Tom OD

I ve had this same issue and it’s ended in a re shoot in a few occasions. It’s worth going through each of your 30 subs and checking the background values. Maybe sone passing thin cloud in a few frames has messed up the overall stack. Certainly shooting with a moon about won’t help, but it might be a rogue frame or two. I can’t remember if I found an issue when I had this problem. I can think of three times it occurred, so as I said I m afraid I reshot the panel in question. Tom

Bloody hell that’s a lot of dust. Great capture. 4 pane mosaic and barely a whiff of dark background space in there. T.

Olly put the light panel on the scope, and at its lowest brightest setting. When I started taking pics, it was giving white pixels on the lower part of the chip through a gradient to black pixels at the top of the chip. After adding in the paper sheets, I was able to take exp to 1.3s, and the gradient started to disappear and become uniform. The dust bunnies then wold show. It took a few sheets of paper to get it to the point where the LRGB were a few seconds long,which gave a good gradient across the flat. Ha flat then become about 20s With these settings, the ADU was approx 20,000 of the full well depth, which I m happy with as 55k is the stated full max. Tom

Hi Alan I just started imaging leaving the camera on power Save, and Low as the settings. Sorry I still have to mail Atik, I got very side tracked, and started on a new mosaic. I m not sure how to write a review of the camera, but I can say that the FITs are very clean. My old 11 meg had a lot of pixels, and bad columns, so each file of the camera is a joy from that point of view. I have been taking 2hrs worth of Lum frames, where normally I would have taken 4hrs of Lum for each Lum pane. In my new 2hr frames the data is clean (so far without flats) and the data of the dim background dust is very evident. I have not taken Ha or RGB frames yet, I ve been just running it for the Lum frames. In short I m very impressed with the camera. The system still has tilt, so I cant give a proper account just yet, but in a mosaic the end downsized frames will not show the tilt issues, especially after the overlaps are blended. The chip is o sensitive that taking flats is tricky. The Ha flat at 6 secs show s agoo even light frame. The lower 0.1s flats for the other filters, are giving bright to dark gradients across the chip that are unusable. So you need a dim flat field box I think to get flats with this chip. Tom.

Try SCNR on the full image, it might only adjust the middle section. T.

Great shot given the latitude. It might be a bit green on my screen in the centre, but you nailed the contrast I think in the dark nebula areas. Tom

Jeez, thats a lot of signal for 2.5hrs per panel approx. Small stars too! super job. Tom

Yes the low gain value is 0 as per Astroart header data. I haven’t written to atik yet as I wanted to get the tests done first so that I can word my mail correctly. I ll send it this weekend. Tom.

Good thinking and yes the values are there. So even though the manual says the Gain goes from 0-35 the Medium and High have much higher values.

Thanks Alan. I was looking at the main gain setting in SGP, but I was not aware of the Cog wheel second option, so thanks for that. I'll add in the meta data to the files too, its good info to have. I'll let the Ascom driver start with the Power save and Low, and go from there for starters. Tom

So a few things must be happening here. Either the Atik amp works differently to ZWO, the most likely I would think, or the software is controlling it differently. Given the chips are all from Sony, I would think that any specific silicon P/N gate signal or what ever it the correct term, will be the same. So any cliff in voltage signal should be the same for all further cameras manufacturers. My data is not showing a cliff anywhere in the Std Dev. (We are taking the Std Dev in ADUs as the Read Noise here in Bias frames) Now the Atik manual is very vague about settings that "PowerSave – This mode allows the camera to shut down non-essential circuits during exposures" Who knows what this means. Maybe Atik are reading this thread and enjoying our struggle here Tom

Yes its fun taking and plotting the data and seeing what the cameras does. Is HCG normal in all other CMOS chips? I dont know, or is it only dependant on how the software reads the chips, sets the gain etc... Tom

Yes a full frame planetary camera seems counter intuitive. Increasing the offset to stop clipping makes sense as I read it. Thanks for all your inputs here. I think its lead me to the Low setting, and Power save. That suggests that it'll also keep the full well depth high. Unless I m chasing super dim nebula, I wont change those settings. Tom

No there is no mention of what the gain and offset values are actually running at in the preset modes Low Medium High. However given the Background values that match the closely the ADU, it looks like they run at 200, 400, 1050. So maybe as the manual says, the Power save, Normal and Fast which show very little differences are like the USB speed in your ZWO menu. I can see how Fast would allow lots of frames to downloading to beat the seeing. I m at a loss to explain the Medium and High Presets though. Looking at the Medium and High frames though, the 0 ADU seems to correspond to the lower x axis, yet the offset appears to be at the 400 / 1000 mark. I guess either the gain is maxed out, and / or internally the s/w is doing something to the chip causing the data to get clipped on the Min values. Very confusing. See attached Stats FOV from the Medium Preset setting on Normal Mode. Tom.

Here are some more results from todays tests. Taken at room temp, and an offset at 400 for the table of varying Gain values. Then I tried different "Power" modes. The Power Save is not the lowest noise / SD value as the manual states. All in all I think it might be best to just go with the Power Save mode, and Low settings that Atik set. There is no obvious HCG cliff in the data as in the ZWO settings. Tom