Lens Test References

<p>As a film guy, I am in a different world now, thinking about getting a digital SLR. With film it is relatively easy to identify the best lenses from all the manufacturers. I realize that with digital, there are many factors such as noise that enter into the equation. <br>

However, I would like to know how various lenses compare, and I would like to know of reliable testing sites that compare specific lenses from several manufacturers.<br>

By best, I simply mean MTF, distortion, etc. Traditional lens testing attributes. <br>

Please provide a link if you know of a good source for this information, and also your personal experience with them if possible.<br>

Thank You</p>

 

<p>Personally, I'd reference a few sites: Photozone.de , <a href="http://www.the-digital-picture.com/">http://www.the-digital-picture.com/</a> , and dpreview.com . Other than those, I'd probably rummage through the forums here and on fredmiranda.com (not necessarily objective) for more hands-on reviews.</p>

<p><a href="http://www.slrgear.com">www.slrgear.com</a></p>

<p>Search for the lens that interests you to see if they've tested it. Open up their interactive, 3-D "blur" charts, which I find far more informative than MTF charts. Note that there are separate charts for full and crop frame. You can also find charts for distortion and CA. Good stuff.</p>

<p>Also <a href="http://www.photodo.com">www.photodo.com</a></p>

<p>You'll find that lenses are lenses. There's very little difference between a "digital" lens and a "film" lens. Digital lenses have heavier rear coatings to reduce reflection back from the sensor. There are also APS-C format lenses (Nikon's DX, Canon's EFS) that are not compatible with film or full-frame digital. Otherwise there's nothing else to know. Different sensors with different noise characteristics and sensitivities are like different films with different grain structures and ISO ratings.</p>

<p>Brent</p>

<p>welcome to the world of 100% measurable reliability in testing. Digital enables you (well it did me) to actually see differences between lenses which I could never see so clearly ever before with film. Not only "resolution" of which is a minor issue if you ask me) but colour rendition and contrasts. When evaluating lenses I use a converter called dcraw to convert my raw images. This simple command-line utility produces a TIFF based on a reference to a "fixed white balance based on a color chart illuminated with a standard D65 lamp. "</p>

<p>Compared to the vagaries of film (film batch, 100% accuracy in processing) you can compare any given lenses and see the results in greater details than you could film (and what about the magnifying loupe you use?)</p>

<p>While it is true that each sensor will record light slightly differently the same is true between brands of film, no?</p>

<p>With reference to lens testing sites, the ones which you know (photodo et al) will remain as applicable as ever, but none of them tell you if you like the lens. I have a Pentax 110 50mm lens which right now I happen to like the look of very much as a portrait lens on my Panasonic G1. I don't think looking at specs I would have been able to infer that in advance.</p>

<p>:-)</p>

<p>Digital makes lens testing <em>much</em> easier, as long as the lens doesn't out-resolve the sensor. The 24 MP full-frame sensors a have about 84 lp/mm, although the anti-alias filter and to some extent (especially for color) the Bayer de-mosaic limit effective resolution to maybe somewhere around 65 lp/mm. The 14 MP "APS-C" sensors have almost 100 lp/mm before the filter etc. Canon's new 18 MP, slightly-smaller yet sensor are about 116 lp/mm. Obviously the same alias/mosaic issues apply to the smaller sensors too.</p>

<p>For readily-available, reasonably-scientific lens tests, in the US at least, I think you look to <em>Popular Photography</em> magazine (skip their subjective stuff, but their numbers tell you something) and the DPReview website.</p>

 

<p><em>"With film it is relatively easy to identify the best lenses from all the manufacturers."</em><br>

<em><br /> </em><br>

The factors that make for excellent film lenses are basically the same as those for digital lenses. There are some factors that are different but they are very technical and are generally all covered by looking for lenses labeled as "digital only" such as Tamron's Di label.</p>

<p><em>"I realize that with digital, there are many factors such as noise that enter into the equation."</em><br>

<em><br /> </em><br>

Noise is a problem with the camera sensor and has nothing to do with the lens.</p>

<p><em>"Please provide a link if you know of a good source for this information, and also your personal experience with them if possible."</em></p>

<p><strong>Popular Photography</strong> has been testing lenses for over 50 years. They archive their old tests at their web site, popphoto.com. dpreview.com is a web only site that does good reviews.</p>

<p>Danny</p>