SC2 Focus Issue

Been incredibly clear and dry in North Carolina last several days. Great planetary imaging. Bad for getting up early for work...

Image train: LX200GPS 10"/moonlight focuser/SC2/FW8/STF8300M.

Using Maxim for imaging.

No issue at all getting sharp focus on the STF8300M. got some great shots of Saturn, Jupiter, Mars, and the Moon.

For some reason I can not get a crisp focus on the SC2. Shot the moon just off the terminator, tried to focus the SC2, and got really grainy - like barely (and really barely) recognizable craters. About a .01 exposure with an O III. The other filters, even at short exposures, of course, too bright, even at terminator. Autodark on, manual exposure setting.

Moved to a very star rich portion of the sky. Again, able to sharply focus the STF, but not the SC2. Had barely recognizable stars (grainy blobs at best, and only really appreciated at x200 in Maxium) with up to 30 second exposures, autodark on. Played with the exposure in Maxim (low, med, high, manual), and manually trying to focus the SC2, but never really got centroids.

30 seconds of course is a long time to try and focus something and wait on the feedback of better or worse.

Any thoughts or ideas on how to get better focused centroids for tracking?

 

That helped - a lot! There was a small bit of plastic. Still having issues with trying to get effective stars to guide with to show up on the sensor, which is messing with trying to get tracking established, whether as camera 2 or by trying to use the AO8.

I have the pickup mirror all the way in, but only get star images along one side of the sensor.

Despite having the image sharply focused on the STF8300 sensor, the central mirror is seen on the SC2 image, which can only be slightly reduced by adjusting the SC2, but never really goes away, so no good centroid.

I can start to get stars at 5 second exposures, again with a central dark spot, longer exposures - which make focusing challenging of course - brighten the stars, but still doesn't remove the central spot, so no effective centroids.

I'm wondering a bit if it's an image train/vignetting thing? the whole train is LX200GPS/Moonlight Focuser/Nosepiece/AO8/SC2/FW8/STF8300M.

Also wondering about the settings in Maxim DL, particularly the stretched view setting, plus the time of exposure?

And finally - is the light supposed to go on and stay on on the AO8? It clicks on then immediately off when I plug in power, but then never goes on again - even when I try to calibrate it, where I can hear the motors moving.

Thoughts? Really appreciate the help here. Been able to figure a lot of other things out, but this seems to stymie me.

 

Thanks Doug, good to know. So used to the light on the STF and the SC2 staying on and thought the AO unit would do the same.

f10

 

It’ll be next week - but will do

 

Oh and thoughts on how to shorten up from the t thread? Not sure how else to connect to the scope or at least nothing comes to mind.

 

If that's a 2.5"CFL moonlight the adapter is easy and the best solution, a 68mm to stl adapter from moonlight, threads right in to the AO-8. This is what I have and do.

 

Mike - thanks for the input - it's a 2" on the back of at 10" Meade, so unfortunately loses the extra 0.5" diameter.

 

Doug - here are the FITS files. a combo of 5, 15/15 auto dark, 20 second auto dark, plus 5 second from the main camera.

Have to look pretty hard on these JPEGs to see the star, but the only really visible one is the mid bottom of each image.

Can get really tight focus on the STF, but as you can see in the FITS - the one and only star the device can see is poorly focused. No matter how much I adjust the exposure time or try to manually focus the SC2, I get the same kind of thing. Really bright star and sort of an image.

I have double checked to be certain the SC2 is all the way out, and I can see it clearly (plus the reflection of the ccd) down the adapter.

 

How do I do that? the postings only let me upload jpg/png

 

Here is the STF8300M 5 second exposure

 

in order: 5 second, 15 second, 15 autodark, 20 second.

 

It does - just included the raw (non dark subtracted images) - you've identified my issue. Despite the main camera being in focus, the manual focus on the SC2 never really reaches focus, and the star images (if they don't have the central dark spot) are only half images. If I do focus it (assuming I can actually see stars in the image), then the main camera is out of focus. I'd be happy with a medium between the 2.

I can hear the shutter open and close (and see it), it looks like it opens fully.

So thoughts?