Quote Originally Posted by kthalmann
I'd also like to call on the collective wisdom of the APUG membership regarding the coverage of the 600mm and 750mm APO Germinars. Thanks to Arne and his articles on these lenses I know what the official specs are. I know that based on these specs the 600mm will cover 7x17 with some left over for movements, but just miss the corners of 8x20 and that the 750mm should cover 12x20 with about an inch or so left over for front rise/shift. However, it has been my experience with other lenses originally targeted at the demanding reprographics industry (APO Artars, APO Ronars, G Clarons, etc.) that the official specs are often very conservative. Those using these lenses for pictorial use (usually involving some type of contact printing) often find they cover considerably more than the official spec would indicate.

So, if anyone has any first hand knowledge of the actual usable coverage of the 600mm and 750mm APO Germinars, please share your experiences here. I don't want to oversell the capbilities of these lenses, but I also don't want any 8x20 or 12x20 users to pass on them due to overly conservative manufacturers specs.

Kerry, in addition to the official 46 coverage specs (calculates to 510mm diameter for the 600mm lens, 636mm for the 750mm lens, and 850mm for the 1000mm lens, all at infinity) there are the mysterious "infinity" circles published in a single typed page by Docter: 585mm for the 600mm lens (52), 715mm for the 750mm lens (51), 895mm for the 1000mm one (48) - this is supposedly all for the barrel versions wide open (!) at f/9. Stopped down, the coverage increases a little further to values up to 57.

Disclaimer: I have not tested these values, these are values from an old Docter leaflet.