Jump to content


OAG & DSLR combination with SCT experience


Recommended Posts

Hi All,

I was hoping to find out if anyone is using DSLR & OAG combination with a long focal length SCT in a heavy light polluted area (I live in London so that's the mark)

How easy/difficult will it be to find a guide star if i choose to use a lodestar x2 or any other super sensitive guide cam?

What is the maximum exposure i should expect before light pollution kicks in? 

Thanks in advance

Link to comment
Share on other sites

I used to use a similar setup with a Celestron C8 SCT and Lodestar guider just north of Manchester, looking south over Manchester. Light pollution was fairly bad. However, by looking at medium to high altitude targets I managed some decent photos. If it gets really bad you can always try narrowband imaging.






Link to comment
Share on other sites

Previously when i was looking at the OAG option (earlier this year), i was in a massive pain on trying to get the OAG fit in within the backfocus range but since then we now have the luxury of multiple spacer combination to ditch the Celestron T-adapter (which is 48mm) and use the spacers in multiple combination instead (I hope i've got this right)

Some people say it's absolute pain in the back side to get guide camera and DSLR to come in focus when using OAG, some say it's a breeze. Not sure what to believe lol

So i'm still here, trolling the possible avenues ... the only hurdle for me is to figure out how bad the light pollution will react to my imaging and finding guidestars in heavily light polluted area

Link to comment
Share on other sites

Getting them both to focus is a pain at first.  I'm a slow learner and I've tried and then ditched OAGs, but I'm back with them now in the shape of the new Celestron OAG. This is a very substantial and well built unit with a good helical focuser on the guide port. I'm rooting for it and want it to work!  I'm imaging at over 2.1 metres and so far in most situations I've picked up a guide star.  There's not much of a problem if you aim high.  I'm doing narrowband at the mo and using a ZWO as the guide camera.  I should add the Celestorn OAG is very nice - but with a focal reducer, Atik + filter wheel + spacer I come in over the recommended back focus distance of 105mm. (mind you images look ok to my eye).  But there are ways to fit in a Canon using slimmer adapters.  

Set up your guider in the day and try and to be logical in measuring the distance of the optical path between guide and main cam using spacers where necessary.  Then set focus with each - main camera first - and leave the guide camera alone after.   Good luck.  It's probably worth it in the end.



Link to comment
Share on other sites

That's what a Nikon spacing should look like to get the guide cam same as Nikon, but will vary for different guide cams I guess. That's the ovl oag from Flo, the stalk in as far as it goes without blocking the Nikon sensor and the  guide cam mount butted up against oag for extra rigidity.


Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.