first go at imaging saturn

Hi ALL,
I had my first go at serious planetary imaghing on Tuesday night (dec30th).
I got shots of saturn and jupiter using my 12" LX200 (F10) +flipmiorror + toucam pro. Jupiter was only ~5 degrees above horizon while saturn was within 1 hr of the meridan, what a dramatic differance it made. I didn't use an equatorial wedge, just used normal altaz mode.

I also had a look at the trapezium with the webcam and it was only then I realised that my collimation was slightly out (not noticable at the eyepiece). I was just about to correct it wheh the clouds rooled in, Murphys law. Next time I'll check it out on a star before I take anyshots.

I didnt use the barlow lens, but should have in hindsight, I generated a 70 frame avi file and used registaxs 2 to allign/stack and process. I also used photoshop to process (20 mins).
I wasn't going to spend to much time given that the collimation was out.



Look at the differance the atmosphere has on jupiter, It was so bad that I had to grayscale it.



This shot of the trapezium shows the mis-collimation.

Hi Dave,
Nice images there. I like the one of the Trapezium. Shows it up very clearly. Interesting how the collimination became more apparent via the webcam. Must try it some night myself.

I was also wondering what sort of magnification does the webcam create. When u see the image on the screen, what sort of magnification would u need in your scope to create something similar.
I tried to quantify the variables involved and came up with the following list:
--- Apparent size of image on screen - this is dependent of size of monitor, screen resolution etc
--- Distance from eye to monitor - typically about 0.5m
--- Apparent seperation between stars in image - can be measured from software such as Starry Night or actually measured by astronomers using various techniques such as CCD cameras etc
For my monitor, I have the following settings: 19" @ 1400 x 1050.
If I get a ruler and measure the distance on the monitor betwen the brightest star in the trapezium and the star to the left of it, I get a distance of approx 5mm.
I can now calculate the angular seperation of these stars in the image as viewed from 0.5m away. I get an angular seperation of 0.573 degrees.
(Circumference of circle with 0.5m radius = 2*500*pi = 3141.59 5/3141.59 = 0.00159145. Multiply this by 360 degrees to get the result)
The real seperation between these stars is 13.3 arcsecs = 0.2217 arcmins = 0.003694 degrees. www.laughton.com/paul/rfo/trap/trap.html
This implies a magnification of 472x....... 1 / ( 0.573 x 0.003694)
For a 12" f/10 as Dave has, this would require a 6.4mm eyepiece to produce a view of the trapezium of similar size.
Does all this make sense and actually give a correct answer? If there's any incorrect assumptions or calcs, I'd be grateful if you'd indicate them as it's a while since I did all these sort of maths!!
Thanks,
Michael

Hi Michael,
That sound just about right to me, funny how the 3 pics i put in here didnt come up, you can copy/paste the addresses shown in your browser to get them on screen.

Hi Dave,

I think you need to close the [img size=320] tag by putting [/img] at the end;



like this:

(no spaces)

You should be able to go back and edit your post and put in the missing [/img] tags. Use 'preview' to make sure it looks right before submitting it.

Regards,
John.

Hi John,
Thanks for that,
the modification worked

Tried imaging Saturn just now. Took an avi of 1500 frames @ 5fps. Did a quick process in Registax and the result is below. No idea why there's no colour. Will check out tomorrow when I'm AWAKE what caused that...must have done something silly


Michael