Need some quick astrophoto advice before clouds hit.

[ubertank]

Hi guys,

I really hope nobody minds me posting in here. I've got the first clear night I've had in almost two months and am playing with my spc900 for the first time. I'm posting here so I hopefully get help quicker as I'm running out of time and needed a quick bit of advice.

I'm trying to image Jupiter for the first time with a modified spc900 and a 200p dob. Whenever I get the scope get on Jupiter, my webcam is for some reason just seeing this:

http://s296.beta.photobucket.com/user/ubertank/media/lskdjfklsfd_zps12b398b2.png.html

Any ideas?

Thanks in advance and sorry again, but I'm pretty desperate

[ronin]

Your scope has a focal length of about 1200mm.

When many image Jupiter they use a Mak of focal length about 1500, they also often fit a barlow of 5x to get the image size up, Jupiter has sufficent light coming off of it. So that makes a focal length equivalent to around 7500mm.

Your image will therefore be 6.25 times smaller (1/6.25).

That is all I can think of, if you have the f/5 version then you are 1/7.5 the size.

This presumes that you question is Why is Jupiter so small.

[long_arms]

Hello,

That is just not in focus in my opinion (I'm sure someone more experienced will correct me)

Just because it is in focus on the eyepiece does not mean it will be in focus with the camera.

Have you tried adjusting focus?

Dan

[Steve Ward]

You're just out of focus by a way , you should be able to bring things to focus if you can get a sharp image through the EP.

If not you may need to add an adaptor to get focus.

[ubertank]

My question really was why can I see the cross, but yeah, it needed barlowing. I have Jupiter in there now and can continue playing with software to try and get a decent image.

No such thing as a stupid question, but that potentially was one . Thanks for the response.

[Steve Ward]

Glad to hear you're sorted and still playing . . .

[ubertank]

Managed to get the image in focus on the capture software screen, but it moved across the FoV screen in Sharpcap in around 5-6 seconds. The slightest movement on the dob meant a good minute to find it again, to then try to make some adjustments on the laptop to improve the image.

Felt like an impossible task sadly. Think I'll just be observing tonight and waiting until I have a moon and a clear sky to practice with. The weather is frustrating, not only due to the limits it places on being outside, but the cripplingly slow pace it reduces your hands on practice to.

[Steve Ward]

You might be better of practicing without the barlow to give yourself a little more 'screentime' . not the easiest thing tracking with a dob .

[ubertank]

Without the barlow I cannot get anything other than the image I linked initially with the focuser in any position.

[long_arms]

If thats the case then if you unscrew the actual barlow lens and screw it directly onto the camera nosepiece, this should decrease the 'magnification' shouldnt it?

But still hopefully give you the focus travel required.

[nephilim]

Size wise I manage this with my old 130mm scope with an EQ2 & 2xbarlow using an xbox cam,

so if you barlow yours in the 200p you should get a really good size, I've recently bought the 200p on an EQ5 but havnt managed any imaging with it yet, I agree with uyou that you should practise on the moon first as it's tricky enough focussing & faffing with the settings while its tracked with the motor drive on my mount so it'll take practise & alot of patience with a dob, also note that the higher the mag you use, the quicker it'll fly across the screen, so IMO on a dob I'd stick with a 2x as I dont think you'd stand a chance with a 5x. As for the cross being visible, as others have mentioned its the focussing, as its focussing on the scopes spider vanes & not Jupiter.

Good luck & keep at it.

Steve

[ubertank]

Hi guys and thanks so much for all the responses again.

Yeah the size was really good actually. It was very similar to what you have posted there nephilim. It was bright, bright white though and I needed some time to adjust image settings to try and get anything other than a white circle. I had probably 5 seconds to make any adjustments before it was gone and then really, really hard to find again and get in such a position it moved across the screen giving me a decent amount of time.

It was frustrating but worth doing to find out that I should probably start on the moon first so I can identify what setting to adjust rather than trying to figure out from scratch within a few seconds.