"High resolution" with the Samyang 135 - Forums

Topic starter

Jan 27, 2020 · Edited: Jan 27, 2020

Since I bought my Samy 10 months ago I've been amazed by the quality of that little lens, all the more so given its ~400 euros price tag.
It is so sharp that its full potential can only be exploited fully with small pixels detectors (~3-4 microns or less). In my first "high resolution" (for that lens that is) attempt on M51, the stars have a FWHM of about 3.8-4 arcseconds (after deconvolution). Of course you can do better with larger instruments, but that is and F/2.0 telelens!
It would be interesting to gather here "high resolution" results. I am really curious to see how far one can go!

CS

Frédéric

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patrick cartou

Jan 27, 2020 · Edited: Nov 29, 2023

Hi Frederic (bonjour)
Excellent idea. I will search in my better images…
Following…
CS
Patrick

PS: je n'écris pas en français volontairement pour que le fil à venir garde son unité ;)

Ben

Jan 27, 2020

Hi Frederic,

Great M51 result. The GIF animation is very instructive. Thanks for your work.

This is M101, with ASI178MM and LRGB filters, shot at f/2.8. Drizzle is "only" x2 :
https://www.astrobin.com/406830/0/?nc=user

Now I have the ASI183MM (same 2.4 microns pixel size). For now I have shot only "big targets" to learn to use this great ASI183MM/Samyang couple. No drizzle, so pixel scale is about 3.8 arcsec / pixel.
For instance this is M33 shot at f/2, RGB filters only :
https://www.astrobin.com/m2o64o/0/?nc=user

I have found that using RGB instead of LRGB increases the details. UV-IR cut for instance has a wide range of wavelengths and it gives less details in my case than R, G or B individually. When I use RGB I do refocus between filters.
Instead of L I shoot Ha/O3 to get a pseudo luminance.

CS
Ben

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Frédéric Auchère

Topic starter

Jan 27, 2020 · Edited: Jan 27, 2020

Hi Ben,

Nice M101! It will definitely be on my list of targets!
What "drop shrink" factor did you use (I think that's the way it is called in Pixinsight from the docs on their website)? I used 50% for M51.

Clearly a wide band filter is not optimum for the resolution. As good as the Samyang is, there is always some chromatic aberration.

Frédéric

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patrick cartou

Jan 28, 2020

Hi all !
Just above two samples
Cygnus veils
Around Sadr
Easy to find many samples on Astrobin with "Samyang 135mm" search
CS
Patrick

Frédéric Auchère

Topic starter

Jan 28, 2020 · Edited: Jan 28, 2020

Bonjour Patrick,
Thanks for the images!
Indeed. And using the "Pixel scale (arcsec/pixel)" filter helps finding the higest resolution ones. But for some reason however some images are not returned. Maybe because the Samyang is sometimes listed as "Samyang 135", "Samyang 135mm" or variations. I'll keep digging…
Frédéric

Ben

Jan 28, 2020

Frédéric Auchère:
What "drop shrink" factor did you use

I think it was 0.80

Ben

Ben

Jan 28, 2020

Ben:
But for some reason however some images are not returned. Maybe because the Smayang is sometimes listes as "Samyang 135", "Samyang 135mm" or variations. I'll keep digging…

Try just "Samyang" because for small pixel scale you are likely to find mostly the 135 mm (and a bit of the 500 mm mirror samyang :-) ).
You can also try "Rokinon", the more US name.

But you are right there are not much images at high resolution. Maybe because sensors with small pixels like IMX183 or IMX178 are relatively new ?
And it looks like people like making "wide field" with the 135mm

Ben

Jan 28, 2020

Maybe you have found them, these ones of mine are 1.9 arcsec/pixel also :

M16

M42

Ben

Frédéric Auchère

Topic starter

Jan 28, 2020 · Edited: Jan 29, 2020

I like the M16!

I'm thinking about motorizing my focusing to be able to control my little setup completely remotely (at least from inside the house for winter nights). Are you satisfied with your belt drive?

F

Andreas Dietz

Jan 29, 2020

Hi all,
here are my "high resolution" M16 and M57, just to complete your list above ;)
Andreas

Frédéric Auchère

Topic starter

Jan 30, 2020

Hi Andrea,

You know I do like your images!
Looking back, all the images posted here are amazing. When I was a teenager, film was still dominating. Taking such pictures with a telelens would have been totally impossible. You would have needed at least an 8" telescope and hours behind a reticled eyepiece… Old man's talk

What a great time to practice astrophotography! Until the starlinks and consorts cover up the whole sky that is.

Frédéric

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Ben

Jan 30, 2020 · Edited: Jan 30, 2020

@Andreas
Lovely images !
When i see your M57, it makes me think maybe it would be possible to do a Samyang 135 Messier Challenge

@Frédéric
I was not satisfied with the belt. My 5V stepper motor is not powerfull. For small rotations sometimes it moved, sometimes not. I was spending too much time to reach nice focus.

Then I upgraded the setup.
I bought this :
https://fr.aliexpress.com/item/32921631923.html?spm=a2g0s.9042311.0.0.1ec66c37STQoCY
* I removed the manual wheel and placed the stepper motor.
* I also used a rigid gear belt, this one :
https://fr.aliexpress.com/item/4000020945901.html?spm=a2g0s.9042311.0.0.1ec66c37STQoCY
Result is like this :
https://www.astrobin.com/f8r43m/

It works much better. But the steps of rotation are not reliable. I mean you can not repeat the same sequence of rotations and go to the same focus point (not powerfull motor - a 12V one would be better, backlash in the gear, etc). So you still play going backward and forward to reach the best focus. The ultimate goal of autofocusing is not possible with this setup. From what I have read on Internet, even with more professionnal lens focusing kits autofocus is not an easy task.

Recently I moved from Sony E mount Samyang to Canon Samyang + filters wheel. I rebuilt my setup withtout the motorized focus part for now. I found that focusing by hand with the help of the gear ring (or also this one link) stuck around the lens is nice. My two last pics were made without the motorized focus. So i wonder about the real benefit of it. Of course if your main goal is to stay in the house and remote focus then you have to go with something like this 8)

Ben

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Frédéric Auchère

Topic starter

Jan 30, 2020

Ben:
Then I upgraded the setup.
I bought this :
https://fr.aliexpress.com/item/32921631923.html?spm=a2g0s.9042311.0.0.1ec66c37STQoCY
* I removed the manual wheel and placed the stepper motor.
* I also used a rigid gear belt, this one :
https://fr.aliexpress.com/item/4000020945901.html?spm=a2g0s.9042311.0.0.1ec66c37STQoCY
Result is like this :
https://www.astrobin.com/f8r43m/

Ah interesting, I did not know these things existed. To avoid backlash, I was thinking of a screw pushing a lever arm loaded with a return spring. I'm focusing manually now and did not have any issue with it. So my main motivation is to stay inside, but that may not be worth it. It takes only a few minutes anyway. Plus I get to see the stars, which after all is the point

I do like the idea of the Samy Messier challenge!

F

Javier

Mar 26, 2020

Hello, I'm Javier Flores and looking for a Samyang 135 to combine it with my Zwo and my Sony.

maxchess

Nov 28, 2023 · Edited: Nov 28, 2023

When I bought my Samyang135 I also bought one of these, allows very fine manual focus and then locks in place. Rarely need to re-focus https://www.ebay.co.uk/itm/305047072048?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=P5oxoo1IQEe&sssrc=2047675&ssuid=Kwq9MhG6R_W&widget_ver=artemis&media=COPY

patrick cartou

Nov 29, 2023

It looks nice and suited for the Samy…thank you !

Patrick

Brandon Tackett

IOTD Staff

Nov 29, 2023

@frédéric perrin

Great topic! I shoot widefield with the rokinon 135mm in combo with my 294 mm pro and zwo EAF + filter wheel. With the 294 pending tbe target I will shoot 1x1 at 2.3 um. You can see a couple of my results at 3.6 arc sec/px.

Cygnus Loop, Sh2-102, and NGC 6940 in a Sea of Hydrogen (Rokinon 135 mm HOO)

Rokinon 135mm SHO Hubble Palette Heart and Soul Nebula: Complete Redo Edit after several incredibly helpful critiques

I have had good results with the set up and great experience maintaining focus all night with the zwo eaf. On nights where seeing is not as good, I will bin 2x2 at 4.63 um which is the base setting for the 294 mm. This set up results in a 7.3 arc sec / pixel.

Flaming Star Nebula and Friends

SH2-171 & 170 : The Red Skull Nebula (modified HOO) Rokinon 135

Single Night Butterfly, Crescent, and Tulip Nebula HaRGB Rokinon 135

Definitely plenty of other images in my gallery with the rokinon 135. Clear skies! -Brandon

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