Jupiter 08/05/2011

[darbyvet (Carl Darby)]

Shot this morning in good seeing.camera working good so 30 fps

[MGTechDVP (Mariusz)]

Hello Carl,

Your Jupiter images are awesome!!!

I tried to get a image of Jupiter using the Imaging Source DMK41AU CCD camera & 2X barlow, I took 2000 frames at 15 fps (1/15th & 1/8sec sec) through each of the Red+IR Cut, Green+IR Cut, Blue+IR Cut color filters and for the luminance channel captured 2000 frames through just the IR cut filter and another through IR cut and the LPR/UHC filter. All channels stacked "best 700 frames" in RegiStax 6.

After not being able to acheive spot on focus, I suspected a collamination problem, it was a little out, so I adjusted it (to me looked like the central obstruction was dead center, and focus/cloud bands were better but still no detail... surely I should be able to get more detail then what I got.

Any hints and advise??

Mariusz

[darbyvet (Carl Darby)]

Hi Mariusz,
thanks for the kind words.What telescope are you using?
I think the DMK21 is better for planetary imaging than the DMK41 because the imge will be smaller on the 41.If you wanted to image the moon the DMK41 is better because you will get a larger field of view and therefore more of the moon in each picture.

What capture program are you using ?
If you are using ICCapture what is you hisotgram looking like when you record.You want the histogram to stretch almost all the way to the right or your images will be underexposed.That may be why you have the "onion rings" in your picture.

What I do is adjust the gain and exposure so that I have the shortest exposure possible whle still having the histogram filled almost all the way to the right.

You want the gamma set to 100 and I generally have the exposure set to 1/38-1/60s for my C11 scope.The bigger the scope you have the more light you gather and the shorter exposure time you need.
Ir doesnt really matter if you have to use maximum gain-it is more important to capture as many frames as you can.


What was the seeing like when you took your video?
I think seeing is 90% of the battle.If you have poor seeing everything is so much more difficulot.If it looks like Jupiter is rippling like it is underwater and it keeps getting fuzzy every couple of seconds you have bad seeing and that seriously degrades the amount of detail you can capture.Most of my images are taken in average seeing, but the ones I just posted were in good seeing and you can see there is more detail and the images look sharper

If you shot 2000 frames at 15 fps that means you were imaging for 2 1/2 minutes per channel? Remeber that Jupiter is rotating very rapidly and you will have some rotation between your color channels if you image for that long. I generally image each channel for 60-75s and then quickly move my filter wheel to the next channel and start imaging again so there are only a few seconds between starting eachy set of images.
There are programs that will de-rotate you images if you have to use longer exposures.

Focusing is really hard, especially if your seeing is not good.You use a Bahtinov mask to focus on a nearby star and then slew to Jupiter or you can try eyeballing the focus by looking at your live capture.I generally eyeball since I am imaging close to dawn and there are not too many
stars to focus on.

If you eyeball the focus it is easy if you enlarge the live image to 150% ans reduce the gain to 50.This makes the image more contrasty so you can see how close you are to focus.It is still a matter of trial and error though to get really good focus.I have yet to take a picture that i think is well focused.

Astrophotgraphy is REALLY HARD. I have huge amounts of respect for many of the folks that post amazing images on this forum.Once you have tried to take a photo of a planet you realize just how hard it is and you really appreciate the skill on people that can produce amazing pics.

I have been imaging for 9 months and I have learned lots already, but there is still so much to learn.I find every time i get my out with my scope it gets a little easier.

[pluck]

Carl,

A really nice job. Rich in colour and features.

Well done indeed.

Paul

[MGTechDVP (Mariusz)]

Thanks Carl,

Some great hints there, but one thing that stood out that was a big YES, was when you asked if jupiter was like shooting through water and losing focus every few second, thats exactly how it was. The Gamma at 100 and shorter capture times is something I'll try next time.

I'm using a Celestron NexStar 8SE on a CGEM mount.

Thanks.

Mariusz

[darbyvet (Carl Darby)]

You are welcome Mariusz,
If you look on Damian Peachs website (www.damianpeach.com) he has a guide to seeing conditions.It is a bunch of youtube videos showing what good and bad seeing looks like.I found it very helpful to be able to judge how good seeing was so I knew what to expect when I processed my images.I have a nexstar 8SE and it is a very nice scope and I did get some pics of Jupiter last apparition.I think I used 1/30s exposure and max gain.

[iceman (Mike)]

Great work Carl, excellent images.

I love those colours.

[atalas]

Excellent Carl!

[midnight (Darrin)]

Well done Carl!

Very good detail there.

Darrin...