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Lens Tests

| EF 28mm f1.8 USM | EF 50mm f1.4 USM | EF 100mm f2.8 Macro USM |

| EF 180mm f3.5L Macro | EF 180mm f3.5L Macro + EF 1.4X II  | EF 180mm f3.5L Macro + EF 2X II |

| EF 200mm f2.8L II | EF 200mm f2.8L II + EF 1.4X II | EF 200mm f2.8L II + EF 2X II | EF 200mm f2.8L II + EF 1.4X II+ EF 2X II |

| EF 300mm f4L IS | EF 300mm f4L IS + EF 1.4X II | EF 300mm f4L IS + EF 2X II | EF 300mm f4L IS + EF 1.4X II + EF 2X II |

| EF-S 18-55mm f3.5-5.6 | EF-S 10-22mm f3.5-4.5 USM | EF 17-40 f4L USM | EF 24-105mm f4L IS USM |

| Primes | 17mm Region | 24mm Region | 28mm Region | 35mm Region | 50mm Region | 100mm Region | 300mm Region | 400mm Region | 600mm Region |

| EF 180mm f3.5L Macro + TCs | EF 200mm f2.8L II + TCs | EF 300mm f4L IS USM + TCs | Tests With the Kenko TC | Macro Tests |

| Filter Effect on Sharpness and AF | Flare and Filters | Image Stabilizer Tests | TC Sharpness | Best of the Best | Method | Understanding the Results | Real World 100% Crops | Tripod Tests | L-Plate Test |

Understanding the Results

Printable Comparative Crops

Monitor Viewable Table

Subjective Assessment of Printable Crops

If you have difficulty interpreting the abstract numbers you can always refer to the 100% crops that will be viewable from each f-stop result page. Look for the "View Crops" link as the lowest menu item.

Printable Comparative Crops

As an aid, various crops of the USAF section of measurement areas covering a range of 50% MTF values have been pasted into a file with the same dimensions as a 20D frame. Click on the downsized version below to get the full resolution JPG.

The 100% crops have been duplicated as 200% version, the upsize performed with CS2 Bicubic Smoother.

The crops have been labeled with the lens used and focal length, f-stop, measurement area letter and average 50% MTF to simplify referring to the results.

It is most instructive to print this plot at your normal print sizes using your normal workflow and examine the results. Note, the crops have been capture sharpened just enough to overcome the camera anti-alias filter. You should add your standard workflow sharpening to overcome resize softening and printer dot gain.

Monitor Viewable Table

Reproducing the sample crops and SFR plots in table form below for easy comparison.

The MTF 50% is a good guide to sharpness, but there are some subtleties; some traces fall fast and then flatten out indicating low contrast but high resolution. I have avoided using these as examples here. 

The examples work through from 16lp/mm (very soft) to 70lp/mm (very sharp). As 100% crops on the monitor using high contrast test targets its fairly easy to discern the different levels of sharpness. However, even under these advantageous circumstances it is possible that one may have to look hard to see the difference between some adjacent examples.

Referring to the Best of the Best plots: Most lenses measured range between 50 and 70lp/mm in the centre dropping to perhaps 40lp/mm in the centre wide open. Whilst APS-C corner sharpness ranges from 50 to 65mm at optimum aperture for full frame EF lenses but the EF-S wide angle lenses may only peak at 30-40lp/mm in the corner. Wide open corner sharpness can drop 30-50lp/mm generally and as low 20lp/mm for EF-S wide angle lenses. Obviously other lenses can perform worse than this as in the example of the wide open corner of the 28mm f1.8 USM. (Note the data for the 50mm f1.4 is old and has been superceded by newer results. The original results are used here to avoid editing this section)

Subjective Assessment of Printable Crops

You can download and print the examples. Your assessment may differ from mine - i.e. it is subjective. All print sizes have been viewed at about 450mm (arms length), which is probably OK for A4 but very close for A3 and A2.  

The print workflow was to rescale the image (same dimensions as a 20D frame) to the target page as defined by the long side at 240 dpi[1] (less about 15mm for unprintable margin) using Bicubic Sharper for down-scalling and Bicubic Smoother for up-scalling. The outputs were then sharpened for printer dot gain using the 240 dpi Glossy Ink Jet setting on the TLR Professional Sharpening Toolkit. 

These were then printed using the Epson Stylus Photo 1290 Premium Glossy Photopaper destination profile to that printer and paper with the following printer settings:

Color Mode

Photo Quality 1440 dpi

High Speed

No Color Adjustment

 

Note [1]: I use 240 dpi rather that 300 dpi as from tests this gives Morie, 360 dpi gives Morie in one dimension (Refer to Workflow).

So what can we conclude from this?

Although not entirely consistent as might be expected from subjective evaluations, good quality A4 prints should be possibly with most lenses giving 33 lp/mm 50% MTF or higher, i.e. not incredibly demanding. Although finer detail can be reproduced, at sensible viewing distances it can't easily be seen. 

For A3 or larger prints 50 lp/mm 50% MTF is really needed and more is desirable.

Sanity checking this. The 35mm DOF circle of confusion criteria is 0.03mm, this represents about 33 lp/m which seems reasonable for an A4 print. This ties up as the recommended circle of confusion is intended for 10X8 inch prints, close to the printable area of A4.

Last Updated 05/06/2008

All Content © 2005-09 Lester Wareham All Rights Reserved     

All material is supplied  as is and without warranty, use at your own risk.  

All opinions stated are the authors own.

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