Jupiter 16th Sept

[Tommohawk]

Hi all

Didn't bother with Jupiter last year and haven't had a chance one way or another to get on it this year... until yesterday. Forecast looked a bit iffy and  only get about a 30 minute window, so need to get set up and focused and remember how to use the software all over again! Using Toupsky for this - its the only one that works properly with the Omegon 385 camera.

This is with my converted 250 Flextube fitted with a 250mm F4 mirror from a Quattro, and the secondary removed and the camera/ 5x powermate  in an adapter mounted on the spider vanes. It works very well mechanically, although focusing is a lot of fun. 

My conclusion with this rig is that the concept is good but the F4 mirror isn't precise enough for planetary work. I hope to rebuild another one with maybe an F5 mirror... needs a lot of custom parts though.

There was minimal turbulence but sadly it was pretty cloudy - I grabbed this between the worst of the clouds. It's not great and this rig has done much better last year with Mars, but couldn't resist giving it a go.

Best of 3 60s runs joined in PIPP best 50%, and then through AS!3 best 50%, tweak in PS. 

Whilst here I have a question and hoping someone can advise - the Omegon camera apparently has 12 bit depth, and claims 126fps at full res.  The ZWO 385MC equivalent camera also has 12 bit and quotes frame rates for both 12 bit and 10 bit. Claimed rate is 120 fps for 10 bit setup. The Toupsky software offers either 8 bit or 12 bit ADC conversion. 

At full res the max frame rates I'm getting are 88fps at 8 bit and 49 fps for 12 bit, so nothing like claimed fps. It's not as bad as it sounds cos I get 165 fps with ROI enabled. Its the same set up that gives me max possible frame rates when used with my ASI290MM, so I dont think its a system issue. Unless theres some way of allocating more RAM.... or something?

Anyhow  - the question is, should I go with 8 bit in order to get higher fps but live with more noise? 

[si@nite]

A reasonable shot there Tom, conditions have not been great of late anywhere in the uk it seems.

Regarding captures in 8 bit absolutely fine there should be no restriction or limitation in the information captured whatsoever, i usually shoot around 90fps with a 640 x 480 window as a rule!

Edited September 17, 2021 by si@nite

[morimarty]

Well done on your image Tom. Thats a very interesting set up you have a Fastar newtonian? I use firecapture and it as two options 8 bit or 16 bit  my asi290mm is 12 bit but I do capture in 8 bit and had no problems or noticed any detriment in quality.

[AKB]

On 17/09/2021 at 19:52, Tommohawk said:

the secondary removed and the camera/ 5x powermate  in an adapter mounted on the spider vanes

I’ve always wanted to try this, although for EAA rather than planetary.  You have a helical focuser?  How do you align?

Tony

[Mr Spock]

Looks good for the UK. Jupiter is just too low here to get anything better.

[Tommohawk]

On 17/09/2021 at 22:59, si@nite said:

A reasonable shot there Tom, conditions have not been great of late anywhere in the uk it seems.

Regarding captures in 8 bit absolutely fine there should be no restriction or limitation in the information captured whatsoever, i usually shoot around 90fps with a 640 x 480 window as a rule!

 

8 hours ago, morimarty said:

Well done on your image Tom. Thats a very interesting set up you have a Fastar newtonian? I use firecapture and it as two options 8 bit or 16 bit  my asi290mm is 12 bit but I do capture in 8 bit and had no problems or noticed any detriment in quality.

Ok thanks for that. I capture in lower bit rate with Firecapture  when using my ASI290MM but not sure about how it works with  Omegon/toupsky combo, Given time I could just experiment but never get enough time/clear sky

6 hours ago, AKB said:

I’ve always wanted to try this, although for EAA rather than planetary.  You have a helical focuser?  How do you align?

Tony

Yes it would be good for EAA, though I haven't done this yet.

Here's a picture of the scope. The idea was to minimise the central obstruction to improve resolution, and also to devise a lightweight transportable strut or truss design for easier transport. I happened to have a 250mm Quattro which I was using much, and a 250 flextube tube only came up for sale, so I combined the two. Coarse focusing is done by adjusting the tube length using the tube extension clamps. Once done thats left alone and then just use the helical focuser to fine tune. I have to focus by Bahtinove which is a bit fiddly but not too bad. 

Target location is challenging. The finderscope is set quite precisely and I can usually get close enough to align the target roughly... it is a bit of fun though!

There is no discernible benefit in resolution but I think thats simply because this grade of F4 mirror is compromised optically. If I were repeating I would probably use an F5.

[AKB]

38 minutes ago, Tommohawk said:

just use the helical focuser to fine tune.

Thanks for that.  A bit off topic, but how did you fix the focuser to the vanes?

[CraigT82]

I love your scope! Top modding that is 👍👍👍

Nice Jupiter... The image is suffering from atmospheric dispersion so squeezing an ADC in there would give worthwhile benefit I think, if you could? 

As for the 8 bit captures, this is recommended as offers best frame rates and it's the stacking of thousands of frames that restores the lost bit depth (I'm some way that I don't really understand!)

[Tommohawk]

23 hours ago, AKB said:

Thanks for that.  A bit off topic, but how did you fix the focuser to the vanes?

Difficult to see from that pic and I'm away at the moment so cant post better one. I got an eyepiece adapter of some sort and drilled out the barrel to attach the vanes with M2 (I think) screws/nuts. That holder is then used to clamp the powermate and the camera is held in the powermate in normal way. It was a bit tricky cos I had to counterbore the barrel from the inside to accommodate the nuts. I ground a special tool - cant remember what I made it from now! The vanes are then tightened in the normal way, but pretty tight..... its surpisingly solid.

 

1 hour ago, CraigT82 said:

I love your scope! Top modding that is 👍👍👍

Nice Jupiter... The image is suffering from atmospheric dispersion so squeezing an ADC in there would give worthwhile benefit I think, if you could? 

As for the 8 bit captures, this is recommended as offers best frame rates and it's the stacking of thousands of frames that restores the lost bit depth (I'm some way that I don't really understand!)

Thanks Craig. As a mod I'm quite chuffed with it, especially as I dont have a fancy workshop. Mostly a question of adapting bits.

I'd like to repeat this scope design with say a 400mm mirror but it could prove to be an expensive mistake!

The ADC could be added in the path - I would just need to adjust the tube length by the length of the ADC. It would add more torsion force to the vanes though, and also the diameter is 46mm which would enlarge the CO which would defeat the object somewhat.

Re 8 bit - yes I gather that with the ZWO cameras at least the bit depth is restored in stacking. That bits a mystery to me too! I just wasnt sure if this would also be true with the OMegon

[neil phillips]

Yes very cool. If you stack using AS/3 Tick the RGB align box it will help. After the fact. Registax RGB Align.

Example

 

 

[Nik271]

Bit depth is important mostly when there is a lot of stretching of the image, e.g. in deep sky imaging. Not so for planetary as the features are fairly bright and it's better to capture as many frames as possible. When stacking the bit depth of the final image will be increased by virtue of the added information. So yes, definitely go for the 8 bit for planetary.

Edited September 21, 2021 by Nik271

[Tommohawk]

Re RGB align, yes done quite a bit of planetary now so familiar with that... But.. just updated to AS3 and maybe I didn't check RGB align. Thanks for the heads up!

Re bit depth, I've always captured in lower bit depth with ZWO firecapture but wasn't sure about Omegon Toupsky combo. Everyone seems to agree is ok so I'll try that. Thanks all. 

[Pete Presland]

some nice details visible there.

[Tommohawk]

Right - been away for a week, back now..... and Neil you were right - I hadn't checked RGB align in my new version of AS!3. Redid the image using similar processing steps in PS and definitely better.

👍

[neil phillips]

1 minute ago, Tommohawk said:

Right - been away for a week, back now..... and Neil you were right - I hadn't checked RGB align in my new version of AS!3. Redid the image using similar processing steps in PS and definitely better.

👍

Yes a nice image there