What's the bigger limit for planetary observing?

[pipnina]

You should try and match your own observations of the seeing with the jet stream data and see if this is indeed influencing your seeing.

James

Good idea! I decided to write it down in a .txt file in a special folder for all the stuff astronomy related on my computer. I included the date and roughly what I saw along with the jet stream speed and location as per that forcast.

It's not very objective science as it's based off written note of my observations. But it'll still be interesting.

[Ags]

Regarding depth of focus, my mak is F13, but I focus by shifting the main mirror, so despite the slow F ratio, I have coarse focussing and poor depth of focus. A fast newt with a 10:1 crayford has better effective depth of focus.

[jambouk]

I mount a crayford on the back of my SCT; get focus in the ball park with the main knob, then fine adjustments with the crayford - going back to the experimenting topic again, i've always wondered if using a crayford on a scope which relies primarily on moving the primary mirror to achieve focus subsequently alters the "flatness" (for the want of a better term) of the field where it comes to focus. I really do need to get a better understanding of light and optics - again i've been saying that for a few years now

James