Function for Ha solar best focus...?

Somewhere to ask questions about the best way to use SharpCap
Post Reply
Maurits
Posts: 12
Joined: Fri Oct 20, 2017 3:16 pm

Function for Ha solar best focus...?

Post by Maurits » Mon Aug 20, 2018 9:22 am

Hallo all,

Is there a function in SharpCap 3.1 Pro where I can see if I have the best possible focus during Ha solar imaging?

I know there is a focus tool with different choices, but I can't see something for solar focusing!

It would be nice if there was a histogram or something else, where you can read for example the best values for this situation on this moment …

PS
Feel free to have a look on my website with a lot of pictures ...
All the pictures from the Sun, Moon and Timelapse are taken with SharpCap 3.1 Pro.

Regards and thanks for reading,

Maurits

www.vistadelcielo.be

User avatar
admin
Site Admin
Posts: 2088
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Function for Ha solar best focus...?

Post by admin » Mon Aug 20, 2018 7:04 pm

Hi Maurits,

you have some great images on your web page :)

I'd suggest using 'Contrast (Edge) Detection' to find best solar/lunar/planetary focus - that looks for how much fine detail there is in the image which is obviously reduced by being out-of-focus. Read more info here - https://docs.sharpcap.co.uk/2.9/#Focusing

cheers,

Robin

Maurits
Posts: 12
Joined: Fri Oct 20, 2017 3:16 pm

Re: Function for Ha solar best focus...?

Post by Maurits » Mon Aug 20, 2018 8:09 pm

Thanks Robin for the quick answer.
Most of my webpage (Sun, Moon and Timelapse) are recorded with SharpCap 3 and 3.1, and I love the way it works :D

Maurits
Posts: 12
Joined: Fri Oct 20, 2017 3:16 pm

Re: Function for Ha solar best focus...?

Post by Maurits » Tue Oct 16, 2018 3:18 pm

Hallo Robin,

A time ago I asked a question about the focus tool: (contrast edge detection).
There is something that I don't understand namely, the relation between the "black level and the telescope focuser position".

When I look in the SharpCap manual and I take an example as described under 14.5 (overview display), than,I do simulation in SharpCap on the computer with Jupiter as example and test camera 2 (high speed).

So far so good, I place the red rectangle on the surface (Jupiter), I move the black level settings until I get a nice green graph in the history.
As the example I see black level 64% and the best score 35,208 (blue line average score).

The focuser position black line indicate 0.

Suppose I have such a thing (in real) on the telescope, what should I do now with the real telescope focusser, so that I have a good focus on the screen?

Regards and thanks for reading,
Maurits

User avatar
admin
Site Admin
Posts: 2088
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Function for Ha solar best focus...?

Post by admin » Tue Oct 16, 2018 6:01 pm

Hi Maurits,

I think you are misusing the black level control - you should use it to exclude the dark area around a planet from the focus score measurement - see https://docs.sharpcap.co.uk/3.2/#Settin ... ck%20Level. That ensures that the focus calculations are not being affected by noise in the black areas that we are not interested in. Once you have the black level setup to shade the dark areas but none of the planet you can leave it alone and then truly start measuring the focus score. In particular in the Test cameras adjust the 'Focus Offset' (https://docs.sharpcap.co.uk/3.2/#Test%20Cameras) to simulate the effect of being out of focus.

cheers,

Robin

Maurits
Posts: 12
Joined: Fri Oct 20, 2017 3:16 pm

Re: Function for Ha solar best focus...?

Post by Maurits » Wed Oct 17, 2018 8:57 am

Hallo Robin,

Indeed I misused the black level control :oops:

Is it so that I don't need the "black level control" (min setting 0 or 2) for focusing on the sun, just turn on the telescope focuser until I have a green histogram?

Regards,
Maurits

User avatar
admin
Site Admin
Posts: 2088
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Function for Ha solar best focus...?

Post by admin » Wed Oct 17, 2018 6:07 pm

Hi Maurits, yes, the green shows for the best score so far, so if you are focusing on the body of the sun, just adjust the focuser to get the best (greenest) possible values.

cheers,

Robin

Maurits
Posts: 12
Joined: Fri Oct 20, 2017 3:16 pm

Re: Function for Ha solar best focus...?

Post by Maurits » Wed Oct 17, 2018 7:55 pm

Thanks a lot Robin,
Regards,
Maurits

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest