I just picked up a Paterson/Philips PCS 2500 (seems to be identical to the Philips PCS 130) 6x7 enlarger which came with three sets of condensers--one for 35mm and smaller, one for 35mm-6x6, and one for 6x7. A quick check with a 6x6 neg reveals that I get the most even coverage with the 6x7 condenser set. Is there any good reason not to use the 6x7 condenser set for all formats? By the way, if anyone is shopping for an enlarger (no, mine isn't for sale), these Philips and Paterson PCS enlargers from the 1980s are really nice and usually go for really cheap, because they aren't so well known. I paid $200 for this one with the three condenser sets, anti-newton glass neg carrier with adjustable masking blades, extra masks for 35mm, half-frame, 126, and mounted 35mm slides, and add-on fine focus control. The enlarger has a heavy single-column design, tilting lens stage and head for perspective correction, and the column is easily rotated for floor projection or the head can be rotated for wall projection. The color version uses an additive filtration system that has never really caught on, but was very advanced for its day and has its adherents.