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05-11-2018, 06:56 AM   #1
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pentax k-1 and samyang 35mm 1.4 soft

hi guys I decided to purchase the lens and am really disappointed in the lens at 1.4 I will send some pics and could anyone please tell me would they be happy..thank you .all shot on solid tripod 2 sec timer f1.4 iso 100

---------- Post added 05-11-18 at 07:05 AM ----------

sorry guys just getting used to how to down sample these images to the forum .there is just something about the images that don't look correct to me ..

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Last edited by andy271; 05-11-2018 at 07:04 AM.
05-11-2018, 07:16 AM   #2
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Depth of Field at f1.4 is miniscule. Try focussing using Live View with zoom.
05-11-2018, 07:31 AM   #3
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What was the intended point of focus and the focus method employed? The Samyang 35/1.4 has a reputation for centering defect and poor infinity focus calibration, but apparent inability to attain intended point of focus for moderate distance is something new.

Assuming magnified live view was used for focusing...If the bag at right was the intended point of focus, the performance is sub-par, but not too bad as f/1.4 lenses go. If the Lens Cal target was intended, this is a major fail all-round. If using AF confirm on the center of frame (the only choice for MF lenses), all bets are off since there is nothing to focus on there.


Steve
05-11-2018, 08:05 AM   #4
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hi kev yes it was liveview focus 16x ..yea steve focus was on the lens cal small centre portion ..no movement as tripod and head are heavy .

---------- Post added 05-11-18 at 08:06 AM ----------

I was around 36 inches from the subject as on the lens cal pdf it says around that distance .


here is a handheld shot ..its ok but I feel something missing .really annoying on the vitamin logo there is slight ghosting on the v or maybe just part of the depth of field not sure what to do now

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Last edited by andy271; 05-11-2018 at 08:12 AM.
05-11-2018, 08:09 AM   #5
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Hard to tell. the entire center looks soft to me. A little bit of front focus maybe. The handbag looks in focus. Maybe post a link to a full size image?
05-11-2018, 08:21 AM   #6
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The lens isn't performing. Refund or replace.
05-11-2018, 08:30 AM   #7
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hi D1N0 ive just set up a fliker account so will link the image




here is the link


https://www.flickr.com/photos/141798256@N02/28167011418/in/dateposted-public/
05-11-2018, 08:36 AM   #8
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QuoteOriginally posted by andy271 Quote
hi kev yes it was liveview focus 16x ..yea steve focus was on the lens cal small centre portion ..no movement as tripod and head are heavy .
If the lenscal target was sharp in magnified live view, but not sharp for the actual exposure, something changed in the time in-between to shift plane of focus an inch or so closer to the camera. Either the focus ring was bumped or something inside the lens shifted. If the latter, send it back.

QuoteOriginally posted by andy271 Quote
here is a handheld shot ..its ok but I feel something missing .really annoying on the vitamin logo there is slight ghosting on the v or maybe just part of the depth of field not sure what to do now
The softness on the "v" is simply due to it's being out of focus. DOF at that distance is only about 0.2".

FWIW, the best way to evaluate corner-to-corner lens sharpness is with a flat target at about 20x the lens focal length distance with care being taken that the lens axis is orthogonal (at right angles to) the intended plane of focus. For a target, I usually use a resolution test target, though anything with high-contrast fine print will do. The Spyder LensCal is a decent tool for determining front/back focus (never a problem with live view), but not so great for lens quality evaluation.


Steve


Last edited by stevebrot; 05-11-2018 at 08:42 AM.
05-11-2018, 08:46 AM   #9
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hi steve thx for that info.even in live view it didn't look as sharp as say my pentax 100 macro or the pentax 50mm macro .I will purchase a test target I think and try that ,would a brick wall be ok to test the image quality
05-11-2018, 08:59 AM   #10
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it is soft for a prime... but, after comparing MTF charts, I realized that some Samyang primes aren't as sharp as Pentax branded zooms. I was comparing the sharpness of the Samyang 20mm 1.8 to my DFA15-30 @20mm to find out that my DFA15-30 is sharper, so i returned the samyang lens.
05-11-2018, 09:16 AM   #11
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yes Im surprised biz maybe I just got a bad copy but I think I will get the pentax 35mm f2 I was tempted with the zeiss 35mm zk version second hand off ebay but after this Samyang it has put me off a tiny bit
05-11-2018, 12:26 PM   #12
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My Samyang 35 1.4 seems quite a bit sharper than that on my K1. Looks like a bad copy.
05-12-2018, 03:59 PM   #13
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I was not joking when I said that buying Samyang requires you to purchase about 5 copies of the lens with a good probability that one of them is decent. My Samyang experience from last 9 months:

-12/2 Fuji X: Damaged rear lens coatings (swapped to new copy by the shop)
-8mm f/3.5 fisheye for Fuji X: Loose screws on rear mount piece (decentered image, fixed myself)
-10/2.8 for K-mount: Aperture lever spring snapped after 2 weeks, repaired lens had something like bear grease on aperture blades -> stuck aperture @ -5C temps
-35/1.4 for K-mount: about as perfect as it gets!

I also had 12/2.8 fisheye back in 2017 for K-mount which was slightly decentered and I had to adjust the focus mechanism to get infinity focus. Some copies have wrong register distance (also in Nikon version) which requires user to install shimms on the back of the lens. Otherwise, with slightly incorrect register distance the lens' field curvature goes very wrong @ infinity focus - impossible to get even focus field without stopping down to f/11 or so.

But, Samyang currently has the most complete prime lens lineup for Pentax. Long tele lenses are missing but I expect such lenses to be ultimate horror story should Samyang make them...
05-13-2018, 04:47 AM   #14
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I think the lens is decentered. The bag on the right does appear more in focus than the lens calibration stand in the middle which seems to be suffering van softness due to spherical aberration. Also the seam on the cabinet and wood texture are sharper under the bag. i'd return the lens.
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