A General Guide to Pentax Lens Compatibility
Posted by: layingback on Tue Nov 15, 2011 14:49
Article originally posted by Dangermouse on Wednesday, October 05, 2011 (10:51:04) as a forum post
Pentax are unique in that every lens they have made since 1975 will fit straight onto their DSLRs, but as may be expected they have added features over the years. Here's a brief run-through for newbies:
The very first Pentax K mount lenses were simply branded SMC Pentax, and are commonly referred to as the K series. Only made from 1975-77. These are completely manual lenses, your DSLR will not be able to set the aperture and you will need to focus manually. In order to use them, set the option in your camera menus to allow the use of the aperture ring. When you turn the camera on you will be prompted for the focal length for shake reduction (just use the thumbwheel to pick the right length then press ok). Set the camera to M, set a suitable ISO and select an aperture. Now compose and press either the green button or the exposure compensation button. You should hear a swishing noise as the camera stops the lens down in order to take a meter reading, it will then offer a shutter speed based on this reading. There is some trial and error involved with older DSLR bodies (which can struggle to meter accurately) but it costs nothing to delete the mistakes.
From the late 1970s Pentax released the M series (branded SMC Pentax-M). These are smaller and lighter than the K series but work in exactly the same way as a K series lens on digital. There was a rather rare AF 35-70mm f2.8 which will not autofocus with a DSLR - it only works fully with the ME F. Used with anything else it becomes a normal manual zoom with a rather heavy motor and battery box slung underneath.
In the 1980s the SMC Pentax-A range replaced the M series. The A series were often optically identical to the M but had an "A" setting on the aperture ring to work with the new Program mode on bodies like the Super A. Thanks to this setting you do not need to use stop-down metering on digital - just set the aperture to A and the camera will be able to set it just as on a modern DA lens. You still need to focus manually and dial in the focal length, but exposure is much simpler to use.
In the later 1980s Pentax released their first full range of AF lenses. The Pentax-F lenses work just like the modern DA lenses on a DSLR, just set the aperture ring to "A". The camera will pick up the focal length from the lens and of course focus for you.
The FA lenses were much the same, although later in life the FA-J series deleted the aperture ring. All will work perfectly on a DSLR. At the same time the "Ltd" designation appeared on a set of three prime (fixed focal length, in this case 31mm, 43mm and 77mm) lenses.
The DA range are Pentax's current lenses. The * designation is used for the higher-quality zooms, with "Ltd" applied to primes. Contrary to some theories these are not limited editions in the sense of only 500 being made, they are limited in that due to the attention to detail required the factory involved cannot make more than a given number per year. "WR" lenses are weather sealed, combined with a suitable body you can shoot in the rain without worrying about drowning your kit.
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