Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

DrRobin

Jupiter from last night - Improving but still some way to go

Recommended Posts

Hi,

As I took our dog out for her last walk of the day I noticed there was a clear patch around Jupiter and as my C11 still has my DFK21 on decided to do a few quick runs around midnight.

These are an improvement on the last set, but looks like I still have some way to go.  I did check the collimation on my scope earlier in the evening with a star, it was slightly out, but the seeing wasn't good enough to attempt to collimate and it was only slightly out, so might not make that much difference.

Robin

All pics C11 with a DFK21.

1/76 sec, Gain 456, 8,000 sots, stacked the best 20%

Jupiter-10-12-13-76th-G456-linked-2a.jpg

1/91 sec, Gain 456, 8,000 sots, stacked the best 20%

Jupiter-10-12-13-91th-G456-linked-a.jpg

1/91 sec, Gain 456, 8,000 sots, stacked the best 20% and around 3,000 frames for the moons.  A mosaic of two shots, it wouldn't fit in one frame.

Jupiter-Moons-11-12-13.jpg

Jupiter-Moons-11-12-13-ident.jpg

Share this post


Link to post
Share on other sites

Hi Robin, as you say, better than your last shots but I think your setup has more to give. What gamma setting are you using on your DFK?

Share this post


Link to post
Share on other sites

Well done getting all those moons in shot Robin. Just be careful with those wavelets its easy to push too far for detail and lose that natural look.

Share this post


Link to post
Share on other sites

You are right there Stuart, they do look a bit over-sharpened.  I keep a file of my settings and just used the defaults.  I might try re-processing tonight.  I managed to get Jupiter and Io in one shot, but my camera was turned wrong to get all of them.  If I had rotated by 90 degrees I might have just got them all in one go.  It is the first time I have ever seen all four moons together, although I know it happens fairly frequently.

Freddie Gamma is 100.

What surprised me last night was how bright Jupiter seemed, I know it is fairly high.  Not sure I am going to get another chance for a few days it is looking cloudy.  Still scope and camera are set up ready.

Robin

Share this post


Link to post
Share on other sites

Hi,

I re-processed the images turning down the wavelets and they look more natural and I think a little more detail is coming through.

Robin

1/76th sec Gain=456

Jupiter-10-12-13-76th-G456_sharp2a.jpg

1/91 sec Gain=456

Jupiter-10-12-13-91th-G456-sharp2a.jpg

1/91 sec Gain=469

Jupiter-10-12-13-91th-G469_sharp2a.jpg

Jupiter with moons

Jupiter-Moons-11-12-13-sharp-ident-a.jpg

Share this post


Link to post
Share on other sites

Hi Robin, its not just over sharpened, that can be a problem its also the wavelets that are used. I prefer wavelet two mostly. Because it produces less noise than wavlet one. wavelet 1 is the finest sharpening. But goes hand in hand with noise. Some choose to use Gaussian blur on there wavlets. I do not. What ever you do. Think in terms of fineness. when you start using wavelet 3. Anything other than a tiny amount. will over bloat the fine detail. Though I use dyadic so those comments reflect that. Linear doesn't really apply to my comments here. ( can see the linear guys saying bloat with wavelet 3 ? )

If the seeing and captures are good, I can do just fine using one wavlet alone. wavlet 2 dyadic no Gaussian blur.

If the capture is super good, a touch of wavlet one can make the shot super fine. But noise will creep in.

Looking at your capture I am certain you should be trying to up the Focal length. The C11 will easily take a 2x barlow. possibly even a 3x. you just need good collimation. Checked and set every time you image.

Lots of cooldown. Then when the planet is highest under calmer air. ( Often theres a slight mist in the uk ) To nail focus at these higher powers. Try standing away from the screen by quite a bit,  about 2 or 3 feet away. Put the planet out of focus. and slowly bring it in. watching the detail on the planet all the time. At some point you should see the planet with a wealth of detail on it. If you do not. either seeing bad. focusing is still out. Collimation is out. Or cooldown  or thermals ( dew shield ) are disrupting the image.  I will post up a example of a avi to give you a idea. Your on the right track. with a bit more I am sure you will do even better. Nice shot will all the moons showing

Edited by neil phillips

Share this post


Link to post
Share on other sites

Many thanks for all the help and advice Neil, having seen your pictures you clearly get it right.  I will give these tips a try next time.  I usually check collimation on a star, but don't always adjust as I find that unless the seeing is stable it is very difficult to collimate a C11.  Mine is fairly close at the moment, in fact if I look at the output of my DFK21 on a defocused star it looks pretty good, but if I take an AVI, stack and then look I can see a slight offset to one side.  SCTs aren't easy to adjust with a laser, you can get somewhere close even with a Hotech Advanced CT, but you still need to do the final adjustment on a star.

My C11 is now mounted in my obs, which is too small for me to fit into so I have to use a camera for everything.  The advantage, apart from it is ready to use for a short imaging session is that it is very close to ambient, perhaps 1 to 2 degrees warmer (unless it is really cold outside) and so cool down time is minimal.

You can see the tube currents on a defocused star during collimation as ripples towards the top of the tube, although now with the scope permanently mounted they are very much reduced.

I like your idea about focusing, just stand a few feet back and tune for best focus by eye.  I have tried a bahtinov mask on a moon before, but with a 2x (or 3x) barlow, it is usually too indistinct to see.  I do have a USB focuser so might look into an automated focus system like FocusMax.

All we need now is another clear patch, preferably before midnight to try this out.

Robin

Edited by DrRobin

Share this post


Link to post
Share on other sites

Hi Robin, give MetaGuide (free download) a go. It is very good for SCT collimation.

Share this post


Link to post
Share on other sites

Hi guys,

Two more goes on Jupiter, one late on Friday night (midnight) and then two attempts last night (10:30 and 11:45). The Friday night session got the scope fully collimated and I took several runs with a 2x Barlow, but after finishing realised I used too slow exposure for the seeing. Last night, the first session got everything aligned and focused, but the cloud and rain rolled in. The second session for 30 minutes got some good AVIs, still trying to process them now.

Neil, I can get about as a good a picture, just using layer 2 sharpening than I could using linked wavelets before, so thanks for the tip. I still have a lot of practise to do and I want to check the collimation again on a star, but the weather is not looking hopeful for tonight.

Freddie, I face Firecapture a try for collimation last season, but ended up further away than when I had started. I have a Hotech advanced CT, that gets me in the right ballpark and then tweak it on a star with a DFK. To make sure it is correct, I have to take a video, process it and en use Mire de collimation to make sure it is spot on. It takes time if it isn't to repeat the process.

Robin

Share this post


Link to post
Share on other sites

Hi,

From last night, three images of Jupiter in a 30 minute gap in the clouds and rain.  Processed with layer 2 wavelets only.

Robin

Jupiter-15-12-13-trio.jpg

Edited by DrRobin

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.