[Autofocus] Allow different binning for different filters

Sequence Generator Feature Requests
1

The autofocus already lets us define different exposure lengths. However, could we have the same ability to set different binning for each focus.

I ask because it would make autofocusing with very narrowband filters much quicker without impacting on the quality of focusing on wide band filters.

2

For narrowband we recommend using the focus offsets and using a Lum (or similar) filter for the actual focusing. Even at 3x3 on my 4nm filters the AF exposures were about 3 minutes a piece to get enough data for adequate focusing. I did this once to setup the offsets and haven’t looked back!

Thanks,
Jared

3

I’m consistently getting good autofocus with 5 and 10 second exposures with a 3nm filter at 4x4. (1 second with lum at 2x2)

Others are reporting 30s at 2x2 for the same filter so I still think this is a simpler solution than offsets and swapping filters.

4

I mentioned this on SGL as something I would find useful. As it stands at the moment I don’t find offsets massively reliable and I believe that better focus is achieved using the filter being used in the imaging run.

To this end, I use 2x bin for focussing, this is fine with broadband filters, 8s per exposure. However when using narrowband 3nm filters I am using 45s exposures to get anything like a decent number of focus stars. I could increase to 3x bin, but if I do tnis I have found that the focus in luminance at 3x is a bit unreliable.

So if I do lum and Ha in the same sequence, I have to keep the same binning for all the filters. It would be great to be able to specify a different binning for different filters.

5

It is my belief that:

  • This is highly dependent on field. If it is star poor, you will need to go much deeper.
  • Even though the data may appear as “good” visually, the algorithms we use are far more likely to be deprived of data in narrowband.
  • Running AF at 4x4 will reduce resolution so significantly that results of AF are not reliable.

These are my beliefs… mileage may vary.