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Any opinion upon the Samyang 135 f/2 for astrophotography?

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#1 Nicola

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Posted 15 September 2015 - 04:29 AM

Glad to hear from the owners, daylight reviews are very good and make it a tough competitor for the Canon 135 f/2 L.



#2 whwang

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Posted 15 September 2015 - 05:12 AM

Nicola, check out this page:

https://www.flickr.c...in/20005540154/

It looks fantastic to me.  But again, I am really nervous about the QC and longevity of Samyang lenses.

 

Cheers,

Wei-Hao



#3 keesscherer

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Posted 15 September 2015 - 05:14 AM

I have a Samyang 135 F2. This lens can be used at full opening (F2) and has sharp star images all the way to the corners. Attached you see the extreme corner of a single 30 second exposure with a Canon 5D full frame and the lens at F2.

There was a thread at a Dutch astroforum about this lens and now everybody wants one (including me)  here is the link to that thread, at least you will be able to see all the images:

 

http://www.astroforu...35mm-F-2-0-lens

 

 

Attached Thumbnails

  • samyang135f2-corner.jpg

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#4 whwang

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Posted 15 September 2015 - 05:23 AM

I have a Samyang 135 F2. This lens can be used at full opening (F2) and has sharp star images all the way to the corners. Attached you see the extreme corner of a single 30 second exposure with a Canon 5D full frame and the lens at F2.

There was a thread at a Dutch astroforum about this lens and now everybody wants one (including me)  here is the link to that thread, at least you will be able to see all the images:

 

http://www.astroforu...35mm-F-2-0-lens

 

 

Thank you for sharing!  I checked the page you referred to, and as you said, I can only see the images.  In post #6, I can see a tilt of the optical axis.  The upper-left corner has very good stars, but there is a hint of magenta halos around stars.  On the other hand, the lower-right (and low-left too) corner has distorted stars with green halos.  This is clearly a focus tilt, and this is the QC problem I am worrying about for Samyang products.  Judging from the Flickr page I posted above, this lens clearly has an excellent design and great potential.  But if the assembly of the lens elements cannot catch up the design, the lens still cannot perform.  Problem can even develop with time.  A lens that's perfect out of box can quickly show signs of misaligned lens elements.  (Two of my relatively expansive lenses do this to me.)  We need to be careful.

 

Cheers,

Wei-Hao


Edited by whwang, 15 September 2015 - 05:24 AM.


#5 orlyandico

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Posted 15 September 2015 - 10:05 AM

I guess the big question is, how does the Canon 135L compare (I suspect the 135L is inferior).  In that case, the relatively small QA problems on the Samyang may not be so bad if (even with the tilt etc.) it matches the 135L.

 

I also suspect that both of these lenses would perform very well at f/4 in which case one could argue that the Samyang is good enough.



#6 keesscherer

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Posted 16 September 2015 - 02:58 AM

The Evryscope is using Samyang (=Rokinon) lenses, they will have judged the Samyang QA: :

 

http://www.technolog...d-an-evryscope/

 

http://evryscope.astro.unc.edu/



#7 whwang

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Posted 16 September 2015 - 03:44 AM

I guess the big question is, how does the Canon 135L compare (I suspect the 135L is inferior).  In that case, the relatively small QA problems on the Samyang may not be so bad if (even with the tilt etc.) it matches the 135L.

 

Canon:

http://www.lenstip.c...ywu&test_ob=320

 

Samyang:

http://www.lenstip.c...ywu&test_ob=442

 

It is indeed true that the Samyang one is much better.  Whether it is still the case when you factor in the potential QA issue in Samyang remains to be seen.  I am sure that there will be happy owners and also unhappy owners.

 

According to the above test results, the Samyang one even rivals the Zeiss 135/F2.  I feel the Zeiss one still gives better stars in the corners wide open, according to the pictures I saw.  However, this difference in optical quality does not justify the huge price difference.  Difference in optical quality plus difference in QA?  Maybe.

 

Cheers,

Wei-Hao


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#8 garret

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Posted 17 September 2015 - 01:10 AM

 

I guess the big question is, how does the Canon 135L compare (I suspect the 135L is inferior)

I own a Canon 135 mm f 2.0 for 4 years especial for AP.

 

With brite stars in the field there are unwanted reflections, the image is a center 50% crop made with a mod. Canon 30 D (just 8.5 Meg-Pixels), in this stacked image the mount did have a tracking error (a small jump).

The edge sharpness with the 30 D is clearly softer then the center up to F# 5.6.

When focus is exactly spot on there are no halo's of any color around stars.

The centering of my copy of the Canon 135 mm lens is perfect, the star-softness is in every corner the same, the shape of the stars in the corner is near-perfect round.

The lens did not work well with a IDAS/ Hutech 'clip-filter' inside the 30 D, with a large external IDAS filter the problem was over, I forgot what the problem was...

 

Garret van der Veen, The Netherlands

Attached Thumbnails

  • hyaden-ip-final-met-pijl.jpg

Edited by garret, 17 September 2015 - 06:36 AM.



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