SonnyE Loc: Communist California, USA

So, I decided to plunder forth and do some testing. I used Deneb as my target, and locked on with PHD2.
My new EAF focuser is working better and better. Last clear skies, I wanted to see how my filters stacked up for what I call "Repeat accuracy". So I chose a filter, LUM, first since it is in Pos. 1, and got the Auto focus in focus. I got 19707 steps as the result. OK, my baseline.

Then I changed to RED, Pos. 2, and ran the Auto Focus with it. Got 19711 steps as that result. I was pleased, the two filters were really close in focus.

So, I forged ahead collecting results through my filters. 19711 steps were the highest out of 6 filters, 19700 was the lowest out of my filters.
The average was 19707.166666> steps. (19707 steps).
So, I'm satisfied my filters are all relatively very close to being in focus as the different filters come into play. I think I am pleased with the matching ZWO ASI did with the set.
Granted, this is just a shade tree mechanic test in the back yard. Not really of value to anyone but me.

I can zero out my focuser at the start (or any time) and just start over. But since it is a Crawford Styled focuser, it has no teeth and is just a friction drive.
If I ever get a new Telescope, I will be sure it has a Rack and Pinion focuser. And I will inquire about backlash as well. But for now, I'm stuck with a Crawford drive. It is what it is.
(But the Repeat Accuracy simply isn't there with this focuser. In my honest opinion.)
So Zero is a bit ambiguous. Best bet is to zero the focuser after alignment near the intended subject for the session, then do the series on the chosen filter. Change to the next filter, run auto focus, and run the next pile of images.

Are you guys doing something like this?

bwana Loc: Bergen, Alberta, Canada

I don't use an automatic focuser but I do agree with you regarding a rack and pinion focuser being the best.

I simply use a Bahtinov Mask for focusing and a good set of parafocal filters (which it sounds like you have).

bwa

SonnyE Loc: Communist California, USA

Yep, that's what I want on the next telescope (As if that will ever happen. LOL! )

Ballard Loc: Grass Valley, California

Hi Sonney
The Astrodon filters I used are advertised as parafocal and indeed they seem to be. I used the luminance filter for focusing and run with that for all the filters. However, I have found that as temperature changes the focal point can change a fair amount on the Meade LX200 (Some of the change may also be due to the atmosphere as the object rises higher), so I always rerun the focus process every 20 minutes when taking images.
I recently changed to a high quality starlight express rack and pinon focuser on my refractor and it works really well, the old one could not handle the weight of the camera and filter wheel.
example image using the new focuser see https://www.uglyhedgehog.com/t-757752-1.html

SonnyE Loc: Communist California, USA

Muh ha, ha, ha...
I found some pearls.
https://www.uglyhedgehog.com/t-755179-1.html

I need info like this to judge if I'm in the ballpark.
Not, I'm in the parking lot.
I am curious about your numbers, though. Why such random exposures?

"The following exposures were used
Luminance - 95 exposures at 2 minutes each
Red - 45 exposures at 4 minutes each
Green - 49 exposures at 4 minutes each
Blue - 50 exposures at 4 minutes each
Ha - 78 exposures at 500 seconds each"

Or was that was left after sorting?

I'm kind of hesitant to put a new focuser on my 80 mm refractor. I was looking at possibilities and found out Walmart sells rack and pinion focuser parts. OK, I'll wait while you get up off the floor and stop laughing.
I can't stop chuckling myself. I'd imagine it's over by the jewelry department.
No, I'd be more apt to buy a new telescope with a R & P focuser. But I can assure you I'd rather retain my male appendages, than to sit as a eunuch out at my mount and be sleeping in the doghouse.
I think I'd be putting lipstick on a pig. I do love my telescope, but there are limits.
So for now, I think I'll have to bumble along.

But could you enlighten me how you came to those exposure numbers?

Ballard Loc: Grass Valley, California

Hi SonnyE
The numbers are a bit random after removing those with bad FWHM or with low number of stars if a cloud passed by. (~10% loss or more depending on the night). To pick the time I use the ASI Studio Deep Sky imaging to run a couple of test shots to check the histogram of the image and aim to keep from saturating any too many of the brightest stars. After a night of exposures I see how it looks and which filter looks like it needs more data to keep the noise low for the stretch I want on the object, then take more that night (weather allowing). Usually the RGB values are pretty much the same expect for those that get tossed out. The luminance is usually a shorter exposure to avoid blowing out bright areas but total time is ~ the same as the RGB shots. Ha I just keep shooting until I get enough data and those take a lot more total time.
Note: on that image I reprocessed to more carefully equalize the background intensity and used the HA as the red channel and it really improved the image. See
https://www.uglyhedgehog.com/t-757752-1.html

SonnyE Loc: Communist California, USA

Yes, I see the differences, quiet an improvement I agree.
I just noticed the exposure stats and got all Curious George on you. Trying to learn anywhere I can.
Thank You for clarifying. It was as I suspected, number adjustment by selection.
I need to do that, too. Instead of grab and go in my Siril processing. This Grasshopper has no patience.

I ran out of time last night with my Flat Files building. I would have had to leave the light on during my last run of Flat files. And my wife would have likely shut it off. She's weird about lights being on.
So they are running today. And I'll likely run some others for variety. Call me a drive space waster.

Tonight might be clear enough to do some imaging here.
But I need to process, not horde more images.

Thank You for your help. Much appreciated!

bwana Loc: Bergen, Alberta, Canada

Have you really tightened down the focuser on your scope. I have a William Optics Megrez 90 with a focuser that used to slip when using a heavy FR/FF and camera. I tightened up the tension and it has worked well ever since.

Just a thought.

bwa

SonnyE Loc: Communist California, USA

Yep. I did try that.
But this EAF wants the tensioning screws removed. Not sure why, other than to insure there is no arbitrary frictions affecting the unit's ability to move.
So at this time I've been trying things their way.

Just now:
OK, so I decided to modify some more. I drilled out the spot on the EAF mount that lands over the Allen screw tensioner and I can get to it without dismantling anything, with an Allen wrench.

So far, only one "failure to move" when the telescope was practically vertical. So I think removing all tensioning is not a good thing with a focuser as bottom drawer as this Orion unit.
I'm just tolerating the short comings for now. I've almost made a silk purse out of a sow's ear. But it seems to have taken a lot of gold thread.