Samyang 24mm f/1.4 is really a f/1.8 lens

Started Mar 23, 2012 | Discussions thread
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Nome_Alaska Junior Member • Posts: 35
Samyang 24mm f/1.4 is really a f/1.8 lens

I just received a new copy of the Samyang/Rokinon 24mm f/1.4 lens from B&H. I really want to like this lens, but I have to say the review is right: It appears to be a f/1.8 lens.

I have a handful of lenses for my EOS and M43 systems, including Rokinon 14mm f/2.8 and Rokinon 7.5mm f/3.5 fisheye. As I descend down the aperture stops, on all my other lenses (including both Rokinons) the camera registers a full stop of light difference.

But not the Samyang 24mm.

Here's an example. I lock in the ISO at 100. I put the camera in a room with even, unchanging light, on a sturdy tripod. For the 24mm lens I get:

At f/5.6 the shutter speed will be 1 second.
At f/4 it will be 0.5
At f/2.8 it will be 0.25.
At f/2 it will be 0.125
At f/1.4 it will be 0.1 NOT 0.0625

I've done this test many many times. Of all my lenses, the 24mm is the only lens that does this. It's acting like a f/1.8 lens because it's not letting a stop more light inside. And, again, this problem was also reported by the review at

I know this is a lame test to do when I should be shooting real photos. But it's not a cheap lens - I paid a ton of bucks specifically for the f/1.4. That's the only reason I got it. I really don't know that the high price tag is worth it now - and I'm a little miffed about the inaccurate description of the lens.

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