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08-08-2016, 01:55 PM   #1
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Tamron f/3.8 will only select f/4 on camera

Hi all,

I know it's a weird stop, and not a conventional stop. But my Pentax F 50 f/1.7 shows up in camera at f/1.7, so why doesn't my Tamron 28-200 f/3.8-5.6 LD Super II Macro show up at f/3.8 on my Pentax K-S2?

Does it still open up all the way? Just doesn't register on-camera?


08-08-2016, 01:59 PM   #2
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The display is probably just rounding up. If you select 1/3 stops on the camera, it may show 3.8, but probably not since it's closer to 4 than 3.5.

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08-09-2016, 03:14 AM   #3
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QuoteOriginally posted by OneDurs Quote
Does it still open up all the way? Just doesn't register on-camera?
The best way to test this is to take a photo at lowest ISO, wide open aperture (as wide as you can select), and a relatively slow shutter speed. Then just take a photo while you are looking into the lens. Do the aperture blades move?
At wide open aperture, the aperture blades should be practically hidden, at least on most lenses.

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