Latest Saturn shots - 14/12/2004

[iceman (Mike)]

Hi guys.

Got up early this morning (bit after 1am) to do some webcam imaging of Saturn, figured the skies would be clear after the storms went through and was hoping for some good seeing.

I didn't get the seeing I was after though, it was pretty darn average actually with the image swimming about badly.

It's still reaaaaally frustrating doing this stuff with a dob and no tracking, but I got a bit better at it today by getting the finderscope alignment more accurate, and my recent changes to smooth the az motion of the base helped too.

I spent more time getting the focus right with the hartman mask today, by using one of the gemini twins as my focus star and getting it pinpoint before moving back to saturn. It's hard even doing that though, with the star moving out of the FOV in 10 seconds I don't have long to get focus right, and the image shakes about when I turn the knobs because it wobbles the OTA. I guess the moonlight focuser will help

I tried at f/5 first but the videos were garbage. Some of the f/10 ones were better, and a couple are worth posting but i'm not sure if they're any better than my previous attempt.

Here's one I tried in black and white capture mode.. 5fps, 0 gain, 0 gamma, 50% brightness.

Stacked about 200 / 400 and processed wavelets in registax. Crop in photoshop.




And here's a colour version, similar settings and similar number of stacked frames.

I'm not happy that I didn't get much detail on the planet or the cassini division (I'll blame this on the bad seeing), but i'm kinda happy that I was able to get rid of the shaking that made a wobbly cassini division last time by ensuring that the scope had settled by letting the object drift into the FOV before I started recording.

Thoughts and comments appreciated!

[Mick (Michael)]

Love the B&W keep up the good work Ice.

[rumples riot]

Very good, great improvement and you can see the cassini division in both shots. Now your starting to cook with gas, I'll be coming to your for help when I can get some Saturn shots. I will try to do some processing on those shots for you and see if I can clear them up. That is if you don't mind.

Paul

[rumples riot]

sorry could not do a lot and did not improve upon your orginal efforts. Thought I might be able to clear it up a little. Still these are great shots. Want to see more of these from you and I am sure that you are now going to get better and better.

[Vermin (Tom)]

You must have better eyes than me RR, I can't see the Cassini div in either shot, just one ring.

Being at a fairly low altitude wouldn't have helped the seeing at all.

Good stuff, keep 'em coming iceman!

V.

[mch62 (Mark)]

Getting ther Ice.
First and very importantly is your scope well colliminated.
Hi resolution shots require the very best incollimation to get good results.
Low power stuff and visual viewing you can get away with a moderatly aligned scope.
But you need to have a Newt as good as possible includeing focuser alignment especially in faster newts.
Also you need to use only shots from the centre of the FOV as coma will degrade images from the outside of the Field.
In a fast scope you only have a few millimeters diameter in the middle that are concidered coma free. The longer F no the bigger that spot gets and the more forgiving on imaging.
So that's one reason you see long F6 + newts.
It may be all that is stopping even better shots.
Can you take an inside and outside of focus shot of sirius for me(like in my review) and send it via e-mail to see what your alignment is like. You can make it a large file size in the e-mail.
Use a 2 X barlow to get high power with the web cam for the test and turn your focuser in and out to get a similar result as in the review.
Again try to use only the centre of the field in the test.
If while doing the test you move the star to the outter part of the field have a look at what it does to the image circles and you will know what coma is all about.
I have tried over the past few night shots of Saturn but turbulance in the atmosphere has been bad with the heat and viewing hindered with dew. my shots did not turn out much better than yours.
It can be frustrating but don't give up, you will crack an excellent image soon.
Tell me when you extract all the frames are any much clearer than others as they drift across the FOV?
Mark

[iceman (Mike)]

Thanks for the comments guys and all your advice Mark..

1. I'm not sure if my collimation is spot on, i'll take a video of an inside and outside focus sirius tonight once it rises, but it won't be too high.. maybe i'll try canopus as it'll be a bit higher.

2. I don't have the luxury of only using the middle of the FOV, because I don't have tracking. With a 2x barlow, the object drifts out of the FOV in around 10 seconds, so I basically have to start recording once it's fully in the FOV and stop recording before it hits the other edge. If I only used the middle, i'd be lucky to get 5 seconds worth of frames and it'd take my 20 joined videos to get enough frames to reduce the noise Re-aligning with the 2x barlow is frustrating enough 3 times let alone 20
I know what you're saying though and I do agree with you, i'll see what I can do.

3. The conditions were pretty bad, seeing was terrible in the videos as the image swum about.. plus dew was really bad, it was literally dripping off the trees above my head. I had to pack up sooner than usual because my mirror was collecting dew and my finder was all fogged up.

4. Yes, some frames are clearer/crisper than others as it drifts across the FOV, mainly due to the seeing i'm guessing but I suppose part of it could be due to coma as well.

I think I also need to be more selective in registax when choosing the frame to base the alignment/optimisation off.. sometimes I just choose the first frame, instead of finding one where the image is clear and sharp.

It's difficult to tell how good it looks sometimes though, because with the gain and gamma so low, it's hard to see the darn image at all, let alone see if it's clear and sharp with the cassini showing etc.

Anyway i've got some more stuff to work on, part of it was definitely seeing and dew this morning, but collimation and coma most definitely could be playing a part too.

I also just need to capture enough frames to be able to stack > 500 and reduce the noise.

It's all practise anyway, only my third time out with the ToUcam so i'm sure i'll improve eventually..

Thanks again.

[ving (David)]

well done ice!

saturn would have been pretty low when you did it so shooting thru the exrta atmosphere wouldnt have helped. I saw sturn last night. wasnt the best viewing.

but then you have to take what you can get right?

[iceman (Mike)]

yeh exactly I think it's just the eliptical path of Saturn or the Earth or something this year, but Saturn is barely getting above 45 degrees altitude.. so seeing is never going to be great this year.

On the contrary though, it's looking like Jupiter is going to go directly overhead this summer, can't wait!

[iceman (Mike)]

Hi Jason! Welcome back!

The bitmap doesn't seem to open for me, and it's over 450k!

Is it possible to save it as a jpeg instead, then it'll show up on the forum properly..

Thanks!

[Vermin (Tom)]

/edit: Ah you fixed it, cool pic!

Astrojase, you might want to convert your attachments to .jpg before posting them 470K is a bit large (the board guidelines call for no more than about 60K max). Think of the dialupers!

V.

[Vermin (Tom)]

Yep, very nice.

V.

[iceman (Mike)]

That's better, thanks Jason!

I'll delete the original post..

Nice image too, but yeh dunno what's up with the colour? Is there an "auto white balance" setting on the camera?

Hope to see you back more!

[iceman (Mike)]

Great moon pic! Was that taken afocally? And of course it qualifies for this forum, but I reckon it deserves a thread of its own!

Gary Beal (gbeal) is selling an astro CCD camera, check the buy/sell forum..

[iceman (Mike)]

Seeker (member of this forum) uses an Atik CCD webcam, which is basically a modified ToUcam which allows for long exposures.

He's taken some great images of deepspace thingos using his atx-70.

I think they cost about AU$500, so I guess it depends what you mean by el cheapo

[iceman (Mike)]

Did a slight reprocess on the B&W one, despeckled and sharpened a bit..

There's a hint of the cassini division but you have to look hard