The 5 Best Pentax MX Lenses

By Nathaniel Stephan
Last Updated: April 9, 2020
Outside the Shot participates in affiliate advertising programs. As an Amazon Associate I earn from qualifying purchases made through links on this site. I may also earn commissions from links to other online retailers. You can see the full disclosure here.

The Pentax MX is a fantastic 35mm single lens reflex (SLR) camera. This post is going to cover the 5 best lenses for the Pentax MX, as well as a small number of alternative lenses.

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

  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 categorized by cost and type of photography. There are many recommended alternatives to select that are in price ranges suitable for the value of the camera.

Standard MX Lenses

The following is a selection of 50mm focal lengths that are compatible with the MX. Back when the camera was being sold as new, there would have been an offer bundling a 50mm lens as kit for a reduced price.

They are called standard lenses due to the fact that the angle of view for the lens is close to what the human eye sees.

SMC Pentax-M 50mm f/1.7

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

Also found at: eBay, KEH, Adorama

If you don't currently own it, the go-to first lens to get is the SMC Pentax-M 50mm f/1.7. The 50mm f1.7 is widely available used, is light, has good image output, is very affordable, and portable. More images have been shot with this lens on an MX than any other lens.

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.
  • Optical multi-coatings to improve output.
  • Easy to find.
  • Comparatively economical.

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 increased weight and size. An f/1.7 or f/2 lens will cost more. The former version, SMC Pentax, and later version, SMC Pentax-A, will both work with the MX.

SMC Pentax 50mm f/1.2

Just like the competing camera brands, Pentax made a 50mm halo lens. The resulting SMC Pentax 50mm f/1.2 is a high-priced, fast, and big piece of glass.

The photo quality falls short of the price tag. Yes you can use a fast shutter speed, but that won't fix everything being out of focus due to a small depth of field.

My advice would be to buy something else and spend the difference on film.

The lens can be hard to find because it will work on Pentax DSLRs so the desirability includes more than use with 35mm film cameras. If you want to find one you may need to check and track what is available in the market through weeks or months.

Find at: eBay or KEH

Alternative Options

Here are just a few other good lenses that are comparable possibilities. As well as 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 are available.
  • Relatively cheap.

Also found at: eBay, KEH, Adorama

Not the best option, the SMC Pentax-M 28mm f/2.8, is still a good choice. In fact, many people do not even consider it a wide angle lens. However, it is a whole lot less expensive than any wider option.

There's an abundance of wider focal lengths to pick from, but they are frequently way more expensive or third-party choices have obvious barrel distortion. On top of that, it is easy to see chromatic aberrations and other optical problems in third-party lenses.


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

Also, keep in mind that vintage wide angle lenses don't incorporate corrections that modern wide angle lenses have. The issue you're most likely to see with vintage wide angles will be visible 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 currently in comparison to when the MX was initially made available in 1976. 100mm or 135mm focal lengths were more commonly used due to their lower cost.

The price difference can be seen when checking what is available online.

More Alternatives

There is an abundance of additional telephoto lenses to choose from. 85mm and focal lengths longer than 135mm are going to be expensive.

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 early 1980s, there were a small number of lenses built by third-party brands that performed better than what Pentax was offering.

A large number of these top performers were released under the Vivitar brand name. Zooms that's got the Vivitar Series 1 branding is going to have the best optics you'll see from a vintage zoom.

Sadly, getting one of these lenses in acceptable condition can be rather difficult. Beyond that, no vintage zooms offer outstanding performance. If you find one available for sale that is cheap enough, it could be worth buying.

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


Here are more options that you can look at if you need a zoom for your MX. None of them are going to be incredible, and you'd probably be better off acquiring a couple of prime lenses instead.

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 choices for the Pentax MX have availability problems. The available supply of Pentax K mount choices is limited, which increases prices higher than you will pay for similar Nikon F mount or Canon FD 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 few people online have experienced problems with balsam separation of the front doublet. This is concerning because even a tiny amount of separation will spread gradually and eventually make it unusable. If you see any evidence of balsam separation, avoid that lens and keep looking.

Vivitar 55mm f/2.8 Macro

Vivitar 55mm f/2.8 Macro Lens manufactured by Komine

  • 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

The best vintage macro lens I've used, the 90mm Vivitar, was manufactured for a variety of camera mounts. However, it will be difficult to get a copy with a Pentax K mount.

The Vivitar 55mm is my second favorite vintage macro lens. Keep in mind that it does have a smaller working distance than the 90mm. It is an excellent choice for table top and close-up photography, but it is not the best if you want to take macro shots at life-sized magnification.

Both Vivitar macro lenses were manufactured by Komine and were marketed under various different brand names. If you decide to look for one also search under the Elicar, Panagor, Quantaray, Rokunar, and Spiratone brand names.

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

For shooting photographs at macro magnification (1x), 90mm-105mm focal lengths will be the most desirable option. You will have a big enough working distance to allow the use of flash, while avoiding excessive weight and excessive 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 Lens Prices

Prices change all the time depending on supply and demand in manual focus glass. Over the past several years, film photography has risen in popularity, which has pushed prices higher.

Additional pricing pressure comes from Pentax DSLR users purchasing and collecting lenses. Third party producers tend not to produce lenses for the K-mount, unlike the Canon EF or Nikon F mounts.

Marketing conditions are regularly changing, and unexpected events can quickly lead to large changes in prices. However, the price differences between options should stay similar.

Taking a look at a variety of sites is an intelligent way to get accurate pricing. If you're fortunate enough to discover a good deal, get it because the best deals do not stick around.

What Lens Mount Does the Pentax MX Use?

The Pentax MX has a Pentax K lens mount.

Introduced in 1975, the Pentax K mount is still used in cameras. It’s a replacement for the M42 screw mount Which was used on cameras such as the Asahi Pentax Spotmatic. Over the years alterations have been made to add CPU contacts, electronically controlled apertures, autofocus, and metering information.

As long as a lens has a physical aperture ring, it will be backward compatible with Pentax film cameras. Keep in mind, it does not make sense to spend money on costly features that are not going to be be used by the camera. The only exception would be if you also own Pentax DSLRs.

It is also possible to use the previous M42 mount lenses by using an adapter. People like to do this as some of the previous Takumar lenses are spectacular. However, I would not advise doing this as finding them without tight focus rings can be hard.

Standard Lens Cap Size

The standard lens cap and filter ring thread diameter used on the majority vintage manual focus Pentax K mount lenses is 49mm. Lenses were sold with slip-on caps, and not the more commonly used center-pinch kind today. If you shop around at what is available, you will find a lack of original lens caps sold with the lenses.

Bear in mind large front elements will need to use bigger caps and filters.

The advantage of using a standardized filter thread size is that you only need to own only one filter set.

Pentax-M vs Pentax-A

Pentax-M and SMC Pentax lenses have a stop-down coupler that allows the camera to have a linkage to the lens. The stop-down coupler enables the camera to know what the aperture is set to so that the light meter can meter correctly without having to rely on stop-down metering.

The Pentax-A series introduced the feature for the camera to set the aperture in the lens. This means that cameras that are compatible with the Pentax-A changes have the capability to do shutter priority and aperture priority modes.

However, due to the fact that that capability is not supported by the camera, it does not make sense to spend money on features that the camera can't use.

Related Posts

That is it for info regarding the best lenses for the MX. Here is additional information that will give you more information about the camera can be found down below:

Leave a Reply

Your email address will not be published. Required fields are marked *

Copyright ©2020 Midwest Redistributors LLC