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John Schneider
31-May-2011, 14:21
Iím rather stymied as to how to use both a CF and a ND grad on a 105 f8 Fujinon-SW, and hopefully also a hood (shooting 6x17). Using a Heliopan 77mm CF bumps the front thread out to 105mm, which is too big to mount to a Lee grad holder/hood. Iím guessing I could rig up placing the grad next to the lens, but then not only do I risk vignetting with the CF now further from the lens, but the grad is between the CF and the lens, creating an issue of how to attach the CF. Has anyone else come across this problem?

SMBooth
31-May-2011, 14:52
John, this is a question born out of ignorance, but why does using 77mm filter expand the front to 105mm. Also is it possible to fit CF to the rear element, not sure what this does optically.

John Schneider
31-May-2011, 15:24
Center filters are necessarily made for wide angle lenses, so the front diameter of the CF (and the front filter thread, if so fitted) are made to be larger than the mounting diameter. It's just the way they are made to avoid vignetting.

Using a CF on the rear of a lens requires a threaded rear element. Additionally, the added piece of flat glass on the rear of the optical path causes a focus shift of about 1/3 the filter thickness, and so requires that the filter be in place during focusing.

Bob Salomon
31-May-2011, 16:38
You need a polarizer in front of the center filter. But using a polarizer on a lens this wide on that wide a format will result in banding in the sky in those areas of the sky that are naturally polarized. So usually a polarizer is not used in this application if there are large areas of sky across the frame.

The title asks about a Pol and a CF. The text talks about a CF and a Grad. Which is it?

You can always use 4 x 6" grads which do mount to 105mm.

John Schneider
31-May-2011, 16:52
The title asks about a Pol and a CF. The text talks about a CF and a Grad. Which is it?

You can always use 4 x 6" grads which do mount to 105mm.

Bob, your eyes are better than mine. Polarizers don't work well for wides, do they? I meant to ask about using a grad and a CF together.

Now that you've shaken my memory, I do have a Heliopan 105mm rotating filter mount for rectangular filters that I picked up from Photomark on a whim a while back. I'll see if my rectangular grads (Hitech/Sinar/Lee) will fit.

Thanks for your ever-helpful advice.