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21

There is a really good tutorial that explains all the details at luminous-landscape.com. If you don't want to read the whole article, this section covers the basics: Here are some rules of thumb for reading a chart... — the higher up the chart the 10 LP/mm line is (the thick lines), the higher the contrast reproduction capability of the ...


8

Zeiss has a pretty good paper on how to read MTF charts. It is rather detailed and extensive, but if you are interested in fully understanding how an MTF represents a lenses quality (and how accurate the MTF may be), it is an excellent read. How to Read MTF Curves A very interesting little facet of the article denotes three important properties of MTF, ...


5

First off, the use of 10lp/mm and 30lp/mm are not really a standard. Depending on the market for the lenses, the brand, and possibly the rough timeframe when a specific approach to producing MTF charts was formulated, the specific resolution of the features of a test chart can vary. Larger format cameras often used 40-50lp/mm test charts, and manufacturers ...


5

The picture height in this context is the height of the image. It is an output-size independent way of specifying the amount of detail contained in an image. For example saying an image contains 2300 lines per picture height means an image has 2300 lines that fit within the height of the image (in landscape format). Regardless of whether you are looking at ...


3

Supposedly the deviation between the Saggital (solid) and Meridional (dashed) lines on the mtf chart can be used to judge the bokeh. If the lines deviate widely from left to right the bokeh can have undesirable qualities. Saggital contrast is measured using a pattern of fine lines parallel to the image diagonal whereas Meridional lines are set at 90 degrees ...


3

They are indeed both a measure of contrast; one is simply measuring it at a much higher frequency than the other so they are measuring for different qualities. The 30 lines per mm test will test the limits of the resolution of your lens, while the 10 lines per mm measurement will not really do so; your lens should have plenty of resolution to get a good ...


3

Producing and comparing MTF's is not really as easy as it may seem. Different manufacturers use different contexts, sensors are often tested in a different context than lenses, and direct apples to apples comparisons can be difficult. That said, the way Canon MTF charts work is fairly strait forward. The 10lp/mm MTFs are intended to measure sharpness at a ...


3

What you are referring to is a chart from Azure Photonics which they call an MTF chart. It says (see source): Distortion : <12~1% (not <12-1%) I believe it is saying that within 12mm of the optical centre the distortion is about 1% <12 I take to mean "within 12mm", and ~1% means "about 1%" The chart measures the % distortion (of horizontal ...


2

SLRGear.com publishes what they call "blur units" (and sometimes "Blur index") in their tests. These seem to be DxO BxUs (aren't TLAs wonderful?)


2

The only Nikon wide prime I've used extensively was the 20mm f2.8D, which I really liked in my film days. The 24mm f2.8D was nice but after borrowing it a few times I decided 20 fit me better. Of course, at the time I never gave a whole lot of consideration to things like distortion, CA, or falloff, so I can't really say how they'd perform on a DSLR. ...


2

I think your only option is the 20mm F2.8D which is exactly what I got and chose after considering the 3 main factors. Was it wide enough? Yes Was it light and easy to carry? Yes and Was it affordable? Yes I've only used it on my D90 at present but I will be buying the D800 and the 20mm will be my walkaround lens. I too have the same ideas as ...


2

Well looking at the data for the Pentax lens, vignetting (very little and less than the Canon), distortion (virtually none) and chromatic aberration (minimal) are nothing to worry about. The main thing to compare is the resolution. They are measuring this in Line Widths per Picture Height (LW/PH). Think of this as measuring the limit the lens can resolve ...


1

As a D800 and 14-24mm owner, let me tell you that this is an excellent match. If the 14-24mm is too heavy/big to be your everyday lens, the only prime I would recommend to you is the 24mm f/1.4, which is as sharp as a scalpel. If you consider the 35mm, look for the Sigma 35mm f/1.4. On the contrary, if you're looking towards ultra-wide angles, check the ...


1

i have a 24 1.8 sigma which i think teams nicly with 50 1.4 and my 100 2.8. i also have a 28 2.8 nikon. i have a d800e but i am looking still for something in the 18mm range because i like to 45-90-45 triangle that 18mm makes on full frame...


1

You can't compare resolution numbers directly between aps-c and FF sensors. The same lens will give you a higer number in FF than in aps-c, usually by a factor of 1.45 to 1.5. So a non-scientific way to compare resolution numbers in photozone site if the tests are in different sensor sizes is to multiply number in aps-c by 1.45 factor (or divide in FF). ...


1

Everything you need to know to understand MTF charts: http://www.luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml



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