View Full Version : "Real"Coverage of 150mm G-Claron
I have heard that this lens in fact will cover much more than the 189mm published image circle, due to a higher level of rigour in establishing the acceptable image. If one used the criteria more commonly applied, what would the experts guess as to the results?
G-Clarons gain a great deal of coverage when closed down below f/22. This makes the longer ones favorites with ULF users. At f/45, a 355 covers 12x20 with room to spare. A 305 covers 7x17 with more range of adjustment than my Korona can utilize. A 150 should offer considerable adjustments on 5x7 and enormous coverage for 4x5.---Carl
Schneider's original info was directed towards the Graphic Arts industry I believe. 189mm is very likely where the mtf curve drops to a point unacceptable to that industry making perfect copies. I'm going to throw out 260-270mm image circle for this lens which all but the last few mm is useable as far as I'm concerned at infinity. On 8X10 i Just vignettes about 3/4 inch and there is visible light fall off out in the extremes. For my purposes it is VERY useable on 5X7 and in fact one of my favorites. Not only is it tiny and light, it's VERY sharp.
I use a 150 G Claron for 4x5 and the 210 for 8x10 and don't recall ever running out of coverage with either lens. The lens gurus here can probably explain this more accurately than I can but my understanding is that the design of the G Claron line of lenses is such that the more you stop down the greater the coverage. In other words, there isn't a single point, e.g. f 22, at which the coverage reaches its maximum but rather it continues to increase as you continue to stop down. There used to be a discussion of this aspect of the G Claron design by Ron Wisner in the bulletin board on the Wisner home page, I don't know whether it's still there or not.
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