Nite Crawler FSQ 106 Autofocus

General
1

Anyone using a NC on a 106 or similar.
Looking for initial AF step. Ron’s guidance is 1500

Peter

1 Like
2

I have one on a SVQ100. He probably got that number from me as that’s what I’m currently using on my setup with my ASI1600 binned 3x3. That’s probably a decent starting point but will likely need tweaking.

Thanks,
Jared

3

Thank you. I started at 800 QHY 16200;FSQ 106 and got a decent curve.

Peter

4

Then I’d stick with that. F/Ratio and pixel size (binning included) can
certainly affect that number.

Thanks,

Jared Wellman
– Co-Founder and Developer
– www.mainsequencesoftware.com

5

I use the WR35 NiteCrawler and an FSQ106ED paired with a QHY16200A. In SGP I set my step size to 200 (bin 2x2). Since the NC uses 0.2667 micron steps, and the CFZ of the FSQ106 at Native F5 is 58 microns (blue wavelength) with the QHY16200. I have tried lower values,which are hit an miss in terms of how well they work, and higher values seem to give me inferior focusing results.

I am curious if the focusing logic in SGP would already account for this however, and perhaps a larger size step (which admittedly produces a nicer curve) may be better?

6

Hey thank you! I used 800 last night and it looked pretty good. The curve was steeper than what I was used to seeing with an 8300 on a slower scope
I may try to flatten it out a bit

Thanks again for the info

Peter Sarnosky

7

Forgot to mention I was only around 55 steps off from where I started with the mask using the very small stars with good symmetry

Peter Sarnosky

8

The CFZ is 217 steps so a step size of 200 gives a move that’s a little smaller than the CFZ. There could be a rule of thumb here, set the step size to between 50% and 100% of the CFZ size.

It should be possible to calculate the slope of the focus V curve away from the focus position by using geometry - the F ratio, focus step size and pixel size.

9

Thanks for all the replies. Last night I tried 200 and got excellent focus but the process took much longer and the slope was quite a bit flatter. Next clear night above absolute zero I will try 400. I think 200 might do very well when I start using a reducer.

Peter