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DSLR - Achieving focus


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I Know this is going to be no small question..

Which telescopes will allow the standard Canon or Nikon DSLR to focus satisfactorily out of the box without the additional cost of buying low profile focusers etc.

Edited by Tinners
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Skywatcher and Orion Optics Newtonians come with an adapter that enables you to screw the camera directly to the focusser in order to achieve focus. If you try to use a camera adapter by plugging straight into the draw tube using the standard eyepiece adapter, you can't reach focus then as the camera will then be too far out from the tube. Hope this helps.

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Just to add, refractors "normally" achieve focus without requiring additional adapters.

However in some cases, (The Skywatcher Equinox ED80 Pro for example), require an additional extender so that the camera is held further back in order to achieve focus without the star diagonal being in place.

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One Celestron refractor with R&P allows for the camera adapter to be screwed straight on the end of the focuser tube, and there is just enough length to achieve focus - my Onyx ED80 has a crayford, and it needs a 2" extender.

M.

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Thankyou for your comments.

What really puzzled me was the number of threads from people struggling to achieve focus using a DSLR.

Your saying this is far more likely a case of "user error" rather than the parts not physically able to achieve focus?

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If the telescope can't achieve focus, an extender will enable this. That is a different issue from people not able to get the camera into focus if everyting else necessary is in place. For that a focusing mask can help - these are available from people like 'Stay Focused', or can be home-made. There was something in the Sky at Night mag on how to do this a few months ago.

M.

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If the telescope can't achieve focus, an extender will enable this. That is a different issue from people not able to get the camera into focus if everyting else necessary is in place. For that a focusing mask can help - these are available from people like 'Stay Focused', or can be home-made. There was something in the Sky at Night mag on how to do this a few months ago.

M.

Not so with most newtonians which do not have enough inward travel on there focusers.

Tinners's I'm not sure about which ones work out of the box but I'm sure someone will be able to tell you.

Regards

Kevin

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Many threads with DSRL focusing issues relate to entry level Newtonians of 5" or less mirrior diameter. I have this problem with my Celstron Astromaster 130 and interestingly, so does my mate with a Skywatcher 130 which includes a camera thread on the focuser.

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Refractors are generally designed for visual use with a diagonal, so back focus is never an issue.

But reflectors are not. When trying to focus my DSLR on my 8" f5 it was very close and I managed to get focus by moving the main mirror up the tube using the collimation adjustments... For my 6" F5 I had to buy a new focuser.

Ant

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Sorry - I was thinking refractors. My Newtonian has the opposite problem, so I tend to forget. I can achieve focus with a DSLR, but not with an eyepiece - unless I use an extension tube. Can the primary or secondary mirror not be adjusted in some way that allows for focus with a DSLR?

I am surprised that the SW 130 is sold as suitable for prime-focus photography, including a thread for a T-ring, if it is unusable. Wouldn't that qualify as not fit for purpose? Mind you, if that were the case, I guess a fair bit of astronomical equipment would also qualify,

M.

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Hitting that sweet spot for absolute focus is a real problem, even if your camera can reach the focal point. You cannot always tell visually. Live view helps enormously, but pop a Bahtinov mask on the end of the scope while focussing and it really does make for pin sharp images.

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