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| Pentax has made a great number of variants of this lens. It straddles the 'normal' 50mm focal length and throws in some macro capability. With digital photography effectively changing the 'normal' range to around 32mm instead of 50mm, these lenses are really cheap on Ebay. They are very uninteresting. I prefer to call them 'close focusing' instead of Macro, but they surelyl are a poor mans macro lens. I think I paid something like $16 for this lens. |
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| On the other hand, this lens is worth plenty. A 50 mm macro, it is optically identical to the newer FA model. The optical quality is excellent and it focuses down to a 1:1 ratio on film, implying that if you get close enough the size of the object in real life and the size of the object on the negative will be the same. Lighting is the difficult issue, as the camera lens is less than 2" from the subject at this magnification. The introduction of this lens ended the need for bellow and extension tubes for the most part. Before this lens came out macro lenses often only were 1:2 in magnification and you needed tubes to finish the job, but this puppy does it all. |
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| Pentax has made a large number of zooms that straddle the 50mm focal length which was 'normal' for 35mm film cameras. Some start as 28mm on the wide end while others start at 35mm and have various maximum focal lengths. Most are 70 or 80mm but some are 135mm. This is one of the less common and longer range models. As with the 35-70 on the top of this list, it has a 'close focusing' mode. |
The last half of the 1980's were very dark days for Pentax in my opinion. Although Pentax first introduced an ME-F in 1981, that was a modified ME with a focusing motor in the lens it was not a marketing success. With the failure of the ME-F, Pentax went on to produce the KA line of lenses beginning in 1983 and 1984 which enabled the 'Super Program' model with programmed metering.
However, in 1985 Minolta shocked the camera tree with an autofocus system that both worked and was commercially successful. This apparently caught the rest of the industry flatfooted. Canon, Nikon and Pentax spent 2 years responding and in late 1987 and 1988 produced auto-focus camera bodies. This required a new lens set. Canon produced a completely new mount incompatible with the previous mount they had used, while Nikon and Pentax used backwards compatible modifications.
Canon put the focusing motor in the lens, while Nikon and Pentax drove the focusing from a motor in the camera body. It also required major re-engineering of both the camera and the lens set. Besides the technical difference of a 'drive shaft' through the mount to turn the lens and one additional electrical contact for data transmission, the lenses to minimize the need for horsepower to focus them needed to change from heavy rotating parts which could be turned by hand, to light internal parts which moved as little as possible and as fast as possible. Pentax called these lenses IF (Internal Focus) lenses. They usually have a ring somewhere you can turn manually, but they are difficult to hand focus compared to the old helicoids that were fairly stiff and turned a lot from one end to the other.
The really big deal for the camera side of things was the need to addd a large battery. The Super Program and functioned just fine with a couple small button batteries as all they did was power the light meter and release the shutter, but suddenly the camera needed high power motor that could crank the focus back and forth. Cameras suddenly got big and ugly. In 1987 Pentax produced the SF series of camera bodies with autofocus that were very plastic looking, bulky and expensive, but continued to offer the manual focus products.
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| Drive shaft (on right) connection in F (and later) lens mount |
Mechanically, the F (and later FA and DA) style lenses are focused with a motor in the camera body which connects with a drive shaft through the lens mount. The photo here shows the back of the lens. When the lens is mounted and locked into position, it aligns with a keyed shaft on the front of the camera body. This shaft necessarily turns fairly rapidly to focus the lens which accounts for the whirring noise associated with focusing this type of lens.
The Pentax-F lenses were around for a couple of years and then phased out in favor of the Pentax FA series. Many of the FA lenses are repackaged F lenses. There is no functional difference between the F and FA lenses as far as the user is concerned. The differences are cosmetic (no garish red/orange lettering) and reportedly in the chip that transmits the lens secrets to the camera body.
One thing you will notice if you use the 'A' series lenses on the digital cameras is that your photos will not have accurate 'metadata' about the focal length and other lens data of the lens used for the photo, because the camera simply doesn't know that information. The reason is that the earlier lenses do not have the 'data connection' which was added to the K mount along with the autofocus drive shaft. The data connection provides the camera body with various data parameters about the lens and at least in the later SDM style lenses interactively provides the data path to control the focusing operation.
I didn't indulge in the ugly plastics of the era, and the only two "F" lenses that have crossed my desk are a couple I bought on EBAY well after they weren't made anymore.