Download M42 Optic Cameras

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Focal length 85 mm Image circle 62 mm Transmission 400-1,000 nm Interface V38 -mount Initial aperture 4.5. Most of its digital SLR cameras. It is commonly used with bigger sensors, e.g. Full-frame or line-scan cameras. Lenses can be easily swapped out thanks to the bayonet mount, but no back focal adjustment is possible. Mxx-mount are different types of camera mounts defined by their diameter (e.g. M72, M42), thread pitch (e.g.

Work, as my hero Jason Scottsays,tends to be fractal. While I was working on myPentacon 50mm f/1.8review, I realised that I could easily break out thesection on using the lens with modern cameras into awhole separate page on using M42 lenses on modern cameras.I found that, too, was fractal,so if you ever find that I've made a chart on interoperabilitybetween every single thing on every camera systemever..well, you know how that came about.

But I resisted the temptation! So here it is, the bigchart of using M42 lenses on modern camera systems.All of these systems will require that an adapteris used; what's being discussed here is how useful yourcamera will be after you've gotten one. Links in thefirst row and first column take you to the relevantsubsections of this page.

Lens mountOptics requiredFocus confirmMeteringHigh-quality adaptersCrop factorNotes
Canon EF/EOS
All autofocus SLRs
NoNeeds chipYesNo1x-1.6xM and Av modes. Rear of some lenses may collide with mirror of the 5D.
Canon FD
manual focus < 1987
NoN/AUsuallyYes1xWon't work on the T50.
Micro Four-ThirdsNoNot neededYesNo2xNo focus-assist, but you won't need it with live-view magnification.
Nikon F
All autofocus SLRs
YesYesSometimesNo1x-1.5xNo metering with cheaper SLRs.
Pentax KNoYesYesYes1.5x
Sigma SA☠ ☠ ☠ ☠ ☠ ☠ ☠NOT RECOMMENDED☠ ☠ ☠ ☠ ☠ ☠ ☠
Sony Alpha
aka Minolta AF
NoNeeds chipYesNo1x-1.5xNeeds a chip to get in-body stabilisation working.
Sony E-mountNoNot neededYesNo1.5xMay need to set camera to shoot without a lens.

What this all means

Optics required

This means that any adapter will require corrective optics to beable to focus to infinity.

The flange-to-film-plane distance of the M42 lens mount is 45.5millimeters. If it's longer than that for your camera system, thenyou're going to have a bad time, because that means you've effectivelygot a small extension tube, and you can't focus to infinity with anextension tube. On top of this, you might have to add on a millimeteror two for your adapter.

You can get adapters with corrective optics, but I don't like theidea for three reasons:

  • The quality of these adapters is far too variable. None of these, as far as I know, are made by serious optical companies. Thus, you're likely to get serious degradation of the image.
  • They act as teleconverters, which exacerbates the crop-factor problem.
  • The above also means that your effective aperture is smaller.

If you want to find out the furthest distance to which you will be ableto focus using an adapter without corrective optics, then try this:

  1. Go to this lensmagnification and depth of field calculator.
  2. Enter the focal length of your lens in the appropriate place.
  3. Set 'focusing distance' to a very large value. Try 50000. (50 kilometersmay as well be infinity.)
  4. Subtract 45.5 from the flange focal distance of your lens mount (inmillimeters), then add an arbitrary thickness for your adapter ifnecessary. So for Nikon F, that's 46.5 - 45.5 + (1 or 2) = 2or 3 mm. Enter the resulting number into the box marked 'extensiontube'.
  5. Hit 'calculate' and the box marked 'effective focusing distance' willtell you roughly where your infinity focus will be. Huzzah!

Try it with various focal lengths; you'll notice that telephotosare much more useful than wide and normal lenses.

Focus confirm

This is important for autofocus SLRs, which do not have opticalfocusing aids like a split-image or a microprism ring, to getaccurate focus quickly. This is especially so on small-sensored SLRswith tiny viewfinders, on which manual-focusing is much harder.This becomes irrelevant if your camera has live view with zoom.


Some cameras are dependent upon the presence of a chip on the lens toknow that there is a lens attached; as far as the camera is concerned,an M42 lens fitted via an unchipped adapter is the same as having no lensat all. Some of these cameras will refuse to meter if they don't know they havea lens attached. If this is the case, you will be stuck in manualmode, and you will have to measure the exposure by other means (or guessit).

High-quality adapters

I use this as shorthand to refer to adapters that were made by themanufacturers of the camera bodies. In this case, Pentax made them fortheir K-mount, and Canon made them for their FD cameras. Canon andPentax are serious companies who know how to make this sort of thingprecisely and consistently. An adapter madein a one-man machine shop in China won't necessarily be produced thisaccurately.

These adapters are not necessarily available new anymore. I'm sure theCanon FD one isn't, anyway (!).

If your only option is to get one of the cheap, non-camera-manufactureradapters and you absolutely must have dead-on infinity focus acrossthe whole frame (such as for astrophotography), then you're going toneed either some mechanical engineering skills or extraordinary luck.

There might be aftermarket ones out there which are made to thequality of Pentax's and Canon's adapters;these guys lookpromising, and expensive.

Crop factor

This is the size of the sensor relative to the size of the 35mm film forwhich M42 lenses were designed. A crop factor of 1x means that the sensoris the same size (full-frame cameras), 1.5x means that the sensor is 50%smaller if you measure the diagonal.

This has three effects, one obvious that you all know about, two lessobvious:

  1. The effective focal length of the lens is increased. For example, a 58mm lens on a camera with a 1.5x crop factor behaves just like an 87mm lens on a film camera. This can either be good or bad depending on your perspective; it's up to you whether your 29mm f/2.8 wide-angle lens becoming a 43.5mm f/2.8 normal lens is good or bad. But do remember that M42 lenses will be designed with focal lengths intended to be useful for a film camera.
  2. You may find that an M42 lens will be less sharp than a lens designed for your sensor. Remember, if your sensor is half the size of 35mm film, then any lens has to resolve twice as well within that area to be as sharp at any given enlargement. Lenses that are designed from scratch to do that have no problems doing so. Lenses designed before your digital camera was even imaginable may not do this very well. This is somewhat mitigated by the fact that all M42 lenses are at least a little sharper in the centre than they are at the edges.
    You won't know this for sure without either getting (and understanding) an MTF chart for your lens, or trying it on your camera. Just don't be upset at the lens for not doing something it was never intended to do.
  3. Connected with the above: We're used to having lenses in sensible focal length ranges that are just about perfect. For example, even Nikon's plastic 18-55mm kit lens is a very sharp lens for cameras with a cropped sensor. A 20mm lens in the 1960s and 1970s, for a full-frame camera, was a serious technical challenge; photographers were happy to sacrifice a little technical quality (or stop down to f/8) if it meant they could have a lens this wide. Thus, once again, don't expect M42 lenses to be as sharp as a lens with the same focal length designed for your sensor.

An unimpressed cat, shot witha Helios 44M-4 58mm f/2.

System notes

For all camera systems

If you have the option for it, shoot your camera in centre-weightedmetering mode. Matrix (evaluative) meters will get very confused bythe dark image coming from a stopped-down lens.

If the camera needs a chip for certain functions to work, it mightbe a bad idea. Cameras have been toasted this wayand it will certainly void your warranty.

Fuji made a series of 'M42' lenses designed for their 'M42' cameraslike theFujica ST705, with an additionalmechanical lug to give you open-aperture metering on those bodies.These will not mount onan M42 adapter, so don't try it. (The silliness goes both ways;using normal M42 lenses on these cameras requires that you hit boththe depth-of-field preview button and half-press the shutterfor metering.)

Canon EF/EOS

Beware of the 5D, and probably other full-frame cameras.The rear element of some M42 lenses will collide with yourmirror when focused to infinity. Seeover here for moreinformation.

Otherwise, you're OK here, except you'll need an adapter with a chipto get focus confirmation. Don't bother with these if you havelive view; use that instead for better results. You used to be ableto get focus screens with manual-focus aids, but Haoda doesn't seem tobe around anymore and KatzEye Optics are no longer taking orders. Ohwell.

Shoot this in Av (aperture priority) or M (manual) mode; theother modes won't work properly.

Because the EF-M mount has an shorter flange focal length thanthe EF mount, M42 lenses work great there, too. Check outthis videoshot with an EOS M andPentacon 50mm f/1.8. Itlooks super to me!

Drivers ivt input devices

Canon FD

The Canon FD mount went obsolete in 1987, but I threw it in with the modern lens mounts for fun. I love theA-1 that much!

As a general rule, if your cameracan do stopped-down metering with Canon FL lenses, it'll probablybe able to do stopped-down metering with M42 lenses via an adapter.I know that the T50 definitely won't work (unless the only shutter speedyou ever use is 1/60). I know that theA-1 andT90 will work, and theF-1, T70 and AE-1 probably will as well.

Canon made an adapter for these, and adapters claiming to be genuineCanon ones are quite abundant.

Micro Four-Thirds

You should be fine here. You probably won't get focus confirmation,but you don't need it with live view. Don't get caught out by thecrop factor, though.

You may have to enable a setting in the menus to tell your camerato shoot whether or not it thinks it has a lens attached.

Nikon F


Takumar 135-600mm f/6.7 mounted on a Nikon D700. Photo by Eric Budworth, used here with his permission.

See 'Optics required' above; theflange-to-focal-plane distance for Nikon is a millimeter greater thanthat of the M42 mount.

Other than that, you should get focus confirmation on all digital bodiesand all AF film bodies,but you won't get metering on many of them. As a general rule, I gatherthat if your camera can meter with manual-focus lenses, it'll give youmetering with an M42 lens mounted via an adapter. The single-digit andthree-digit cameras (except the old D100) should all be fine, and soshould the D7000.

Download M42 Optic Cameras Nikon

I'm not sure it's worth bothering with on Nikon. On the other hand, see whatthis guydid with a D700, Pentacon 135mm f/2.8 and non-correcting adapter. Itlooks fantastic!

Full-frame shooters should be especiallywary of adapters withcorrective optics. Eric Budworth, a reader of my site, tookone for the team and bought an adapter with corrective optics to usehis monster Takumar 135-600mm on his full-frame Nikon D700.Surprise: the optics in the adapter he bought did not covera full-frame sensor! Here's what it looks like shooting ablank subject:

Photo by Eric Budworth, used with his permission.

This was not disclosed when he bought it, and it was not a batchdefect because the supplier of the adapter admitted it was a known limitationof their adapters. This isn't inherent to having an adapterwith corrective optics; it's a fault with adapters made byfirms who are not serious optical companies – and none of the companiesthat make these adapters are serious in the same way Nikon, Canon orPentax are).

My readers are the best, though; nobody would know this without actuallybuying one, putting it on a camera and reporting back to me with theresults and sample images. Thank you, Eric!

Pentax K-mount

Pentax are real compatibility superheroes, as always.They care so much about lens compatibility that they've ensured youcan use your Pentax digital SLRs with old Pentax lenses that wentobsolete in 1975. Did you know that Pentax even sellsan adapterso you can use lenses from their medium format camerason your digital and 35mm SLRs? No sane person has ever used one, which means thatPentax even loves insane people, too. Thanks, Pentax! For contrast,some Nikon F-mount digital SLRs won't meter with manual-focusNikon F-mount lenses that Nikonmakestoday.

Pentax made anM42-to-K-mount adapteruntil not so long ago. I don'tthink it's still being manufactured, but you definitely want tofind one of these rather than the knock-offs; even if I didn'tknow that the genuine Pentax adapters are mechanicallysuperior, I'd recommend you buy one just to thank Pentax forcaring so much about you.

We love you too, Pentax! ♥ ♥ ♥

Sigma SA mount

I've marked this as 'not recommended' because there are reports ofaperture stop-down pins on 'auto' M42 lenses interfering with themechanics of the camera. This is OK if you only intend to use lenseswithout aperture stop-down pins, but it could get very messyotherwise.

A solution to this is to use an adapter with a flange topush the stop-down pin so that it doesn't interfere with themechanics. The problem with this, as far as I can tell, isthat the location of the stop-down pin is not standardised in theM42 system. Thus, to ensure it works with all M42 lenses, youneed quite a wide flange. But, that also means thatsome lenses with large rear elements will collide with thisthick flange, and thus you will not be able to focus toinfinity.

'Not recommended', despite the bold red capital letters andskull-and-crossbones symbols (Unicode is fantastic,isn't it?), is not the same thing as 'certain death awaitsthee'. It means I think it's probable and I don't want anyoneto be angry at me for saying something was OK when it was not.I don't own a Sigma camera, so anyone should feel free tocorrect me ifthey have tried it.

Sony Alpha (previously Minolta AF)

There's a whole FAQ about thisoverhere. You will need an adapter with a chip to get SteadyShotin-camera image stabilisation, otherwise, as long as your bodyhas an option to shoot without a lens attached you should be ableto shoot in aperture-priority mode, if you have the latest firmware.Otherwise, M is supposed to work. I haven't tried any of this,butthoseguys have.

Sony E-mount

The tiny flange-to-focal-plane distance of the E-mount lensesworks in your favour here. There's so much free space to play withthat you can even get a tilting adapter!

You may need to go through your menus to change a setting thatallows the camera to fire without a lens fitted. (Remember, thecamera doesn't know it has a lens attached via an adapter.)

Download M42 Optic Cameras

I don't know how focus confirmation works on these cameras, orif you have zoom on live view. I suspect on the latter count thatyou do.

The Helios 44-2lookspretty funny on a Sony NEX.

A very serious cat, shot witha Helios 44M-4 58mm f/2.

On 'auto' and 'manual' lenses

Early M42 cameras had no ability to stop down the lens whileshooting. You would open the aperture to focus, then manuallystop down the lens to meter (if you had a TTL meter!) andshoot. These lenses are called 'preset' lenses.

Later, manufacturers added mechanisms to cameras and lensesthat would allow the camera to do the work of stopping down thelens. You'd still need to meter while stopped down (cameras hada button or lever on board to activate the meter and stop downthe lens), but you could focus wide-open and the lens would bestopped down when you fired the shutter. These lenses are called'auto' lenses; that's about as much automation as you'll getin the M42 system.

For backwards compatibility with older cameras that did notsupport this 'auto' feature, most lenses had an 'M/A' switchthat would allow you to operate them as preset lenses. Thetrick here is that your digital camera with the adapter isexactly like one of these ancient cameras becauseit doesn't have a mechanism to stop down the lens either.

(Side note: The Pentacon 29mm f/2.8 did not have an M/Aswitch; instead,it had a spring-loaded button on the side of the lens whichwould stop down the lens when pushed in. If you're shootingthis on a camera which does not have a stop-down mechanism,then you either have to shoot itwide-open or hold down the button while shooting. This is apain, and it also means you're prone to camera shake, makingit nearly useless for tripod-duration exposures. A shame,because that lens really needs to be shot at f/8 or f/11 tobe really sharp.)

So, if you're looking for lenses to use on your digital SLR, I'drecommend you do one of the following:

  • Get a preset lens, or a lens with an A/M switch. As said, this is most, but not all, M42 lenses. Just look for either the lack of a stop-down pin on the rear, or the presence of an A/M switch.
  • Modify your lens. This is usually not a very difficult operation; I've done this before. But do bear in mind that this will destroy any collectible value your lens has, now or in the future. You won't worry about this with lenses like the Helios 44-series; these were made in untold numbers and will likely always be ludicrously cheap.
  • Get an M42 adapter with a flange to push the pin down. I personally would not do this (which is why I don't recommend using M42 lenses on Sigma cameras). Some adapters have a very wide flange that will interfere with the mechanics of your lens and prevent you focusing to infinity. Others have a narrower flange that might not be wide enough to reach the stop-down pin on all lenses. Also remember that the internal mechanics of these auto-only lenses were never designed to have the stop-down pins held flush with the body of the lens full-time; I won't discount the idea that you could damage the lens' mechanics if you do this for long enough.

Andre, shot witha Pentacon 135mm f/2.8.


Download M42 Optic Cameras Wireless

It's up to you whether it's worth doing this. For Nikon, I'dsay it's not; they barely work on many camera bodies, and youwon't get infinity focus on any of them. Besides, three of theircheapest plastic lenses (18-55mm, 50mm f/1.8D,55-200mm VR) are opticallyso good that you don't need these weird ancient manual-focuslenses. But once again, always listen to theguy doingit and getting astounding results, not to the guy with the opinions whois not.

On the other hand, there's a lot to love about M42 equipment:

  1. Digital SLR film-makers who like primes will love lenses like the Pentacon 135mm f/2.8; there is nothing made today at any price that gives you manual-focus so precise, and very few lenses have such amazing bokeh. And I suspect they'll love the old preset M42 lenses with stepless aperture rings.
  2. Most M42 primes are made of solid metal, so those of you that like holding a good, solid chunk of engineering will be happy.
  3. M42 lenses are cheap, and so those of us who like playing with stuff have no reason to not own a few of them.
  4. Some of them are cheap and astoundingly good, like the aforementioned Pentacon (£30 for a 135mm f/2.8!) and a couple of other cheap mid-tele surprises that I've read about.
  5. Even the less stellar lenses can be used for fantastic results if you know how to use them.

Let me know how youget on with them!

Help me

I can't own, test, or research every possible camera system, soyour camera system might be missing. I'd like to know how M42 lenseswork on othercamera systems that I have not listed, and especially, I'd like toknow how they work on professional video camera setups. If you'vetried this, let me know.

Download M42 Optic Cameras Night Vision

Thanks to Jenn, Jenna, Trissy andAngelique for proof-readingthis for me.

Download M42 Optic Cameras Camera

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