Swillis

@TiffsAndAstro Now I've seen it as the piglet, I don't think in can go back! 🤣 Nice work for one night

Pun intended? Looking forward to seeing your 450k sec version

Are the exposure lengths the same? Can you (I mean your friend) compare side-by-side, and check background signal and target signal?

Thinking about this a bit more... At f2.8 we would want to pass 653.3-656.3 for Ha, a 3nm range. What wavelength are the pre-shifted filters shifted too. I think the baader f2 filters 3.5/4nm fwhm, so even it was optimised to the range I calculated the the extremes of that range would not be at the peak transmittance? At f2 the range of wavelengths we would need to pass would become even wider. Does this sound right? I could be completely wrong on this with my knowledge being a few days old...

Thanks @SteveNickolls I will give that a watch later. I think I came across as discussion on CN which referenced this. @Elp the question was do you need pre-shifted filters, or can you use a wider band pass filter instead. This would rely on there not being too much light pollution which would be an issue with the wider band pass. Looking at Cuiv's spreadsheet, for the SY135 @f2.8 the peak for Ha would shift by 3nm at the edge. I think a lot of the fast filters are very useful for fast scopes with central obstructions but the SY still receives a fair amount of light which does not get shifted. The wavelength doesn't shift within the central ~12mm of the radius, so a reasonable amount of the signal would get through without a central obstruction. Theory is one thing but practical experience may tell a different story. Also I could have made some mistakes and incorrect assumptions with the spreadsheet.

Yes, it's less of a shock when you look at the prices for individual filters, and then compare to other brands. Would the f2 filters work in a slower scope? Or are they shifted too much? I need to get the camera first and will probably get LRGB filters first so plenty of time for more research...

Thanks @Elp I'm sure those filters do a great job but that's a few more pennies than I was planning on spending. But you get what you pay for... I did a bit of looking around and this topic came up previously in this thread (back on page 4), where 5 & 7nm are mentioned as working with this lens. I also found this page interesting where someone has determined where they get a drop off in signal Vs f ratio https://digitalstars.wordpress.com/2020/11/29/empirical-evidence-on-narrowband-filters-with-a-fast-telephoto-lens/ Thanks Simon

Hi all, I have been thinking of upgrading from my Canon 600d to a 533 mono astro camera. I wanted to ask what narrowband filters everyone is using with the SY135? I know that band shift would be an issue with this lens. Are you using pre-shifted filters? Or can you get away with a wider band pass filter? I have seen Cuivs video on bandshift and have downloaded the spreadsheet calculator, but haven't had chance to plug the numbers in yet, also real world experience is just as useful as the theory. I am in bottle 5, so light pollution is not a big issue for me. So I'm not after the narrowest of narrowband filters. Thanks in advance Simon

That's great. I didn't realise that. When stacking multiple sessions, you can easily see if one session was better or worse than the others just from looking at the plot. I certainly find the graph a much better way to visualise this than just a list of numbers.

I hope you manage to recover some of your data. That sounds like a bit of a nightmare, but probably better than loosing the rig. The targets are not going anywhere soon (mostly). It's probably not much use with an ASIair, but I use a Synology NAS also, and have it setup to sync with my imaging miniPC, so the files are transferred in the background whilst imaging. I can then pick them up on the other computer when I come to process them. It also means I have the files in one place so its easier to move from one computer to another. @900SL you mention transfer was slow? I originally had it setup with quickconnect but this goes via a server so was painfully slow, but the local connection was very quick for me.

HFR=3.65 in NINA for me right now if that helps. I'm in Bracknell.

Also, have you checked the Sirilic log to see if has any errors? We're all the images registered properly?

Can you take the r_pp_lights from Sirilic and stack them manually in Sirilic and see what you get? Maybe there is an error in the Sirilic script which means they don't get stacked or only one gets stacked.

Have you checked all the intermediate files are created in the directories you expect them to be in? I have not used Sirilic, but do you get a console view like in Sirilic where you can see what has happened in the background? That may help work out where the error is.

Don't think it's a BST thing, as the blip is in October. Must be the latter...🤣

I think using what you have to start with is a great way to get into the hobby. Whatever level we are at there is always more investment we would like to make in upgrades. This is however not a cheap hobby, but you can be budget conscious along the way. Certainly while you work out if it is for you or not As suggested above a barn door can be a cheap alternative and is a good project to keep you busy on those cloudy nights. There is always second hand gear to consider. Once you get to enough posts you get access to the classifieds section. And mostly the stuff sold on here is well looked after.

Hi, @Chuleton08 it might help others answer your question if you could give more info on which software you used for stacking and post processing? Also what steps you took with post processing would be helpful to know. Also if you could share the output file from you stacking software that would also be great. Others will then be more able to identify where any issues are. Thanks Simon

Thanks @WolfieGlos I just thought that was due to my DSLR (and not having enough data) and reaching the limit of where I can stretch before bringing out the noise I'll have to give it another go and try your method. Thanks again

I have just tested Sirilic and you can use a constant bias value. Just click edit and type in =2048. @TiffsAndAstro thanks for the recommendation, I'll probably stick with manual in Siril for most cases just so I know more about what is going on, but I can see this being useful with more than a couple of sessions to stack.

@alacant I'm already using Siril manually and use 2048 as bias (also 600D). It wasn't clear from the suggested video if you could do that in Sirilic.

Didn't expect GFP to pop up on here Thanks for the recommendation I gave this a watch and it looks fairly straightforward now. Will give it a try the next time I have multiple sessions to stack. The only thing I was unsure of was of you can use a constant bias value rather feeding it a set of bias frames. I'll have to look at the docs

I did look at Sirilic a while back but it looked a little complicated, and I just ended up figuring out to use Sirilic manually. Maybe I'll take another look again You've certainly made some very quick progress. Keep posting, I have enjoyed following your threads.

If you were to stack each session individually, then as elp says you can check the quality of each session and identify and issues specific to that night. You could then load in all the preprocessed (pp_) calibrated files as a new sequence then register and stack as one batch. I originally used the scripts for Siril, but I started using it manually and found it to be quicker. I took me a little time to figure it out and I made a few mistakes so had to go back and forth a bit, but I would go back to the scripts now. Overall it was a lot easier than I thought it would be. I like that you can view the graphs showing how good the data is, which can help in deciding what cutoffs to choose for which frames to stack.

Have you got mirror lockup set? I had issues when trying to use this with an intervalometer. Also, you might want to check if exposure bracketing on? Simon

Is there a custom white balance set? If you are looking at the preview on the back of the camera, it will use the white balance which may reduce the pink/red hint. When saving as raw, the white balance is not used (only for preview and jpeg)