M42 mountings and it's variations.

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

L37 and M42 screwmount systems have got to be the most popular systems in the history of photography, nearly every manufacturer of the industry has subscribed to them at one time or another. The Humble M42 mount appeared on the earliest 35mm SLR's after WW2 and continued in manufacture right up until Digital SLR's replaced them. However, camera development from the sixties on found the system wanting. Soon TTL metering was introduced, in the late sixties, This system embodied a light sensor, coupled with the shutter, enabling the user to set both aperture and shutter to the correct exposure for the film while presetting the lens iris. By the end of the decade, `Automatic' lens and cameras had appeared and could be stopped down from the camera during setting, then `automatically' during exposure (didn't we think we were modern?). By the mid seventies, various attempts at designing an open aperture by several manufactures including Pentax, Mamiya and Fuji appeared, but although their respective systems worked quite well, they weren't cross compatible, this was the beginning of the end for the M42 mount, diehards like Praktica and Zenit however, continued. When the Berlin Wall came down Praktica, very sadly, split the scene, as did DDR's Carl Zeiss, Mayer Optik &Co. Zenit continued into the new millenium, but no longer holds sway, for even these went the PK way.

This was "How I Remember It" and I think I've largely got it correct, correct me if you will, but my point is this, when TTL was introduced, the M42 mount was pretty much a simple screw fit without frills, after this, when manufacturers attempted to develop upon this standard by including extra mechanical and electrical features, just how prolific was this? Myself I can list four that I have seen, Pentax/takumar, Mamiya, Fuji and Pentacon/Praktica. Was there more? I'm sur there were because during the sixties and seventies competition between manufacturers was heavy and consider how many of them used the M42 system, Europe and Far East.

It would be great to see some of these systems described in here, with pictures, I'm sure there were some innovative attempts that would be highly interesting to the technically minded buffs among us?
watching this space................[url]

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On this model of Mamiya the lens has a catch on the rear of the aperture ring that engages with this lever (red arrow), pulling this down against a spring (green arrow) to couple the aperture ring to the meter, providing open aperture metering, I've seen a Fujinon lens with this fitting, so maybe Fuji shared this system? I think this dates from the late sixties but I'm unsure, anyone?

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

Pentax also had a system up and running on M42, possibly in the early seventies. I've only seen a few lenses, but not a camera, there must be some about as these lenses are quite common. Here are a couple of Takumars, a 2.8/105 standard M42 (Left) and a 2/55 with the extra adaptations.

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kds315* · Expire: 2021-03-09

L37?? You mean L39, commonly noted as LTM "Leica Thread Mount" meaning M39 x 26tpi

peterqd · Expire: 2014-01-04

TTL metering started in the early 60s with the Topcon, followed very soon by the Spotmatic. I think you mean open-aperture metering, but even then it didn't set the shutter speed. You had to do that manually. The meter was never coupled to the shutter until the advent of cameras with auto exposure (like the Penatx ES) well into the 70s.

You don't mention the evolvement of manual, preset and automatic lenses.

Sorry, but I think your article needs major correction.

Nesster · Expire: 2014-02-20

Good point... My thoughts are that open aperture metering and aperture priority automation were pushing the limits of M42, and the mount lost its universality with each manufacturer's separate solutions. The bayonet mounts just started to seem more modern... so M42 lost market cachet. That, plus the coming program automation is what finally ended M42 as commercially viable, at least in the West.

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

L39! yup gottit, thanks mate! I have a Zenit 3m that size, works very well, I crank it over now and again to keep it free.

TTL through the lens metering came first, then later on open aperture was added onto that. I'm not to sure of the dates they appeared, indeed you may be right. What interests me is the variety of attempts made with the M42 standard, there's likely more than the ones I mentioned.

peterqd · Expire: 2014-01-04

iangreenhalgh1 · Expire: 2014-01-07

Well, there may be a very minor technical difference, but in practice, M39 and L39 are interchangeable. The difference between the two is often lost due to manufacturing tolerances.

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

Hi Peter, Ian,

So it shouldn't be possibly to interchange lenses then? BUT you can! without force, just like they're the same thread. The Zorky 4's lens on the Zenit and vice verse. THE difference is the REGISTER is different by close on 20 mm (a guess, don't take me to task!)

I'm guessing here too, the L 39 and M 39 are designations of different registers, L 39 for Leica fitting and M 39 for other metric fittings, it is normal to write a metric thread size as M XX on fittings, so I'd presume Zenit did the same, don't know of any other reflexes that used that lens fitting, but there was a Leica accessory reflex viewer that fitted a leica to allow reflex viewing/focusing on their early rangefinders, IIIg's & etc., But don't know about the fitting used on the lens.

peterqd · Expire: 2014-01-04

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

On a lens with a short shank that'll not notice, but I'll concede, it isn't a good idea to mix them. Not that there's a need to, unless doing close up with the Zenit and I have better cameras to do that with if I needed.

But back to "Open aperture metering on M42". What else was out there then? Innovation is a pastime for camera designers, so there has to be more than the ones I've mentioned.

Nesster · Expire: 2014-02-20

How did the Chinon Memotron do it?

peterqd · Expire: 2014-01-04

martinsmith99 · Expire: 2013-11-18

The only cons to the Memotron that I've noticed is that the shutter release is a hair trigger.

I can't say I've noticed any metering issues as I didn't know about the issues that Peter mentioned. I'll put it down to luck.

Mos6502 · Joined: 20 Jun 2011 Posts: 960 Location: Austin

Acutally the meters were coupled to the shutter speeds. They just didn't set them. The only SLRs with TTL metering not coupled to the shutter speeds that I can think of were the Edixas. Topcon not only brought TTL metering in 1963, but they brought open aperture metering, both the lens and shutter were coupled to the meter. The Spotmatic out in 1964 was the first M42 camera with TTL metering, but the lenses were not coupled to the meter, thus the necessity of stopping down the lens to get a reading. The Prakticamat came out in 1965 and was the first European SLR with TTL metering.

Coupled meters had already been used on the Miranda Automex (1960) and the Nikon F's Photomic metering viewfinder (1962) but these did not meter through the lens. An external meter was coupled to both the lens and the shutter speed dial, effectively providing "open aperture metering" in the way that couple meters had already been doing on rangefinder cameras.

peterqd · Expire: 2014-01-04

Nesster · Expire: 2014-02-20

The lovely Pen FT also had an uncoupled TTL meter.

buerokratiehasser · Joined: 12 Jun 2011 Posts: 470

I think newer Prakticas had extensions for electric coupling, I'd have to look the name up but I think I saw a screw mount with round segmented pads. Not that these were common

sonyrokkor · Posted: Sat Nov 17, 2012 9:55 pm Post subject:

peterqd · Expire: 2014-01-04

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

I do believe the Pen F and FV are a bayonet fitting peculiar to the classic OM Pen F series. But the OM FTL WAS an M42 screw-fit, but would only suit an OM FTL. http://www.cameraquest.com/olypenf.htm

Praktica had an electric lens system that relayed the iris setting to the meter via two contacts on the lens flange, but I don't know if there was a locating peg to ensure an accurate connection?

Reading the Wikki http://en.wikipedia.org/wiki/M42_lens_mount is quite informative, but may not be the whole story. I does however illustrate just how adaptable the M42 system was.

peterqd · Expire: 2014-01-04

The first Praktica with the electric open-aperture metering was the LLC, introduced in December 1969. Very advanced for its time, with vertical metal shutter.

You can find out all about Praktica cameras here
http://www.praktica-collector.de/

There was no locating peg. The electric mount had three long brass contact strips (I doubt they're gold!), to allow for variation in the lens threads. This was the main shortcoming of M42, bayonet mounts have much more precise fitting.

Here is the mount on my PLC2, sorry for the awful pic. The strips are in a very shallow channel around the threaded opening, which allows the spring-loaded contacts in the lens a little space, but they do retract into the lens below the face of the mount. The black ring is a plastic rubbing strip.

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

Pic looks good on my screen MAM! I hadn't seen this mount before, only the lens, on which the contacts are small. My MTL50 has a plastic ring in the same position as those contacts, so the metal threaded mount is probably unchanged too. Handy to know that while robbing for spares?

TAo2 · Joined: 09 Mar 2012 Posts: 319 Location: Scotland

Aaaaaahh - Fujica...my Fujica...

This is the Fujica ST801............
#1

Fujica's top of the range, released 1972. The first SLR tae use LEDs in the metering instead of needles. Open aperture and TTL, with 2 blue silicon sensors,giving an average reading for the whole viewfinder area. Another 2 firsts. The metering worked with any lens or accessory but not open aperture.

Ah have one of these...Fujica ST901...

#1

Released 1974. Has all the innovations of the 801 but dropped the exposure LEDs for shutter speed LEDs at the top of the viewfinder(with warning indicators for over/under exposure).

Like the Mamiya, the 901(and the 705, 801) had a small flange on the lens and a pin on the body at the lens mount tae enable open aperture

#1

#2

The ST901 was a very sophisticated camera in its time. Mine's works with all my M42 lenses, with TTL. Ah love using it.

Ye can understand why M42 went its way . Camera companies desire tae sell their own, innovative bodies and lenses plus a lack of desire tae adopt a common mount and electronic system. Why spend huge sums on R+D, if someone's gonna charge £100 less for the same or similar lens.

MTHall · Joined: 07 Nov 2012 Posts: 120 Location: England UK

Quite so TAo2, it's the capitalists way. but the writing was on the wall for M42 already, that was why other mounts were adopted. It lacked the precision in location of a bayonet mount, so necessary if there is to be more mechanization than just auto aperture. The big brands had already got their own mounts, Cannon, Minolta, Nikon and eventually Pentax, all had their own type of bayonet. It didn't completely keep free of cheaper lens makers producing competitive lenses tho'. Tamron, Makinon etc., were quick to jump into the aftermarket of accessory lenses.

BTW nice Fuji's and good photo's