Primary Mirror and DSLR Prime Focus

[Keithp]

Hello all, just doing some tests over the weekend with the new kit, it all hooks up okay but looks like I've got the primary focus problem.

Skywatcher 250px + Canon eos 500d.

I found that removing the 2" to 1.25" adapter and putting the camera up to the focuser with it fully wound in I could achieve focus on some trees about 250/300 yards away. I've read elsewhere on this forum it's possible to move the primary mirror up the tube. Looking at the amount of travel I need, at the focuser end of things, it appears to be about 6.5mm (1/4"). Does this correspond to the amount I need to jack the primary up on it's adjusters or is it a case of trial and error?

Ultimate solution is to get the low profile focuser...but I did'nt want any more rain/clouds down here in Somerset;)

Regards

Keithp

[Merlin66]

Yes, is the basic answer, but I'd allow a bit more just to give some allowance for the T adaptor and some focussing, probably 10-12mm.

[Keithp]

Cheers Merlin, I'll try that when I get home tonight.

Regards

Keithp

[Keithp]

Don't work, one of the adjusters sprung off the thread before I could get the mirror far enough up the tube. Temporary solution after I got the adjuster back on... I connected the camera to the t peice adapter and fitted this to the 2" eyepeice holder, I found I could get focus on the trees about 250/300 yards away.. of course I don't know how this translates to looking at stars, the moon etc.

Is it possible to remove the primary mirror cell and replace the threaded rod with longer peices of thread? I know the local hardware store sells threaded bar. Not yet taken the primary mirror cell apart.

Another posibility is this

Adaptors - Max DSLR Camera Adaptor

If I used this straight on to the focuser where the normal 2" eyepeice holder goes it would get me at least 2" closer than what I can achieve now, allowing me a fuller range in the focuser.

Any advice greatly received.

Regards

All

Keithp

[Keithp]

Anyone?

Thinking of sending off for the DSLRMax thingy, hopefully to get it before the weekend...weather looking better.

Regards

All

Keithp