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INDI Library v1.8.5 Released (19 Apr 2020)

April 2020 release of INDI Library v1.8.5 introduces new drivers while providing fixes and improvements to existing devices and core framework.

For those with focus issues

2 months 1 week ago
hy
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For those with focus issues #51202
I get many more stars with my f/5.6 scope on a typical image.
For an R,G, or B filter I use 3s exposure, gain 200 in the focuser (ASI1600 camera) and on most of my attempts was getting ~70 stars.
For Ha/SII/OIII I use 5s and get a similar number of stars.
Also, fwiw, I use a binning of 2x2 on my focus images.

If you aren't getting lots of stars, can you try adjusting your focus exposure and see if that improves things?

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2 months 1 week ago
mlarsson
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For those with focus issues #51203
Hi!

You use 2x2 binning? I've been experimenting with that. What is your pixel scale? Mine is 1.42 arcsec/pixel with this setup. Problem is that you would want the star spread over several pixels, wouldn't you? As opposed to alignment, where I use 4x4 bining to make it fast, and just a few secs exposure time.

I do not focus in Ha anymore, I have Ha loced to Lum in the filter dialog/window, and an offest of 97 ticks, measured as a mean over 25 focus attempts on a mag 2 star.

Magnus


C8, Losmandy G11, Canon 1000D astromodified.

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2 months 1 week ago
universalmaster
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For those with focus issues #51205

hy wrote: I get many more stars with my f/5.6 scope on a typical image.
For an R,G, or B filter I use 3s exposure, gain 200 in the focuser (ASI1600 camera) and on most of my attempts was getting ~70 stars.
For Ha/SII/OIII I use 5s and get a similar number of stars.
Also, fwiw, I use a binning of 2x2 on my focus images.

If you aren't getting lots of stars, can you try adjusting your focus exposure and see if that improves things?


The galaxy image shown above is ~40 minutes of exposure and does not show that many stars in the field. Downscale the exposure to 1-10s and you only get a handful of stars showing up. The focal length is 1320 mm and chip is ICX285AL, so FOV is 0.39 deg. x 0.29 deg, which limits the number of stars in the field.
I'll try 2x2 binning to see if it helps.

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2 months 1 week ago
hy
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For those with focus issues #51206
I see--I do not have experience with longer focal lengths. You may be right about that. Can you up your gain as well (of course, don't clip too many stars, though).

Here's a recent sub of mine (240s blue filter 1x1 binning gain 75 bortle 5 skies) uploaded to astrometry.net for the Sunflower Galaxy: nova.astrometry.net/user_images/3492359#original (hasn't finished yet, as I write this).
This is the full resolution from the ASI1600mm pro and my refractor, and the pixel scale should be about 1.34 arcsec/pixel

I understand your argument against 2x2, I thought the same, but honestly a friend recommended it and I found he was right, it worked for me. Try it!

I think it's important to get a reasonable exposure for focus, hence the gain 200 and binning 2x2 (of course, I could use longer exposures, but that increases the time for AF, and this tradeoff seemed to work for my setup).

I focus in Ha and it works fine for me. I really think the key is getting a lot of stars to average the HFR over. Even if you can't get 70 like I do for the wide field, if you can get 20, you may find an improvement.

I was tempted originally to try and write a better star-detector/hfr-calculator, but then I realized Jasem had put in a scheme (SEP) that had been worked on for years by the pros, so I figured that was something I wasn't going to improve upon.

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2 months 1 week ago
TallFurryMan
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For those with focus issues #51213
If you are using the Scheduler, and you image an area which has no, nearly no or actually fake stars, you need to change your workflow.

Add a first target as observation, where you know you can run a reliable focus. Enable the focus step, and add a short dummy capture sequence (you will trash its result). This will be your focus stage.

Then add your object as second target. Make sure you do not tick focus, and make sure the associated capture sequence does not trigger a refocus. Configure it so its total duration is shorter than the delay you want to between each refocus.

Then arrange your observation session to have focus, observation, focus, observation, etc. This makes your focus workflow independent. Just make sure your focus target is always visible during observation :)

You can use the same idea when unable to align on an object because of the lack of stars. Use a dummy intermediate job to approach and sync your mount, and untick align from your observation job.

-Eric

HEQ5-Pro - Atik 314E - Orion ED80T - DMK21 on Orion 50mm
DIY 3D-printed Moonlite and FWheel RGB/LPR
KStars and indiserver on two Atom 1.6GHz 1GB RAM Linux, VPN remote access

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2 months 1 week ago
mlarsson
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For those with focus issues #51218
Hi!

hy wrote: Use it with an Annulus of like 25% 80%. )


What is your reasoning here? Why not 0% 80%? The 80% makes intuitively sense, due to vignetting etc, but why avoid the center? Or do I misunderstand it (I'm good at misunderstanding things here)

Magnus


C8, Losmandy G11, Canon 1000D astromodified.

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2 months 1 week ago
gilesco
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For those with focus issues #51220

mlarsson wrote: Hi!

hy wrote: Use it with an Annulus of like 25% 80%. )


What is your reasoning here? Why not 0% 80%? The 80% makes intuitively sense, due to vignetting etc, but why avoid the center? Or do I misunderstand it (I'm good at misunderstanding things here)

Magnus


I had the same thoughts as you, I guess it might depend on your target, if you have a bright small galaxy at the centre of your field of view then it might cause star detection issues. So when dooing nebulous images I have been setting 0% - 75% for my focusing (although still manually focusing in and out and just using it as a tool rather than autofocus).

__
I blog my progress: www.coochey.net

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2 months 1 week ago
hy
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For those with focus issues #51221
Yes, that's it, not absolutely necessary to avoid the center/typical target area, but if you can get plenty of stars elsewhere then why not. If you're starved for stars then see if it works fine including it. I guess removing the edges would be avoiding areas that can have more coma, which might adding noise to the hfr values.

I just images m95/m96 where the galaxies weren't centered but I didn't change the annulus, and had no issues, so it's just something to make things run more automatically, that I've adopted from others, and I've seen bad star detections, eg in the center of m31, but the averaging and outlier removal would likely have avoided issues.

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2 months 1 week ago
DerPit
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For those with focus issues #51223
Two things coming to my mind reading this:
  1. Star detection
  2. As Hy says, use SEP. It's what sextractor uses. And I wonder if results would get better if you switch the camera to 8bit. PHD2 seems to perform (for me) substantially better in 8bit mode.
  3. star field area
  4. One other reason to use a ring is a (possible) field curvature. For 1-star focus a suggestion also is to use a star half or 2/3rd away from center, then both center and rim would still be in the depth-of-focus range...

openSUSE Tumbleweed KStars git INDI git
GPDX+EQMOD, CEM60EC, ASI1600+EFW+EAF+ASI290 mini

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2 months 1 week ago
mlarsson
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For those with focus issues #51241
Hi!

So I am testing full field with SEP as star detection. One thing that happens here, is that the focuser moves a lot! The first move is 500 tics. BUT: I have set initial step size to 100 and Max Travel to 400... So how come it moves this much? I have those more conservative values so as not to land it too unfocused settings, increasing the risk for misidentification of stars.

Did I miss something?

Magnus


C8, Losmandy G11, Canon 1000D astromodified.

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2 months 1 week ago 2 months 1 week ago by mlarsson.
mlarsson
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For those with focus issues #51243
Sorry, that was not caused by full field. But by "Linear". I had it set to Linear algoritm. When I switch to Polynomial, it behaves more reasonably.

Log attached, regarding the linear stuff. By the end of the log - I guess it is a bit long-ish, but by the end there are focusing with Linear.

Magnus


C8, Losmandy G11, Canon 1000D astromodified.
Attachments:

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2 months 1 week ago
hy
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For those with focus issues #51253
Magnus,

Sorry, looked at your log and something is clearly broken (I mean likely software) for your setup.
I'll look further. Which moonlight focuser are you using?

It didn't look to me like you had any successful focus runs with Linear. Is that correct?

Hy

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