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Adapted Minolta AF = manual only: focus my wire?
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PostPosted: Thu Apr 14, 2022 2:07 pm    Post subject: Adapted Minolta AF = manual only: focus my wire? Reply with quote
Stupid question perhaps. Kind of borderline AF - MF.

In another thread someone mentioned an adapted Minolta AF lens. Not wanting to hijack that thread I am starting this one with my question.

I don't own any Minolta AF lenses (yet .... ?). Looks like these are a standard AF lenses of their time, with electronic contacts. An adapter for these lenses would have to have a mechanism to adjust the aperture because you can't do that on the lens. A bit clunky but workable. I generally use Novoflex adapters, so that would be covered.

Question is this. Most AF lenses that I am aware of are "focus by wire" which in my limited experience with AF lenses will not work without power going to the lens. With an adapter (such as the Novoflex) there is no power to the lens. In other words, either the Minolta AF lenses have a mechanically coupled focusing ring (Yay!) or won't be able to focus (in which case, what is the point).

Am I getting any of this wrong?

Regards, C.


PostPosted: Thu Apr 14, 2022 2:28 pm    Post subject: Reply with quote
Answering my own question: these are screw drive, so mechanically coupled. Although if the camera has to drive the screw I imagine there is not much resistance when manually focusing without the screw engaged with the camera?

Regards, C.


PostPosted: Thu Apr 14, 2022 2:28 pm    Post subject: Reply with quote
Depends first on which body you may want to adapt these.

On Sony A7 series or any E-Mount body, Sony offered adapters (LA-EA) that can both adjust aperture natively and offer AF depending on the lens/adapter combo you use.

LA-EA1 is for APS-C bodies and offers AF only with lenses that have the built-in AF motors like Minolta or Sony SSM. With screw driven lenses MF only and no resistance to focus rotation
LA-EA2 is for APS-C bodies and offers AF on all lenses through a simulated SLR AF system built-into the adapter so there is a semi translucent mirror like on their SLT bodies which causes a loss of 1/3 EV of light.
LA-EA3 is for full frame or APS-C bodies and offers AF only with lenses that have the built-in AF motors like Minolta or Sony SSM. With screw driven lenses MF only and no resistance to focus rotation
LA-EA4 is for full frame and APS-C bodies and offers AF on all lenses through a simulated SLR AF system built-into the adapter so there is a semi translucent mirror like on their SLT bodies with the same 1/3EV of light loss.
LA-EA5 is for full frame and APS-C bodies and would provide AF on all lenses but this only works with a limited number of bodies like A6600, A7R4, A9 and A1

Models 1 to 4 are probably discontinued by now so only available in the used market
All of the above will not work with the Minolta/Sony APO TC's. Some other brand TC's may work but it will be a case by case situation.

I have models 1 to 4 and with some lenses and bodies, AF is a struggle sometimes with the EA1 and EA3 models with SSM lenses and this is mostly caused by the body's limited AF capabilities.

For other brands of bodies, adapters will be mechanical so no AF will operate and the aperture control can be done on some adapters through a rotating ring that does not allow you to know which exact aperture you have set except at minimum or maximum aperture settings.

And yes, the MF resistance is totally absent when the AF screw is not engaged in a mechanism


PostPosted: Thu Apr 14, 2022 2:39 pm    Post subject: Reply with quote
Thank you. I would be adapting this to a micro four thirds body. Come to think of it, I have a Nikon screw drive AF lens I picked up at some point (28-80mm 3.5-5.6D). I am sure the Minolta is built better than this Nikon is and it has a very short focusing turn, less than 90 degrees. And as you say, no resistance whatsoever.

Regards, C.


PostPosted: Thu Apr 14, 2022 7:30 pm    Post subject: Re: Adapted Minolta AF = manual only: focus my wire? Reply with quote
connloyalist wrote:
Stupid question perhaps. Kind of borderline AF - MF.
...
I don't own any Minolta AF lenses (yet .... ?). Looks like these are a standard AF lenses of their time, with electronic contacts. An adapter for these lenses would have to have a mechanism to adjust the aperture because you can't do that on the lens. A bit clunky but workable. I generally use Novoflex adapters, so that would be covered.


I have long experience with nearly every Minolta AF lens ever manufactured.

So here are a few remarks concerning manual focus (MF) operation of these lenses.

1) Most Minolta AF lenses DO NOT have their own motor for AF. All those lenses can be used as "MF lenses"
2) There's a handful of "Minolta XI zooms" plus the AF macro zoom 1x-3x from the early 1990s which are "focus by wire". They can't be used as "MF lenses"
3) There are a few Minolta AF lenses with built-in SSM or conventional motors (mainly the Minolta AF 2.8/70-200mm APO G SSM, the MinAF 2.8/300mm APO G SSM and the Minolta (Tamron) AF 2.8/28-75mm. The SSM lenses work extremely well in the MF mode, the AF 2.8/28-70mm however has an extremely steep focusing (which annoyingly goes "the wrong way" = the Nikon way, unlike all other Minolta AF lenses ...).
4) There are a few late MinAF lenses (mainly latest versions of 2.8/50mm Macro and 2.8/100mm Macro as well as 3.5-4.5/24-105mm) where the focusing ring doesn't couple directly with the focusing mechanism - there is some annoying play. Not recommended for manual focusing.

Most of the first generation MinAF lenses ("beercan" series) have a very slim focusing ring; however, since focusing is so smooth, it never really bothered me. Others really hate it, though ...



connloyalist wrote:
Question is this. Most AF lenses that I am aware of are "focus by wire" which in my limited experience with AF lenses will not work without power going to the lens. With an adapter (such as the Novoflex) there is no power to the lens. In other words, either the Minolta AF lenses have a mechanically coupled focusing ring (Yay!) or won't be able to focus (in which case, what is the point).

Am I getting any of this wrong?

Regards, C.


As I said above, by far most MinAF lenses have a mechanically coupled focusing ring (roughly about 100 different lenses). About half a dozen has "Focus by wire" (the XI lenses), and three lenses have with built-in focusing motor AND mechanically coupled MF.

While the "beercan" series of lenses is not as good as today's best MF/AF lenses, most of its primes are slightly better than the previous (last) generation of Canon/Konica/Minolta/Nikon (you name it) MF lenses. Most MinAF "beercan" zooms are significantly better than the typical 1975 OEM zoom. Notable exception is the MinAF 4/24-50mm.

S


PostPosted: Thu Apr 14, 2022 7:46 pm    Post subject: Reply with quote
This is why removing the aperture ring from their lenses by a number of makers was always one step too far for me. Perhaps a good marketing/business model choice, but a silly engineering choice; you can have both electronic aperture control and mechanical aperture control as a switchable option on a lens, it's not rocket science but it would cost (a little bit) more.


PostPosted: Fri Apr 15, 2022 8:27 am    Post subject: Reply with quote
RokkorDoctor wrote:
This is why removing the aperture ring from their lenses by a number of makers was always one step too far for me.


Not for me though Wink I quite like the ability to have

1) aperture control directly on the camera (especially with the front wheel on the Dynax 9), using the right hand,
2) AND manual focusing on the lens, using the left hand


RokkorDoctor wrote:
Perhaps a good marketing/business model choice, but a silly engineering choice; you can have both electronic aperture control and mechanical aperture control as a switchable option on a lens, it's not rocket science but it would cost (a little bit) more.

Do you mean a solution like the one on Mamyia ZE/ZM cameras and Sekor E/EF lenses? No independent aperture control mechanism in the lens (just as in the MinAF lenses!), but an aperture ring linking electronically to the aperture control mechanism which is built into the camera (not in the lens)?

S


PostPosted: Fri Apr 15, 2022 9:56 am    Post subject: Reply with quote
stevemark wrote:
RokkorDoctor wrote:
This is why removing the aperture ring from their lenses by a number of makers was always one step too far for me.


Not for me though Wink I quite like the ability to have

1) aperture control directly on the camera (especially with the front wheel on the Dynax 9), using the right hand,
2) AND manual focusing on the lens, using the left hand


RokkorDoctor wrote:
Perhaps a good marketing/business model choice, but a silly engineering choice; you can have both electronic aperture control and mechanical aperture control as a switchable option on a lens, it's not rocket science but it would cost (a little bit) more.

Do you mean a solution like the one on Mamyia ZE/ZM cameras and Sekor E/EF lenses? No independent aperture control mechanism in the lens (just as in the MinAF lenses!), but an aperture ring linking electronically to the aperture control mechanism which is built into the camera (not in the lens)?

S


No, I mean a different solution. Most (not al) aperture assemblies consist of three main parts: the aperture blades (obviously Wink ) and then two rings; not sure of the names but let's call them the stator ring and rotor ring. The stator ring is usually a heavier static ring and the lightweight rotor ring rotates. Each of the aperture blades has one pin located in the stator ring, and another pin located in the rotor ring. The usual configuration is that the aperture actuation mechanism rotates the rotor ring. But there is no reason that stator ring needs to be static. The rotor ring could be actuated electronically with the stator ring locked in a calibrated ("electronic control") position, whereas the stator ring could be controlled with the a manual control ring with the rotor ring locked in a calibrated "manual control" position. This would allow for both fast electronic control of the aperture, as well as slower preset-style manual control of the aperture. The only visible difference would be the rotational orientation of the (e.g. hexagonal) bokeh balls in out of focus areas and diffraction stars.


PostPosted: Fri Apr 15, 2022 12:20 pm    Post subject: Reply with quote
I see in a list of Minolta AF lenses that they exist in 5 and 8 pin versions. Presumably the 8 pin lenses have more functions that require additional pins? Is there an essential difference between the 5 pin and 8 pin lenses?

Regards, C.


PostPosted: Fri Apr 15, 2022 1:11 pm    Post subject: Reply with quote
connloyalist wrote:
I see in a list of Minolta AF lenses that they exist in 5 and 8 pin versions. Presumably the 8 pin lenses have more functions that require additional pins? Is there an essential difference between the 5 pin and 8 pin lenses?

Regards, C.


I believe the 8 pin lenses have a motor in the lens for focusing, whereas the 5 pin ones don't. There may be more differences, I'm sure other members can confirm.


PostPosted: Fri Apr 15, 2022 1:22 pm    Post subject: Reply with quote
RokkorDoctor wrote:
I believe the 8 pin lenses have a motor in the lens for focusing, whereas the 5 pin ones don't.


If this is the case, does that imply that the 5 pin lenses are adaptable with dumb adapters whereas the 8 pin lenses are not?

Regards, C.


PostPosted: Fri Apr 15, 2022 1:36 pm    Post subject: Reply with quote
connloyalist wrote:
RokkorDoctor wrote:
I believe the 8 pin lenses have a motor in the lens for focusing, whereas the 5 pin ones don't.


If this is the case, does that imply that the 5 pin lenses are adaptable with dumb adapters whereas the 8 pin lenses are not?

Regards, C.


No.

As I clearly said before, only the small series of "xi" zooms from around 1992 CANNOT be focused manually with "thumb" adaptors. Actually they are not even zooms, but varifocal lenses: When zooming, the AF motor was spinning as well to keep focus at the required distance.

There are 8pin MinAF lenses WITH integrated AF motor (but fully MF capable using "thumb" adapters) such as the 2.8/70-200mm APO G SSM, the 2.8/300mm APO G SSM and the 2.8/28-75mm.

There are also 8pin MinAF lenses WITHOUT integrated AF motor (also fully MF capable using "thumb" adapters, of course), such as the latest versions of the MinAF 2.8/50mm Macro, 2.8/100mm Macro, and the MinAF 3.5-4.5/24-105mm.

S

EDIT for an overview over selected (good) Minolta AF lenses you can download (or buy) my book on the Sony A900 here:
http://www.artaphot.ch/minolta-sony-af/alpha-systembuch

Pages 24-103 are about the most important Minolta / Sony AF lenses (mostly Minolta, though)


PostPosted: Fri Apr 15, 2022 2:35 pm    Post subject: Reply with quote
stevemark wrote:

No.

As I clearly said before, only the small series of "xi" zooms from around 1992 CANNOT be focused manually with "thumb" adaptors. Actually they are not even zooms, but varifocal lenses: When zooming, the AF motor was spinning as well to keep focus at the required distance.

There are 8pin MinAF lenses WITH integrated AF motor (but fully MF capable using "thumb" adapters) such as the 2.8/70-200mm APO G SSM, the 2.8/300mm APO G SSM and the 2.8/28-75mm.

There are also 8pin MinAF lenses WITHOUT integrated AF motor (also fully MF capable using "thumb" adapters, of course), such as the latest versions of the MinAF 2.8/50mm Macro, 2.8/100mm Macro, and the MinAF 3.5-4.5/24-105mm.

S

EDIT for an overview over selected (good) Minolta AF lenses you can download (or buy) my book on the Sony A900 here:
http://www.artaphot.ch/minolta-sony-af/alpha-systembuch

Pages 24-103 are about the most important Minolta / Sony AF lenses (mostly Minolta, though)


Apologies for not reading your earlier post correctly.

Regards, C.


PostPosted: Fri Apr 15, 2022 8:05 pm    Post subject: Reply with quote
One other point about the Minolta Xi series lenses:
Not only can you not MF with these lenses, if you have LA-EA2 or the LA-EA4 adapters, the electronics doesn't seem to couple with the lenses, so there's no AF either. And also that means that the "power zoom" won't work.

So all up, steer well clear of the Xi series lenses.
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