The 5 Best Pentax KM Camera Lenses

By Nathaniel Stephan
Last Updated: April 9, 2020
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The Pentax KM is an excellent 35mm film single lens reflex (SLR) camera. This page will go into the 5 best lenses for the Pentax KM, plus a small number of substitute lenses.

In a hurry? Here's the 5 best lenses for the KM:

  1. Kit Lens - SMC Pentax-M 50mm f/1.7
  2. Wide Angle Lens - SMC Pentax-M 28mm f/2.8
  3. Portrait Lens - SMC Pentax 135mm f/2.5
  4. Zoom Lens - Vivitar Series 1 28-90mm f/2.8-3.5
  5. Macro Lens - SMC Pentax 100mm f/4 Macro

The best Pentax K mount lenses are grouped by kind of photography and price level. There are a number of recommended options to choose from that are in price ranges matching the value of the camera.

Standard Focal Length Lenses

The following is an assortment of 50mm focal lengths that are compatible with the KM. At the time when the camera was available for sale as new, there was frequently a discount available to buy a 50mm lens with the camera as a kit.

The 50mm is known as a standard lens because the angle of view is similar to what the human eye sees.

SMC Pentax-M 50mm f/1.7

  • "Kit" lens for the KM.
  • Awesome value.
  • Light, small, and compact.
  • 49mm front filter threads.

Also found at: eBay, KEH, Adorama

If you don't already own it, an excellent first lens to get is the SMC Pentax-M 50mm f/1.7. The 50mm f1.7 is easy to find, has terrific image output, is cheap, portable, and lightweight. It is the most used lens on the camera.

The 2nd version, the SMC Pentax-A 50mm f/1.7, is also a good buy.

SMC Pentax-M 50mm f/1.4

  • Exceptional optics.
  • Improved performance because of optical multi-coatings.
  • Easy to find.
  • Comparatively low-priced.

Also found at: eBay, KEH, Adorama

The SMC Pentax-M 50mm f/1.4 is nearly a stop faster than the f/1.7, at the added cost of additional weight and size. Expect to pay more than you would for an f/1.7 or f/2 lens. The subsequent revision, the SMC Pentax-A, and earlier version, SMC Pentax, will both work with the KM.

SMC Pentax 50mm f/1.2

Similar to competing camera manufactures, Pentax produced a fast 50mm lens. The resulting SMC Pentax 50mm f/1.2 is an expensive, fast, and large piece of glass.

The lens can be tough to come across because it will work on Pentax DSLRs so the appeal includes more than usage with 35mm film cameras. If you want to locate one you'll need to check and track what is offered over weeks or months.

Find at: eBay or KEH

Alternative Options

Here are a few other good lenses that are comparable possibilities. Along with 28mm or 35mm focal lengths.

SMC Pentax 50mm f/1.2AmazoneBayKEHAdorama
SMC Pentax 50mm f/2AmazoneBayKEHAdorama
SMC Pentax-M 28mm f/2.8AmazoneBayKEHAdorama
SMC Pentax 35mm f/3.5AmazoneBayKEHAdorama

Wide Angle Lenses

SMC Pentax-M 28mm f/2.8

  • Great combination with a 50mm lens.
  • Super Multi Coating (SMC) to improve output.
  • Many copies can be found.
  • Relatively low cost.

Also found at: eBay, KEH, Adorama

The SMC Pentax-M 28mm f/2.8 isn't the best option. The reality is, many do not even consider it a wide angle lens. Even so, it is substantially cheaper than any wider alternative.

There's an abundance of wider Pentax focal lengths to pick from, but they're frequently significantly higher-priced or third-party options have obvious barrel distortion. On top of that, it is easy to see optical defects like chromatic aberrations in third-party lenses.

More Options

The general relationship for prices is easy to understand. As the field of view gets wider, the lens will cost more. Fast lenses will also have higher prices.

Be aware that vintage wide angle lenses don't have corrections that modern wide angle lenses have. The most obvious issue with older wide angles is going to be apparent barrel distortion.

SMC Pentax-M 20mm f/4AmazoneBayKEHAdorama
SMC Pentax-M 28mm f/2AmazoneBayKEHAdorama
SMC Pentax 18mm f/3.5AmazoneBayKEHAdorama
SMC Pentax 24mm f/2.8AmazoneBayKEHAdorama

Portrait & Telephoto Lenses

SMC Pentax 135mm f/2.5

  • 85mm substitute.
  • Excellent value.
  • Relatively inexpensive.
  • Widely available.

Also found at: eBay, KEH, Adorama

The 85mm focal length was not as frequently used as they are today in comparison to when the KM was first introduced in 1975. On account of being less expensive, 100mm and 135mm focal lengths were more commonly used.

You can see the price difference when looking at available listings online.

More Alternatives

There are many telephoto lenses to pick from. 85mm and focal lengths longer than 135mm will be higher priced.

SMC Pentax 85mm f/1.8AmazoneBayKEHAdorama
SMC Pentax 85mm f/2.2 SoftAmazoneBayKEHAdorama
SMC Pentax 105mm f/2.8AmazoneBayKEHAdorama
SMC Pentax 120mm f/2.8AmazoneBayKEHAdorama

Zoom Lenses

Prior to the release of autofocus, in the 1980s, there were a few lenses produced by third-party manufacturers that performed better than Pentax's offering.

A good deal of the best performers were released with the Vivitar brand name. Zooms that has the Vivitar Series 1 branding on it is going to have the best optics you can expect to see from an older zoom.

Unfortunately, obtaining copies of these lenses in good condition can be quite challenging. In addition to that, no older zoom offers noteworthy performance. If you see a copy on sale that is cheap enough, it could be worth purchasing.

Vivitar Series 1 28-90mm f/2.8-3.5

  • Covers a popular zoom range.
  • Great for portrait or wildlife photography.
  • A rare time when a third-party lens is the better choice.

Also found at: eBay and KEH

Alternatives

Here are more alternatives that you can look at if you want to have a zoom lens for your KM. None of them are going to be spectacular, and you'd probably be better off acquiring a couple of primes.

SMC Pentax 85-210mm f/3.5AmazoneBayKEHAdorama
Vivitar Series 1 70-210mm f/3.5AmazoneBayKEHAdorama
SMC Pentax 45-125mm f/4AmazoneBayKEHAdorama

Pentax Macro Lenses

Macro lens selections for the Pentax KM suffer from problems with availability. The supply of Pentax K mount options is tiny, which pushes prices higher than you will pay for equivalent Canon FD mount or Nikon F mount options.

SMC Pentax 100mm f/4 Macro

  • Ideal focal length for 1x magnification.
  • Widely available.
  • Mediocre value.

Also found at: eBay, KEH, Adorama

A small number of people online have encountered problems with balsam separation of the front doublet. This is worrying because even a small amount of separation will expand gradually and eventually make it unusable. If you think you see balsam separation, avoid that copy and keep looking.

Vivitar 55mm f/2.8 Macro

Vivitar 55mm f/2.8 Macro Lens
  • The second best vintage macro lens I've used.
  • An outstanding lens for close-up photography.
  • Can achieve life-size magnification without needing an extension tube.

Also found at: KEH and Adorama

My favorite vintage macro lens I have owned, the 90mm Vivitar, was manufactured with a variety of mounts. Unfortunately, it's challenging to get a copy that has got a Pentax K mount.

The Vivitar 55mm is the best vintage standard focal length macro lens I have used. Keep in mind that it does have less working distance than the 90mm. It is great for close-up and table top photography, but it is not the ideal choice if you would like to capture macro photos at 1:1 magnification.

Both Vivitar macros were produced by Komine and were sold under various different brand names. If you decide to search for one also check under the Rokunar, Spiratone, Quantaray, Elicar, and Panagor brand names.

There is a Vivitar 90mm Macro Review and a Vivitar 55mm Macro Review.

For shooting photographs at life-sized magnification, 90mm-105mm focal lengths are going to be the best option. You'll have a large enough working distance to be able to use flash, while staying away from increased weight and increased costs that come with longer focal lengths.

More Alternatives

SMC Pentax-M 50mm f/4 MacroAmazoneBayKEHAdorama
Lester A Dine 105mm f/2.8AmazoneBayKEHAdorama

Used Pentax Lenses

Demand and supply will set the price of vintage manual focus lenses. Over the past few years, shooting film has expanded in popularity, which has pushed prices higher.

Additional pricing pressure stems from Pentax DSLR users purchasing and collecting lenses. Third party manufactures tend not to make anything for the K-mount, unlike the Canon EF or Nikon F lens mounts.

Economic conditions are regularly changing, and unexpected changes can lead to large price movements. However, the relative prices between options should stay the same.

Checking a couple of sites is a smart way to get accurate pricing information. If you are lucky enough to come across an excellent deal, buy it due to the fact that the best deals tend not to last very long.

What Lens Mount Does the Pentax KM Use?

The Pentax KM uses the Pentax K lens mount.

Released in 1975, the Pentax K mount is still used in current cameras. It’s a replacement for the M42 screw mount that was found in previous cameras like the Asahi Pentax Spotmatic. Over time alterations have been made to add metering information, autofocus, electronically controlled apertures, and CPU contacts.

Provided that a lens has a physical aperture ring, it will be backward compatible with Pentax film cameras. Keep in mind, it doesn't make sense to waste money on costly features that can't be useable. The only exception would be if you also own and use Pentax DSLRs.

It's also possible to use the older M42 screw mount by using an adapter. The older Takumar lenses will be the best to use. Even so, I wouldn't recommend doing this as finding them without a tight focus ring can be difficult.

Lens Cap Size

The standard filter ring thread and lens cap diameter used on the majority older manual focus Pentax K mount lenses is 49mm. Lenses were originally sold with slip-on caps, and not the more prevalent center-pinch type found today. If you shop around at what is available, you'll discover hardly any lenses sold with matching lens caps.

Keep in mind large front elements will need larger filters and caps.

The benefit of using a standardized filter thread size is that you only need to have a single set of filters.

Pentax-M vs Pentax-A

SMC Pentax and Pentax-M lenses were designed to include a stop-down coupler that provides the camera to have a mechanical linkage to the lens. The stop-down coupler makes it possible for the camera to know the aperture is set to so the light meter can meter accurately without being required to use stop-down metering.

The Pentax-A series added the capability for the aperture in the lens to be controlled by the camera. This means cameras that support the Pentax-A changes have the ability to do aperture priority and shutter priority modes.

Having said that, due to the fact that that capability is not supported by the camera, it does not make sense to spend money on features the camera cannot use.

Related Posts

That's it for details regarding the best lenses for the KM. Here is further information that will give you more information about the camera can be found down below:

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