All, I picked up an FA 28-70 F4 from KEH this week to use as a lightweight travel lens on my MZ-S. The intent was to replace my FA* 28-70 F2.8, which is just too freakin' heavy for backcountry skiing and such. I got mine for $120 including shipping. Here's a comparison review between the two lenses.
First, my subjective impressions: Neither lens has IF, so both change length a little when zoomed and focused. Front elements on both rotate when focused. Both lenses maintain aperture when zoomed. The F4 has the standard FA lens plastic body, but it feels fairly solid without a lot of play in the zoom or focus rings. The FA* design and its perceived shortcomings have been beaten to death on the PDML before, so I won't go into details. My FA* is a late-production version and works very well mechanically. The FA* on an MZ-S is quite front-heavy, even with the battery grip. The F4 feels better balanced for handholding to me. I like FA* auto/manual clutch action and power zoom. Now, on to optical performance. I horseraced the lenses by doing a "brick wall" test at F4--F22 (in one stop increments) and 28mm, 50mm and 70mm. Camera on tripod, of course, with mirror pre-fire and Fuji Provia 100F loaded (on a side note, I've been shooting medium and large format lately. 35mm chromes are really small). Center resolution at all F-stops and focal lengths looks equal under a cheap 30x magnifier. The corners of the F4 are generally a tiny bit softer than the FA*. This appears to be the case across focal lengths and apertures. The corners of the F4 exhibit a little light falloff wide open at 28mm. Otherwise, exposure looked similar for both lenses with one exception: the F4 seems to underexpose bit a bit at F22 compared to the FA*. According to the on-film data recorded by the MZ-S, both exposure times were identical. The irises on both lenses look perfect to me. Both lenses exhibit almost identical barrel distortion at 28mm and a tiny bit of pincushion distortion at 70mm. My overall impression is that the F4 is optically almost equal to the FA* at all apertures except F2.8, which the F4 cannot do. The F4 build quality is fine and it is much smaller and lighter than the FA*. While the FA* has a certain cachet that the F4 cannot match, I think the F4 is a better "bang for buck" lens overall. Comments? Questions? Let me know.... --Mark
