geeklee

Finally a few clear nights recently and the chance to hook up the Samyang 135 again. This is with the Samyang 135 @ ~F2.6 (49mm step down ring). Both processed in PixInsight. Alongside the ASI 533MM - 4h Ha, 2.5h OIII, 1h SII. NGC 7822. A quick 2h on M31 with the ASI 533MC (as my 533MM had to go back for a look by the retailer) The Samyang punching above its weight again - it always puts a smile on my face (once the frown of spacing with a camera change has subsided 😅) Thanks for looking.

I've used this and a ZWO EAF with belt and custom system on a camera lens at and below zero. I think the RedCat has been down to -11 degC (colder than I had the camera cooled!) once. No issues observed. I have a dew heater on the RedCat - around the base (ish) of the lens hood. I guess a very small amount of residual heat will move through the metal frame of the telescope as well?

Both really nice images Carole with loads of detail and lovely palette. Like many others I prefer the first image - stars / star count looks great. The ultra narrow band filters do such a good job of this, as mentioned by some others.

Really cool Ciarán. The ability to work on a starless image gives so many options. The original combination was already really good and showed off some dust but the final image is something so different with so much more showing through.

Fantastic set of images @Mr_42tr0nomy The depth and detail of the Ha (and the narrowband in general) is stunning and love the various palettes produced to show this off. Superb!

I think they're just visible in these stacks too:

Thanks for sharing the data @powerlord I wonder if whatever is causing these diffraction (?) patterns clearly seen on brighter stars is also causing all smaller stars to be square/diamond? Then maybe impacting the data in general. The Ha is really clean. Two simple crops at 1:1 from the Ha stack. EDIT: sorry you beat me to it @powerlord

Of course not! I don't think anyone is implying that. Your test is suggesting that 24 hours of mono data doesn't produce an image anywhere near as good as your OSC equivalent (for you). I don't personally think that would/should be the case and I'm unsure why your image doesn't reflect that. As you say, so many variables. I don't think there's been any sort of fighting either

I think the only conclusion I'd come to from this much data in mono is that acquisition, equipment or processing had some challenges. That much mono data on a bright object like IC1396 should have produced something quite different in my view. For a laugh, I applied 60 minutes of Ha from an Atik 460EX (Yes, a CCD! 😲) and 6nm filter as Lum to the JPG above (so far, far from ideal processing wise), but still got something sharper, with good stars and more subtle detail (and that's 6x less Ha than quoted). The 460EX Ha was just HT stretch and a little NR. I couldn't fix the colour!

Fantastic Adrian ( @Adreneline ). Love the star filled image the most - a perfect balance of processing the differing parts and bringing them together. The PI annotated image is just the cherry on top, hammering home just how big an area of sky you've managed to cover in Cepheus. All the more impressive that it's in UK skies, only the start of October and you didn't start your posts with "Well, it's been 5 years in the making but..." Look forward to more updates.

Great update Adrian. In the UK and this early on in the year (ref dark skies), you've done a superb job to get as much good data as you have already and retaining the patience to chip away at it knowing how worthwhile it'll be at each stage and at the end. For anyone imaging a small part of this, it's a great reference image to see that object in the surrounding area and what it might be interacting with.

I think this was one of the earliest things that was "fixed". I found it very noticeable and didn't like it much either. If you check https://www.rc-astro.com/resources/StarXTerminator/ and look down the "AI Version History" table near the bottom, it was mainly resolved in AI6 (Nov 2021). It's not something I notice now. EDIT: It's being frequently updated as well.

If I remember right it has a grub screw that loosens and lets you slide off the coarse adjustment knob.

Great stuff Adrian. Really interesting seeing the variations on the data you captured. Like Sh2-240, I can't get away from enjoying this in an HOO style palette. I like the unaltered SHO though, that green Ha really works to show off the faint stuff 👍

Super smooth detail in the nebulosity @scotty38 Great start with the QHY294. Background level looks a touch high on my screen but... minor thing What Antlia filters did you use? 3nm Pro / 4.5nm EDGE ?

It does. Grant @ FLO provided some good insights on best fitting, so worth an email. I ended up doing it very slightly differently (re-using the thumb screw) but still seemed solid.

I realise this 😉 I've never exposed long enough to get my histogram peak anywhere near there in narrowband (1/3rd along). Here are three example single subs - using a 6nm Astronomik MaxFR Ha filter (@ ~F2.6) 300s: 180s: 120s: I managed to find an old sub from just a UVIR cut filter on an OSC camera (533MC Pro) and the Samyang. Understandably the peak is further to the right as this was F2 and broadband.

I think you're making life unnecessarily complex for yourself doing this. Not sure about the 1/3rd distance from the left - that might be a DSLR thing? If you do the above, you'd need a set of darks for each gain/offset pairing. While this isn't difficult it seems like added complexity for no gain (pardon the pun). You'd have to be extra careful, not only during calibration but every time you connected the camera to make sure the gain/offset was set just for the filter you were using. When using this combo (Samyang+183) I kept things simple - unity gain and the default offset. That way I knew whichever program, set of darks, flats etc I was using, it was all going to match up with the lights. I don't think tweaking the offset would have been a deciding factor in any part of my finished image 🙂 What rig do you have holding this combo and what sort of room is free in the imaging train? I had mine in a set position and didn't change it - the FOV was typically wide enough even with this small sensor to work around. In addition, the Samyang requires precise backspace setup and I was loathe to change anything when I had it set 😅

I've also found my Ha & OIII MaxFR have no halos or reflections in the Samyang -> spacer -> EFW -> 183MM solution. I have the 1.25" in the EFWmini and they are fine for the small sensors, but as mentioned in your quote, won't be ideal with the next step up (1600/294) at high speed. I'd probably have got the 31mm if I could go back I've seen the 1.25" used with the 1600 (perhaps stopped down a touch) and they calibrate fine (again, are you losing a little signal with this? I'm not sure).

You're right @aleixandrus there isn't a consensus and you'll see plenty of the Baader 7nm Ha being used without a problem - whether this loses a little signal, I'm not sure. Some of us also stop down the lens a touch too which would help. I personally have the Astronomik MaxFR Ha and OIII - these are rated for fast systems but also claim to go up to F8. I emailed Astronomik recently and they confirmed that while each filter has a specific transmission, the aim is to get a certain percentage peak transmission at each end. For example, my Ha is Tmax 95.9% and states F6.1 - F2.2. I also use a normal 6nm Astronomik SII filter and this states on the back Tmax 93.6% and F-infinity - F2.3!! It's very confusing as this would indicate that if you get lucky you could get a normal 6nm filter that'll work well at high speed too. Their marketing doesn't help! A wide filter - like 12nm - should have even less issues. I typically shoot my Samyang stopped down ~F2.6 (and also used a 183MM). Hope this helps.

Thanks for posting these @david_taurus83 (and @barkingsteve in his thread). I've not had a chance to try mine out yet!

Superb image Jim. Really enjoyed the framing to pull in all those faint galaxies. 👍 The annotated image is a nice addition. As always it helps zero in on some of the really small ones.

That's a cracker Adrian. Excellent processing with the weak and strong nebulosity flowing together so well alongside the excellent star control. The starless one is so good - for a change enjoyed viewing the image in its entirety as big as you can - brilliant depth throughout.

That looks great, thanks @tomato 🤣 I'm just the same. I know the deals are always on, every day, but I always think I might miss one that's just the type of print I want (as they do seem to vary the very good deals vs normal deals). For now... it only takes 2s to delete it every day 😅

Yeah, a calendar could be a struggle! 😊 The latter months may just have placeholder text of "TBC" (To Be Captured ! 😅)