
I would not rely on the polar scope being aligned in the mount axis correctly from the factory. The eq6 Yahoo group is full of stories about it. Needs to be done if using it, otherwise hair-loss results.....
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Old 04-09-2008, 05:22 PM
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If i were you I'd go the 450D.

Keep in mind the standard lenses that come with the cameras are pieces of junk... and getting a good quality lens for astrophotography is recommended.

I polar align using my EQ6's polar scope, then using my telescope, drift align to get as close as possible to the SCP.

Using a shutter release on my 350D i've taken a shots at nearly 4 minutes without guiding...
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Old 05-09-2008, 12:51 PM
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kosh (Goran)
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thanks for your replies everyone.

I've d/l the manuals from canon and i'm reading through those to get an idea of their capabilies.

I think i'll go the 450D though. I can only afford the standard lens though as i'm only going to use the lens on until i get an OTA that i can shoot through and for family snaps.
Other than that, now i just need a good price and some more money!!
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Old 05-09-2008, 12:55 PM
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Quote:
Originally Posted by kosh View Post
thanks for your replies everyone.
I think i'll go the 450D though.... , now i just need a good price and some more money!!
Check out d-d photographics, they have a great range of products and great to deal with.

http://www.d-d-photographics.com.au/canon450d.htm
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