Pitch Black Skies

Yes, the screenshot is from the LP test last night, just a blank patch of sky. I didn't save the subs, I just screenshot them for the ADU readings. The fit file is M101 from a session a few weeks back. I haven't ever adjusted the offset as I don't understand it.

I just want to add a screen shot of a bias and a 300sec sub of LP from my ASIair Pro too, to make sure I am reading it correctly.

I don't understand. Do I need to do some calibration as part of the experiment?

@vlaiv Bias_1.0ms_Bin1_533MC_gain100_20220420-140701_-10.8C_0002.fit Light_M101_300.0s_Bin1_533MC_gain100_20220402-231650_-10.0C_0002.fit

My results: Mean ADUs Bias 2797 30s 2822 60s 2847 120s 2896 180s 2948 300s 3047 The closest I can get to 56.25e was with the 300s sub. √3047 = 55.19e I didn't feel confident about exposing longer than 300s but I need to do that to reach 56.25e. Although is 300s+ not a bit excessive for an optimal exposure time with this camera? 1200 ADU above the bias mean ADU doesn't seem practical from the test results. For 300s I was only 250 ADU above it..

I think I've read that swamping the read noise X5 is a safe exposure length guideline. How do I know I am swamping it X5? Is it a case of measuring the ADU from a bias frame and then taking an exposure until it is 5x that ADU? My camera is 533MC Pro. I use unity gain 100 under Bortle 4.

But wouldn't the histogram be over on the RHS then? I will try the bias method, sounds very straight forward.

UV/IR filter

M106 and neighbours Just over 3 hours worth of guided data with a Skywatcher 130P-DS and a ZWO 533 MC-Pro. Pre-processed with DSS and post-processed with Siril.

Just to give an update.. The mount is actually a bit quieter. It's not a huge difference but it does sound smoother. Guiding numbers seem to have improved slightly too.

Yeah it's only couple of months old. Not sure what I was expecting really. It's my motors that are noisy. The belt mod can't help that.

It looks a lot cleaner when I put it through Topaz, however I only have the trial version. Another goodie for the wish list.

Ah I see, I was trying to move the midpoint before I had even pressed the auto-stretch button I see why the 32bit is so important now. My thinking about the gain is if I increased to 200 I would have lower read noise and shorter exposure times leading to tighter stars possibly?

It's just that when moving the midpoint slider, the histogram is moving very erratically. Do you think it would be better in future if I increased the gain to say 200 instead of unity 100?

First attempt with Siril

I've noticed that my histogram is way over to the left. Does that mean I'm clipping my frames? The image is 24 hrs of 300s @ unity gain under Bortle 4. I'm using 130P-DS and 533MC-PRO. There is a ton of detail in the auto- stretched image.

I have a primary baffle fitted to my 130P-DS and I'm wondering if it would actually be better to remove it. The baffle is designed to cover the 3 primary mirror clips and it does an excellent job at that. However, there is another method to remove the interference from the primary mirror clips and that is to fix the primary mirror to the backplate with silicone adhesive, and ditch the clips completely (credit to Alacant for this idea). This method has the added benefit of also preventing lateral movement from the mirror cell. The main reason I am wondering about whether to remove the baffle is because it is increasing the telescope's focal ratio, consequently slowing the telescope down. With the baffle fitted, I have calculated the focal ratio to be 5.45. Focal length ÷ aperture = focal ratio 649mm ÷ 119mm = 5.45 Without the baffle, I have calculated the focal ratio to be 4.99. Focal length ÷ aperture = focal ratio 649mm ÷ 130mm = 4.99 This means that without the baffle, the telescope is 84% faster for the same SNR? Focal ratio^ ÷ focal ratio^ 5.45 × 5.45 = 29.7 4.99 × 4.99 = 24.9 24.9 ÷ 29.7 = .84 For 10hrs of data with the f5.45 I would only need 8.4hrs with the f4.99 Apologies in advance if this has baffled anyone

How can I download this? I'm on Windows. Had a search for it last night but no joy.

Thanks for the feedback, I'll have another attempt.

Okay I've just figured out how to do it. It doesn't show a drop-down menu in the file type for me when saving. It just says 'All files' and I have a manually type either .jpeg, .PNG, etc after the file name to get it to save it in that format.

Pity about the patent, however you're obviously very mechanically and inventively minded so maybe you can come up with another clever concept some time? Thanks for sharing your interesting story.

@Dave S @The Lazy Astronomer I use Startools. It seems to only output as .tiff. What about loading it into GIMP and exporting from there? I suspect the tiff viewer app on my phone is the culprit.

After I process my images on the laptop, I usually transfer the .tiff to my phone via bluetooth. When I open the picture with tiff viewer app the image looks poor. I'll then open the .tiff with Adobe Lightroom and export it as .jpg for uploading to this forum. The end result always looks degraded. Is there a better way to go about this?

That's really cool, didn't realise you were behind it, excellent work! It's probably because my mount is practically new. Had I of waited another few months, the graunching sound would more than likely have crept in. Like you said anyway, it's the numbers that matter. I'll be able to test it tonight and give an update.

What kind of numbers are you achieving on guiding now?