Beginners slr advice

[Stu Ward]

Hi

Tried out some moonage last night with my 8" dob and a 550d Attached via t- ring.

I found it really difficult to achieve good focus and ended up snapping blind really.

Any tips on how to achieve good focus ?
I've had much better results using a very old 2mp nikon camera that can autofocus through an eyepiece adapter !

Thanks

Stu

[ZeroID (Brent)]

Yep, not an easy task for sure. Do your best via the view screen or eye viewer, take a shot then inspect it on screen, magnify. Try again after minor adjustment, repeat and rinse. Lock the focusser if you can when you get it right.
My focusser now has a wee marker on the barrel to indicate correct position but you stil have to tweak it each time.

[graham.hobart (Graham stevens)]

I use a Canon 1000d and if yours has live view or even USB connection you can use a natty software programme called 'Astrophotography Tool (APT)- it's really easy to use the live down load and programme features to programme a run of say, 5 sec exps for deep sky, then use them to focus on. Course it means lugging a laptop outside! Of r the moon you could use much shorter exps and twiddle with the focus then.
It works on all EOS cameras. www.ideiki.com/astro/
Graham

[Davros (Lauren)]

Can you reach focus with the DSLR on the dob. A lot of dobs require the tube to be shortened or primary mirror moved to be able to achieve focus.

[Stu Ward]

You can use the skywatcher 1.25 ep adapter base that screws into the t-ring therefore being just short enough !

[mangrovedutch (Dutch)]

Live viewand magnify is the best option.

Dutch

[graphworlok (James)]

I could not obtain focus with my EOS40D and 8" newt - the DSLR sensor is set a fair way inside the camera. The only way i managed was via using a barlow - apparently they change the focal point. This increased the already noticable shake from my EQ3 so that attempting any images was pointless. Even moving the primary mirror as far up the tube as i could was no help.

[ballaratdragons (Ken)]

When I focus my Canon 350d I connect to the laptop, open up a capture program (I use ImagesPlus), open the Focus Tool window and I set the image time to 2.5 seconds.
Then I let the camera repeatedly snap away, and I focus the images as they come in every 2.5 seconds.
The ImagesPlus Focus tool has a graph showing when you are at best focus.

If you don't have ImagesPlus, or a Focusing tool, just take an image repeating automatically every 2.5 seconds to get a nice image to focus on.

I think most capture programs allow you to download an image automatically repeating.

[joecool (Mark)]

Look for "Super cheap Bahtinov mask cut for you. Choose from MDF or Acrylic" in iceinspace classifieds. I think this link may work http://www.iceinspace.com.au/forum/s...light=bahtinov

Then use a program called bahtinov grabber (free). http://www.njnoordhoek.com/?p=330#comments

I have 2 of these and they are sweet! I got the acrylic ones and attached 2 green wall plugs to each to hang them off the scopes. Take your measurements carefully for the sizes, but once you have them centering them is not critical. Don't forget to remove them before slewing!!! hahaha done this!

Mark.