> > Not sure if the list is quiet or I'm not receiving email. > It's been quiet for a couple of days.
I picked up the EF70-200 f2.8 IS yesterday, what a beast/toy! Also got a B+W Pro F (whatever that means) UV filter for this lens, so I decided to try some informal lens test this morning with the 70-200 and the 100-400 (with an 8 year old B+W UV filter) with filters on and off. The target is a glossy ad print of very good quality (i.e. sharp character fonts) placed 9 feet away from a Manfrotto tri-pod mounted lens/camera, both lens at maximum focal length, ISO 100, aperture at 5.6, shutter at 1/1000 sec, MLU and remote cable release were used, IS is turned off, RAW format and compared the result after converting to .tiff without any sharpening, I also shot one image in RAW and jpeg quality 8, then quality 10 for comparison. I noticed a few odd things right away: 1. With the AF switch turned off on the EF100-400 after getting an initial focus lock with the filter on, I took the second shot with the filter removed, and noticed there is a very small but noticeable image shift, upon reviewing in Photoshop, it appears while the left and the bottom sides of the two images line up, the top and right side of the second image (w/o filter) appears to have shrunk just a very very small amount, but more importantly the second image is clearly out of focus. This aligned with an observation someone made a few days ago that the filter does throw the focus out by 1/3 thickness of the glass, but I didn't think it would be quite as visible. 2. The same check was made with the EF70-00, the image without the filter again is just a hair smaller than one with the filter, the image with the filter on when the AF lock was made is a bit softer/out of focus compared to the one without the filter which is very sharp and has good contrast. 3. These shots were then repeated with the AF switch turned on to ensure each shot is as focused as it can be, both lens showed a very small amount of image shift with the filter on and off, I suppose this could be caused by slight alignment change as I take the filter off. Overall it appears the image without the filters come out just a bit better, the contrast is a bit better, the color is a bit denser, but the quality difference is very very small and not easily observable. The last test was same image in RAW, jpeg quality 8 and then quality 10 as set in the camera, I found that RAW does indeed give the best result, but jpeg quality 10 follows very close behind, the difference is a little smeared color transition near any sharp edge that has large difference in colors, and much cleaner and more even light color background in RAW than jpeg. I will continue to shoot with the filters on as locations I typically shoot often have blowing dust, oily film etc., I will live with a very tiny loss of quality for the peace of mind the front element is well protected, I will also selectively shoot RAW when lighting is difficult or if I know a particular image is going to need every little detail of every pixel, otherwise I will still shoot jpeg quality 8 for those less demanding subjects. Ken * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
