jupiter with an 8" skywatcher and toucam

sebastion (Sebastion) · #1 23-09-2010, 04:15 PM

i have recently begun basic astrophotography, and have attached two images of jupiter. my questions are, are these images out of focus or is there more work to be done in post processing? perhaps it is a seeing /optics issue? any comments/feedback appreciated. thanks

wasyoungonce (Brendan) · #2 23-09-2010, 04:21 PM

Photos are not attached?

Anyway...when focusing for Jupiter...focus the moon(s) to nice sharp dots.

asimov (John) · #3 23-09-2010, 04:32 PM

Are you using an IR/UV cut filter?

sebastion (Sebastion) · #4 23-09-2010, 04:35 PM

not on these ones, but i have with similar results.

asimov (John) · #5 23-09-2010, 04:42 PM

Well, at your current image scale, you won't notice a great deal of difference between an IR/UV cut filter or not, but most will advise you (like me) to put it on & leave it on. It's usually part of the problem regarding focus. Colours 'bleed together' without a filter because webcams see a lot more wavelengths (IR & UV) that the eye cannot, & the cam can't focus all these different wavelengths. The effect is worse if the target is at a low alt.

DavidU (Dave) · #6 23-09-2010, 04:58 PM

Exactly what equipment are you using?

sebastion (Sebastion) · #7 23-09-2010, 05:23 PM

the toucam 840 pro2, orion 2x shorty barlow, on heq5 and k3ccd soft

asimov (John) · #8 23-09-2010, 05:57 PM

You could probably add a 3X barlow to your kit for a bit more scale with your newt.

Getting back to your initial concerns: The pics look like a combo of things. Seeing, possibly not quite collimated, optics not quite at ambient. Combine all those little things (plus no IR/UV filter) & end up with a poor result.

sebastion (Sebastion) · #9 23-09-2010, 10:34 PM

thanks for the responses.
one last question, how is the standard crayford style focuser on the skywatcher compared to an actual 10:1 focuser?
i can get the moon to focus sharply, as with dso's. all of which leads to the conclusion that the seeing conditions are the major factor in this

anybody have some experience with this?

bmitchell82 (Brendan) · #10 24-09-2010, 11:02 AM

The standard focuser will get you about there.

Thoughts :-

Critical focus zone for my 10" is 47 micron (yes very tight) ide say your 8" will be just a little bit more say 100 micronish.

The way to make it better isn't just by adding a 10:1 focuser its adding a Quality focuser that can handle the weight of your equipment something like Moonlight (Great) or Feather touch (Best).

Further to that you have a newt, your using a barlow with the F ratio being quite low i think they are F5? Collimation becomes critical. Do yourself a favor get yourself a set of Cats eye collimation tools (no im not advertising them because i get a spin off). I use these tools and can vouch for the difference they make. No hassles, highly accurate passive collimation (no batteries needed).

These are 2 of the main things that i can offer you from my little chest of info. Good focuser makes life a happy place to be, and collimation will squeeze every last bit of data out of the lemon with clarity..!!!

Also what Asimov said will be a good 60% of that problem you are noticing. For future ref there is a way to tell if your tube is at ambient temp or if the seeing is nasty. go to a star and defocus it untill you see the secondary shadow nice and big. To learn what you are looking for, stick your hand infront of the tube, notice the heat currents flowing off of your hand. Once your good with what your looking for, look around the edge of the defocused star. Use your hand to find where the top of the tube is (heat rises) do you see any shimmering or heat currents? Now focus the star to about half way of what you had, does it shimmer itself (scintillation is the scientific name for it) if its madly flicking though colours its bad up there, if its quite stable, then you have good seeing time will give you the exp to judge all these things quickly.

Hope that gives you a bit of help

Brendan

Logieberra (Logan) · #11 24-09-2010, 11:17 AM

What does the IR/UV cut filter connect to, the 1.25' 5x powermate threads?

And where do you get them cheap?

P.S. I'll be using a similar setup when my toucam arrives from the UK.

bmitchell82 (Brendan) · #12 24-09-2010, 01:17 PM

Im pretty sure logan that the power mates have a filter thread on the end so that is where i would be putting them.

Get a good quality one look at Bintel, Andrews, though also look to the states Opt corp, Hong Kong pete. They should be able to give you a look at price.

As for what is quality and what isn't John (asimov) should be able to point you guys in the right direction, though Astronomik, Baader are 2 decent quality brands i know of.

sebastion (Sebastion) · #13 24-09-2010, 04:01 PM

thanks brendan, perhaps the collimation is the likely factor. i discovered the mirrors centre spot is not actually in the centre, also suspected that the critical focus was tighter than the factory focuser can adjust to.
the ambient temp is not the problem, the scope has been cooling for three or four hours usually. seeing and collimation are the culprits.
thanks everyone.

Logieberra, powermates have the 1.25" thread on the bottom.

Logieberra (Logan) · #14 24-09-2010, 04:02 PM

Nice. Thx. Have you strapped a cpu fan on the back?

Don't quote me on this, but I think that the experts run the fan all the time, and shut it off temporarily when they're shooting...

Logie.

asimov (John) · #15 24-09-2010, 05:41 PM

Quote:

Originally Posted by Logieberra

What does the IR/UV cut filter connect to, the 1.25' 5x powermate threads?

And where do you get them cheap?

P.S. I'll be using a similar setup when my toucam arrives from the UK.

Get the Baader. As far as 'cheap' you'll have to shop around a bit.

Personally, I'd be wacking the filter on the nose cone/adapter, that way it's doubling as a dust protector even when not in use. This would depend on the adapter though. All Toucam adapters are threaded to take filters.