Autofocus Issue with

When I run an autofocus with images are acquired, but the HFD is not measured. Therefore the autofocus fails. I tried reverting back to the release version, but if I do that my hardware profiles are not loaded.


This is almost always a settings issue. If you can provide logs first (and then possibly an AF Pack), we can take a look.

Here is a link to the log file:!ArTitUkqc-OYgeQ0-pxIjeYLMUt1JA?e=ilcf69

The time of interest is [11/14/19 22:15:43.219].



You typically should not try to perform auto focus with a narrowband filter. While it’s possible, it will take forever… a 10 sec exposure through Ha is not nearly long enough. It would need to be 45-60 sec or more depending on its rating.

What most people do is determine the difference in focus positions between a LUM filter and each NB filter. You record these deltas then perform AF with the LUM filter and, after completion, adjust focus by that delta. Just explaining the process… of course, SGPro automates all of this for you.

Check out the section on “Setting up your rig”

I could get the old autofocus routine to work with (bin 2) 25-30s exposures using 3nm NB filters and scopes that are not very fast (for example, f/7).

I do now use filter offsets, but I calculated those offsets by running a series of 30s NB autofocus routines and comparing the final focus position with my 5s Lum autofocus numbers. It would be a pity if this no longer works with the new autofocus routine. Indeed, using a Bahtinov mask is not an option for people who have remote scopes. There may also be some people who (for whatever reason) would prefer to run autofocus using a NB filter.

I get very nice focus curves with the new focus routine using 12 second exposures for all my NB filters using my TV127 refactor at /f 5.2. I would guess something else is going on.

Do you find a difference using your NB versus your LRGB? Are any of them focusing for you?

Here is a plot of the Temperature dependence of my filters on the TV127, provided by the wonderful SGP AutoFocus Viewer program developed by @mikaelA :slight_smile:
The “Analyze filter” drop list cycles through each filter, showing it’s regression line and formula.
I used the following exposures for these focus runs: L=5, RGB=7, NB=12.


And the filter offsets are calculated automatically:

ANALYSIS OF TEMPERATURE COEFFICIENTS --------------------------------------------------------------------------------------------
HFR = a*T + b
a: slope
b: intercept at T = 0
SGP temperature compensation factor: -a
(Negative temperature compensation ratios in SGP indicate that your focuser will move INWARD as temperature drops)

Filter Lum : a = 5.4 steps/deg, b = 20977 steps, SGP factor: -5.4 steps/deg
Filter Red : a = 5.4 steps/deg, b = 20986 steps, SGP factor: -5.4 steps/deg
Filter Green : a = 5.2 steps/deg, b = 20989 steps, SGP factor: -5.2 steps/deg
Filter Blue : a = 5.2 steps/deg, b = 20977 steps, SGP factor: -5.2 steps/deg
Filter Ha : a = 5.0 steps/deg, b = 20979 steps, SGP factor: -5.0 steps/deg
Filter OIII : a = 5.2 steps/deg, b = 20964 steps, SGP factor: -5.2 steps/deg
FILTER OFFSET CALCULATION -------------------------------------------------------------------------------------------------------
Filter offset calculation using the linear regressions.
Offsets are calculated at the middle temperature of 45.1 deg
Filter Lum : 0 steps
Filter Red : 7 steps
Filter Green : 3 steps
Filter Blue : -10 steps
Filter Ha : -17 steps
Filter OIII : -24 steps

AF Run Date Time Pos HFR Temp Filter Misc Target
File ID = 20191015195556
1 10/15/19 20:02:39 21269 2.62 52.88 Lum Successful
2 10/15/19 20:05:54 21268 2.89 52.88 Lum Successful
3 10/15/19 20:11:20 21266 2.94 52.52 Lum Successful
4 10/15/19 20:14:48 21272 3.16 52.34 Red Successful NGC6914 Reflection Nebula
5 10/15/19 20:18:37 21265 2.72 52.16 Green Successful NGC6914 Reflection Nebula
6 10/15/19 20:22:15 21251 2.84 51.98 Blue Successful NGC6914 Reflection Nebula
… (all focus runs are listed)

This version of the SGP Logviewer that Jerry refers to is not released yet, but it is coming soon. I hope to post it tomorrow! :slight_smile:

I’m doing a focus analysation run now so it would be cool to get access to the new version soon :grinning: