SharpCap Forums

Hello,
Question relative to fwhm:
1. The value is given in pixel or other?
2. I have a celestron nexstar se with its original knob to focus. The camera is the zwo asi294 mcpro. Adjusting the focus on arcturus but i never obtain a value better than 6 and i Try to do the adjustment very slowly.
Is that normal or there is some tips to have better values ? Stars are not saturated When i adjust focusing.
Thanks for your replies.

Hi,

the values are in pixels.

You can check out the field of view calculator (https://astronomy.tools/calculators/field_of_view/) for your exact setup, but an 8" SCT with a 294 camera has a pixel scale of about 0.5 arc seconds per pixel, so you are unlikely to get very small FWHM as typical 1 to 2 arc second seeing will make for wider stars. Also, with an SCT, tube currents and/or poor collimation can really affect the sharpness of the image.

cheers,

Robin

Thanks a lot. New in astrophoto but I really enjoy and also enjoy sharp cap thanks again

Get an electronic focuser and learn to use it with Sharpcap autofocus you will be glad you did, especially with the se. I have an 8" SCT and it is hard to get in the 5s and stay there but auto focus configured properly and run every half hour or so will make a difference. If I just let it go my focus will degrade quickly

yomamma wrote: Wed Jul 26, 2023 3:42 am Get an electronic focuser and learn to use it with Sharpcap autofocus you will be glad you did, especially with the se. I have an 8" SCT and it is hard to get in the 5s and stay there but auto focus configured properly and run every half hour or so will make a difference. If I just let it go my focus will degrade quickly

Thanks a lot , it’s what I will do