How to check a used 14mm 2.8 before buying?

I don't normally buy used lenses, and especially one that is known for such variety in QC... but that could happen buying new anyway too.

So how do I actually check the lens to make sure it's "good enough" - what benchmarks would I use?

I recall hearing about uneven focusing across the frame and the distortion (but not sure if the distortion differs across copies?)

Many thanks! This lens looks harder to buy than I thought...

I don't think you'd be able to tell on an LCD on the camera, especially stopped down.

You'd really need to pixel peep on a monitor to see it most likely.

Maybe wide open (F2.8) and minimum focus distance and then compare corners on LCD at highest magnification?

Very best,

MalVeauX wrote in post #18457763
I don't think you'd be able to tell on an LCD on the camera, especially stopped down.

You'd really need to pixel peep on a monitor to see it most likely.

Maybe wide open (F2.8) and minimum focus distance and then compare corners on LCD at highest magnification?

Very best,

Hmm, could also ask them to send me a sample shot... just of a wall with detail on it? To check evenness throughout frame?

kaitlyn2004 wrote in post #18457779
Hmm, could also ask them to send me a sample shot... just of a wall with detail on it? To check evenness throughout frame?

Brick wall or tree foliage at F2.8 and F16 should show something if there's something. Just don't misjudge distortion for out of focus.

Very best,

I'd suggest to just buy the Rokinon variety 14mm 2.8 brand new from reputable store. Return for new if needed.

01Ryan10 wrote in post #18461584
I'd suggest to just buy the Rokinon variety 14mm 2.8 brand new from reputable store. Return for new if needed.

Why do you recommend the more-expensive rokinon if they're all just rebadges? What's the difference in buying the namebrand?

kaitlyn2004 wrote in post #18461812
Why do you recommend the more-expensive rokinon if they're all just rebadges? What's the difference in buying the namebrand?

I mean...buy any name, just make it new.

Brick wall, make sure you are set up parallel and about 8-10 feet away. Check each corner as compared to the middle.


Checking on the screen was plenty for me to see trouble in a potential purchase so I declined. It was craingslist/in person though.

You could see a lack of sharpness in the corners on the screen!? Can this lens be that bad sometimes?

At the corners of an image check for coma and try finding reviews and see if the lens is tack sharp or known for soft images . Yes a brick wall is good . Ask for an unedited image in RAW so corners can be checked up close .

Look at the lens very closely--even using a magnifying glass-- for any signs of impact. Look carefully around the focusing ring for any misalignment. Look through it, hold it up to the light, angle it to your eye, for any signs of scratching or fogging or fungus. Twist the focusing ring off the camera and listen and feel carefully for any rubbing. Put it on a camera, focus at different distances and listen to the motor carefully. Watch it as it focuses for any hitches.

Smell it--yes, smell it.