Just bought the Samyang 7.5mm f3.5 Fisheye lens... any quirks?

Check that the adjustment/tightening ring around the rear element is sufficiently tightened, if too lose focus might be off.
Even so, the focus calibration isn't that accurate - I suggest you determine where hyperfocal/infinity actually is and either remember the position or mark it. On mine infinity is about 1.5mm short of the infinity mark.

 

This is more a question the a suggestion. I'm sure you noticed that if you keep the lens perfectly level and in the middle of the frame the horizon appears flat. I do not know if these things, one or both, are requirements for best defishing or not.

 

See here if you are brave:

[DIY] Fixing the Rokino/Samyang/Walimex 7.5 MFT Fisheye Focus Issue

 

Note also that there is curvature of the field of focus. The center of a wide, flat image shot wide open will be sharp and the edges slightly out of focus. Stop down a bit and it's a non-issue.

 

I just got the Rokinon version and so far have been very pleased. Sharp as is often stated corner to corner, and easily defished (I am using it for mostly 4k video on a Gx8 with its 2.7 crop) in either my NLE or LR for stills. At the B&H sale price of $200 I couldn't click buy. Size is great and with the ability to use aperture preferred makes your camera basically a point and shot for stills. Tired it on my EP5 and Gx8 and am very happy.

 

Just a little heads-up for people who use this fisheye as a fast fun lens (which it do quite well): It pays to move your hand consciously away from the front of the lens after focusing - you'll have your fingers in the picture otherwise.

btw. My lens doesn't really show any real optical problems - I guess I was lucky (so far).

M.

 

Yip, also need to be careful about your toes or a hat if you're wearing one. It's almost safer to use the camera in rear screen mode sometimes!

I haven't ever heard of optical problems from this lens - it's always consistently sharp. Only issue ever has been miscalibrated focus.

 

I just captured one of these also! I've used several fisheye lenses in the past and really liked the Pentax SMC 17/4. I am looking forward to receiving this, checking that rear element & having some fun  

 

It's a wonderful lens, sharp and renders like lenses that are far more expensive. It improves your photography by forcing you to think more about composition and is more flexible than I ever imagined. I've found the positive tips in this thread to all be true. The forum users Jonathan F2 and Sesser have also suggested using the Nikon 10.5mm and Sigma 8mm FE profiles in Lightroom when post processing. I use the Nikon one, but both are really useful in getting other looks from this lens.

 

Some reviews say it underexposes when used in nighttime (i presume in A or M mode), even with flash, up to 2 stops. I just used it few days ago in this scenario, and it showed true, but +0.7 or 1 flash exp handled it nicely.

definitely this. Still haven't gotten around to do that on my copy.

Some people suggest to mark the 1meter (or whatever suits individual needs) mark, as the lens has only 0,25 and infinity, with no marks between it.

 

certainly I've thought " oooh, I'll use the FE " but then when I compose, sometimes the subject doesn't suit ( eg cars from certain angles ). Personally, I love mine

 

this review gives more info on both the markings and the exp compensation.

 

You might enjoy it even more than you expect, I know I did. At 5.6 or 8 the lens is very good. De-fishing is not that hard in most software and had less quality loss than I expected. The close focusing possibilities and deep Doff make it a great close up lens.

 

My advice for using a fisheye? Corners, corners, corners!! It is not very easy to compose a fisheye, since the field of view is so huge. Good advice above about watching fingers and hat brims. If you can keep awareness about how the corners look, I think it helps. My next advice: get close, close, close!!

 

Using f4.0, estimate 4' out and place some detail at that distance...then focus there using magnification. Everything from 21" to Inf. will be in focus. From the test charts I've seen, f4.0 is about the sharpest. Definitely watch the fingers...been bitten a few times with that. Learn when shots want de-fishing and when they don't...so you don't get crazy with it. There are times when a little distortion left in the shot looks good. Calibrate the in camera level indicators and use them...when you get the camera sitting level and straight, distortion in the central 2/3rds is actually not bad.

 

This lens is awesome, one of my favorites. Search the forums for Lightroom lens profiles which will let you apply different profiles for defishing; I typically use rectilinear if I feel the need to defish or am looking for some drama, but the stereographic projection profile is sometimes useful. Very often paying attention to the horizon allows you to come away with shots that need no defishing at all yet are not obviously fisheye. A good rule of thumb I picked up from someone here is to set your aperture at ƒ5.6 or ƒ8, roll focus slightly off infinity, and then forget it. The super-deep depth of field is what makes this technique practical, but the same deep DOF characteristic allows for shooting wide-open when your field of view is further away, such as it would be with cathedral ceilings and such. Lastly, if your camera offers focus-peaking, use it as a reality check. Have fun with it!

 

Oh, another thing people do when defishing is to crop the edges, which can get a little stretched out in some situations. Defishing can also push items at the periphery off-frame -- If you expect to defish, you can compensate for this by allowing some breathing space at frame's edge.