Spongey

Very nice! What scope are you using? Also good to see that you aren't having reflection / halo issues like I am. Hoping I just got a dud or that flipping the filter will solve my issues. Also, what readout mode are you using? Gain 50 seems like an odd choice considering HCG kicks in at gain 56.

There is no specific orientation marking, but their website says that the non-ghosting side should be towards the sky, so that is how I installed it. I have yet to hear back from them but will update this thread when I do. I've also flipped the filter to see if that helps, but with no clear skies forecast it doesn't look like I'll get the chance to test any time soon.

Thank you Peter, I can only hope to get to your level one day! Cheers, as said I've emailed their support line asking for feedback but no response yet. You're correct, I do suffer from pinched optics in the cold. I detailed it in another thread as linked below. I have accepted it as a 'signature' of my scope, and it doesn't bother me too much.

I had a clear patch last night, and despite a flurry of other issues with my gear, I was able to capture a total of 13x300s subs on IC410 with my new QHY268M and Antlia 3nm Pro Ha filter. Shot at gain 56 offset 10. This is the full field of view, only cropped to remove stacking artefacts around the edges. Uploaded in 1:1 for all your pixel peeping desires Shot with my Esprit 100 and CEM40. Very happy with the camera so far! I do notice the halos around the bright stars at the bottom of the frame, and have got in touch with Antlia about them. CC welcome, as always

Nina crashed just after I went to bed so only managed 13x 300s in the end A quick stack and stretch, no other processing applied. Honestly I am both amazed and thrilled with this outcome! I can only imagine what 5+ hours would look like. I do have a halo on one of my stars at the bottom which isn't ideal. I might try flipping the filter.

Managed to snatch a clear spot. First 300s sub with 268M and Antlia 3nm Ha Pro. Gain 56 Offset 10. Calibrated and stretched, that is all. Having a host of other issues with my focuser etc. so used the bahtinov mask for this one. Amazed with the depth from a single sub though... Taking some more subs now before the cloud comes in later tonight. Will stack tomorrow and see what I can get Cheers

Hi, are there updates to share about the progress of this project?

Incredible depth for a single 300s sub! I'm dying to get mine out under the stars, but it might be a while until we get a clear night here

Updated BasicCCDParameters based on 99s and 999s darks: Gain 0 offset 10 Gain 56 Offset 10 Dark current looks better on these, but still higher than expected / published. Not sure of the root cause, I don't think the script works well with such small values of dark current. In any case I'm not concerned.

Some more info incoming... I ran the BasicCCDParameters script using some of my calibration frames for both Gain 0 Offset 10: and Gain 56 Offset 10: Looks like the specs match up quite well with the published graphs. I do note that the dark current seems quite high, but this is based on relatively short dark frames and it's been noted already that using short darks for this messes up the script. I'm taking some 99s and 999s darks at the moment so will re-run the script with these once they are done.

I'm also using -10 degrees. At this level of dark current going to -15 isn't necessary imo, and sticking with -10 means I can safely achieve that temperature all year round.

From what I have heard, some CMOS cameras can exhibit strange banding or blotchiness in very short exposures. I don't see any of that in my master bias or in the darkflat, and the statistics tool in pixinsight shows that they are almost identical.

Bias exposure length was set to 0 in NINA, FITS header reads it as 0.000001s Yes, calibrate flats with master bias (not superbias - there is conflicting info about this process), and calibrate lights with master dark and master flat. Cheers

So I've just stacked 30 dark flats at 0.68s each for my Lum filter and flat panel and the result is attached. My conclusion: dark flats are not necessary with this camera and a master bias is sufficient to calibrate flats correctly. My reasoning: The master bias I attached in my last post is essentially identical to this. Master darkflat.xisf

It is a good question and one I'm not sure of the answer to just yet. I'll be building a flat library tonight and will also take some flat darks to compare with the bias frames. My understanding is that flat darks are preferable to bias frames with cameras that have unusual very short exposure effects (e.g. ASI1600). When dark current is negligible (which it is at -10c) and the camera is stable at very short exposures, bias and flat dark frames are essentially identical. From what I have seen and read, people with the QHY600 / ZWO6200 have been using bias frames over flat darks with no issues. I would hope that the IMX571 would be similar in this regard. In any case shooting off 50 bias frames doesn't take long!

My camera arrived yesterday and looks great, it is a big beast though! Very well packaged from MA so top marks there. I've attached a few photos: Filters are Baader LRGB, and Antlia 3nm PRO Ha, Oiii (waiting on this one), and Sii. I managed to build my bias and dark library overnight too, and have attached some files if anyone wants to poke around. Each stack is 50 subframes. I've never used a cooled camera like this before but they look good to me, with minimal fixed pattern noise and few hot pixels. Looking forward to first light with my first foray into mono imaging!! Cheers Gain 56 Offset 10 Master Bias.xisf Gain 0 Offset 10 Master Bias.xisf Gain 56 Offset 10 300s Master Dark.xisf Gain 0 Offset 10 180s Master Dark.xisf

While I agree with everything Vlaiv has said, is it not true that scopes with a central obstruction will be affected worse by filter 'aperture stop' effects due to fast f ratios? As a higher proportion of waves come in at an angle, more light is lost when compared to a refractor of the same speed. I seem to recall reading an article on this some time ago, I think it was documented over on CN. I'll try to find the link. Cheers Edit: found the thread

I will detail it for sure, though I will most likely start a new thread dedicated to the 268M as this one has wandered very far from it's original intent.

My 268M has just shipped! Should be here over the weekend or Monday. I can't wait!

Great info, thank you. Looks like the package includes everything as stated by QHY in this post and diagram (blue and red), minus the filter wheel:

First batch of 2600MM finished!

I've just re-read the post and he mentions that the tilt adjuster adds 5mm. I've asked for a photo / further clarification.

I believe that he is referring to this top 'plate', which is screwed into the camera. On previous cameras such as the 268C this top plate is not present and instead is replaced with the dovetail style attachment. I have read people saying that this dovetail is what was labelled as the tilt plate on the previous cameras, hence my previous comment regarding the poor translation. If this is actually a tilt adjuster then that would be quite useful, but it doesn't look particularly easy to adjust if it is! Based on the below diagram for the 268C, it looks like this is simply the top part of the camera, which encloses the sensor chamber. Removing the top plate and adjusting the screws in the above photo would not be a good idea in that case. My suspicion is that the top plate as above simply replaces the dovetail attachment and serves no tilt adjustment function.

Some info on the 268M and its supplied adapters: https://www.cloudynights.com/topic/753265-received-my-qhy268m/#entry10841589

I have ordered the QHY 268M for similar reasons to those mentioned above, but primarily availability and price. If the two cameras were the same price then I probably would have gone with the ZWO, but £400 is a significant chunk. If I end up needing a USB hub then I'm sure the savings from the camera will cover it Considering both of these cameras are based on their colour counterparts, one other thing possibly worth noting is the issues with residue on the 2600MC sensor due to grease used in manufacture. I haven't heard of any similar issues with the 268C.