amfoto1 wrote:
You didn't mention what camera you have, but some are unable to focus when there's not sufficient light. The 60-600m is an f/4.5-f/6.3 lens... As a result, at the longer focal lengths of the lens, and with a C-pol added that's costing as much as 1.5 to 2.25 stops of light loss (depending upon how strong effect you dial in), you have the equivalent of only about f/10 or f/13. r
Depending upon the camera you are using, that might not be enough light to AF. Or, you may have to limit the camera to use only specific AF points that are able to focus with less light.
Yes, the lens is still f/5.6 or f/6.3.... However, Imagemeister is correct. It's the light lost to the C-Pol filter that makes the camera unable to focus... The same as it's the loss of light when you add a teleconverter that makes AF impossible (again, it depends upon the camera and the AF system it uses). It doesn't matter whether the light is lost to a dark filter or to a smaller effective maximum aperture.... When there's not enough light for the camera to focus, it won't focus!
There are "high transmissive" C-Pol now, which aren't as dark as standard C-Pol. They give similar polarizing effect, but with less loss of light. Not a lot different though.... I'd estimate there's maybe 2/3 or 1/2 stop less light loss.
You didn't mention what camera you have, but some ... (
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Yes the filter makes it unable to focus, but the aperture is still in the range where it attempts to focus. The camera is just not getting enough light to succeed. The OP said:
captxmas wrote:
I have tried to use two different 105mm polarizers and the lens will not deliver a sharp image until it is removed.
The images, while not "sharp" would seem to be view-able if not usable. So it seems the AF is trying to work. It would have been nice to see the image and know the settings used.