Hi, Jim ... Well, I don't have a 77mm, but I do have the 43mm, and I do have four or five 85mm lenses, as well as several 35mm lenses, numerous 50mm lenses, several 28mm lenses, etc. IOW, not only do I have lenses close to the same focal lengths, but I also have several lenses of the same focal length.
Without being specific, lenses of the same focal length can have differences in bokeh - the out of focus area - contrast, sharpness, the ability to resolve fine detail, light fall off, the relationship of the main subject to depth of field, and color rendition. There have been several, if not numerous, posts here which show the differences between the 77mm and some of the 85mm lenses, and Fred Wasti has done some DOF studies, as well as comparing many 85mm lenses. I think Bruce Dayton (or maybe John Mustarde) have some photos showing the bokeh and DOF for one or two of the 85mm lenses, and I believe Tom V. has just recently posted some 77mm shots. Apart from optical characteristics, one has the physical differences to consider. The size of a lens may be more important to one person than another. I know that I love the optical properties of sharpness and color saturation (although I don't shoot much color) of the A*85/1.4 over the M85/2.0, but there are times when I want to use a lens that's less conspicuous or intimidating, or not so sharp. Not only are the absolute optical and physical characteristics a consideration, these optical characteristics must be considered wrt to the type of photography you do, the size and type of prints you make, and your own sensibilities as well as those of the people you photograph. So, depending on the result I want, and the circumstances of the photographic situation, I may choose one lens over another. For example, let's take 35mm lenses. If I were making some photographs with several focal lengths, I may choose to use lenses of all the same series. Since the color rendition of several K-series lenses are similar, but different than that of the A-series lenses, I may not want to mix different series lenses when doing work where I want all the photographs to have a similar look. Likewise, the OOF areas may be different with, for example, an A-lens that has 9 aperture blades as opposed to a K-lens with only 8 or a lens with but 6 aperture blades. If I want my bokeh to be similar, or have a similar feel, I may choose to use lenses with similar construction and optical characteristics (please note that the number of aperture blades is not the only factor that affects bokeh). So, only you can determine what qualities are important to you. Those that suggest the 77mm and the 85mm lenses are "interchangeable" are right only from the point of view that their focal lengths are similar. The fingerprint of these lenses are different. If your photography is such that these differences, however strong or subtle they may be, are of no consequence, or your prints are of a size where the differences are not readily observed, then it matters little about the individual characteristics of the lenses. But if you make larger prints, if you're sensitive to the subtle variations of the properties of different lenses, if you want a series of photos to all have a similar look and feel, then you must consider that lenses are not always interchangeable based solely on focal length. [EMAIL PROTECTED] wrote: > > Shel > Many times I have read similar remarks from you. I am intrigued about this > and wonder what differences in characteristics there are between the 77 and > the 85. Do you have both? Could you offer a little more information? > Regards > Jim > > Shel wrote: > > Hi Bob ... > > > > While I agree that it's probably a good idea to explore a wider range of > > primes at first, I don't see the 43mm/50mm and 77mm/85mm lenses as > > "duplicating the glass." The characteristics of these lenses are very > > different, and having a 43/50/77/85 combination will cover a wide > > variety of situations. It's not just the focal length that one should > > consider when working with primes. > > > > I'm surprised that you don't have a K85/1.8 ... we must rectify that > > omission ASAP. > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . -- Shel Belinkoff mailto:[EMAIL PROTECTED] http://home.earthlink.net/~belinkoff/ - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
