markj Loc: Lakewood Ranch, FL

Just received a used Samyang 12mm f2 wide
angle lens. The condition is as advertised, excellent like new, good for me. My question is that when I rotate the focus ring all the way to the left expecting the infinity sign to line up on the white dot, it doesn't, really not even close. Same thing when I rotate the fing all the way to the right, it goes pass the 0.2 meter reading.
Is this typical? Any other Samyang 12mm owners experience the same? Photos seem great though.
Hate to think it's quality control issue.

Grahame Loc: Fiji

There's lots written on the web regarding different Samyang models quality control when compared to supposedly the same lens models that are labeled Rokinon.

There's also lots written about inaccuracy of the infinity positions and stop and ways to adjust this yourself. You may have one that someone has already adjusted. These issues are normally to do with users wanting an 'exact' position for focus on stars.

If it were mine I would simply undertake some testing with far targets such as horizon, moon or stars and see if you are able to manually focus in front and behind the subject.

Orphoto Loc: Oregon

Many newer lenses have that odd L shaped symbol near the infinity mark. My understanding is that based on environmental conditions such as temperature, actual infinity will be somewhere in that range.

Many lenses allow focusing past infinity. This is not a design flaw or quality control issue.

On the near end of the focus throw it means nothing that a precise number is not at the very edge.

imagemeister Loc: mid east Florida

I had the 16mm f2 and did focus testing and made my own marks .......

wdross Loc: Castle Rock, Colorado

Reminds me of my film days. Most lenses focus beyond infinity these days. And if the true close range is actually 0.19 meters, I would expect the dot not to line up with the 0.2.

Temperature affects the long focus the most, hence the ability to go beyond infinity. As an inspector, I worked large parts. I was measuring a 38 foot long piece of milled aluminum sheet. When they were done milling, the machinist placed the skin in a different area where the temperature was 90° F. When I measured the length, it was off by a 1/8 of an inch - well beyond the tolerance of +/- 0.030". I went back to my desk and got the expansion rate from my machinist handbook. After compensating for temperature, the length was less than 0.010" off. So for the focus at infinity on something even as small as a lens, it has to be given some mechanical latitude to compensate for temperature.

If the lens is sharp and can be focused at all distances, you have got a good lens.

Boris77

I do not remember the last time I set a lens for short distance via the print on scale. Obviously you need to test the lens for distances you can measure IF you intend to use the markings, and establish a real and useful infinity setting that you can set via the scale. It does not matter where infinity mark is as long as you can see and use it.
As sloppy as turning a lens is I can not believe that temperature will affect the infinity setting, unless you are cooking the lens in a desert environment, and I only set the scale in dark situations.
I do own lens that can not be set per their markings, but I do have guide mark selected for Infinity.
Boris

wdross Loc: Castle Rock, Colorado

Unfortunately, temperature affects modern lens design. In the film days, manufacturers would set infinity at the exact design spot and rely on depth of field to cover infinity if it moved. But these days, with aperture settings of 0.9 to 1.2, depth of field will not cut it. Therefore, the newer lens designs will focus past the actual set infinity point of the actual design. With the autofocus systems, they will find the correct focus wherever it is, even if it is beyond the actual infinity focal point of the design. This makes it easier to design the focusing mechanism. In the case of focus at infinity, especially with objects like the moon and stars, Olympus even developed a special algorithm for focus at the distance end of the focus just for the moon and stars. By not having to spend lots of money on design and manufacturing, and relying on software, algorithms, and electronic systems, the manufacturers saved money and, ultimately, saved photographers money. And if you don't believe that temperature affects imaging at long focusing distances, just ask any astrophotographer about temperature effects.