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Old Apr 28, 2007, 9:34 AM   #11
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ditto tom, a lot of rambling with no substance.

great example tho. was this with the *80-200? actually from here and a couple of other forums i'm glad i haven't upgraded yet. maybe this will have been addressed by summer. have you had problems with manual focus lenses.

roy
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Old Apr 28, 2007, 10:06 AM   #12
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Roy,

The squirrel was with the A* 200 but I have been having issues with all my lenses with shallow DOF, but not macro shots.

It seems to be an issue from about ten yards out and no matter what I do the results are not reliable. I even tried to back focus a bit, but all I got with that was what I saw in the veiwfinder, a soft image. I am begining to suspect the movable sensor, but then there don't seem to be any problems with the K100 along these lines.

If I do a focus check at 45 degrees along a yardstick, the focus is right on, but in real life I am back to front focus, so I don't get it.

The link I posted claims there is more DOF in the viewfinder than on the sensor, so there is no reliable way of getting sharp focus, at least with the fresnal lense in the viewfinder. I don't have a split image screen, so I don't know if that would solve the problem or not.

Tom
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Old Apr 28, 2007, 10:30 AM   #13
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That is an interesting article Tom and it certainly presents a plausible theory. I can't say that I have noticed anything along these lines with the K100 where my F 50mm 1.7 is one of my most reliable lenses, even wide open. There are few things in life so frustrating as a sporadic problem that you cannot repeat reliably to test.

Tim
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Old Apr 29, 2007, 3:55 AM   #14
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ennacac wrote:
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Roy,

The squirrel was with the A* 200 but I have been having issues with all my lenses with shallow DOF, but not macro shots.
Well macros are more controlled situalions.... depending on the lens, and specifically designed to do so.


But today got my most recent EBAY acquisition a 2x Tamron TC.... near USELESS on my 100-400mm (Yet just fine on my 1.7 50mm prime, 28-70mm Sigma and even Pentax 70-200mm.... for DOF AF 2x 4000mm ws just pushing things a bit too far.... though could do it MF tiwsting focus ring like 1/16th of an inch or less.)

And it wasn't until I went to MF I realized just why that tele 2x mag was so RAZOR THIN DOF

The 1.4x TC works pretty well on the 1-400mm but 2x on a 400mm is asking a bit much. Plus THE 2X Stop loss late in the day.

But COULD do it MF..... af no way between light loss and barely and very FINE manual manipulative focus vs AF.
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Old Apr 29, 2007, 11:23 PM   #15
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Thanks for posting the article - perhaps the reason I haven't had any problems is that I was testing with the wrong lenses - I used the 3.5 Phoenix, the f4 A*300 and the DA 50-200, but not the M 50 1.7. I'll try that tomorrow and see if I get different results. Recently most of my photos have been either macros or ones with bigger apertures. When I did use the lenses wide open, I tried with and without SR but didn't so much notice a difference with focus, as I found out that SR works - I had far more pictures with camera shake without it (SR being your problem did come to mind). I think it has more to do with the viewfinder, and that the article might be on the right track. Maybe I do want to invest in a Katz split focus lens.
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