Jump to content

Sketches

ASKAR FMA180 40mm aperture apochromatic telescope.


Recommended Posts

4 hours ago, LaurenceT said:

Sorry for the newbie reply but how would I display a full resolution image, I've done so much processing of it?

I see the image as being 1000 X 1000 ish but it should be 3000x3000pixels from a IMX533. It's hard to assess stars on a resized image. 

Link to comment
Share on other sites

1 hour ago, Adam J said:

I see the image as being 1000 X 1000 ish but it should be 3000x3000pixels from a IMX533. It's hard to assess stars on a resized image. 

I understand, thanks, I will have to work out where in the  process it got reduced.

Edited by LaurenceT
Link to comment
Share on other sites

2 hours ago, Adam J said:

I see the image as being 1000 X 1000 ish but it should be 3000x3000pixels from a IMX533. It's hard to assess stars on a resized image. 

Image after processing and stretching in APP, exported to Dxo Photolab just for conversion to JPG. This is full size:

1890175734_California_neb_2022_NOV-Luminance-session_1-csc-St_DxO3size.thumb.jpg.9598d799051226d8a2aa1707d851db83.jpg

Edited by LaurenceT
  • Like 3
Link to comment
Share on other sites

3 minutes ago, PadrePeace said:

Seems that red/blue star fringing  you had in the first image has gone completely here. Have you done anything to achieve that or was it a conversion anomaly?

It would seem that the fringing only appeared after my attempt at further processing!

Link to comment
Share on other sites

30 minutes ago, LaurenceT said:

It would seem that the fringing only appeared after my attempt at further processing!

Well one thing we would need to fix next before any further assessment is your back spacing as you don't have enough. Are you measuring 55mm from the back of the corrector or from the back of the extender that is matched to the corrector, it should be the latter. 

All in all a good first image though. 

Adam 

Edited by Adam J
  • Thanks 1
Link to comment
Share on other sites

48 minutes ago, Adam J said:

Well one thing we would need to fix next before any further assessment is your back spacing as you don't have enough. Are you measuring 55mm from the back of the corrector or from the back of the extender that is matched to the corrector, it should be the latter. 

All in all a good first image though. 

Adam 

Thanks for the reply Adam, much appreciated. This is the setup I'm using:

20221126_193343.thumb.jpg.8cf38a1adc8eba6f3d37ec4b21cdf376.jpg

Link to comment
Share on other sites

That’s bang on 55mm. But there is something going on in the corners. Is there UV/IR cut filter in your 11mm adapter? For any extra glass in the optical path you need to add 1/3 of its thickness to your BF.

Edited by PadrePeace
Link to comment
Share on other sites

14 minutes ago, PadrePeace said:

14DC6AD6-EDDA-41A9-B246-2815735D464A.thumb.png.9dd41937df797956addba84d08e03978.pngBack focus is different to the focus you achieve using a bahtinov. What AdamJ is seeing is the comet shaped stars flying outwards in each corner.

So is there a mismatch between the scope and the flattener/reducer?

Link to comment
Share on other sites

13 minutes ago, PadrePeace said:

This article explains Coma which is what this looks like. 
https://www.google.co.uk/amp/s/photographylife.com/what-is-coma/amp

 

Is your scope new?

I bought it used .

Edit: I've just checked the scope and the reducer wasn't absolutely screwed into the scope, there could have been a centimetre or slightly more of rotation 🙄

Edited by LaurenceT
Link to comment
Share on other sites

44 minutes ago, LaurenceT said:

I bought it used .

Edit: I've just checked the scope and the reducer wasn't absolutely screwed into the scope, there could have been a centimetre or slightly more of rotation 🙄

Rotation would not matter but if it's not fully tight that could give tilt. 

  • Like 1
Link to comment
Share on other sites

3 minutes ago, Adam J said:

Rotation would not matter but if it's not fully tight that could give tilt. 

Try it now you are fully tight and submit the result here. If you still have that in the corner then try adding 1mm of backspacing. 

  • Like 1
Link to comment
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
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.