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Old 08-07-2008, 09:01 AM
TrevorW
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Eyepiece Projection

Advice sort on best T-adapter to buy for eyepiece projection of planets. Make and who from for best price??

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Old 02-08-2008, 08:03 PM
TrevorW
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Hey 137 looks later ad still no advice come on hard hard could this be ????
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Old 03-08-2008, 11:35 AM
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Bellbuoy (Peter)
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T Thread adapter

Try Matthew Lovell at Telescopes and Astronomy (South Australia). He's always helpful and prices are pretty good.
http://www.telescopes-astronomy.com.au/
I bought an aluminium T Thread adapter for a Philips webcam from him recently. I screwed it onto a camera adapter that I bought secondhand with my scope.
EP projection was a little tricky to set up because the adapter shifts the EP away from the normal focal point. I'm using the standard Skywatcher 10mm Plossl with an SPC900NC and getting a similar effect to a Barlow. With a 20mm EP I get about the same magnification as at prime focus.

Kind regards,
Peter
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Old 06-08-2008, 07:00 PM
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Merlin66 (Ken)
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T thread to 1 1/4" Baader adaptors

http://www.iceinspace.com.au/forum/s...ad.php?t=34450

They also do an adjustable version, just right for your needs.
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Old 12-08-2008, 01:50 PM
TrevorW
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Ok brought and adapter from MAS used three different EP's with it the camera etc on my ED80 couldn't get anything to come to focus

Help ideas suggestions anyone !!!

Thanks
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Old 12-08-2008, 02:59 PM
bato (Luke)
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Trevor, I only just discovered that my T-Adapter would accept an eyepiece for eyepiece projection. I tried it out the other night on the moon and i just looked through the viewfinder of the camera to get it to focus. It was no where near where it was when using the scope in prime focus (ie. with no eyepiece) but it wasnt all that hard to find. It was actually closer to where it would have been if the diagonal was fitted. There seemed to be quite a bit of range where it was in focus.
To get a more acurate focus Im sure that hooking it up to a laptop would help.
Just for reference Im using a 90mm f10 refractor and Canon 400D.
Hope this helped a bit, otherwise Im not sure.

Luke
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Old 12-08-2008, 04:19 PM
TrevorW
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Luke I'm using a f7 80ED which has 70mm of focuser travel and the MAS adapter can be adjusted by another 50mm, even after a lot of fiddling the only way I could get anything to focus was holding the camera another 50-100mm back by hand. Can't mount in a diagonal just to cumbersome. Wouldn't have thought I needed so much back travel to focus.

Thanks
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Old 12-08-2008, 07:43 PM
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Hi Trevor,

One of these might do the trick for you. I picked one up earlier in the year when I purchased some other items from this seller. From memory, it was only about AUD$ 15 delivered.
http://cgi.ebay.com.au/T-to-T-telesc...713.m153.l1262

I purchased for eyepiece projection pictures of Saturn and Jupiter using a DSLR (and comparison to my beginner webcam & Meade DSI efforts with barlows).

Have not used it yet ... still waiting for clouds to clear!

Cheers,
Jeff
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Old 13-08-2008, 10:06 AM
TrevorW
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Jeff the MAS adapter I have accepts the eyepiece thanks anyhow the problem I think is back travel, how much distance from the EP to camera CCD is required to achieve focus.

If the EP is a 20mm then the FL of the EP is 20mm so I would assume that amount of back travel (approx) is required to bring the EP to focus then the image that is projected onto the CCD should be in focus.
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Old 15-08-2008, 09:30 AM
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Bellbuoy (Peter)
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Trevor
You might care to check out my post #19 under the thread "CCD Imaging Advice" (sorry, don't know how to make a link on this system). There are some photos of my setup for prime focus and EP projection with a webcam on a small Newt.
I think the idea is to keep the camera close to the EP and move the combination away from the prime focus point (in or out). Don't try to focus the EP for visual first. It's like the camera is wearing the EP as a corrective lens. You don't need to focus a pair of glasses to see through them. I did a Google search on eyepiece projection and came up with a diagram (attached) which made things clearer (no pun intended).
In my case I often remove the eyepiece holder and screw the camera adapter directly onto the focuser. This is a bit awkward because I have to turn the camera as well. This gives me more range of focus outside the prime focus point.
Attached Thumbnails
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Last edited by Bellbuoy; 15-08-2008 at 02:06 PM. Reason: correction
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Old 15-08-2008, 11:54 AM
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Hi Trevor,

I agree with Peter's explanation.

In other words, the focal length of the eyepiece (eg. 10mm or 20mm) is actually the distance of its focal point towards the primary mirror. ie. the focusser needs to be moved in/out so that this coincides with the focal plane of the primary.

The light cone emanating from the eyepiece is fairly parallel (and how far it remains crisp for viewing/imaging is "eye relief", typically about 10 to 20mm). That's my current understanding anyway.

Cheers,
Jeff
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Old 15-08-2008, 08:14 PM
TrevorW
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In the MAs adapter I have the clostest distance from the eyepiece to the CCD would be approx 70mm
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Old 15-08-2008, 10:00 PM
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Distance which I have from eyepiece (with eyecap removed) to CCD is 25mm (37mm from CCD to camera front minus 12mm which the eyepiece potrudes from the T-ring face). I suspect the eyepiece projection adapter you have is a bit different than mine (see photos below).

Hope this helps.
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Old 03-09-2008, 03:57 PM
TrevorW
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Sorted the problem with a 2" and 3" extension tube from Bintel

Cheers.
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Old 03-09-2008, 10:02 PM
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Good stuff Trevor.

Still have not tried my projection adaptor for planetary pics ... having too much fun with widefield DSOs at prime focus.

If you get some focussed Jupiter shots, would be interested to see.
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