Icesheet

As Vlaiv stated, astrophotography bears little resemblance to day photography. For example you mention conversions of focal length to full frame equivalent. The focal length is the focal length and that’s what will test the precision and accuracy of the mount you choose not the size of the sensor. Of course you should consider sensor size, FOV and pixel scale when considering the framing of your object but there is no crop factor as you commonly hear in landscape type photography. Also, it’s unlikely you will be shooting anywhere near ISO65. I’m not familiar with the PhaseOne’s but it’s unlikely to be under ISO800. It’s not clear to me exactly what you would plan to shoot. Is it landscape milkyway type photography or, do you plan to do deep sky astrophotography? You mentioned a 240mm lens with 2x tele-convertor. If you really plan to shoot at 480mm then one of the strainwave mounts mentioned would probably be your best bet as you would have to guide anyway. As an aside I wouldn’t use that lens with the tele-convertor as f9 would be slower than you want for night sky photography. If it’s more widefield work then there are a plethora of sky trackers that would work for you. The Fornax Lighttrak ii is probably the most accurate on the market and will handle the 240mm lens without guiding. It lacks GoTo though. The Star Adventurer GTi has Go To and seems to be popular. Or you could consider the Benro Polaris if you will only shoot at shorter focal lengths as it negates the need for polar alignment and you can shoot fully automated panoramas which may be of interest to you. There’s likely to be some great advice on this thread but also use YouTube as a resource as there are plenty of content creators doing a wide range of astro work. Edit: Apologies, re-reading, I see you mention deep sky. Then, I would not recommend the Benro Polaris for that. Probably a strainwave mount would be best but factor in what else you need for guiding and polar alignment. I would also look for another option other than using the 2x convertor with the 240mm lens.

You know, I actually haven’t even compared to see if dithering has made a difference in my images. In the main I’m dithering for drizzle integration in PixInsight but I haven’t checked the difference between a drizzled and non drizzled. I really should but just accepted the general consensus that it was worth it. I think a small polar alignment error may not provide enough random movement to replicate a true dither but I’m no expert either. May be time to make a comparison of what I have!

I imaging at 1.94”/px with <5kg on the Sightron carbon fibre tripod so I don’t think tripod stability is the issue here. At least it shouldn’t be. I do have a Berlebach uni tripod I could test. The power supply is something that keeps coming up so I should definitely check that out I think. How is your guiding with the RC6?

Thanks, I don’t think I have any back up software and I haven’t experienced any of the other issues you mentioned but I’ll keep an eye on it. I use the IMX571 so I’ll look into that. If I can limit the dithering it’s going to make a huge difference. Thanks! I’m going to look into the power supply issue with the RST135 to see if that may be contributing.

For RGB it’s 120-180s and for narrowband it’s 300s. I did change to every two and I suppose I could go to every three frames for RGB exposures. Ok, interesting to know that 5 pixels was not enough. So, going to 30 you noticed a difference in the final image? I haven’t spent much time analysing the mount to be honest but I am aware that sometimes it doesn’t play well with a 12v power supply and that’s what I’ve been using, so I may have to look into that as a potential source. I use the Sightron carbon fibre tripod and I don’t think wind is a factor here. It’s pretty stable when just guiding normally. Just seems to go haywire after a dither. Would dithering induce vibrations?

I’ve recently noticed that my imaging efficiency is low. Basically, I need up to 1.4 hours for each hour of actual gathered data, depending on exposure length. I think I’ve narrowed it down to dithering and in particular the time to settle. What I’m not sure is if this is down to the settings I have chosen or the ASI air and/or mount itself. Here’s a screenshot of my current settings in the ASI air On my latter part of my last run I changed to dithering every 2nd frame and that helped a little. Still, it seems it’s the settling that’s causing most of the issue. After a dither the guiding is quite erratic and frequently a new exposure starts after a 60s timeout. For info the mount is a Rainbow Astro 135. Guiding maybe hasn’t been as good as I would necessarily want but it’s under 1”RMS in general and given I’m imaging at 2”/px I’ve not spent anytime trying to optimise. Anyone had a similar experience and can suggest a good way to approach this so I don’t waste even more imaging time?

Looking at this again it seems like I still had a slight gradient. This a new version with an ABE. Think this is better?

First time capturing and processing a dark nebula. I had aimed for 7-8hrs integration but only ended up with 5.5 then had to throw away another hour. So, with 4.5hrs I was worried I wouldn’t have enough to work to work with. In the end I’m happy with the result considering but I did have to push quite a bit and I think that shows when you look closely. Will definitely get more integration time here and would love to eventually incorporate the squid and fireworks galaxy in a mosaic. Seen some great dark nebula work here so hoping for some constructive input on processing. Askar FRA400 and ASI2600MC 140x120s 30x dark, bias and flats Processed in PixInsight

Nice image! Definitely invest in a wedge and convert the AzGti to EQ mode. This will make a world of difference! As mentioned, as much integration time as possible

Thanks, I’ll look into the GAME script too. Actually, made some progress last night so hoping I can get a satisfactory result.

Another great image! How are you adding RGB colour to the Ha stars? I did use star removal and I can keep it small enough it’s really the halo that I’m struggling with. You don’t seem to have any here which I’m jealous of!

Fantastic image and I would happily take your Altinak in all its glory! Yes, StarNet and StarXterminator can’t remove everything and that doesn’t help matters. Another great image and it’s very well controlled here. I did think at the time that I should have taken some shorter exposures! I’ll try that next time I have a clear night. My dual narrowband subs have tighter stars as expected but I really don’t like the stars from the L-extreme filter.

I've collected some dual narrowband and RGB data on the horsehead but I'm really struggling to control Alnitak in what is an image I'm otherwise delighted with. I've attached a screenshot of the STF of the RGB stack and the best draft I have come up with so far. To me it really distracts from the final image. I've tried masking while stretching with/ without stars. Clone stamping, star reduction. Nothing seems to control it or I'm left with a ugly artifact. Anyone out there with any Alnitak magic bullet?!

One of the best I've seen 👏

Thanks @vlaiv. So presumably I can do this with existing exposures I have that have tracked across the different Bortle zones in my area on the same night? Now that I think about it I have noticed a trend from the PixInsight subframe selector that my exposures seem to get poorer as the night progresses. I wonder if that correlates with moving to a more light polluted part of the sky.

Does anyone know the background of this table, how it is measured and how reliable it is? I was obviously aware of the hugely detrimental effect of light pollution but hadn’t really seen it set out numerically like this. That’s mind blowing to me and potentially hugely significant. According to light pollution maps I image from just inside a Bortle 4 zone. However, depending on the direction I image it can be towards B2/3 or B5/6. Given the significance of the apparent jump from 4-5, I wonder if my imaging time is better spent solely towards Bortle 4 and under. Could anyone suggest what I could do to test this? Edit: Apologies, I see this is in an Observing forum. I can start a new topic in an Imaging forum if it’s preferable.

Thanks ☺️ Yeah, I did actually know this. The word ‘apparent’ was my lazy attempt at acknowledging it. Funny you should mention daytime photography. I just watched a video where a very popular landscape photographer discussed resolution in this context and it annoyed me enough to comment on his video. I’ll need to be clearer next time!

Here's the widefield for reference...

Another target I haven't paid much attention to previously. Clear skies with a nearly full moon turned my attention to the Veil nebula for the first time. I imaged it for 3.5hrs with the Askar FRA400 and ASI2600MC but I didn't think the widefield image was so appealing, so I cropped to the West and East side of the Veil despite losing some apparent resolution. I found it hard not to push the saturation too much on these. I still think I've maybe gone too far, what do you think?

Yeah I did use BXT, SXT and NXT. I’ve only recently got the FRA 400 and I’ve been very happy with it. It has been hassle free and has given me round stars into the corners. I think the trade off is it’s maybe not as sharp as other scopes but processing techniques help there.

Yeah it’s HOO data. Maybe, it’s better described as pseudo Hubble palette? I used one of these narrowband scripts in PI to map it. I shoot from Bortle 4 according to the light pollution maps. Depending on target that can be towards B3 or B5.

Surprisingly, this is a target I have not shown much interest in. However, I had unexpected clear skies and no time to search for something else and this fitted perfectly in my FOV. Actually very happy with the final outcome for ~4hrs of integration Askar FRA400 with ASI2600MC 40x300s with l-extreme 10x120 for RGB stars. Processed in PixInsight

Congrats! Well deserved 👏🏻

Yeah, good idea. I’ll test with and without a mask. Will help with some selective colour saturation too.

I thought running SCNR might actually remove some of the OIII signal. I’ll definitely give that a go when I try again. Will also see what I can do in photoshop although I haven’t used that in ages. Thanks 😊