Kobie

I saw in one of the discussions, which I cannot find now, where somebody uploaded a lens chart (if it is called that). It is a graph that showed a lines per unit on the y-axis and aperture on the x-axis. Then at each aperture 4 different focal points. From this chart you could clearly see where you would get the best picture.
Can anybody direct me to where I can find charts like this for my Canon lenses?

BillyP Loc: Cedar Point, NC

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CHG_CANON Loc: the Windy City

They're called theoretical MTF charts (Modulation Transfer Function). They're put out by lens manufactures, but I've only seen them referenced in lens reviews. The image below was taken from the 100-400L II review at the Digital Picture website. Most detailed reviews will include the MTF chart such as this review http://www.the-digital-picture.com/Reviews/Canon-EF-100-400mm-f-4.5-5.6-L-IS-II-USM-Lens.aspx

How to read can be found by googling "theoretical MTF charts". One detailed explanation can be found at "Understanding MTF charts" at http://luminous-landscape.com/mtf/

Thurber Mingus

If you are looking for this, you can find it at www.lenstip.com. Open up your specific lens and you will get a general overview, but if you click "review" on the top right, then "image resolution" you'll find the chart for that lens. As I understand it, anything over 40 lpmm is very good resolution.

(Download)

fergmark Loc: norwalk connecticut

I am happy to see a reference to the luminous landscape website. I wish people would look at what is available there. A real wealth of information into understanding about cameras and photography.

How to read can be found by googling "theoretical MTF charts". One detailed explanation can be found at "Understanding MTF charts" at http://luminous-landscape.com/mtf/[/quote]

joer Loc: Colorado/Illinois

The key word is theoretical and may not reflect lens variation or use. I look at it as more of indication of the design.

It's funny (not), most of us buy the long zooms because of the high prices of telephoto primes and yet zooms are at their worst at the long end. Are manufactures ignorant of these practices or is it just too difficult to do at moderate cost.

John N Loc: HP14 3QF Stokenchurch, UK

I used to read SLR magazine (U.K.) back in the 1970's/80's. They printed an actual LPM (lines per millimeter) graph for every lens reviewed. Much simpler to understand.

royden Loc: Decatur, GA

http://global.canon/en/c-museum/series_search.html?t=lens&s=ef

This is not what you're looking for but may find useful.

amfoto1 Loc: San Jose, Calif. USA

MTF charts do not show "where you would get the best picture". Their curve is a graph showing the lens' resolution with two or three different types of standardized targets in the center of the image area, partway to the edge, and at the extreme edge or in the corners of the image area. With a zoom an MTF chart usually shows a specific focal length setting... so multiple MTF charts are needed for different focal lengths. MTF charts do not show lens performance at different f-stops or real world use.

What you might find more useful is the-digital-picture.com website's lens reviews and especially their comparisons. Bryan Carnathan owns the site and does exhaustive tests of each lens, including test target shots at all of a lens' available apertures and with zooms at different focal length settings. In many cases the lenses are also tested on several different cameras. And, where appropriate lenses are also tested with teleconverters (unfortunately the specific brand or version of TC usually isn't known... just whether it's 1.4X or 2X). Perhaps best of all you can compare any two lenses side by side, so it's possible to see how a lens you're considering purchasing stacks up against a lens you already have and are familiar with.

A few suggestions if you use that website for comparisons...

Try to select the same camera for both lenses and preferably one that's the same as what you have or one with a similar resolution sensor... or at least be sure that both lenses' tests were done with the same or similar cameras. For example, I use Canon 7D Mark II a lot and try to compare using that or 70D which use essentially the same sensor. If that's not possible, I'll just make sure both of the comparisons use the same or very similar camera, even if it's different from what I am using. But I try to keep in mind differences in the cameras. For example, many recent tests of EF (full frame) lenses there have been done with the 50MP 5DS-R... That ultra high resolution camera is really demanding of lenses... a real "torture test" for them. But it's resolution also works out to be pretty close to that of the 7D Mark II's smaller APS-C size sensor when you consider the density and size of both cameras' pixel sites.

Keep in mind that the test pattern shots you're looking at at that website are highly magnified. So actual images will be a little to a lot "better" than what you see, unless you make extremely large prints from them and then view them from ridiculously close.

Like MTF charts, the test shots are done at center of the lens (usually the sharpest), part ways to the edge, and in the extreme corner (usually the least sharp). You can change the lens stop to see how it changes the image.... try to select f-stops that are what you're likely to use... for example a larger aperture for a telephoto to be used to shoot sports or a small aperture for a wide angle you'll be using for landscape photos.

Also keep in mind that some things - such as a bit of chromatic aberration exhibited by a lens that's made obvious by the black and white test target - are actually pretty easily corrected in post-processing, some automatically with "lens profiles" or even corrected in-camera with some later models. The test images are "uncorrected" on purpose. So it's also important to read the detailed review.

You also can compare other factors, such as propensity to flare, optical vignetting, and lens distortions (barrel and pincushion that a zoom might display at different extremes of its focal length range)

MTF charts and lens specs such as size and weight are also available and any two can be compared.

I usually start by reading the detailed review, which are available for almost every Canon EF and EF-S lens every made.... then I look at the "Image Quality" comparison as described above... then the other comparisons of flare, vignetting, distortion and lens specs.

In addition to Canon lenses, tests and reviews are available for many third party from Sigma, Tokina, Tamron, Samyang (Rokinon/Bower/etc.), as well as some Zeiss (Sony) and Nikon lenses.

DXO Mark is another website that provides lens comparisons... but they boil it down to a "grade" for a lens in different types of uses.... some of which may be pretty far from "real world" use of a lens... and seem to be rather subjective. Personally I find the-digital-picture.com MUCH more informative and useful.

dpreview.com is another good, thorough review website.

Ken Rockwell also does a lot of reviews and comparison, but his emphasis is a bit more toward Nikon gear (though there is a lot of Canon, too).... and a lot there seems rather opinionated. It can make for an interesting read, but I'd take info from Ken with a grain of salt.

It also can be useful to read actual user reviews on the retailer websites and discussion on forums like this, but you have to keep in mind that peoples' experience levels range wildly and very few have had much opportunity to actually compare multiple lenses (or other gear) side by side... plus user reviews are often given during the initial rush of excitement purchasing a new item and with minimal real world use of it done yet. So, take these with another grain of salt, though they can be interesting and useful.

SalvageDiver Loc: Huntington Beach CA

Here's another website that contains a large database of lens data, including MTF charts.

http://allphotolenses.com/