Preventing SLR 'sag' - advice needed!!

[Beardy Bob]

Hi folks,

Now I've got used to taking astrophotos I've started going about 'fine tuning' the system. I have a 350d coupled to a Celestron 80ed via a t-adapter and 2" extension tube.

To cut a long story short, the problem I have is that the extension tube doesn't couple rigidly to the focuser and 'sags' slightly with the weight of the camera, causing star trailing in that corner of the image.

I haven't got much experience of different adapters and telescopes so I don't know what is at fault and what I can do to remedy this problem. Could my cheap extension tube and t-adapter be the culprit or is it that a more expensive telescope would have a better focuser and 'grip' the extension tube better?

[Merlin66]

Unfortunately not an uncommon occurrance!!

I have similar problems hanging heavy spectroscopes of focuser tubes..... my answer is to use a metal strap (25mm x 2mm) between the instrument and the piggyback camera adaptor. ( It also acts as a safety strap so the camera can't fall!!)

Others, I think, may have tried the new Hotech compression adaptor.

[Beardy Bob]

Hmm, thanks Merlin. I haven't considered straps and bands and the like, but it somehow doesn't seem 'subtle' enough for the amount of money everything costs! The added advantage of it preventing the camera from crashing unceremoniously to it's almost certain destruction if it slips from the focuser is quite an attraction though!

I'd like to hear from someone who has experience of using an expensive adapter like a hotech though if there's anyone out there...