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ChrigelKarrer

DxO Labs tested Lenses for D800

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DxO Labs just released the 3rd page of their review about lenses for the D800.

Unfortunately the test of wide angle lenses is not ready yet, but should be published soon.

 

 

http://www.dxomark.com/index.php/Publications/DxOMark-Reviews/Which-lenses-for-your-Nikon-D800

 

Chris

Edited by ChrigelKarrer

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Perhaps I'm missing something here, but I find the DxO lens ratings confusing, and almost useless. The scores they show are only for the "best" aperture, which in most cases is wide open or very close to the widest open aperture. These apertures are not applicable to most general shooting because we have to stop the lens down farther to get the depth-of-field we need, especially when we use the lens behind a dome port. I want to know how that wide-angle lens performs at apertures at f5.6 and f8 and f11. And just because one lens performs better wide open than another, that does not mean it performs better at those practical shooting apertures. I also haven't seen how much each of the five categories; sharpness, transmission, distortion, vignetting and chromatic aberration is "weighted" in the final lens score. Flare, which I find is sometimes a very significant factor doesn't seem to be considered in the DxO testing.

 

Underwater, in most cases the distortion isn't visible as there are few straight lines. And there are software "fixes" for distortion, and vignetting and most chromatic aberration. Transmission is usually "offset" with exposure, which is what most TTL metering systems do by calling for slightly longer or shorter exposure times. The true sharpness of a lens, particularly at normal shooting apertures, is what I consider to be most important.

 

Fred

Edited by divegypsy

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Perhaps I'm missing something here, but I find the DxO lens ratings confusing, and almost useless.

I don't think you are missing anything at all. Trying to provide a single all-encopassing figure for a lens or camera is where DxO fall down. Image 'quality' means different things to different people (as you explained in your case) and to make sense of their tests they need to be understood and appreciated individually. A global end figure is completely meaningless and DxO would be far more credible if they dumped it as an idea.

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I think DXo tests are a valuable overall guideline to any of the products they test, particularly when trying to make decisions on value for money comparing lenses or cameras. Of course they do not incorporate many of the other features that one looks for in a lens or camera, but used intelligently I think they are helpful when comparing products that otherwise have similar features.

Any shooting situation, such as underwater etc will of course, change the calculus - but still helpful I think particularly when comparing products that may have hugely varying prices.

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I think DXo tests are a valuable overall guideline to any of the products they test, particularly when trying to make decisions on value for money comparing lenses or cameras.

I'm afraid that this is exactly where I disagree. Its the overall guidance that's the problem. Individual tests can be quite useful. Combining them is subjective and fails to take into account the numerous differing uses to which they may be put. If DxO left out the overall scores, then people viewing their data would need to appreciate the tests more and rely less on an overall 'pseudofigure'. I've discussed this on another forum recently and there was substantial division over it, but IMHO the overall figure is meaningless. Value for money has many important factors which lie well outside performance figures too (such as resale value) so I'm not sure that a DxO figure has much relevance here either.

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Underwater, in most cases the distortion isn't visible as there are few straight lines.

I think that a lot of this community are using their camera also for land shots where the lenses will be used in a different manner and probably more like DoX evaluate them.

And there are software "fixes" for distortion, and vignetting and most chromatic aberration.

Sure there is software doing this, but starting with a lens who distort, vignette and/or produce chromatic aberration will lead to a bad immage quality, especially on a high-end camera having 36 megapixels.

Lightroom does this functions surprisingly well but watching the picture zoomed in it will reveal the loss of details.

The D800 i a camera giving the possibility to do a 25% crop of the picture and still producing a excellent image quality, but in this case any calculated, weighted correction will be revealed.

 

I find it also interesting how certain lenses perform, the $2950 Carl Zeiss Distagon lens to $409 for a Samyang 14mm f/2.8 IF ED UMC Aspherical is just a delusion for example.

I grew up wih the knowledge and belive hat Carl Zeiss lenses are the top of the top and i - if my budget would allow it - would had bought one for land use without further investigation so

i am thankful for this test as he delivered me the raw data to investigate further before buy a expensive lens.

 

Chris

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Having bothered to look at a few lenses which I am familiar with on the DxO website, I am now even less impressed at their ratings. I find that they just don't bear out my personal 'real world' ratings of the lenses I am very familiar with at all, and are overly complicated. Some manufacturers publish lens characteristics data (Zeiss and Leica for example) which is pretty comparable - MTF charts, distortion and vignetting. This is I believe theoretical, design data, and needs to be understood to be useful. The digital revolution has spawned a glut of testers who claim to supply objective data (although I notice DxO do comment that some data is subjective) and it IS difficult to determine what is good and useful and what is bad and useless. But overall scores are IMHO pointless (and I used to carry out MTF testing for a living many years ago).

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I also believe that the DxO tests are useful when comparing Lenses.

However, real life usage is more important. Here is also the problem hidden.

The Nikkor 14-24mm is generally a much better Lens than the 16-35mm.

However, for UW it is the other way around!

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Lens test reports that I find much more useful than those on DxO can be found at www.photozone.de. What I really like is that they give a "standard" MTF result for lenses at a range of apertures. They also give very specific distortion and chromatic aberration numbers at the various f-stops all of which helps you decide what may be the best apertures to use for your needs.

 

What no regular lens tests seem to evaluate is the performance of the various wide-angle lenses at the close focusing distances which is what we utilize when we use a wide-angle behind a dome port. Lenses typically are designed for best performance at infinity and near infinity distances. Close focus performance is lower. How much lower we usually have to find out by personal experience.

 

But unless the technical performance of a lens is really bad, image content - what you choose to shoot and how well you frame it and light it is far more important.

 

One thing you usually get from the major manufacturers, like Nikon and Canon, is consistency in construction quality. At www.photozone.de they gave the Tokina 16-28mm a good review optically, but said that there was significant decentering of elements in the first sample they bought and tested, and that their results were based on that second lens. Some of us here on Wetpixel have seen the same thing with Sigma lenses - that sometimes one is quite good and another example of the same lens type is not very good.

 

You pay for what you get. But you don't always get what you pay for.

 

Fred

Edited by divegypsy

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What no regular lens tests seem to evaluate is the performance of the various wide-angle lenses at the close focusing distances which is what we utilize when we use a wide-angle behind a dome port. Lenses typically are designed for best performance at infinity and near infinity distances. Close focus performance is lower. How much lower we usually have to find out by personal experience.

Fred

Some manufacturers use 'close-range-correction' (floating element) designs for their wide-angle lenses. These usually consist of a seperate group of rear elements which shift as the lens focuses closer. The downside is of course a more complicated design and thus higher price. So cheaper lenses tend not to have such features incorporated into them. For example Canon's expensive 35 f/1.4 L lens is a floating element design whilst the far cheaper 35mm f/2 is not. Whilst both appear to be reasonable lenses in tests (at infinity - though I find the L better at wide apertures in practice), the 35L is far better at closer focus in my experience. (And you are right, we usually have to find out close range performance by experience).

Edited by Paul Kay

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