Panasonic 7~14mm or Olympus 12mm ?

Started Jan 18, 2013 | Discussions thread
Anders W
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Re: Thanks for all the replies and suggestions
In reply to slimandy, Jan 22, 2013

slimandy wrote:

Anders W wrote:

slimandy wrote:

Anders W wrote:

slimandy wrote:

Anders W wrote:

slimandy wrote:

Anders W wrote:

Yes, they test under lab conditions, just as Photozone.


To be honest I'm not a fan of Photozone either but I quoted them because I can't find reviews from professional photographers they way I can with Nikon gear. At least some of their samples are real world pictures and not just test charts and studio still lifes.

I have no trouble making sense of test charts, studio still lifes, or MTF values. Just a matter of learning how one set of observations translates into another. The same is true with respect to DxO figures about sensor performance. I have no trouble making sense of those either since I have spent the time required to see how they translate into aspects of image quality that my eyes can see.

I have no problem at all understanding and interpreting the charts so I do look at the lab results, but they are not what I will shoot in real life so they only tell part of the story.

Could you please elaborate? What part of the story are you missing?

The bit where you use the lens to do the kind of photography that I will actually do!

Yes, but what bit, more specifically, is that? You say you have no difficulty understanding the lab results so what more specifically, expressed in terms of optical properties, is it that they don't tell you?

All of it! I don't shoot in a lab. I want to know about AF speed, bokeh, flare, etc. etc. out in the field where I shoot. I want to know how it does in real-life use rather than still life or test charts. You can evaluate sharpness, contrast, CA etc. in a lab and that's all good, but it's not what I shoot and won't tell me the whole story.

MTF (resolution, contrast), CA, AF speed, and bokeh can be evaluated in the lab, yes, and there's no problem generalizing those results to the field. A partial exception might be flare where there's a prominent light source that we might have difficulties properly simulating in the lab.

One example of a lab that tests all of these things, and for the most part does it pretty well is Lenstip.

The trouble with looking at "real world pictures" is that those will never allow you to directly compare two lenses to one another unless they happen to be taken under identical conditions such as those in Amin Sabet's test of the 7-14 versus the 9-18 that Optical1 linked to here.

For obvious reasons, the lens test sites would have difficulties accomplishing directly comparable sample shots outside the studio inasmuch as this would imply that they would have to shoot new "real world pictures" of all lenses already tested for every new lens they test.

If a highly skilled photographer whose reviews I trust were to use a lens extensively and write his review on it that is the most useful info I could get. I do not need to pixel peep with identical shots side by side in order to form an opinion.

Your call of course. But in order to form an informed opinion about the relative performance of two competing lenses, I'd like to see them shot/tested side by side under identical circumstances. I'd also rather see for myself than go by someone else's opinion, even if it's a person whose judgment I trust.

I will see for myself after I buy the lens. Until then I need to decide which to buy.

So do I. I was referring to the information I prefer to rely on before I get to that stage. I'd rather not personally evaluate more lenses than I actually have to so I want to make the prior screening as efficient as possible.

Furthermore, I don't think that being an outstanding photographer is either a necessary or a sufficient condition for being a good lens tester or lens designer. Some people may have great optical skills without being great photographer and some great photographers don't know a whole lot about optics.

Hence I like to read reviews from someone I trust. You don't need to know about optics; you need to know how the lens handles and how good the results are. I'm a photographer, I make photographs; I don't make lenses.

If you want to know how good the results will be under a variety of circumstances, you need to know about optical aberrations and their various manifestations. Otherwise, you won't know what to look for.

Here's an example of a review (comparison of the new Oly 17/1.8 with the 20/1.7) by someone I consider a very good photographer. I find his sample images very helpful. Yet, I strongly disagree with some of the conclusions he draws. Can you guess which?

http://blog.mingthein.com/2012/11/17/olympus-zd-17-1_8/

Curiously Ming Thein is a reviewer that I do trust. He does get quite technical but at the end of the day his sample photos are real-world photos and his conclusions are based on things that matter such as AF speed and image quality.

I would like to know where your opinion varies and why.

Some examples:

Ming says: "The 20/1.7 has the highest overall scene contrast, but the 17/1.8 wins out in microcontrast and reproduction of fine detail structures – personally, I prefer this as it gives me more latitude for processing before the shadows and highlights block up."

My comment: It's clearly evident from Ming's samples that the 20 does better with respect to global contrast and microcontrast (the contrast between smaller details) alike. When Ming says that he has "more latitude for processing [with the 17] before the shadows and highlights block up" he means that he can apply more sharpening. But the point here is that the 20 simply needs less sharpening by virtue of having more microcontrast in the first place. And not having to sharpen (much) is preferable on all counts. It doesn't increase the noise level and yields a cleaner, more natural look.

Ming says: "What will affect resolution (and perceived acuity) far more is lateral chromatic aberration."

My comment: It will not, at the magnitude shown here, affect resolution or acuity to any measureable degree once corrected. And this particular aberration can be corrected easily/automatically and without any downsides in PP.

Ming says (still talking about lateral CA): "We’re now seeing CA from all three lenses, with the 17/2.8 once again faring the worst. The 17/1.8 is slightly better than the 20/1.7. Interestingly, not much changes even when you stop down."

My comment: Why is it interesting (surprising) that not much changes when stopping down? It is well known that lateral CA (unlike longitudinal CA) never changes as you stop down.

Ming says (about vignetting on the 17/1.8, which he appears not to have measured systematically): Vignetting is also fairly negligible too, even wide open.

My comment: Look at the Lenstip review here which shows the lens to have very significant vignetting until well stopped down (worse than the 20, which hardly excels in this particular area).

Ming says: "The 17/1.8 renders out-of-focus areas with a rounded softness and lack of hard/ bright edges or double images, even against complex background textures."

My comment: A close inspection of the blur discs (in the problematic transition zone) shows them to have properties very similar to that of the 12/2, which (for good reason) came in last in the test/poll of bokeh among MFT WAs reported here. With the 12/2, the poor bokeh doesn't matter much, at least for my usage. With the 17/1.8, it is of somewhat greater concern since I am more likely to end up with at least parts of the frame outside the DoF whether I like it or not (although I'd rarely go for subject isolation by means of background blur with what is effectively a 35/3.6). The 20/1.7 is better in this department (although it is certainly no bokeh king).

Ming says: "I would not buy the 17/2.8 unless size is a critical priority, or you know that you’re going to be shooting only static objects stopped down; otherwise the slow AF speed will drive you crazy. The Panasonic 20/1.7 is in a similar boat; it’s faster to focus than the 17/2.8 and optically better, but nowhere near as fast as the 17/1.8."

My comment: See here.

In spite of the above, I appreciate Ming's review very much because of the evidence he puts at my disposal, which I can judge for myself, without relying on his comments.

Even when I read the opinion of someone I trust I reserve the right to disagree, and the most important opinion is always my own! I am assuming you prefer the Pany 20mm to the Olympus 17mm f1.8?

I have mixed feelings. On an FL basis I have a marginal preference for the 17 (35 mm EFL). However, it is inferior to the 20 (as far as we can tell at this point) when it comes to global contrast, resolution/microcontrast, vignetting, and bokeh. It also has some upsides (less PF, better build, marginally faster AF, less noisy AF, distance scale, less risk of banding with the E-M5 at really high ISOs) but as things stand right now, I am not really tempted to exchange my 20 for the new 17. That's a pity. I had hoped I would be.

That's another decision I have to make actually. I was assuming I'd get the 20mm pancake but now wonder if I should get the 17! More than one person has commented on the slow AF of the 20mm lens.

As to AF, see my comment to that point in Ming's review above.

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