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Digital SLR Lens Versatility

We show you a selection of adptors to increase your Pentax camera's lens armoury.

Posted: 09/01/2012 - 08:58

Pentax' K-bayonet lens range is large, especially if you also consider all the discontinued options going right back to the 70s. But why limit yourself to one brand when there's a huge variety of other solutions available too? Peter Bargh looks at what you can mount on the front of your Pentax SLR.

The independents

At one time there were dozens of lens brands, today these have dwindled down to just a handful, the main ones being Tamron, Tokina and Sigma. Independent lens makers have a lens available in a number of fittings, and while Canon and Nikon are always catered for, most also have a version in a Pentax KAF fit. They offer an alternative to models made from Pentax. They are usually less expensive, with similar optical quality, in fact some of Pentax' lenses even come from the Tokina factory. The independents tend to cover the more extreme/specialist options too so if you are after a huge telephoto or a telephoto macro you may find a better choice. The lenses have electronic couplings so focusing and exposure all works correctly.

Where it all started

Pentax K to M42 Adaptor

Ever since Pentax introduced the K bayonet they have been making a simple accessory to take their older lenses. The K-M42 adaptor is a slim silver ring that fits into the bayonet mount and provides an M42 thread for older Pentax Spotmatic screw thread lenses. The adaptor fits flush to the body so infinity focus is maintained.

Screw thread lenses were made by a variety of camera manufacturers including Zenit, Praktica, Chinon, Yashica, Fujica, along with just about every lens manufacturer. Lenses can be picked up for next to nothing on eBay and you can find everything from wide-angle to super telephoto. The downside is the slow speed of changing lenses... bayonet is much faster. Also many of the older lenses are single coated and do not perform as well as their multi-coated predecessors. All auto functions are lost, but you can shoot in manual or aperture-priority.

M39 Lens To Pentax PK

M42-M39 Adaptor

If you have the K-M42 adaptor you can buy a M42-M39 stepping ring so Leica screw thread lenses can be attached. There's also a direct M39 to Pentax K adaptor available. Leica lenses were renowned for their incredible quality and are very compact. All auto functions are lost, but you can shoot in manual or aperture-priority.

Reverse adaptor

Lens Reverse Adaptor

A reverse adaptor is useful if you are interested in macro photography. It has a PK bayonet on one side and a filter thread on the other. You attach the adaptor direct to the camera body and then turn a lens round and screw it in backwards on the cameras adaptor. The result is a lens that focuses extremely close to the subject (it won't focus on infinity).

Reverse adaptors tend to be in 49mm, 52mm and 55mm threads, but stepping rings can be bought to accommodate larger sizes. You would need to buy a step down ring (lens)mm-(adaptor)mm. So any make or size of lens can be attached with this gadget, but you may get vignetting.

All auto functions are lost, but you can shoot in manual or aperture-priority.

Coins taken using a Samsung 50-200mm lens on a reversing ring
A close up of coins taken with the Samsung 50-200mm zoom mounted on a reversing ring.

Lens converters

In the days of film there were few adaptors to attach different fitting lenses to your camera. A company well known in the photography industry called SRB in Luton would attempt to make most accessories, but a glass element is needed to allow focusing on infinity. Today several Chinese factories have started manufacturin g adaptors and there is quite a good selection. Pentax owners can buy ones to mount Minolta MD, Nikon AF Lens, Leica R and Voigtlander DKL Lenses to their camera. All auto functions are lost, but you can shoot in manual or aperture-priority.

You may already have a range of Pentax fit lenses and be considering a different brand of camera. Adaptors are also made to use your lenses on other cameras.

There are versions for M4/3 (Micro Four Thirds) (for Olympus EPL1, EPL2, EP2, EP3 and EP1, Panasonic G1, GH1, GF1, G2 and G10 cameras), Canon EOS, Sony NEX E Mount Adapter (for NEX-3 and NEX-5), Sony Minolta Alpha mount, Nikon mount adapter, Samsung NX (for NX10 and NX5 cameras), Ricoh GXR A12, Olympus 4/3, Pentax Q and Nikon 1 J1 and V1.

Again auto coupling is lost but some of the autofocus ones have connection pins to allow focus confirmation. All focus on infinity and some need a glass element to achieve this.

Tamron Adaptall

Tamron Adaptall Mount

In the days of film Tamron made a range of Adaptall lenses. These lenses came with a separate detachable mount, which fits to the base of their lens. They had mounts for every camera going including Pentax K and KA mounts. It was a highly sophisticated system with a superb range of high quality optics... one of the best being the 90mm macro, they also had the best 500mm mirror lens and some incredible performance zooms in their day.

Other manufacturers, including Vivitar and Soligor, tried to emulate this, but didn't pull it off in quite the same way.

Tamron Adaptall 500mm Mirror Lens
  A thrush taken using a Tamron SP 500mm f/8 mirror lens on an Adaptall 2 mount

T2 mounts

T2 Mount

Like Tamron's Adaptall, a T2 mount screws to the base of a mountless lens. This was a universally accepted system produced by several lens manufacturers. The lenses, mostly old single coated presets, can be found on eBay for next to nothing. The 400mm f/5.6 is a good one to pick up. This system had no form of automation.

Pinhole lens on a T2 Mount

A garden tap taken with a Pinhole lens attached to the camera using a T2 mount

Medium-format lens adaptor

Pentax made adaptors for their medium-format camera lenses to be attached to their 35mm and digital camera bodies. There was one for Pentax 67 lenses and one for Pentax 645 Lenses. They have since been discontinued but the Chinese have copied these and also have versions for Kiev 60 Pentacon 6 and Hasselblad (HB). The lenses are bulky on the camera body but their bigger image circle means you are utilising the best part of the glass, so photos should be optically superior.

BPM Mount Converter

BPM Mount Converter

Here's an unusual and very rare item that takes a BPM bellows mount on either side. You attach a camera mount on one side and a lens mount on the other. It means you have access to all the mounts that the British company BPM made in the 80s, including long forgotten ones such as Exacta and Praktina, as well as others not catered for above, including Canon FD, Contax Yashica and Leica M. You can pick the mounts up on eBay and some second hand dealers. The disadvantage with this item is that it acts like an extension tube so infinity focus is not possible, but it's ideal if close up photography is your thing.

Canon FD lens mounted on a Pentax K20D
This is a close up of a glass diver ornament with blue led lights in the background. It was taken with a Canon 85mm f/1.8 on the BPM Mount Converter to illustrate the lens' bokeh.

And finally

You don't even need to mount a lens on your camera. Try holding the camera body in one hand and a lens positioned in front of the camera in the other and move the lens forwards and back until an image is clear in the viewfinder. Take care not to poke the lens inside the body or catch the back of the lens on the body to avoid damage. With this method anything is possible, obscure enlarging lenses, medium and large format, weird and wonderful, suck it and see! Cup your hand at the back of the lens to stop stray light getting into the finder. Although the stray light effect can be quite interesting if you want lower contrast and flare filled creative shots. Remember though, any lens that is moved away from the sensor will not focus on infinity if it was designed for that format.
This technique works best on cameras like the M 4/3 where the lens needs to be positioned at a short distance in front of the camera.

The DIY approach

Try making your own adapted lenses. Buy cheapy broken lenses off eBay (one with a PK mount) and unscrew the PK mount, then glue or screw whatever you want on the front of the mount. Strong body mounts can be used if you cut the middle out before sticking something on the front.

There are some clever engineer type photographers who actually strip a lens down and exchange mounts. This is quite complex for most of us, but if you're feeling handy with tools you could give it a go - you can find step by step illustrated articles byt those who've achieved this on the Internet.

We hope you found this guide useful and if you attach unusual lenses to your camera let us know in the comments below.

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