Originally posted by MikePerham Well, difference of opinion is what makes the world go round. I have been using my 16-50 for portrait work and switching to the 50-135 to get a bit longer ...would dearly love a fast 55 prime for this purpose; have not had one since I abandoned Canon. And actually the 55 is closer to an 85mm (55 X 1.54 = 84.7), which is the focal length I used back in my F1 days (that I traded to an LX). Always liked the rendition of head and shoulder available light shots with that lens.
The 55 is closer in theory to 85mm, but it does not exactly behave like one. Read on ...
Originally posted by AM2 ... I'm also in the camp that simply doesn't buy the idea that the 55/1.4 is the APS-C equivalent of the 85/1.4. The magnification is not the same, the field curvature values are not the same, the blur is not the same. If I want the same sized frame as 35mm fullframe gives with an 85mm, I'll take a few steps back, but a 55 is a 55 and an 85 is an 85mm!
Exactly. The 50mm actually performs better as a headshots portrait lens on a DSLR than my FA 85mm did on film, simply for the fact it can closer focus and crop tighter. And that's even at the 50's film equivalent of only 75mm.
Originally posted by Caat They have the same optical design so performance will be, or should be identical. The MTF difference at photodo is likely due to sample variation.
Absolutely not true. Close, yes, identical, NO. There are other elements that go into a lens, such as the back inner coatings and depth/ length/size of the filter ring area and rear element area, and additional "innards" that can affect flare and light entering those exact same elements. Hard to explain, but look inside the front and rear elements of the FA and F 50's and you will see what I am talking about. The different outer components of the F and FA also have different insides that you don't see.
For whatever reason, the F series has always come out slightly better in tests than their "near identical" replacement FA's. Both on photodo, other review sites I have seen, and from personal reviews, which there are even some here on this site.
The F 50 1.4 got a 4.6 rating on photodo vs. the FA's 4.2
The 135mm F got a 3.5 vs. the FA's 3.2
The 100mm 2.8 F macro got a 4.3 vs. the FA's 3.9
This is not just differing samples, and the 50mm F's rating of 4.6 on photodo is one of their highest ratings of any lens they've tested (only a Canon and a Contax scored higher), and I doubt even the best FA 50mm sample could achieve that.
Originally posted by JonPB FA 50mm/1.4: 7 elements in 6 groups. DA* 55mm/1.4: 8 elements in 7 groups. Source:
Pentax Normal Prime Lenses
I'm no expert on optics, but I think that means they have different optical designs.
He was talking about the F 50 f1.4vs. the FA 50 f/1.4.
Originally posted by Wheatfield Disagree if you like, I wasn't comfortable with the working distance of the FA50/1.4 in the studio, but I am (just barely) comfortable with the 55. It could be a bit longer, but we take what we are given.
The 50 is definitely too short.
Too short? It crops a tighter head shot than my FA 85mm did on film. Not sure why you can't get portraits with it in a studio??