9.11.2012

Another shot taken with the Sony Nex 7, an adapter, and a Sony SAM 35mm 1.8 DT lens. What's the deal?

35mm 1.8 on an adapter.

I've decided that most people who talk about the performance of cameras and lenses have never shot with cameras and lenses or, what they've shot are flat, ugly and useless two dimensional test charts.  I've been looking a PhotoZone.de's reviews of different lenses on the Nex 7 and they speak as if there is a known sharpness issue with the Sony Nex 7's sensor. According to their numerical results you should be seeing a sharp center surrounded by a sea of optical jello in the image above. But the image above was shot hand held, without the benefit of image stabilization and at a fairly wide aperture. To make matters "worse" it was used near its close focusing limit which, for a lens not blessed with floating elements, should be its worst case scenario. It was even a manually focused lens hanging off the front of an adapter ring.  And yet, to my eyes the bowls in the center seem sharp where I've focused on them and the bowls in the bottom left hand corner of the frame seem to be sharp as well.

Could it be that I'm just lucky at picking out specific cameras and fortunate lenses while all the review sites are getting rejects? I doubt it.

 It finally dawned on me.  I must be doing something wrong. I must have forgotten some esoteric technique that allows me to really see these optical combinations in the eery light of their inadequacy. Oh well, I'll keep testing.  Something will come to me.



11 comments:

Anonymous said...

In the real world things are round, not flat. Therefore a lens that is perfect on a flat subject, like a test chart, will suck in the round world and vice versa. The coffee cups are a perfect example of a curved field lens in a round world. Looks to me the lens designers did a good job and the Internet Experts didn't.

I've found that when it comes to camera and lens testing, that-if-you-want-it-done-right-do-it-yourself. Seems like you feel the same way.

c.d.embrey

Daryl Davis said...

It's easy to be a technician. It's much harder to be a photographer. Don't ask me how I know this...

Richard said...

Everybody buys lenses online, they are very expensive and everyone is terrified of making the wrong choice and looking bad. Even when you look at a lens in a camera store it is impossible to determine its quality. With that said, lenses have improved a lot over the years in terms of optical quality with improved coatings and computerized designs. Barrel construction is seldom discussed, sadly.

Rules of thumb...
With few exceptions, primes are sharper than zooms. Telephoto lenses have less problems with aberrations then wide-angle lenses. Generally, you are safest to buy lenses from the company that made your camera. A very rare lens is sharp at the widest aperture; lenses are usually the sharpest between f4 and f8. Lenses can have wonderful qualities, such as color and bokeh, and not be tack-sharp.

The best lens to shoot a flat test chart with is an enlarging lens, it was designed for flat sheets of paper.

Lenses, like life, are full of compromises. People need to get over it and just try to take the best pictures they can.

Will said...

You can't possibly be a professional photographer and NOT know that your camera is faulty. Return it and get one with proper jello. I have the same problem with my D800 -- my left focus point is sharp no matter what I do. Unfortunately, I'm past the return period and can't get one that's blurry. I'm too scared to look at my NEX-7 photos now -- they may be sharp. I'm screwed.

Lanthus Clark said...

Hi Kirk,

You are probably just not a good enough photographer to replicate the crappy results the "test" sites get on a consistent basis. But if you continue to practice really hard I am sure you can achieve the same over time. It would also help if you would stop taking photos so regularly and consistently, and only ever take photographs when a new lens or camera comes out, and then only of test charts and brick walls. I hope you take this sound, well researched, advice and put it into practice so that you can then blend in to the mass of sub-par snappers who prefer to show us what lenses can't do in the corners instead of what you can do with just about any old camera as a seasoned professional photographer.

Of course you could just go and make some great pics instead and stand out from the crowd. Life is so full of difficult choices...

Have a great day!

Lanthus

Keith I. said...

Kirk, please stop proving them wrong. You are forcing me to come up with new excuses for my photos.

Keith I. said...

PS The Sony SLT-A99V is available for preorder now.

Jim said...

I have a friend who reads all the reviews and then doesn't buy anything because a) the lenses aren't sharp or b) there are known 'issues' with (fill in the blank). I keep telling him that no photographer I know spends their day shooting test charts and they somehow manage to make good, occasionally even great photos. But he's still waiting for the camera the reviewers can't find fault with. Meantime I'm making photographs with a "kit lens" that is supposedly no good.

Dennis said...

I thought the issue had to do with the short registration distance and angle of incidence being problematic with the 24MP sensor. With a DSLR lens on an adapter, you're avoiding that issue; you're no more likely to see it than you are shooting the A77. Note: I have not used the NEX-7. I have no idea if the problems reported by photozone are real, overblown, or irrelevant. (Actually, since seeing those tests, I've wondered about it - whether the tests are accurate, and if so, if it's any more than an academic issue, because what's reportedly soft is generally going to be OOF unless you're shooting brick walls).

Just to back up my theory here ... you can compare the CZ85/1.4 on photozone shot on a 12MP DSLR versus the NEX-7. The curve for the NEX-7 shows a slightly bigger drop in corner performance (versus center) and particularly at f/1.4 as compared to the curve for the 12MP DSLR but the measured results on the NEX-7 are better (or no worse) at all tested settings on the NEX-7. (What it's really showing is that the 24MP APS-C sensor shows the limits of the lens, while the 12MP sensor does not). On the other hand, if you compare the SEL18-55 tested on the NEX-5 and NEX-7, it shows much worse results (in absolute terms) on the NEX-7 outside the center of the image. So I think the jury is still out.

Note: I find it amusing that so many respondents are quick to scoff at negative reviews and people who take those reviews seriously, yet are more than happy to believe your contrary view without investigating the issue further. If I were in the market for a NEX-7 and had any intention of using the lenses that are reported to be problematic, I would most definitely look for more info or rent the gear first.

Corwin said...

Theres thing called field curvate. Not much lens have perfect flat field of "sharp". Some (like Zeiss Planar 50mm f1.4) are actually designed to have "look" and not flat field. So obviously shooting flat target with such lens cant give enough corner sharpness. But in real life, it has absolutely no effect, unless you want to use it for landscapes (and besides, most ppl dont look into corners of photo).

NEX-7 isnt exactly optimised for rangefinder lens or lens with very short flange focal distance (unlike NEX-5N, but that probably wasnt intention of Sony, it just worked by accident). But thats absolutely no issue for you, cause you are using dSLR lens on it and that distance is exactly same as in A77. As long as one uses dSLR lens via adapter with NEX-7 there should be no issue with corner sharpness, cause theres no reason for it.

Issue with NEX-7 is 1) field curvate and ppl which shoot flat targets at close distance 2) rangefinder or mirrorless lens 3) too thick IR cover glass, which causes problem with number 2). And last 4) ppl which talk too much and shoot just test charts.

Wally Brooks said...

or maybe you pick your lens, focus manually or with focus peaking, pick your aperture so the image is as sharp as your experience tells you, and make a great sharp image. Knowing your gear and how to use it is more important than flat chart testing.