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Old Sep 18, 2006, 5:33 PM   #1
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I own this lens but because it's Ricoh mount it has electric contact for automatic aperture in different place than pentax, so I can only use it in M mode. aperture ring has values from 2.8 to 16, the question is: at 70mm widest aperture is 2.8, at 210 it's 4 BUT: if I leave aperture ring on 2.8 at 70mm and zoom to 210mm still at 2.8 does it change 2.8 to 4? and does it change all following stops higher? I mean does 8 become 11, 11 become 16 and so on? is f2.8 position at 210mm really f4, is f4 at 210 f5.6?
does anyone know the answer?

greg
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Old Sep 18, 2006, 7:35 PM   #2
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no, after it changes to f4, all the other smaller apertures are what the lens is set to..

roy
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Old Sep 19, 2006, 3:40 AM   #3
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It is perfectly normal for a not-constant-aperture zoom...

When set to maximum, it mantains the maximum aperture at each focal lenght, which vary in zoom range...

Could you post some shots from this lens at 70f2.8 and 210f4 ? I'm very interested...

Thanks.
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Old Sep 19, 2006, 3:56 AM   #4
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thanks, so it means that when I set it to 2.8 or next one at 210 it's f4 but when I go higher like to f8 it's 8. I mean going below f4 on aperture ring at 210mm doesn't change anything.

cartman: small problem with that, because it's not communicating with camera there's no exif info so I don't know which aperture I used. and shooting couple pictures right now at home wouldn't do this lens a justice. I can tell you that at 210mm f4 it's quite soft but stopped to 5.6 and higher it's very sharp lens. you can see photos I took with this lens here: http://s63.photobucket.com/albums/h1...chester%20zoo/

greg
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Old Sep 19, 2006, 4:53 AM   #5
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Set the camera to M mode and at 70mm f/2.8 adjust camera speed until you get correct exposure.

Then try taking a series a shots and manually adjust the zoom from 70mm up towards 210 and see if the shots get darker and or if the images EXIF data shows a different shutter as the camera attempts to adjust shutter speed for correct exposure.

I think you will find Robar and Cartman are correct, thoug not all zoom lens have not-constant-aperture. My Tokina RMC 80-200 has varied f/stops from f/4.5 up to f/22, but the front of the lens says f/4.5 so min edoes stay at f/4.5 when I zoom.

Hope this helps.

Crash
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