geeklee

The lens won't go round to the infinity marker (it will go under the "L") but you should always compensate for the thickness of the filter - the fact its broadband or narrowband should make no difference (very very slight filter thickness tolerances aside). It's like spacing for any scope, you need to get it right for the best results.

It's compensating for the short backfocus while focusing at infinity, but if you think of the lens as a DSLR lens then the spacing from the back plate should start at 44mm (like all DSLRs - it's the distance to the sensor). If you're short, it'll focus at infinity before the L, but still focus. If your DSLR was attached, you'd see it focus just before infinity marking (under the "L") for stars. BTW, that's a cool adapter system you have to mount the lens. Here's mine - Camera (6.5mm), EFW (20mm), Spacer (16.5mm), Baader aluminium ring (1mm) = 44mm (+ extra spacers for 1/3 thickness of filters). I'll tag @Adreneline as I think he may have a photo of his DSLR attached to the lens and focused on stars. EDIT: With the 585 sensor, you may get away with just getting it very close to the L, like just 44mm (and maybe a little for filters). The issue is trying to get it spot on while retaining room to auto focus. Too much spacing and you'll never get focus (as I found out the other week!)

Fantastic result Oskari - nice background, strong colour, detailed and clean transitions from background and faint arms. I like the contrasting colour of the core too.

It's tricky - aim for the typical values and go from there - 44mm + 1/3 filter thickness. General consensus is aiming for the focus point to land under the "L" on the focus ring. 0.1mm spacing makes a huge difference. I've just got my Samyang rig hooked up again (just in time for everything disappearing ) and had some comedy spacing challenges where I'd forgotten just how much small spacing changes affect things. Definitely worth checking Astrobin for anyone using the same combo with the filter(s) you're looking at. If you'd like a go in AstroPixelProcessor, PM me a link to the files and I'll happily try it there.

Two great results Chris. Great colours in the first especially still showing the contrasting blue in and around the Cone. Nice one getting the Samyang piggy packed so it could take part and double your options/output!

I believe the ideal approach is to resample (bin) first in software while linear then start processing. Sometimes I'll process and then slightly resample at the end if I feel like the image scale isn't really adding anything or I could clean it up a touch with no real loss of perceived detail. In PixInsight I use "IntegerResample", in case it's called the same in Siril. Yes!! You should have a lot of fun with this lens. I've just been playing with mine again these past few days while under a big moon (I'd retired it for a while). Looking forward to seeing your output from this lens.

That seems pretty decent Vs value of camera. Hope you get a good outcome - it sounds like there's every chance of a sensible repair cost, making it all worthwhile.

Apologies if you mentioned it in the thread Steve, but did you have to cover shipping both ways or will they cover one way? If you did, was it reasonable?

This is definitely where resampling could be our friend. Each of those 15 minutes resampled x2, x3, x4 etc would kill the noise (as long as you don't want to try and get out much background stuff) and you'd still end up with a reasonably sized mosaic. Your full size image here is 10401 x 3786, but is it showing any more than if it was at 5200 x 1900 (or less). This linked image is silly (21 panes), but was a fun couple of hours during a brief clear spell. Each sub was resampled massively. Any reason for a new scope is always welcome 🤣

Brilliant result Chris. Good stars and star colour and I like the framing from the mosaic. I need to check where this is in relation to my garden obstructions! I fear I've missed it. Great idea iterating over the mosaic in short bursts - UK sky experience has taught you well 🤣 🤣 Maybe one day

Great result. I've been meaning to revisit my own version of this from a few years ago - tighten things up and maybe let better noise reduction make it easier on the eye. The faint tails that curl back look great on the really long / dark sky integrations.

That would be awesome, thanks Steve. I'll drop you a PM. If anything I'm more worried about the image scale and quality of my Luminance! Yours looks like its still has bags of signal even in those challenging conditions (RASA hoover!)

I have around 6 hours of Luminance data shot with a RedCat+294MM of the area around the Iris. I don't have great skies but I'd like to try and combine it with some RGB if anyone has something around the same focal length. You're welcome to this Luminance in return. I may not use the data but am interested to try. Thanks. Focal distance - 246.53 mm Pixel size - 4.60 um Field of view - 4d 16' 34.5" x 2d 53' 11.3" Image center - RA: 21 05 59.102 Dec: +68 10 24.28

Yes, if it's not calibrated with flats, I can definitely see why you'd get unexpected results. Could you take some flats with the rig just now or has it been broken down? These things (tricky backgrounds) can be brute forced but you always compromise something. I see @Elp has provided some specific Siril advice, good stuff 👍

While I doubt this is causing the tunnel effect - Generally I would move a few of the background points off the very faint tails of M51 just to give you the best chance of proper background (I'm being quite coarse here, you may not need to remove/move the same amount). If you think your background is quite simple, you could also increase the smoothing. M51 is looking really good and a nice overall FOV! Otherwise, just make sure the data is calibrated correctly. When you've calculated the background, if Siril then has a "Show background" option you can assess what it thinks the gradient is. I'm sure a Siril expert will be along shortly to help though!

It could be the blind leading the blind here (!) but have you clicked "Compute Background" yet?

Great result so far, the Ha looks lovely! Good luck with the rest, should be cracking final image.

Thanks Chris 😊 😆 I recently imaged Melotte 15 at the same focal length with the 150P-DS and it was everything I'd hoped it would be. I thought I'd get the same result with a similar bright object I was keen to see at this slightly longer FL. There's just something about the framing & FOV (feels like it needs to be slightly wider or much tighter), the lack of detail... If the clouds are making you a bit data starved, you're very welcome to the masters to have a look and process (drop me a PM).

Now you're talking! This is a much better idea 🤣

There's been a couple of unexpected but welcome moonless clear skies recently so I got the chance to complete a few new images. This first one is ~4h Luminance from my 150P-DS+ASI533MM with ~1h colour from my Epsilon 130 that's working on another project. A late night start for this and I'm sure we'll start to see more over the coming months. NGC4435-NGC4438, M86 and M84 take centre stage for part of Markarian's Chain. This is worth some annotation as there are galaxies everywhere - even if just faint smudges. During a couple of breaks between objects recently, I shot ~90 minutes with the Epsilon 130+2600MC on M44, the Beehive cluster. Lastly, I had been looking forward to imaging IC410 at 675mm for months but despite 6 sessions and almost 21 hours (almost evenly split across Ha, OIII and SII) I just can't get anything that particularly appeals to me. While some of the Ha & SII data was compromised by the moon I thought I'd compensated by shooting enough extra. Shot with the 150P-DS and ASI 533MM. Here's one version (of the many sitting on my hard drive!) All pre-processed in APP and processed in PixInsight. Thanks for looking!

It's interesting to see the differences even despite differing skies/conditions and integration. Good luck on the longer term version - with the dual Esprit, it might come soon enough!

Perfectly understandable, more so with our infrequent clear nights. The suggestions all have a familiar look about them - fast reflectors! The Epsilons are at least designed to be collimated on the bench. I hadn't realised the long lead times on new ones at the moment - your pre-order for the 160ED could have been the only scope you'll ever need/want if you can go a bit slower (relatively ) Perhaps locate/request some full size raw RASA subs from similar skies and judge the quality and signal.

It's not so much the collimation as - hopefully - that's not something you should have to do (often/at all) nor want to on an expensive F2 system! For me, it's the margin of error for what you consider "good enough" This is vasty subjective and no different it seems for RASA images - where speed is king. If you do need to tweak things (whether that be collimation or some tilt etc) and have minimal clear nights like a lot of us, could you see yourself sticking it out? How good will be good enough? I take it size and weight aren't a factor for yourself or mount? With two scope options ranging from F2 to F3.6 (with reducer) and a possible budget of ~£2.2K to~ £3.1K you've got a big margin there - could anything else sit in that gap? How critical is the speed as - again - that's quite a difference in aperture/speed with the two options. It sounds like most of these are the items you've already thought about!

Thanks for the feedback Adrian, really appreciated. A few evenings spent under the stars with a CTU to get as close as I can with stock equipment! A little residual tilt (that BlurX typically tidies up) and some mild flaring which I'm OK with 😊

That's an awesome bit of detail in the second image that's now coming through. Great perseverance on this one. Absolutely, that can't be a fun game! 😆