I thought this could be an interesting topic. Particularly for those who use multiple systems or formats. Personally I've experinced that my intended usage for something I've bought change over time. I originally bought my MF system in order to shoot aurora Borealis with relativel fast (for MF) prime lenses. Now, I use the 645 system as my main outfit with zoom lenses. I do only nature photography. Mostly landscapes but also wild-life and macro.
As I said above my main outfit is the 645NII with the 33-55/4.5, 75/2.8 and the 150-300/5.6 ED IF. The 75/2.8 will be replaced (or more correctly, augmented by) the 55-110/5.6 zoom. For close-up's I use the Pentax S82 close-up lens which delivers surprisingly good results with the 150-300 zoom as long as I avoid the longest focal lenght (where the image becomes somewhat soft; but only with the close-up lens). I may add the 400/5.6 for wild-life. Actually, the 645 system offers advantages over 35mm at this focal lenght range (about 300mm in 35mm terms). I can use much faster film and still get as good or better result than with 35mm with slower film. Hence, the 400/5.6 effectively is as useful as a 300/2.8 for 35mm but weighting and costing significantly less. In addition, I find I can handhold the MF outfit at slower shutter speeds than I can with 35mm. I have shot at 1/90s hand-held with a 300mm and the images are sharp (to my surprise). Even Provia 400F pushed to 1000ISO gives remarkably good results with the 645. However, if something nice happens with the Pentax telephoto line-up for 35mm, I might rethink the purchanse of the 645 400/5.6 lens. My 35mm gear is used for aurora borealis photography (the Pentax LX). I use the MZ-S with my 600mm lens. And also macro with my 200mm. Otherwise, I use 35mm for the really long and hard mountain hikes. The more "normal" mountain trips I use the 645. I then use the MZ-S + 18/3.5, A 24/2.8, FA 31/1.8 Limited, FA 43/1.9 Limited and FA 77/1.8 Limited. I may substitute the 77 Limited with the M 80-200/4.5 zoom lens if I anticipate the posibility of nice telescapes. I have to be careful with the weight of the 35mm gear because it easily loose its value for this use as my MF system is that lightweight. In the fall I may substitute the MZ-S with the LX due to the fact that the nights get dark and there might be low-light photo opportunities where the LX excels. I also appreciate its low apetite for batteries. The MZ-S needs batteries every 30 rolls or so which means that I almost always replace batteries in the middle of some serious shooting situation. However, the MZ-S metering capabilities generally makes it worth it. I'm considering a Pentax 67 with the 55 and the 75mm lenses for aurora and roadside, boatside general photography. It would have been nice though if Pentax came out with an upgraded 67 as hinted at. P�l
