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Thread: DXOMARK,

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    Super Moderator NEF.D90's Avatar
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    DXOMARK,

    Aloicious I see you posting links from here all the time for different camera related reviews and comparisons.
    Would you shead a little light on who DXOMARK is and what we can do on their site?
    If your going to dream, Dream Big!

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    Administrator Aloicious's Avatar
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    Dxomark actually makes some image editing software, but they also go through and do testing on lenses and sensors and compare their performance...they're a decent site to do technical comparisons on, but they're not without their flaws. some folks don't like their testing methodology, others don't agree with their findings, etc. and they have good points, but its just one piece of the puzzle, like most things on the internet, you don't want to take their data straight up as gospel, but it can help with researching lenses and bodies and stuff. another good site I go to is photozone.de, they do good testing, but they also don't have a lot of newer lenses/bodies they've tested either.
    -Justin

    Bodies - D800E
    Lenses - Sigma 18-35 f1.8 DC | Zeiss 15mm f2.8 ZF.2 | Zeiss 21mm f2.8 ZF.2 | Sigma 35mm f1.4 Art | 105mm f2.5 AI-S | 70-200 f2.8G VRII | 200mm F4.0D Micro AF | 300mm f2.8 VRII

    My PhotographyWild Blog

    C&C is always welcome on the images I post.

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    Super Moderator NEF.D90's Avatar
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    Awesome, so photozone.de might be a good place to look for information about the capabilities of a used lens that one might be looking at. Or even an older Body perhaps.
    If your going to dream, Dream Big!

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    Administrator Aloicious's Avatar
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    yeah, like all reviews, they're all just pieces of the puzzle, so research them all, but don't rely on any one specific place to tell you what to or not to buy.

    for example, I like Dxomark because they test everything the same, so although their method may not be perfect, at least you know that comparing their own tests, to their own tests, they're a decently done comparison. they also only test one copy of the lens, so there are some lenses that tested mediocre or even poor, which don't line up with the general consensus...the zeiss 21mm f2.8 ZF.2 lens is an example of that, their tests showed only marginally decent results, but its WIDELY known as one of the best 21mm lenses ever made by any manufacturer (and I have one and tend to agree that it is absolutely fantastic, which isn't what their testing shows). so I have to think their copy of the 21mm was faulty or something....so, y'know, use it as part of your research, but not the end all-decision making factor.
    -Justin

    Bodies - D800E
    Lenses - Sigma 18-35 f1.8 DC | Zeiss 15mm f2.8 ZF.2 | Zeiss 21mm f2.8 ZF.2 | Sigma 35mm f1.4 Art | 105mm f2.5 AI-S | 70-200 f2.8G VRII | 200mm F4.0D Micro AF | 300mm f2.8 VRII

    My PhotographyWild Blog

    C&C is always welcome on the images I post.
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    Super Moderator NEF.D90's Avatar
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    What do these terms mean to me?
    If your going to dream, Dream Big!

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    Administrator Aloicious's Avatar
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    I basically ignore their 'overall' score, they use that to try and create a composite overall score of how good a lens is, but 'goodness' can be wildly different among different people so trying to create a composite 'goodness' score is a little misleading.

    the sharpness score is basically how well the lens is able to resolve detail, higher numerical scores are better, but this is just peak sharpness, not taking into account sharpness across the frame, but you can look at their sharpness field maps to get a better idea of that.

    the transmission score is how much light the lens transmits, i.e. a f1.4 will have a better score than a f2.8, I don't find this score particularly useful, there will be slight variances between lenses of the same advertised aperture naturally. so a little difference doesn't mean much to me. it might be more useful for those who do video work though. a numerically smaller number is better.

    The distortion is how much distortion the lens displays, a lower percentage is a flatter image (less barrel, i.e convex, or pincushion, i.e. concave, distortion)...this can vary a bit, the sheer number doesn't tell you much in terms of type of distortion or complexity, and different types of lenses will naturally have more or less distortion, this number isn't TOO useful, unless you're comparing very similar lenses (i.e. any supertelephoto lens will have MUCH less distortion than a ultra wide angle, but if you're comparing 2 different ultra wide angles, or 2 different telephoto lenses, it can give you a general idea. but I'd look into the actual distortion type and complexity before taking just a generalized non-specific percentage if its something you're concerned with)

    The vignetting is the light falloff towards the edge of the frame measured in exposure value. a lower numerical number is better. in this example you posted the lens at the very far edge of the frame is 1.2 stops darker than it is in the center of the frame. again this is a value that different types of lenses will exhibit differently so it's not really a useful tool for figuring out the 'better' lens if you're comparing very different types of lenses (i.e. ultra wide vs telephoto), but if you're comparing two similar lenses, it can be a worthwhile value. but vignetting is something that can be corrected without too much problem in post production too, so for me, this isn't a deal breaker, but at least something to be aware of.

    the chr. aberration is measuring of the CA, or color fringing, lower numbers are better with less CA. this value also doesn't take into account the TYPE of CA, or where in the frame it is seen, but it is a good comparison tool on how well the lens corrects for CA.

    you can also go into their measurements area and look at field maps of things like CA and sharpness and vignetting to get an idea of how the lens performs across the frame which is also helpful.

    however DXOMark isn't the end all of if a lens is good or not, there are multiple lenses I don't agree with their findings on, and they only perform the tests once for one copy of the lens, so they fail to take into account possible production problems in their specific copy of the lens, etc. but at least they are one of the more scientific testing sites, so I like to use their results along with other testing site results, and real life user reviews all together when comparing lenses or researching them prior to purchase rather than relying on one set of test numbers from one specific place.
    -Justin

    Bodies - D800E
    Lenses - Sigma 18-35 f1.8 DC | Zeiss 15mm f2.8 ZF.2 | Zeiss 21mm f2.8 ZF.2 | Sigma 35mm f1.4 Art | 105mm f2.5 AI-S | 70-200 f2.8G VRII | 200mm F4.0D Micro AF | 300mm f2.8 VRII

    My PhotographyWild Blog

    C&C is always welcome on the images I post.
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