Can't focus with ED80 and Canon 700D

[Lukeness]

As the title says.

I have the canon 700D connected to an extender (forget the name) which i can put a lens in to increase magnification of the image taken and that fits into the eyepiece of the ED80.

So my question is, even with the telescope extended out and using the extender, I still can't focus in on a star. Is there a way around this? As it seems if I could move the camera back like 5cm I could get a clear shot.

Any help is appreciated

[ollypenrice]

What are you trying to image? Planets or deep sky objects?

If it's deep sky then the last thing you want is an eyepiece in the system or anything else to extend the focal length. This will slow the f ratio down disastrously. At native focal length the scope is already slow. In fact the best way to use the ED80 for deep sky is to fit the focal reducer / field flattener.

For the purpose of estimating the right place for your chip without any EP or reducer in the system simply put a tape measure at the objective and measure back to the focal length specified (ie 600mm) and that is the approximate position for the camera's chip. You'll probably need an extension tube since most refractors are intended for visual use and are short enough to allow a star diagonal to be fitted. These take up a lot of back focus which is usually replaced by an extension for imaging to avoid more optical surfaces.

Olly

[Lukeness]

I was trying to image Sirius and the Orion Nebula. I got them fine without the eyepiece fine.

[carastro]

Try just using the Canon and no extension pieces or extra lenses.  As Olly says you should not use extra magnification or this will extend the focal ratio and make data gathering much more difficult.

I don't need to put in an extender on any of my 3 refractors Olly.

Carole