Minolta MD mount to M42

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matchat

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Hi there, I know that it is possible to get M42 to K mount adapters and would like to know if these can be bought for M42 to minolta md mount.
 

Dave Parker

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matchat said:
Hi there, I know that it is possible to get M42 to K mount adapters and would like to know if these can be bought for M42 to minolta md mount.

I bought one several years ago from Cambridge Camera Works, the little bugger was not cheap, if I remember right it was about $35, your best bet now a days is probably ebay, I see them come up quite often on there.

Dave
 

David Brown

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matchat said:
Hi there, I know that it is possible to get M42 to K mount adapters and would like to know if these can be bought for M42 to minolta md mount.

If you want to mount a "pentax" screw mount lens on a Minolta MD (or MC) body, yes, those adapters are available. They're on Ebay all the time. Mail order might work, too. A local camera store - just explain to them that it is not for digital :rolleyes:

Cheers

David
 

lesdix

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Take a look at:

http://www.srbfilm.co.uk/

I got exactly that adapter from them and use it regularly on my minolta MD mount body. SRB film services (UK based) supply just about every adapter you could ever want. The only drawback is that if the M42 lens is automatic i.e. you cannot stop it down manually then you can only use it at full aperture.

I bought it some years ago but it was not that expensive I recall.



Les
 

Dave Parker

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lesdix said:
Take a look at:

http://www.srbfilm.co.uk/

I got exactly that adapter from them and use it regularly on my minolta MD mount body. SRB film services (UK based) supply just about every adapter you could ever want. The only drawback is that if the M42 lens is automatic i.e. you cannot stop it down manually then you can only use it at full aperture.

I bought it some years ago but it was not that expensive I recall.



Les

A.most every M42 lens I have ever had, has been both auto and manual, there has always been a switch on the lens barrel, real close to the aperture ring, to allow you to manually stop down if you wish, many of the old T-Mount M42(preset) did not have this switch though, and have a double aperture ring for the aperture control.

Dave
 

Seele

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First of all, I think it is instructive to get the terminology right. The manual focus, focal-plane-shuttered Minolta SLRs have a mount called the "SR"; "MC mount" is actually short for "SR mount with additional Meter Coupling", and "MD" adds another coupling which enables the aperture to be set by the camera body, necessary for programmed or shutter-speed priority exposure automation; but the mount is still SR mount.

However, the SR mount also includes an internal iris diaphragm actuator, so some lenses without automatic diaphragm, even when in SR mount, cannot utilise its full functionality, and require the iris to be stopped-down manually, which also means stop-down metering is required if the camera has TTL metering.

Minolta supplied adapters for using M42 and Exakta lenses on its cameras for quite some time, it is possible to find original ones but perhaps possible to find aftermarket ones, although it is not known if that for the Exakta mount was ever made by aftermarket makers.

Since the aperture stop-down actuation system works in a radial direction, and the M42 arrangement works in a direction parallel to the optical axis, using an adapter to fit a M42 lens to a Minolta camera means that the diaphragm will never be closed down to its selected value automatically by the camera. So the lens has to be made to work as a fully manual lens where the aperture has to be manually closed down.

Many early M42 lenses (and even some later ones) have pre-set manual diaphragms, like those in T-mount which, obviously, has no auto-manual switch. But for a M42 lens with automatic diaphragm, the mechanism has to be disengaged or you will be shooting at full aperture no matter which aperture setting you have selected. In that sense, if you have a lens with automatic diaphragm but without a switch to disengage it, you would not be able to use it correctly via this adapter: the first lens that comes to mind would be Hugo Meyer's Domiplan standard lens.

Different adapters are designed differently, however. When Praktica introduced the B-series, the adapter for using M42 lenses were designed concurrently to ensure maximum compatibility; therefore, inside the adapter is an additional flange, so when the lens is screwed into the adapter, the flange pushes in the actuator pin all the way home, so even without an auto-manual switch, the lens is forced to work as one with manual diaphragm. Pentax should have done that with the adapter when it switched from M42 to the K-mount, but as all Pentax M42 lenses with automatic diaphragm were equipped with the auto-manual switch anyway, the adapter does not incorporate that flange to force the lens to work as manual, which might have caused some grossly over-exposed negatives.
 

Dave Parker

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Seele said:
First of all, I think it is instructive to get the terminology right. The manual focus, focal-plane-shuttered Minolta SLRs have a mount called the "SR"; "MC mount" is actually short for "SR mount with additional Meter Coupling", and "MD" adds another coupling which enables the aperture to be set by the camera body, necessary for programmed or shutter-speed priority exposure automation; but the mount is still SR mount.

However, the SR mount also includes an internal iris diaphragm actuator, so some lenses without automatic diaphragm, even when in SR mount, cannot utilise its full functionality, and require the iris to be stopped-down manually, which also means stop-down metering is required if the camera has TTL metering.

Minolta supplied adapters for using M42 and Exakta lenses on its cameras for quite some time, it is possible to find original ones but perhaps possible to find aftermarket ones, although it is not known if that for the Exakta mount was ever made by aftermarket makers.

Since the aperture stop-down actuation system works in a radial direction, and the M42 arrangement works in a direction parallel to the optical axis, using an adapter to fit a M42 lens to a Minolta camera means that the diaphragm will never be closed down to its selected value automatically by the camera. So the lens has to be made to work as a fully manual lens where the aperture has to be manually closed down.

Many early M42 lenses (and even some later ones) have pre-set manual diaphragms, like those in T-mount which, obviously, has no auto-manual switch. But for a M42 lens with automatic diaphragm, the mechanism has to be disengaged or you will be shooting at full aperture no matter which aperture setting you have selected. In that sense, if you have a lens with automatic diaphragm but without a switch to disengage it, you would not be able to use it correctly via this adapter: the first lens that comes to mind would be Hugo Meyer's Domiplan standard lens.

Different adapters are designed differently, however. When Praktica introduced the B-series, the adapter for using M42 lenses were designed concurrently to ensure maximum compatibility; therefore, inside the adapter is an additional flange, so when the lens is screwed into the adapter, the flange pushes in the actuator pin all the way home, so even without an auto-manual switch, the lens is forced to work as one with manual diaphragm. Pentax should have done that with the adapter when it switched from M42 to the K-mount, but as all Pentax M42 lenses with automatic diaphragm were equipped with the auto-manual switch anyway, the adapter does not incorporate that flange to force the lens to work as manual, which might have caused some grossly over-exposed negatives.

Thanks, that was a great education, not that I know, that it actually applies to real life shooting situations, but filled in some of the blanks that I have found over the 25 years I have been shooting Minolta gear..

I am glad someone had the time to learn this amount of information and pass it along to the rest of us.

Thanks again.

Dave
 

Seele

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Feb 2, 2004
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Sydney Austr
Dave,

Thank you for the appreciation; the evolution and mechanics of lens mounting systems has been my pet project for many years and I had written a number of articles on the subject too. If I am going to put everything together it would be quite a tome I am afraid!
 
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