Its just not working

[rgb (Russell)]

Hi

I'm guessing I am doing something very wrong, it would be appreciated if any one knows what I may be doing wrong. Attached is the picture I get - It's essentially the tube and secondary mirror...

I have a 10" reflector. I am connecting my Canon 450D with an appropriate T-ring and a Hotech 2" adapter.

Thanks in advance.

Russell

[omegacrux (David)]

Hi Russell
Try without the adapter
Might be worth a try
My t-ring screws straight to the focuser and achieves focus

David

[Tony_ (Tony)]

Hello Russell,

I image with an SCT or refractor so I'm not sure - but I think that is the collimation pattern of an out of focus reflector.
So you will need to adjust your focus (like David advised).
Also I think the collimation pattern should all be centered - so your collimation is out? You can search how to collimate your scope.

Regards,
Tony.

[RobF (Rob)]

Would be helpful to see the camera in your focuser and what type of scope it is Russell? Reaching prime focus is a right pain in many standard reflectors without moving the mirror up the tube, changing focuser, or shortening/removing an adaptor at your focuser.

You're definitely not there currently though, and you do need to work on your collimation. You can work on prime focus during the day by pointing it all out the window at a distant object too by the way.

[Jon (Jonathan)]

Hi Russell,

Your problem is achieving focus. There may well be issues with collimation, but they are not important right now.

With many reflectors, it's not possible to get focus on to the sensor of your camera with the standard amount of travel allowed by your focus mechanism. The chip in your camera sits too far back.

The solution is to get your camera closer to the primary mirror. As has been suggested above, see if you can do without the adapter. I made mine work by getting some long screws that hold the camera in place directly in the T-ring. Very dodgy, but it works!

Alternatively, you may have to move the primary mirror up the tube a bit (1-2 cm). This sounds scary but with some scopes can just be a matter of replacing the bolts that hold the primary mirror in place with some longer bolts - just $3 at Bunnings.

There are lots of threads on this on the forum, if you search for "Newtonian camera focus" or similar.

[doppler (Rick)]

I have a 200mm f6 1200mm newtonian and had to move the primary mirror 50mm up the tube to achieve prime focus with my dslr camera. But I now need to use an extension tube with my eypieces for visual. Before I moved the mirror I could get focus with the camera using a 2x barlow lens.... but it made the scope 200mm f12 2400mm ok for the sun moon and planets but a bit slow for deep space.

[rgb (Russell)]

Thanks for the advice!! I have a few things to work on and it sounds like its the focus and then maybe collimation. I tried to have a play tonight but I live near the city in an apartment and just don't have enough room to test it here. I'll have a play with the T-ring/adapter, failing that I'll getter some larger bolts and try bring the mirror forward. It might be a week or so but I'll post how it goes. Thanks!!!

[Garbz (Chris)]

Originally Posted by Jon

The chip in your camera sits too far back.

Or too far forward which is the issue I had.

Originally Posted by rgb

Thanks for the advice!! I have a few things to work on and it sounds like its the focus and then maybe collimation. I tried to have a play tonight but I live near the city in an apartment and just don't have enough room to test it here. I'll have a play with the T-ring/adapter, failing that I'll getter some larger bolts and try bring the mirror forward. It might be a week or so but I'll post how it goes. Thanks!!!

To identify what you need take your scope somewhere where you can see something far away. Can you see mountains or distant buildings from your window?

During the day set the focuser at one end of it's travel and then hold a white card up to the back of the camera and move it back and forward until the image is in focus. Measure the distance of focus, and then adjust your focus the other way and repeat. That will tell you where you roughly need to be between.

[Jon (Jonathan)]

Originally Posted by Garbz

Or too far forward which is the issue I had.

Oh, yes indeed, it can be that way around. But that's much easier to resolve - just get a 1.25" extension tube that fits in the eyepiece holder, into which you fit the camera.

If the camera sensor is too far back to achieve focus, then you have to get it closer somehow - which in a Newt means moving the primary mirror up the tube.