I definitely blame my daughter for starting this. I was at the local camera store today, and looked at their collection of used lenses. They had a Canon FD 70-210 f/4 lens. Manager said, "30 bucks". Looked through all the lenses and went back to it, and said, "$25, right"? "Actually, I said $30, but sure, $25". So another FD lens has joined my collection. Will have to do a little better setup, but a quick hand-held test with the various lenses I have that can shoot at 100mm: From left to right: Canon LTM 100mm f/3.5 Sony SEL 55-210 (Max aperture @100mm is f/5.6) Canon FD 70-210 f/4 Canon FD 100-300 f/5.6 The most portable award goes to the Canon LTM. This thing is tiny. The SEL55-210 and FD70-210 feel pretty similar in weight, yet the SEL has AF and OSS. The FD100-300 is a behemoth; and a bear to hand-hold/focus/shoot. Need a very fast shutter speed if you're going to hand hold, the shake is tremendous. Focus peaking was actually best on the SEL. I was using the EVF attached to my 5n, and I did find that most of the lenses peaked better at the lower magnification for MF-Assist versus the higher magnification. I actually preferred to go to the larger magnification so I could see the focus on this quick set of tests; But as always, every situation differs. The two FD lenses focused easiest. I think the LTM has gotten a little stiff. The focus by wire of the SEL lenses is always a little weird, and was the hardest to fine tune. The following test shots were done in A mode, ISO-1600, auto WB. My intention was to set all the lenses at 5.6 after focusing wide-open - But I may have forgotten on some of the shots - I just don't remember. All images are straight OOC jpegs, re-sized for posting. In all the pics, I tried to focus on the eyes of the larger tiger in front. First up, the Canon LTM 100mm f/3.5. 1/80th sec, probably f/3.5 for that shutter speed compared to the other shots. Then the SEL55-210. 1/40th @ f/5.6 Now the Canon FD 70-210. 1/50th sec, not sure if f/4 or f/5.6 And finally the Canon FD 100-300. 1/60th @ f/5.6 Unfortunately, as I put each lens on, I didn't always reset to the same position. So the next test will have to use a tripod for a consistent location. Also, the 100-300 has a minimum focus distance of 2 meters, of which I was in the general area, but felt I had to back up a little more to get the same focus spot. I definitely leaned in with the 70-210, but without automatic EXIF data, hard to tell if I hit 100mm exactly. With the FD70-210 and the SEL55-210 so close in weight, I may want to carry the FD instead of SEL. Still not sure yet, as I would really miss the OSS, but like the full stop or better performance of the FD. If I were shooting off a tripod, and didn't need AF, the FD would be a winner. But if I were taking a kit on vacation, I think I have to take the SEL. I'll need to take more images and do more comparisons before I come to a final conclusion. But $25 for the FD vs $350 for the SEL? If you haven't got one, that's definitely a cheaper alternative.