Which would be the best focus tool

[cardanoc]

Hi

I've been wondering about this, and would like to get your input.

For solar imaging(i.e., sunspots) which is best to use:

Contrast (Edge) Detection, Histogram Range (Brightness Range) Detection, or Fourier Detail Detection.

For solar proms, which do you think is best?

Thank you.

Conrad Cardano

[admin]

Hi,

I personally tend to use the simple Contrast (Edge) Detection for solar imaging and it seems to do the job. The biggest problem with solar focusing is that the variation in seeing can cause fluctuations in the measured sharpness of the image that makes it hard to see the variations caused by focusing at times - this affects all of the three options equally.

I'm not sure that you need to specifically worry about focus for prominences - once you have focus on the disk (which is probably easier), you will be in focus for the prominence too.

cheers,

Robin

[eosman]

Hi..
I tend to use the zoom tool and get a magnified view of the image...then look for specific area such as a AR Spot and observe it for awhile and adjust the focus to get the best result, the same with Proms, I use Spicules along the limb.
As Robin mentioned the seeing depends on local issues such as houses with heat haze and upper air turbulence and changes so fast, add to it the aperture of the scope the larger the scope the worse the effects seems to with a given sensor.
Hope this helps
Regards Les