Originally Posted by
Drew Wiley
The inner thread diameter of the CF is 82mm, the outer much larger, almost a funnel effect, so that the lens/CF combination can be used with maximum movement when stopped down to the rated f/22 or so recommended with CF filters. I don't see how a Cokin ND grad is going to help even things out if the bigger elephant in the room is circular falloff itself, which the CF corrects. A Cokin ND grad would also introduce a bit more spacing and flare issue. Ideally, it would be used even further oversized outside the 90 lens/CF sandwich, which would still allow a circular contrast filter to be used in between if desired. If one opted for the smaller 90/8 Nikkor with a 67 CF instead of the 90/4.5 with an 82mm CF, then the cumulative density of all that intervening filtration can make considerably dimmer focus and composition a distinct chore, so in this respect the brighter 90/4.5 SW is a distinct luxury. Yes, the CF can be used optionally. But if movements are modest, and it's well stopped down, then the 77mm system might work. You would just have to look through the cut corners of the ground glass to see if there's any mechanical vignetting or not.
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