How to achieve focus with Canon EOS400 and Skyliner 250px OTA ?

[Vega]

I'm planning ahead in my hopes to eventually have a setup capable of doing prime focus photography through a mounted skyliner 250px OTA. Having had a play with my Canon EOS 400D and 250px, I cannot get enough inward focus. Here's the 'bits' that I use

-Standard adaptor that comes with the skyliner to turn the large hole in the focuser to a 2" hole (why the focuser hole isn't 2" to start off with is anyone's guess)

-Canon T-ring with this SLR to 2" adaptor attached

-Then the obove slots in to the first one mentioned

Focus is just out, the culprit seems to be the 2" skyliner adaptor mentioned. It seems to raise everything quite a bit not allowing me to focus inward far enough. Has anyone else found a system that allows any Canon EOS to achieve focus on this OTA ?

Cheers

Matt

[FLO]

The Synta focuser has a Direct SLR Connection facility. Unscrewing and removing the 1.25" eyepiece tube from the black flange will reveal a T-thread which will accept a T-Ring for direct connection.

HTH

[Vega]

Duuuh... I never thought of that.. will have another play tonight, thanks Steve.

Vega

ps I sent a pm, you've probably guessed my plans for the winter period

[Ant]

Focus is just out, the culprit seems to be the 2" skyliner adaptor mentioned. It seems to raise everything quite a bit not allowing me to focus inward far enough. Has anyone else found a system that allows any Canon EOS to achieve focus on this OTA ?

Cheers

Matt

I had the same problem on my 8" Newt.

Steve is right you can use the direct connection - but you cannot then include 2" filters in the optical path.

There is a low profile version of the "2" skyliner adaptor " available. I know because I had one - I bought it from a guy at Kelling about 4 years ago (then foolishly sold it), I have been unable to find anywhere that sells them since...

Ant

[Vega]

Luckily, I tend not to use filters too often with the DSLR.. (My LP filter kills the colouring on my images and I get better results without filters, looking back, I bought the wrong brand/type but thats another story ). With the synta direct connection method, It's still a 2" hole on the focuser end right ?

Matt

[Ant]

I think it's bigger than 2" - so vignetting WONT be a problem.

Ant

[bern]

The restriction will be the inner part of the male T thread on the focuser, this is about 35mm so shouldn't be a problem.

I'm reliably informed that a certain astro retailer will have a solution to the filter issue for this configuration btw

bern

[Vega]

Thanks all, I haven't actually attached it all together but I took a look at the 1.25" holder that came with the dob. As Steve said, unscrew the 1.25" EP holder et voila... a T-ring compatible holder which will indeed hold the camera close enough to the secondary mirror to get focus.

Thanks again

Vega