Imaging with the Samyang 135mm f2

[Elp]

This one works too and is much cheaper than the filter drawer adapter:

https://www.firstlightoptics.com/zwo-accessories/zwo-adjustable-eos-lens-to-t2-adapter-for-all-asi-cameras.html

This adaptor can be split in two, for the SY135 you don't need the extension bit and can leave that in the box.

All you then need is the female m42 to female m42 camera coupler ring attached to the camera nose to connect to the back of the lens adaptor.

Edited May 15, 2023 by Elp

[LaGuille]

Thank you very much for these answers. These are two perfect pieces for the Samyang + 294mc combo. No need for anything else. I will think about which one to choose between these two models. Thanks!!!

[Adreneline]

No astro-darkness and just 10 x 300s of S, H and O but it's not turned out too bad considering the lack of data.

Sadr is such a challenge to process - it's determined to steal the show.

Using the latest incarnation/variation of my SY183 setup + 6nm filters.

Will it ever stop evolving?

[tomato]

Great widefield image, I'm at a loss why folks pack up when astro darkness goes, given how much the kit and software processing tools have progressed.

[Elp]

I don't get it either. Its usually my most productive time. I guess staying up until the early hours to pack away or something plays a part, as well as the milky way being in line with the horizon most of the dark time, in winter you can be productive in the evening and still get decent sleep.

[gorann]

58 minutes ago, Elp said:

I don't get it either. Its usually my most productive time. I guess staying up until the early hours to pack away or something plays a part, as well as the milky way being in line with the horizon most of the dark time, in winter you can be productive in the evening and still get decent sleep.

Well, you do not image from 60 degrees N.😁

[Elp]

Obviously the closer to the earth poles, you get extremes of long daylight and night, maybe change to HA solar imaging when night doesn't allow? You know, just another wallet shrinking exercise...

Edited May 20, 2023 by Elp

[gorann]

2 hours ago, Elp said:

Obviously the closer to the earth poles, you get extremes of long daylight and night, maybe change to HA solar imaging when night doesn't allow? You know, just another wallet shrinking exercise...

I have been slightly tempted by solar imaging but decided that getting a break from imaging and enjoy the summer is actually  quite nice😎

[tomato]

‘

17 hours ago, gorann said:

Well, you do not image from 60 degrees N.😁

Yes, there are limits, but there are some folks on here at lower latitudes who down tools in Nautical darkness or stop LRGB imaging the moment the moon makes an appearance. IMHO clear sky time in the UK is just too precious to throw away just because it is not ideal conditions.

I’d rather get a full night’s data rather than snatch 20 minutes between the clouds.

[Uranium235]

Just keeping the gear ticking over with an hour on M101

More of a corner test than a serious image...

However... im my time away Ive noticed just how bad the night sky has become, there is an unnecessary amount of space junk orbiting this planet now. Not one sub was left unblemished.

Mr Musk... you have a lot to answer for.

 

[Simon Pepper]

7 hours ago, Uranium235 said:

Just keeping the gear ticking over with an hour on M101

More of a corner test than a serious image...

However... im my time away Ive noticed just how bad the night sky has become, there is an unnecessary amount of space junk orbiting this planet now. Not one sub was left unblemished.

Mr Musk... you have a lot to answer for.

 

Corners look good. Also there is a SN in M101 currently pretty sure I can see it in this image. Can’t see any Musk trails thank goodness for software 

[Adreneline]

11 hours ago, Uranium235 said:

More of a corner test than a serious image...

I envy you your lens corner performance.

My SY135 has a dodgy corner as seen in this raw, linear, unprocessed sub - it's no big deal but nevertheless it is frustrating.

I am convinced there is no droop or misalignment of any kind in my mounting arrangement and nothing I do changes the situation.

Once BlurX has done its magic and I've cropped off the edges it does not detract from the overall image.

I still think that for a consumer camera lens it out performs many so called astrographs.

[gorann]

4 hours ago, Adreneline said:

I envy you your lens corner performance.

My SY135 has a dodgy corner as seen in this raw, linear, unprocessed sub - it's no big deal but nevertheless it is frustrating.

I am convinced there is no droop or misalignment of any kind in my mounting arrangement and nothing I do changes the situation.

Once BlurX has done its magic and I've cropped off the edges it does not detract from the overall image.

I still think that for a consumer camera lens it out performs many so called astrographs.

I heard Russ Croman on TAIC recently telling that a new version of BlurXT is around the corner (AI 3.0) and it is even better at fixing corner stars.

[Adreneline]

7 minutes ago, gorann said:

I heard Russ Croman on TAIC recently telling that a new version of BlurXT is around the corner (AI 3.0) and it is even better at fixing corner stars.

Interesting. It is not just a SY135 problem that's for sure. I know in my case it is not a sensor problem because I have used the ASI183 with a RedCat and an Askar 180 and the corner stars are consistent in all corners. All the image train is screw-tight rigid and I have even tried different spacer rings but the problem persists. DynamicCrop sorts it 😆

Edited May 23, 2023 by Adreneline

[gorann]

8 minutes ago, Adreneline said:

Interesting. It is not just a SY135 problem that's for sure. I know in my case it is not a sensor problem because I have used the ASI183 with a RedCat and an Askar 180 and the corner stars are consistent in all corners. All the image train is screw-tight rigid and I have even tried different spacer rings but the problem persists. DynamicCrop sorts it 😆

Croman's talk on TAIC is well worth watching. He explains how deconvolution works and at the end he discloses what the coming version can do:

 

[Uranium235]

On 15/05/2023 at 11:01, LaGuille said:

Thank you very much for these answers. These are two perfect pieces for the Samyang + 294mc combo. No need for anything else. I will think about which one to choose between these two models. Thanks!!!

Dont forget this option:

https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html

It takes you away from inaccurate bayonet fittings, to an all solid, all-threaded connection. You'll need it at f2

Plus, it leaves space for a proper FW (or EFW).

[Uranium235]

On 23/05/2023 at 11:11, Adreneline said:

I envy you your lens corner performance.

My SY135 has a dodgy corner as seen in this raw, linear, unprocessed sub - it's no big deal but nevertheless it is frustrating.

I am convinced there is no droop or misalignment of any kind in my mounting arrangement and nothing I do changes the situation.

Once BlurX has done its magic and I've cropped off the edges it does not detract from the overall image.

I still think that for a consumer camera lens it out performs many so called astrographs.

It is possible to fix it, but the adjustment is so small Im not sure a shim thin enough exists...lol

The top left corner is intrafocal, so (try to picure this) that corner needs to be "pushed out" (so to speak). Though thats easier said than done. Its going to be something like 0.01mm or something ridiculous like that (maybe smaller).

If i had the tools, Id build a tilt adaptor to fix it - one based on shims rather than inaccurate screws,that way you can measure out the adjustments exactly. I kinda have the concept, but  its needs thinking time.

Whether its the lens or the fittings, it can be tweaked. But.... if it aint broke (and youre happy) - dont fix it!

[Adreneline]

24 minutes ago, Uranium235 said:

But.... if it aint broke (and youre happy) - dont fix it!

Thanks for the detailed response Rob.

I'm not sure I want to start playing with 0.01mm shims to correct such a tiny amount of tilt - I know the devil is in the detail and it would be nice to think it was perfect but .... 

I've looked at screw tilt adjusters in the past and came to the conclusion I could spend numerous imaging sessions chasing my tiny amount of tilt and not do any imaging!

Let me/us know if ever you produce your shim design!

Thanks again.

Adrian

 

[emyliano2000]

I don't know why I haven't done this earlier because I had the Samyang 135mm lens for quite a while.

Last week I finally put it on my qhy294m. I had a Deep Sky Dad autofocuser too so I managed to pair it up with the combo. This week I had my first session and I used the lens wide opened at f2 to collect as much data as I can in a 5 min exposure.

I ran it for 2 and a half hours on the Sadr region and I absolutely love it. I added another 15 panels on this so it will probably take me 16 clear nights to finish it off but for now, here's my take on the Sadr region in SHO.

Emil

[SAW]

I'm still struggling to get decent stars in the corners using the Samyang 135mm and 2600MM. I've tried loads of different spacing, shims etc Have I got a bad quality lens ?

I'm looking for something to replace the Samyang now with something that I can use the 2600MM on and still get a good wide field of view.

[Adreneline]

1 hour ago, SAW said:

I'm still struggling to get decent stars in the corners using the Samyang 135mm and 2600MM. I've tried loads of different spacing, shims etc Have I got a bad quality lens ?

Can I ask what spacing you have between the back face of the lens and the front face of the 2600MM?

I noticed in an earlier thread (M42 et al) that you mentioned introducing an additional 0.5 mm shim/spacer. My experience of using this lens is that introducing (or removing) a 0.1 mm shim is often too much and will give rise to a significant change in (a) focus position and (b) star shapes. I have three or four ~0.1 mm shims along with ~0.2 and 0.5 so I can get step values between 0.1 and 0.5 when fine tuning. Spacing and alignment are so critical with this lens. I've owned mine for more than three years and I still can't get it perfect in one corner despite trying numerous mounting arrangements to try to ensure the alignment is perfect and the spacing is as close as I can get to within the base of the 'L'.

I am a firm believer that the focus mark should be within the base of the 'L' when focussed on a star field. I have used a Canon 6D on my lens and it focus almost dead central in the 'L' base. @Uranium235 has suggested introducing 0.01 mm shims/wedges to correct the final issues I am having but I for one don't want to go that far - it is what it is and once BlurX has worked its magic viewing at 1:1 the stars look fine to me. In my case I am convinced it is either a lens or alignment problem as the problem persists even if I swap from using my ASI183 to an ASI1600.

I now use two PrimaLuce Labs 80mm rings to support the camera (a perfect fit) and the lens (a perfect fit if I remove the padding) and if an error exists it is less than 0.1 degree (relative to a reference flat surface) - see image above in this topic thread.

You also mention using the lens at f4. I use mine at ~f2.6 achieved by using a 49 mm step-down-ring which gives much cleaner star shapes than using the in-built aperture control in the lens.

1 hour ago, SAW said:

I'm looking for something to replace the Samyang now with something that I can use the 2600MM on and still get a good wide field of view.

There are Askar alternatives at 135, 180 and 200 mm f.l.

HTH

Edited May 28, 2023 by Adreneline
Further clarification

[Uranium235]

You do get the occasional duff sammy (ive had one lemon out of 5), but getting the focus mark on the L (as mentioned above) and doing away with baynoet fittings can do a lot for you.

The only reason why shims work for me is becuase the plate that fixes the T-Ring to the camera is square - which means I can adjust each corner individially, and to an exact distance (using feeler guages).

I'd have to repliate the plate design to suit all CMOS/CCD cameras, easier said than done!

[Petrol]

I'm also struggling with stars in the corners 
I've used the Samyang with an ASI 294MC - 4144 X 2822, 4.63μm pixels and was reasonably happy with the results. I've had to replace the ZWO camera and have gone for a Player One Poseidon-C Pro (IMX571) 6252 X 4176, 3.76 μm pixels. I appreciate that bigger sensor means bigger problems but I want to do my utmost to get the stars sharp at the edges. Some mozaic attempts would be great so you can see where this is going.  I have a ZWO Cannon to T2 Adapter that holds a dual band filter. Whilst it does the job, there's play in the bayonet fitting.
I assume the way forwards it to go for the Astro Essentials Samyang screw on plate, then attach a Zwo filter drawer to house the IOptron dual band filter. I also assume this would give me greater flexibility to get the back focus spot on using extension tubes.
When using the Zwo bayonet adapter, neither the Zwo or Player One cameras focused in the centre of the "L"

I appreciate that tilt is also critical at F2, the Player One camera has built in tilt adjustment which is one of the reasons I bought it. My questions before I throw any more money at it are.

1. Am I right in thinking that the optimum back focus is achieved when the lens is focused within the "L"?

2. If get both the back focus and tilt spot on, will the stars be round right across the image?

3.  Will any vignetting will be sorted out with flats?

Any help would be very much appreciated. I think the Samyang lens is awesome when set up properly. If I can get the stars sorted, I'll fit an auto focuser.
Thanks for looking
Clear Skies
Pete

Cropped images from my Samyang / Player One OSC Cam.

[Adreneline]

Hi Pete,

2 hours ago, Petrol said:

Am I right in thinking that the optimum back focus is achieved when the lens is focused within the "L"?

In my opinion this is essential. I used my SY135 with my Canon 6D in January this year and took a photo of the focus position after using the autofocus routine in the ASIair and checking with a BM, this was the result:

No two lens are identical, no two cameras are identical. The back focus of the cameras themselves is subject to a manufacturing tolerance so in the case of a ZWO camera you cannot be sure it is spot on 6.5mm. I fail to understand how some people state the definitive spacing is 44mm (say) for the SY135 when used with a ZWO camera. Filter thickness will have affect the spacing. I use 1mm Astronomik filters so in theory they affect the spacing by ~0.33mm.

2 hours ago, Petrol said:

If get both the back focus and tilt spot on, will the stars be round right across the image?

Haha! You would like to think so! Again, this is my opinion only, but the SY135 is a consumer dslr lens not a dedicated astrograph. If you are lucky it will be a good one. (I recently bought a dedicated astrograph lens which had been tested prior to despatch but it still didn't perform as one would expect; I am awaiting a replacement).

2 hours ago, Petrol said:

Will any vignetting will be sorted out with flats?

Well mine is! I guess it comes down to the quality of the flats.

This is my current setup - I've been through so many iterations and variations I've lost count.

I am sure there is no misalignment or droop and the NB filters I use focus in the middle of the 'L' and I still have a slightly dodgy corner. It is what it is and I am happy  

HTH

Adrian

P.S. I am also a firm believer in using a step-down-ring and not using the aperture control on the lens. I use a 49mm sdr so the lens operates at about f2.6 and you don't get facets around the stars.

 

 

Edited May 30, 2023 by Adreneline
Typo & clarification

[barbulo]

In my case, the focus point is beyond the L mark. Moreover, I had to remove the locking screw to let the autofocus routine work. This Nico Carver's vido explains how to.

Edited May 30, 2023 by barbulo