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04-13-2014, 07:19 AM   #1
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Samyang 14mm Focus to Infinity Photo Sample Test

I'm having some difficulties with focusing samyang 14mm to infinity since it doesn't have a hard stop infinity focus and other metering options are pretty not calibrated. So I took one indoor and one outdoor random photo and compared the results between f2.8 to f11. As you can see below it's really confusing. I'm really no expert at DOF calibration so I did this very primitive comparison test.

Please share your thoughts and help me decide to find the right spot for infinity at various F-stops.
And most people say there is two different type of samyang 14mm. one is sharp lens other is soft lens. I don't think I have the sharp one.





Last edited by Nitrogliserin; 04-13-2014 at 07:33 AM.
04-13-2014, 07:28 AM   #2
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Yeah, I have the same problem. My Samyang 14mm has miscalibrated distance scales, but looking through viewfinder or liveview I can't notice when it focuses to true infinity. And pixel peeping later is too confusing.
What I heard is a good alternative is to buy a TC and focus on an object that is around 1-2m away (measure the distance between sensor and object. Sensor is lens mount+4.5cm). Calibrate to that object and the rest should fall into place.
But I haven't tried it myself, I just rely on the DoF. Which is not always possible.
04-13-2014, 07:38 AM   #3
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I've seen that solution but haven't tried yet. From my test it seems the infinity is center point between 3 meters and infinity mark but can I rely on that? I'm not sure.
Why most lenses still don't have hard stop infinity focus anway? I recently bought Sigma 17-70C and the correct infinity is at 2 meters.
04-13-2014, 08:10 AM   #4
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Not about this lens but it may give you some ideas.

Review of the Zenitar 16mm 2.8

A lot of the Zenitars came with Infinity focus problems. Mine did and this routine worked.
It maybe adaptable to the Samyang.

04-13-2014, 08:11 AM   #5
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looking at the photos the "teal" i think is where its at. (EDIT: thought now i think the blue also looks okay - do more tests!) Thought i would do a few more 2.8 tests. This is the easiest way to way to if you are hitting the infinity mark. No need to examine any other aperture. There is only one type of samyang a sharp type. The soft types are just decentered versions due to the poor quality controls at their factory. again to tell the sharpness is by looking at the center and corners at 2.8. can you ever get the center to be sharp (i think you can). are the corners relatively sharp at 2.8? more importantly are they equally sharp at 2.8? you would need a brick wall for this. keep in mind this is an extreme wide angle meaning that no such lens is "pefectly" centered'. there is always some variation between the corners. the questions is how significant is it. For instance if one corner is slightly behind, by turning the focus ring a mm in left or right can you get it to sharpen up? when you stop down does it sharpen up and "catch up"? if the answer is no, then the decentering is pretty significant. lastly, i assume the next step is to adjust the focus ring. this happens to be super easy with samyangs (i have done it on my 8mm). there are few screws hidden under the rubber on the focus ring. lift up the rubber on the focus ring, set the focus at the correct infinity position. unscrew the screws (you dont actually need to remove them - just losen them). then turn the focus ring such that the infinity mark is now at the right place. tighten the screws and adjust the rubber.
04-13-2014, 09:31 AM   #6
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QuoteOriginally posted by oxidized Quote
looking at the photos the "teal" i think is where its at. (EDIT: thought now i think the blue also looks okay - do more tests!) Thought i would do a few more 2.8 tests. This is the easiest way to way to if you are hitting the infinity mark. No need to examine any other aperture. There is only one type of samyang a sharp type. The soft types are just decentered versions due to the poor quality controls at their factory. again to tell the sharpness is by looking at the center and corners at 2.8. can you ever get the center to be sharp (i think you can). are the corners relatively sharp at 2.8? more importantly are they equally sharp at 2.8? you would need a brick wall for this. keep in mind this is an extreme wide angle meaning that no such lens is "pefectly" centered'. there is always some variation between the corners. the questions is how significant is it. For instance if one corner is slightly behind, by turning the focus ring a mm in left or right can you get it to sharpen up? when you stop down does it sharpen up and "catch up"? if the answer is no, then the decentering is pretty significant. lastly, i assume the next step is to adjust the focus ring. this happens to be super easy with samyangs (i have done it on my 8mm). there are few screws hidden under the rubber on the focus ring. lift up the rubber on the focus ring, set the focus at the correct infinity position. unscrew the screws (you dont actually need to remove them - just losen them). then turn the focus ring such that the infinity mark is now at the right place. tighten the screws and adjust the rubber.
I just adjusted the focus ring (yeah it's pretty easy, thank you for your help) and set it to teal color but like you said blue also looks OK.
difference between teal and blue, teal is a bit sharper. colors look much bolder.
but for the outdoor shot at f2.8 blue is sharper in center but teal is much sharper in corner.

Looks like desired center and corner sharpness are crossed between teal(3.5m) and blue (3m)

04-13-2014, 10:31 AM - 1 Like   #7
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yea, its a very close call. keep in mind both the corners and the center will not be sharper in the same shot due to the field curvature, which is extreme with this lens (meaning whatever the lens is projecting onto your sensor is not flat)
http://www.cheyennezjphotographer.com/wp-content/uploads/2013/07/Field-Curvature_LR.jpg
this means blue is your true infinity focus. the infinity mark should correspond to where the center achieves its optimal sharpness.
04-14-2014, 01:16 AM   #8
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I will set it to blue and do more tests.

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