First bash at Saturn with a Phillips SPC900NC webcam

I picked up a SPC900NC webcam and an adapter from ebay after doing a bit of reading on webcam imaging. (Excellent overview here: home.versatel.nl/m.m.j.meijer/D_I_Y/spc900nc.htm ). The adapter has threads so I added a Badder IR/UV filter.

I had a heck of a time trying to get a sharp image as the non-stock Revelation focuser on the SN10 was either too close to the secondary without an extension and too far from the secondary with one*. I suspect I need a focal reducer - can anyone comment? The only thing I could do was to raise the 1.25 inch adapter a little and tighten down the retaining screw on the focuser which is not ideal. Seeing was ok but a bit misty.

I took 7000 frames of video using wxAstroCapture , I had previously discovered that if the sample format isn't changed to RGB24 from YUV420 Registax will crash out (running it in Debian Linux under Wine) but I didn't know there was a file-size limit - more on this later. My initial test capture was 7000 frames** at 33 frames per second with the gain set as low as possible. Tracking wasn't too bad on the LXD75 though I think it needs some more work or possibly a less hefty OTA.

Registax crashed out when I tried to feed it the one-point-something gigabyte file so I copied around 600 frames into a separate video. I'm still quite green on all of the features available in Registax so I didn't play around with the processing too much.

Anyway, to get to the point, here's an image based on the 600 frames, not wonderful but a good start I think for about £50's worth of 'imaging hardware':



If anyone has any comments or questions (or admonishments) I'd be glad to hear them.



* I suspect that the rather poorer stock focuser would not have been able to place the sensor at the correct focal distance at all.

** No specific reason for choosing 7000 other than I didn't want to rely on the mount for more than a few minutes, the polar alignment scope wasn't properly centred at the time so I didn't get a good fix on the celestial pole.

I am not familiar with ccd for imaging.
But I think you did well with this image and captured ring detail.
Very well done..

Second bash, same camera mounted on the Intes MK-67. Saturn was around 15 degrees above the horizon, seeing was terrible thanks to looking through the murky city air and spotty cloud. For some reason there was far more chromatic aberration with the camera than with the diagonal and eyepiece so I'm wondering if collimating with the diagonal is a good idea. Here's the result of stacking 2000 frames taken at 5fps:



I probably should wait until I get to a better site but enthusiasm gets the better of me.

Hey Martin.
You really need to be imaging saturn when its abit higher off the horison then that, also you really need to visually check the collimation without a diagonal visually,
The image looks a lttle ober exposed, maybe next time, reduce the exposure and youre discovering like the rest of us, focusing is everthing.
I have to say I dont see alot of chromatic abberation in your image.
I'm adapting my MK67 for lunar imaging and will give it a go this week, I find the image scale for the planets very small for imaging, a barlow is a must for this scope for imageing..
Also, get better results at somethinbg like 15-25 fps as it has a way of freezing the seeing. At 5fps, each frame has a chance of been smeared by the seeing.

That's a fine first attempt at Saturn.
Saturn is an amazing object to observe and image.
If you can increase the magnification, you may find it easier to capture more detail in the rings and balance the contrast.

Michael.

Many thanks for the feedback everyone.

Dave:
I must admit that I didn't want to stay up past midnight, Monday being a 'school' night , so I limited myself to 9-12pm (two hour cool down is recommended for the mak, I'd set up at around 7). I'd started imaging as an after-thought - I'd been reading up on collimation technique prior to buying the scope and got conflicting views on diagonal versus straight-through collimation. One camp made the assumption that if the observer will be using a diagonal then the scope should be collimated with it in place. I think a bit of experimentation is called for.

I found focusing the camera to be tricky, the OTA has a crayford but no fine focuser, it was hard to determine if adjustments were making any difference on the laptop screen.

As for the frame rate, I tried to balance the amount of noise I was seeing at higher capture rates with my perception of how clear Saturn appeared to be. I generally have a play with the manual controls in wxastrocapture as I've read that underexposure is preferable to overexposure but I seem to have missed the optimal exposure in this attempt. I think I'll aim for higher frame rates next time.


Obviously I'm probably not doing any of this in the most optimal way but I'm hoping what I lack in skill can be offset with enthusiasm.