Imaging with the Samyang 135mm f2

[Swillis]

Thanks for all the advice. 

Since I already have the redcat mounting bracket, I have ordered the redcat handle and will just have to deal with the restricted rotation. 

@Space Oddities my redcat ring appears to hold nice and tightly. To me anyway, but then again I've not tried to see exactly how tight it is

8 hours ago, aleixandrus said:

very important to not over tighten the screws as the printed material will suffer from microcracks with will lead to major fails without notice.

😟 think I'd be a bit worried about this happening...

I'm not considering an EAF, yet, but it looks like deep sky dad does a kit for attaching an EAF to the samyang lens

https://shop.deepskydad.com/product/samyang-135-wo-redcat-ring-zwo-eaf-dovetail-kit/

Thanks again

Simon

Edited September 12, 2023 by Swillis
Forgot something

[aleixandrus]

21 hours ago, Space Oddities said:

@aleixandrus I'm using this rotator from TS Optics: Teleskop-Express: TS-Optics Rotation Adapter, Filter Holder and Quick Coupling - M48 to T2 thread

Oh, that thumb screws mislead me, I've already checked that rotator but I can't use it as it uses too much backfocus (I added a filter wheel so I'm close to the limit of total backfocus).

16 hours ago, Swillis said:

 think I'd be a bit worried about this happening...

Well, although it may happens it is not that frequent. And carefully checking the equipment from time to time is always good idea even with metal parts. I found my camera loose after one session and even today I don't understand why. Of course it didn't break anything but it ruined one imaging night. Simply check printed parts from time to time and don't over tighten the screws and you will be fine. But if your RedCat rig works... fabulous!

[Space Oddities]

I also have this T2-T2 rotator here, it's only 5.5mm thick. I don't think there is a thinner one out there! It's stronger than it looks and works fine. 

If you can squeeze it between your FW and camera, you might have enough back focus distance left. The only drawback is that the screws might be located in an awkward position you can't reach due to the EFW.

https://www.teleskop-express.de/shop/product_info.php/info/p5547_TS-Optics-T2-360--Rotation-und-Schnellkupplung---nur-5-5-mm-kurz.html

 

ok I just tested and the screws are easily accessible with an EFW mounted. That makes up for 34mm with the EFW and camera.

Edited September 13, 2023 by Space Oddities

[aleixandrus]

To be fair I also see that rotator but it feels quite cheapo so I quickly dismissed it. Well, based on your words, it could have been a mistake. Do you feel it may introduce some tilt or it seems strong enough? I will explore that option again but after all the backfocus/tilt issues, I'm very reluctant to make any change in the assembly for a while. I'm also in the middle of my "Cygnus mosaic" project I've shared some post behind so I won't change rotation for some time. Thank you so much for sharing, I am very grateful.

[Space Oddities]

I had the same concern but it's actually solid enough to carry my camera. I haven't been bothered by tilt nor measured it, so I can't really say, but it seems quite flat and self centers itself due to its shape. A bit pricey sadly though!

[Petrol]

Honest opinions on this please.
2.5 hours of 180s subs with flats & dark flats from a bortle 4 location
Player One Poseidon-C Pro (IMX571)
ZWO dual band filter (not recommended for fast optics)
ZWO autofocuser
EQ5 mount guided
I appreciate OSC has it's limitations but I'm looking to improve
All comments very welcome
Clear skies
Pete

[aleixandrus]

On 18/09/2023 at 01:20, Petrol said:

Honest opinions on this please.

I really like the image, I don't think the OSC is imposing a limitation here, specially with that sensor. Just keep adding more light :)

Regarding processing (and I'm not the one you should ask for advice), the background is a bit darker to my taste, specially in the bottom left. From the compositional point of view, that left area don't add to the image so I would try to crop the image a little or pull out a bit more info in the dark areas. However, I like the nebulosity a lot, specially those reds, it feels quite natural. But if you lift the dark areas you can try to increase a little bit the exposure in the light areas to match the overall contrast. Maybe you can try to add some overall contrast, not sure if this will lead do a better image but you can try and compare. Finally, while I like the star reduction and the no-halo around them, the brighter stars are a little bit misshapen with some faint halos. This also happens to me with the Samyang as I'm way undersampled so they are a bit blocky and the BlurXTerminator can't fix them 100%. I don't feel this is a problem as it only shows up when you zoom 1:1 but, well, it worth to point it out.

Comments beside, I really like the image. Oh, yes, I love those reds to the point I'm thinking to re-process my SHO Pelican and North America and do it again, this time HOO 😄

[powerlord]

On 18/09/2023 at 00:20, Petrol said:

Honest opinions on this please.
2.5 hours of 180s subs with flats & dark flats from a bortle 4 location
Player One Poseidon-C Pro (IMX571)
ZWO dual band filter (not recommended for fast optics)
ZWO autofocuser
EQ5 mount guided
I appreciate OSC has it's limitations but I'm looking to improve
All comments very welcome
Clear skies
Pete

nowt wrong with that - very nice. I've never had any issues with the L-series dual band with the the SY135. Looks like ZWO duo does a good job too.

One tip, try to keep your darkest blacks at around 30/30/30 RGB. Maybe 15/15/15 lowest. There should be a clear gap on the left side of the histogram. Chances are there's some Ha you've clipped out there in the dark bits. Other than that though, very nice and sharp. Nice contrast and colours.

[gorann]

The data is good and processing is also generally good except that I agree with @powerlord that the sky is too dark and likely clipped. There should be some space at the left side of the histogram and you may have missed out on some structures there in the darker regions. Your histogram clearly suggest some clipping:

[Petrol]

Thank you for taking the time to help me out guys, I genunely appreciate it. This was suppost to be a 4 panel mosaic but I ran into problems with the other 3 panels. The mount wouldn't slew far enough in NINA after a flip because I had mount limits enabled in Ascom. I just stacked the one panel.
I've had another look at it and as you say, I've clipped the darks by an awful lot! I use starXterminator then stretch the background using the histogram. I wasn't aware but theres a lot of data is in the stars image. I think I need to lift the darks in the stars image before using pixel maths to recompile them. I've stretched the original stacked image and I've lost a huge amount of data by not stretching the stars image properly. I get red halo's around stars of a certain colour and it's a real pain because I have to clone them out of the background image. From what I've read, the dual band filter doesn't focus certain star colours properly when using fast optics, a downfall of OSC.

Next time it's clear, I'll go back to a dark site, focus on one target and get maybe 8 hours of data before processing. I've spent quite a lot of time setting up this mobile rig thanks to @Adreneline and I'm convinced it can produce some decent images with improved skills and processing. I appeciate it can be a delicate subject criticising someone elses work but it's so much easier to improve with guidance. It's also 100X faster than trial and error! Again thank you for your time, it's very much appreciated.

Best regards
Pete

[ollypenrice]

New image from our Samyang here.  Love that lens! 

 

[Petrol]

That's not an easy act follow Olly. Awesome doesn't come close!

 

On 28/09/2023 at 15:35, ollypenrice said:

New image from our Samyang here.  Love that lens! 

 

That's not an easy act to folllow Olly. Absolutely awesome but here goes.
9 hours from a dark(ish) sky. I stopped a couple of nights in my motorhome near Fleetwood to do this. Moon was out though. OSC,  (IMX571) chip

 

Please feel free to be brutaly honest, I won't be offended. All I want to do is improve!

Clear skies

Pete

 

 

 

 

 

 

 

 

 

 

[8472]

Here's a newCepheus image of mine with my Samyang, QHY mono and HOO filter set.

Just over 15.5h, lens wide open

 

[Petrol]

4 hours on the Heart and Soul, Player One OSC. Rig is still work in progress.

 

 

Clear skies
Pete

[Budgie1]

Having been graced with a couple of good clear nights this week I've been running two rigs, my main rig and dusted off the Samyang 135mm connected to a ZWO ASI294MC Pro with L-eNhance filter, all on my old EQ5 and run using ASIAir Mini.

The second night is running as I type, but on the first night I got a couple of images, stacked & processed in PixInsight:

IC1396 with gain of 200, offset 30 & 3h57m 180s exposures.

NGC1499 with the same camera settings but only 1h45m

[Budgie1]

And here's two from the evening of the 11th November. Same setup as above with ASI294MC Pro and L-eNhance filter using 200 gain & 30 offset at -10°C.

The first one I did was NGC7822, the Cosmic Question Mark, and this is 5h28m at 240s exposures, stacked & processed in PI.

As this one went out of view, I was going for NGC7000 but then spotted that Sh2-240 Spagetti Nebula had appeared from behind the trees and managed 3h40m of that. Much more time needs to be added to this, as can be seen from the results, but it'll get better as the year progresses.

 

[aleixandrus]

Very nice images @Budgie1! May I point one thing? it seems to me that the California and the Spagetti pictures have a bright large spot in the middle... not a vignette but kind of. The other two seems fine to me. I may be wrong but, well, I think it worth pointing it out

PS: Love that Spagetti!

[aleixandrus]

Weather is being awful but I had some data to work with in the meanwhile

 

 

[Budgie1]

4 hours ago, aleixandrus said:

Very nice images @Budgie1! May I point one thing? it seems to me that the California and the Spagetti pictures have a bright large spot in the middle... not a vignette but kind of. The other two seems fine to me. I may be wrong but, well, I think it worth pointing it out

PS: Love that Spagetti!

It's my processing of the images that's caused the bright centres in those two. I was rushing a bit to get them done as I had 5 stacks from the weekend to process. I do like to keep the images on the light side as I feel you loose faint detail from nebula if the background is too dark.

I've had a wee tinker with them and I think they look much better now. The Spagetti had the data rung out of it, as it's a very faint object and 3h40m isn't anywhere near enough, but darkening the centre of the California has brought out a lot more cloud detail. 

Edited November 13, 2023 by Budgie1
Wrong image.

[aleixandrus]

I like the new versions. The Spagetti is a nice target but, as you said, is quite faint specially in the O3 channel. I have some Ha data taken with my previous setup configuration I will have throw away as I won't be able to combine with the new one I hope to obtain in a near future (very different rotation and backspace configuration). I need some clear nights!

[Adreneline]

One hour of S, H and O over two nights with the SY135 at f3.0

Pre-processed using APP beta26 - I really like the graphs providing normalised image quality data - a lot easier than SFS in PI.

Processed in PI with XSuite - nebula stretched with EZ-SS; stars stretched using MaskedStretch.

Edited November 25, 2023 by Adreneline

[gorann]

19 hours ago, Adreneline said:

One hour of S, H and O over two nights with the SY135 at f3.0

 

Pre-processed using APP beta26 - I really like the graphs providing normalised image quality data - a lot easier than SFS in PI.

Processed in PI with XSuite - nebula stretched with EZ-SS; stars stretched using MaskedStretch.

Amazingly deep for only 3 hours. You even managed to catch that elusive SNR G132.7+1.3.

[Adreneline]

1 hour ago, gorann said:

Amazingly deep for only 3 hours.

Thanks Göran

I've owned my SY135 for five-and-half years and during that time I feel I have tried every configuration known to man! 😆

I think I have finally hit upon the sweet spot using the lens with a step-down-ring to set it at f3.0 along with 3nm Antlia NB filters and my ASI1600MM.

Okay, I've stopped down the lens and lost some photons/fortnight but that loss is far outweighed by the flatter image and better star quality across the whole image.

I have finally found a mounting configuration that has eliminated all the misalignment and I've nailed the backspacing.

I am now going to weld it all together so I am never, ever tempted to take it apart again. 🤣

The SY135 is a winner for me - it just needs t.l.c. to get it to deliver - and patience - and persistence - and bloody mindedness 🤣

[Elp]

22 hours ago, Adreneline said:

One hour of S, H and O

That's very nice. Just been looking at my data of this and compared 2 hours Vs 7 hours, surprised there's very little difference between the two other than minute noise levels and the darker areas are more defined. I always wondered what differences there would be as when I started mono I only usually did less than 5 hours total across the three bandpasses.

[Elp]

Finally got around to finish it once I had the RGB: