I've dusted off the LX-90 with the arrival of my new Lepus 0.63x focal reducer. I trialed the setup on M8 (Lagoon) as follows:
Mount: Standard fork for LX-90, unguided.
Camera: Canon EOS 1100D (unmodified).
Imaging done with BackyardEOS v3.
Imaging consisted of bias and lights only at ISO1600 with 2s/5s subs. Total time is 11 minutes. FOV is 36.3 x 28 arcmin after my severe cropping. Up is -67.6 degrees E of N.
I admit to not spending much time on the processing (DSS/CS2), there is fainter nebulosity there, but I couldn't bring it out without burning out the core.
One issue was the limit in elevation; at most I can image up to 62 degrees- the camera, adapter and focal reducer stick out quite a ways. There is a slight curvature when you look at the flats, easily correctable with Gradient Xterminator (or flats) and I'm happy with the wider FOV! All I need now is to get a wedge and guiding system for longer subs!
Unfortunately the chances of the DSLR picking up any photons in 5 second subs is pretty low - not much higher than false signals from read noise sadly. If you could capture a couple of hours worth of subs you may be able to get a reasonable image.
Is there any chance of getting longer subs? Even going to 10 second subs would be equivalent to capturing 25x as many subs.
Go for 10secs and up your iso 3200 and run of some darks and see how it goes, your stars are round so you should be able to do it with ease. Your on the right track though and done your homework
Thanks for the comments. Yep, the exposures were too short- as evidenced by the individual histograms hard up to the left... Once I get the X-Wedge and an Orion 80mm ST for a guider, I'll aim for higher sub exposures.
There is an IIS member who regularly posts pictures taken with his 12" lx90, that is alt azimuth mounted , using exposures around 20 -30 seconds and they are very good. He uses 100's of subs. If you accurately align your telescope During setup you too should be able to manage such exposures at iso 1600. Your telescope has half the light gathering power of a 12" but you should still achieve some good pictures at those exposures.
Regards philip
I routinely image with my LX90 in alt az mode with 40 second subs after a good alignment process. I tend to do the standard alignment then do 3-4 more sync alignments in various points of the sky. Then before an imaging run I do two syncs on stars surrounding the object to be imaged. I use the focusing tool magnification function in BYE to accurately centre the objects being synced on. 40 second subs gets a huge amount more signal into your light subs. Even with poorer alignment you should be able to get up to at least 30 second subs unguided in alt az.
