8.08.2012

According to all the test reports my (fill in the blank) lens is not sharp in the corners.

Hmm. I'm a portrait photographer.  Do I really need ultra-sharp corners?


I love manufactured conundrums.  How could I not? I was in the ad business for years before becoming a full time photographer.  We thrived on finding the "pain" for consumers and then giving them a "solution".  "The Malls are too crowded?  We've got acres of free parking!!!"

I was thinking about this after I caught myself mindlessly reading a lens review of the Sony Nex 18-55mm lens on SLRgear.com. They have a nifty-charty thing that shows the performance of the lens you might be considering. It uses colors to show you how sharp a lens is at different apertures and different focal lengths and in different areas of the frame. But here's the issue for me:  I think that the only lenses that test really well on flat charts are macro lenses meant to do well when photographing flat charts because they are made to photograph flat charts.  The rest of the lenses that I'm interested in don't really need to do that, do they?

But the test sites need us to be fearful about picking lenses so they can get eyeballs.  The information can be useful but only if you apply it to your ways of working...

When I looked at the performance of the kit lens for the Nex system I at first was excited to see that, even wide open, it was very sharp and performed very well in the center of the lens.  The air was let out of my balloon when I read on and did all the interactive stuff with the cool graphic sliders. Seems the lens is not as sharp on the corners.  In fact, you've got to stop it down to f8 to get really good corner performance.  Most reviewers tell me that the kit lens won't come close to providing enough performance (across the full frame of the sensor) to work well with the 24 megapixel sensor in the Nex7.  And then there's all the fringing I might find when I do high contrast photographs of little, naked tree branches against the stark sky.  Oh my.

I let my sometimes rational brain take all the information and put it into my mental processing blender and it came out giving the lens a big C+. A snob like me would never consider shooting with it.  Never mind that I actually love lenses that have a high core of sharpness wide open and then gracefully devolve on the edges and corners.  And that includes most of the portrait lenses I have used to best effect, as well as nearly every 50mm lens on the market.

Oh the damage we do to ourselves when we have too much information and not enough theoretical depth to process the information optimally for our own individual needs.

All lenses have curvature of field.  Some are corrected for this and they make really good optics for people who need to photograph stuff that has straight lines.  These might be architectural photographers, still life photographers or technical photographers.  The overwhelming majority of the lenses we buy are used to document life around us.  And the majority of the lenses I buy are pressed into the service of photographing people.  We generally don't need stringent edge to edge sharpness and total lack of optical faults when we use lenses wide open.  We need optics that are crispy enough to do the job.

Many years ago Leica made lenses that the best photographers in the world absolutely swore by.  They still do. But strangely enough, when the lenses from Leica were tested in conventional, flat target ways, they never seemed to put up numbers that matched what we saw on film (or now on our monitors).  Then I read a white paper on optimum design for lenses based on their intended use and I got it. To make a fast, high aperture lens you need to make some compromises.  To make a zoom that's consistent across the zoom range you've got to make some different  compromises and if you want a flat field lens that does good single planes of focus and even illumination you've got to make still other compromises.  The trick is to test the different kinds of lenses and find the ones that work for your style of shooting.  There a few perfect lenses that I can actually afford.  The designers can correct for a lot but would you be willing to pay $10,000 for a 10 pound f4 prime lens to hang on the front of your tiny camera?

And you have to know what compromises are involved.  For example, the 85mm Zeiss 1.4 lens is a super duper optic but in order to make it fast and sharp Zeiss sacrificed corner sharpness wide open and also the design of the lens means that you'll get appreciable focus shift as you stop down from f1.4 to f4.0.  Especially at closer (portrait) distances.  The work arounds are to only focus and shoot at f4 and smaller or to do all of your fine focusing for close up work with a magnified live view image and with the lens stopped down to the actual shooting aperture.  And Zeiss and Lloyd Chambers will tell you that.  You can't have it every which way.

So what am I getting at?  Only that the two lenses I bought for the Sony Nex 7, the 18-55 and the 50mm 1.8 are both more than sharp enough to make wonderful portraits in my style.  Even when used wide open.  The "nifty 50" that everyone loves for the Canon has pretty atrocious performance on the test charts as do most of the 50mm 1.4 lenses from the major makers.  The thing that makes them popular though is the sharp center core and the ability to use them at faster apertures than most zoom-only users ever dream of.  You can't have everything in a lens.  That's why I have separate Macro lenses for those special moments when I find myself longing to shoot test charts.

Measurements are great but interpreting correctly is the part that counts.

Yes, I've gone crazy with the Lightroom presets today.  I'm sure I'll recover.

22 comments:

D&E Photography said...

I understand wanting technical performance, but frankly the flying chart monkeys make my brain unsharp in the corners. Post up any photo example on a forum and there will be three replies asking for a 100% zoom of it. They'd probably ask Picasso or Van Gogh to zoom in too. I hereby nominate you honorary captain of the anti flying chart monkey society for the preservation of photographic common sense :)

Lanthus Clark said...

After years of taking photos I have yet to hear anybody say to me that their portrait isn't sharp in the corners. I am not sure why people have that sort of obsession with anything other than a macro lens that may or may not need to be sharp in the corners. How many people actually need the corners sharp even for most of the stuff they do with their macro's is probably also very debatable.

I have used all kinds of cameras for all kinds of work, horses for courses kinda stuff. And one time I shot an entire wedding with a Nikon F801s and a 50mm lens (don't ask why) and the pics from that wedding are still some of the most popular when folks look at my work.

Maybe there needs to be a more complete discussion about this unrealistic obsession, but I am willing to bet it's the same as a friend said when I asked him if he wanted to own the huge American 4X4 standing in his workshop and he said no, because he already has a big... uum, you know what. ;-)

Richard Parkin said...

It seems that even macro lenses do not do well in test charts according to Roger Cicala in his recent LensRental blog entry where he reported that the usual test charts are not designed to test lenses at the short distance appropriate to a macro lens, see:
http://www.lensrentals.com/blog/2012/07/imatest-macro-results-with-apologies-to-the-nikon-105-vr-micro

Robin Wong said...

Kirk,
Thank you again for sharing your thoughts, though your opinion usually go against the norm of what the majority of the crowd believe in, or was led to believe. I think obsession with technical perfection when it comes to camera and lenses have offset the many other important elements that truly create good photographs. Many times, the equipment and tool at hand are more than sufficient to deliver great results, if the photographer has the right artistic vision and technical proficiency to optimize the use of their gear, which you have always proven to be the case.

I would like add something to your sentence: "Oh the damage we do to ourselves when we have too much information and not enough theoretical depth to process the information optimally for our own individual needs."

I think it takes more than just theoretical depth. It takes practical experience and knowing how to apply those abundance of information into real life shooting. As you have appropriately put, there is a difference between shooting mere, boring test charts, and those lovely portraits you have been showing us all. Knowing is not enough, it takes years and years (you have decades !!!) of shooting and being in the field to develop that sort of practical sense.

Oh, one last thing, I found your latest book at Kinokuniya (inside KLCC Shopping Mall, the twin towers), one of the largest and most reputable bookstore in Kuala Lumpur. Evidence here: http://3.bp.blogspot.com/-LplxIEp5Vyc/UCKGvjjqMMI/AAAAAAAASlI/hc6A9IvUREQ/s1600/P1010736.jpg

kirk tuck said...

Robin, Thank you. I appreciate having you comment on my blog. And I think it's really, really cool to see my book in a bookshop in Kuala Lumpur. Amazing. Thanks for sharing it.

ODL Designs said...

Another great read Kirk, and I laughed at your naked little tree branches comment. Personally I like to frame a lot of my images very asymmetrically and have found a couple of the 50's really didnt work for my style (such as the Sony 1.4)... But different strokes and all that, I still agree with your article.

Great pictures, she seems to pose effortlessly, and you managed to find some very pleasing natural light.

Ab

theaterculture said...

I have this amazing book, first published in 1943, called _1001 Ways to Improve Your Photographs_. Article contributors include Ruth Bernhard, Edward Kaminski (who was the head of the Art Center College program in Southern California that pretty much set the standard for photographic education in the Life Magazine era), Weegee the Great, and some guy named Ansel Adams. I can't remember who wrote the article on portrait equipment, but I can darn remember that he recommends keeping a ladies nylon stocking in your kit to stretch out over the lens for that lovely soft-focus effect.

Funny how different people's concerns are when the metric is "whether or not the photos look good" rather than "objective performance on standardized tests."

wjl (Wolfgang Lonien) said...

No one makes Noellia look like you do, Kirk - bravo again. And yes, the 50s I have (two OM Zuikos and one Zuiko "Digital" (Macro)) and had (Canon 50mm 1.4 during my film days) were / are all good. Maybe I just didn't try them on too many flat surfaces or against tiny naked tree branches ;-)

cidereye said...

Nice article & portraits Kirk!

Made me chuckle thinking on that man spent years believing the earth was flat and with some putting so much faith on flawed optical laboratory tests shooting at flat surfaces to decide on whether they will make a purchase or not.

Some real good kit lenses at the end of the day for peanuts prices, I've found the Sony 18-55 pretty good so far and have only used it indoors as of yet. Mind the Pentax, Nikon 18-55's are stunners for the money as is the little cheapo Oly 14-42 for 4/3 - especially when you consider how much the superb Zuiko 12-60mm is.

Just consider the poor bloke sat in his lab that has to do these dull shots all the time. And at the end of the day all for what in our round wonderful 3D world?

typingtalker said...

While most blogs write about cameras, you write about using cameras.

Jan Klier said...

Nice post. I appreciate you chipping away at the Internet silliness.

It goes along with how you define an expert. Per Wikipedia (not that it is as reputable as E Britanica used to be [sic!]):

"An expert can be, by virtue of credential, training, education, profession, publication or experience, believed to have special knowledge of a subject beyond that of the average person, sufficient that others may officially (and legally) rely upon the individual's opinion."

Followed by "Historically, an expert was referred to as a sage (Sophos). The individual was usually a profound thinker distinguished for wisdom and sound judgment."

Seems to me the online camera discussions have taken the same path as history - going from thinking and sound judgement, to the modern courtroom version of expert, that solely has to point to a few credentials and sound smart to make the point everyone wants to hear....

I remain: Shoot more, talk less. If you like it, good. If your clients like it, great. If your client keep hiring you, excellent. Nothing else matters.

David said...

Wow an other practicle, useful, and intelligent post. How do you do it. The kirk band will shift to calling you "commom sense Kirk".
With all the junk on the web its amazing that people still read it all. But then we need you to put it all straight.
This is all tongue and cheek. I really apreciate your view. And it is needed as I am finding most camsra/lens discusion is from collectors or kids and not from experiensed photographers or even users.
I picked up a used SLR/n and I find it light, amazing image quality, super quite shutter and best of all I want to use it. As a hobbiest that is the most important feature.
All the best.

David said...
This comment has been removed by a blog administrator.
Low Budget Dave said...

One of the first articles I ever read about the hobby said to get the subjects eyes in focus. It was accompanied by a helpful hint that almost every lens was sharpest in the center.

I usually try to shoot "Mona Lisa" angle portraits, with the left eye in the center (horizontally), and then crop the vertical dimensions to the "golden section" 0.618, or to the rule of thirds, depending on what looks best to me.

Because I am not always able to plan my pictures, I frequently end up with water towers, trash cans, and clutter in the corners. Having a lens that failed to keep these in focus would be a huge improvement.

Bold Photography said...

I wouldn't be in such a hurry to go past the initial presets -- Noella does them justice...

While I do LOVE shooting with super-uber-amazing sharp lenses... I frequently have to defocus the results if I'm shooting humans - they're too sharp.

How many women ask "hi, could you take my photo, oh, and make my pores REALLY stand out.. and these age lines? Make them visible to someone across the street, please..." ...

Jan Klier said...

Just saw this blog post, and thought the conclusion was quite relevant to the gear lust discussion:

"The easiest way to get into trouble — and ultimately force yourself out of your dream job — is to spend your hard-earned money foolishly. [...] Every working professional I’ve ever met who has managed to sustain a long-term photographic career is at heart both canny and cost-conscious, with one eye at the viewfinder and the other watching the bottom line." - from Derek Shapton http://www.derekshapton.com/planet_shapton/?p=1727

hugo said...

Interesting read. I cannot agree more with you that "test charts" are such a biased way of looking at a lens performances. I would add the biggest problem is that even on the same website test charts of different lenses are not consistent with each other ...

Kirk, would you happen to know where to find this white paper on optimal lens design ?

kirk tuck said...

Do a search for the writer, Erwin Puts. He did an amazing book about Leica and lens design. He made the book downloadable for free. That's the best resource I can find on short notice.

jelly gamat luxor said...
This comment has been removed by a blog administrator.
kirk tuck said...

I almost hate to ask but, what is blogwalking?

snafuubar said...

Blogwalking, a popular term among the Malaysian, Indonesian, and Philippines bloggers but a rather obscure term in other parts of the world. What is it actually?

What is blog-walking?
Blogwalking is a technique to increase blog traffic by visiting other blogs and leave your marks there. The other blogger is then expected to reciprocate by visiting your blog.

kirk tuck said...

Didn't like ole Jelly's inference so I deleted it. Everyone is always looking for the devious motive. Sometimes people are just genuine. Get over it.