Today I have just started with guiding and I wonder what guiding error do you typically get in your environment
and what value do you call good/poor? For example today I read a value of about 1.7" RA/DEC in ekos. Is this a good value in a big city?
Currently my guiding scope looks out of a window and I assume a lot of seeing from the house wall heat .
I am not very familiar with seeing values and that's why I ask you.
And I am a bit confused by the so called "Rayleight Criteria" that describes the lowest possible resolution of a scope by the diffraction and aperture. For my guiding scope (8x50 viewfinder with webcam) I got 0.025*550nm/5cm = 2.75 arcsecs. Why do I get 1.7 arcsecs if the rayleight limit is 2.75 arcsecs or do I mix up different things here?
--= human, without Windows™ =--
pls excuse my bad english!
Good or bad depends on many things, like the f-ratio of your scope and seeing etc. I have a C8 with a f/6.3 focal reducer. At my location, in a suburban area of a quite light polluted part of Scandinavia, without observatory, I feel that below 2" is acceptable. On good nights I get 1" or less, These are RMS, measured by PHD2.
In the end, good is what gives you a photo that satisfies you. So, I actually stopped looking at the real performance of my guiding. In my case photo's turn out fine when I'm below 1.7", but I get down to 0.4-0.5" on nights without too much wind.
On a clear night without wind I usually get around 0.4 to 0.6 in RA/DEC.
With a bit of wind goes to 0.8 but even with that I can get good photos between 300 and 600s of exposure.
This on a moderated polluted suburban sky.
Oh, ok. Thank you. So I have a lot space to optimize to smaller values or rather smaller values are technically doable . I used ekos internal guider. I don't know how much it differs to the other boths but I'll first stick with it and see how different night conditions will influence my rms value. I currently just running dry runs out of my window as long as I plan to move everything out stationary on the balcony.
Thanks, I didnt knew that!
--= human, without Windows™ =--
pls excuse my bad english!