Bernd Limburg replied to the topic 'ASI294MC, Bias and exposure time?' in the forum. 2 weeks ago

Yes, if you select „bias frame“ exposure time will always be the minimum possible time regardless of your input. If you want to vary exposure time, either select „dark“ or „light“.

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Bernd Limburg replied to the topic 'What is a good HFR with autofocus?' in the forum. 2 weeks ago

Hi,

with the same camera, but with Celestron C9.25 with f/6.3 reducer (= 1457 mm effective focal length), on a good night I usually get HFR values around 2 pixels, from a non-saturated, medium-bright star. Depends on star brightness, exposure time during AF and very much on seeing conditions.

Translated into arcseconds: alpha = arctan(object size / focal length)

In my case object size is 18.5 microns (2 pixels radius = 4 pixels diameter = 4 x 4.63 microns), so my half-flux discs have a diameter of 2.6“.
In your case (100ED has FL = 550 mm, right?): Object size = 13 microns (2 x 1.4 x 4.63), so your half-flux star discs are 4.9“.

Normally, resolution is seeing-limited, 1“ would be excellent (mountains, no turbulences, dry air) and 4“ would be bad seeing. I would expect your discs can go down to 3“ or 2.5“ as well resulting in a HFR size of 1 pixel or slightly below that.

CS

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Hi,

at least for the ASI294MC this adjustment is permanently written into the FITS, which is not optimal. It is a property of the ZWO Indi driver. On the „Controls“ tab in the driver you can adjust „WB-R“ and „WB-B“. But, as said, this is baked into the FITS raw image. I would leave the WB-R and WB-B at 50 (neutral gain) and do color correction in post.

CS, Bernd

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Bernd Limburg replied to the topic 'Celestron Motorised Focuser - Is it supported in EKOS yet' in the forum. 3 weeks ago

Hi Hans,

I use a XBox 360 controller as a joystick to focus. The SCT focuser driver has joystick support. And to slew, to set slew speed, to park, to unpark, to abort motion („panic button“), as the EQMOD mount driver has joystick support as well. Great when observing visually. The XBox 360 USB receiver works perfectly on the RPi 4.

CS, Bernd

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Bernd Limburg replied to the topic 'Newbie need advise on buying his 1st GEM' in the forum. 3 weeks ago

Hmm, I don‘t think that the SkySync will work with the HEQ-5 but I don‘t know for sure.

I‘m using the HEQ-5 with Indi on a Raspi which has internet connection (via my house wifi). So the EQMOD driver gets the coordinates and local time from the Pi, so no need for a GPS module. But if you‘re out in the field, a standalone GPS receiver is nice and comfortable.

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Bernd Limburg replied to the topic 'Newbie need advise on buying his 1st GEM' in the forum. 3 weeks ago

Hi Mohamed,

I have a Skywatcher HEQ-5 which is in the same class as the AVX. Costs just below 1000 Euros here in Europe. I have it loaded with almost 10 kg (Celestron C9.25“) which is the upper limit for AP IMHO. I‘m really satisfied with the mount, I decided to buy a HEQ-5 and not an EQ-6 because of the price (I had a budget of 1000 as well) and the lower weight (I have to carry it out and into the house every session...).

The Skywatcher EQs work with the Indilib EQMOD driver which is really nice and loaded with options. What telescope are you planning to use with the mount?

CS, Bernd

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Bernd Limburg created a new topic ' Astroberry and PHD2 built from sources' in the forum. 3 weeks ago

Hi,

is it possible to update PHD2 within the Astroberry environment by building PHD2 from Git without messing up the system? The apt update/upgrade procedure is always a bit outdated (still PHD 2.6.7).

Thanks, Bernd

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Great guide, very helpful for Astroberry as well! Used it to install a SSD mounted at boot time, works perfectly. Lots of space now and fast, especially important for FireCapture when it writes the video files. On the SD card, this was nearly impossible.

I have two questions: How can I back up the SD/SSD combo to an external image file? It‘s a bit different from the situation with just a SD card. And how would I restore this backup, just in case?

Thanks and CS, Bernd

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Bernd Limburg replied to the topic 'Bias frames - No data/empty?' in the forum. 3 weeks ago

Did some more testing with my ASI294‘s bias frames. After powering on the cam and doing bias frames with shortest possible exposure I get correct frames with a median value as expected (depending on the offset I chose). But once I do exposures > 1 s (all fine with them) and then do bias frames < 1 s again, these frames are all zero. The magic threshold here is 1 s; above it‘s OK, below it‘s all black. Until I powercycle the cam.

In light frames > 1s I notice an all zero pixel column to the very right of the image. Maybe they are opaque covered „dark pixels“ for doing an automatic dark correction? Some CMOS sensors have this feature. Maybe some sort of auto dark offset correction kicks in once the first exposure was taken > 1s? For astro purposes, I think this should be deactivated in the cam‘s firmware (or whatever code is responsible for that)...

Anyway, I now do only use frames > 1s exposure, be it light (of course :) ), dark, flat or flat-dark. And I don‘t use bias frames at all. The 294 has so high amp glow, it doesn‘t help being able to scale bias-corrected dark frames as PixInsight can (for example). And in the end, my images look quite OK, so no problem... But I would like to understand that behaviour.

CS, Bernd

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Bernd Limburg replied to the topic 'PHD2 update in SM?' in the forum. 3 weeks ago

You can backup your Pi’s SD card before and then try without risk.

I‘m asking me the same question and will give it a try with a current backup as a joker. In my case it‘s a bit more complicated since I run the Pi from a SSD (in combination with a SD card). Maybe a bit more work then in case I have to revert to my backup just in case...

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Bernd Limburg replied to the topic 'PHD2: Some windows unreadable due to font color' in the forum. 3 weeks ago

@jugglerkris: Thanks, this workaround to change the theme only for PHD2 works great and all windows are perfectly readable (what I tested so far)! And KStars' and Ekos' windows are not affected. So, problem solved!

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