OM MF Lenses On OM-D E-M5

<p>I have just read a very detailed review in Amateur Photographer magazine. One comment is that aperture control is retained for OM lenses.<br>

What exactly is the situation? Is this a unique feature of this model or is such control available with Olympus E-P and E-Pl models via the correct adapter?</p>

<p>Olympus OM lenses have mechanical aperture rings right on the lens, so the aperture can be controlled regardless of what camera the lens is mounted on. It will be manual aperture (open to manual focus, stop down to meter and take picture), and no information is sent to the camera.</p>

<p>My fault for careless wording, or was that the case for the reviewer?<br>

I use manual aperture control all the time with MF lenses on my E-P2 via adapters. The wording was "OM lenses still benefit from aperture contol". This suggested to me full-aperture metering or at least full aperture focusing, the diaphragm being closed automatically for exposure.</p>

<p>I don't see that the E-M5 will work any differently then the other cameras with an adapter. The OM lenses are all mechanical. To have auto aperture, a lever on the back of the lens has to be moved to close the diaphragm down. Maybe someone could design an adapter that would have a button built in to close the aperture.</p>

<p>Given that it uses the same adapter, no, you will not have aperture control on the camera. You will have to continue using stop-down metering, as Ron mentions. The Olympus adapters are "dumb" adapters, in that they do not facilitate communication between the camera and lens, which would be impossible anyway, as the camera is electronic, while the lens is mechanical. I do not believe that your review was contrasting the E-M5 with the PEN cameras; rather it was just letting people unfamiliar with micro 4/3 understand that you are still able to adjust the aperture of the lens, despite it not being mounted on an OM body. I suppose that one could design an adapter that read the aperture of the lens like an OM-3 or OM-4 did, and then converted that information into an electronic signal, but that adapter would likely be prohibitively expensive, larger, and draw much more power from an already strained battery (since mirrorless cameras already draw significantly more power than DSLRs).</p>

<p>I'd call it a careless bit of writing illustrating the complexity of the english language and how people interpret what they read ... that can be a serious problem.</p>

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<p>The Olympus adapters are "dumb" adapters, in that they do not facilitate communication between the camera and lens, which would be impossible anyway, as the camera is electronic, while the lens is mechanical.</p>

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<p>It's not "impossible" at all. You'd need an adapter that included a mechanical interface to the lens linked to an electronic interface to the camera. The higher-end Nikon cameras are still fully compatible with old Nikkor manual focus lenses (they don't even need an adapter, since the basic lens mount is still the same), so obviously it can be done if a manufacturer wants to do it. But I don't see that it would be economical for Olympus. The adapter would end up being expensive and it probably wouldn't sell well enough to justify the cost of developing it. Since Micro Four Thirds cameras don't have an optical TTL viewfinder, there's no great benefit to keeping the aperture open most of the time.</p>

<p>Thanks, Folks.<br>

The reveiwer should have added "as with all adapters for all m4/3 cameras". I have challenged the editor about it.<br>

It would have been really useful for macro, where the DOF is very small, and approaches equality in front of and behind the principle plane of focus. Hand held focusing, especially on live and active macro subjects, at maximum aperture would give the best sharpness with auto diaphragm.</p>

<p>Yes Craig, which is why I wrote in the same post that:<br>

"I suppose that one could design an adapter that read the aperture of the lens like an OM-3 or OM-4 did, and then converted that information into an electronic signal, but that adapter would likely be prohibitively expensive, larger, and draw much more power from an already strained battery (since mirrorless cameras already draw significantly more power than DSLRs)."<br>

The Nikon lenses keep compatibility with mechanical lenses by retaining MECHANICAL linkages on the mount. <br>

Harold, I think you have merely inserted your own hopes into the reading of the review. Contrast what they were saying with mounting, for example, Canon EOS lenses, in which the aperture is stuck wide open. They never stated that control was given on-body or in camera; merely that you can still control aperture of old lenses. I'd hope that you would understand that the camera behind the adapter cannot somehow magically change the adapter. If the adapter doesn't have any pass-through controls, I don't know what you were expecting. It seems that the E-M5 has had a lot of hopes and dreams piled upon it, from the idea that it will somehow magically bring back full compatibility with 4/3 legacy lenses, to the thought that it has D800-beating image quality, to this apparent misunderstood statement that it can control old manual-focus lenses. It's going to be so disappointing when this thing finally hits stores :(</p>

<p>"Harold, I think you have merely inserted your own hopes into the reading of the review." Not at all. I am not looking for a reason to buy the M5, not least because of Olympus' policy of issuing a series of models with little differences but just enough built-in obsolescence.<br>

OM lenses can be used on any 4/3 or m4/3 body via adapters, also on some DSLR bodies, etc. To describe some attribute in terms of OM lenses, without mentioning any other mounts was misleading. For my E-P2 I currently use Lietz R manual lenses as my main ones with most of the others Tamron Adaptall-2 SP, with various mounts in my kit. I also use a Lumix 7-14mm for the wider end. So there is not much holding me to the OM mount for digital. (The extra flexibility would be welcome).<br>

I was not advocating full aperture metering (it would still have to be stop-down metering) but the amount of force to move the diaphragm lever would be tiny, compared to AF, and a tiny solenoid could easily do it.</p>

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<p>You guys are overthinking this I think.... every single lens built for Olympus digital cameras contains one component that mechanically closes the aperture and another component that translates a digital aperture signal into a mechanical setting, as well as an AF motor. How would an electro-mechanical adapter for an OM lens be any different? In fact the OM lens line used fixed aperture stops in full stops and only had 1/3 stops at the fastest settings so the pin could sit in a groove on the adapter that reads the pin setting using very very simple sensors. Firing a lever with enough force to close the shutter could be accomplished using the same amount of power as an on-board flash by using a capacitor. It would be trivial to design such a device, the real problem would be pricing for such an unprecedented piece of equipment.</p>

<p>Thanks, Patrick.<br>

You have put into more succinct words what I was thinking and trying to write. If someone took the initiative to modify an existing line of adapters, perhaps with a tiny radio-controlled model servo and linkage, mounted externally, they might make some money. Although closing down of the diaphragm by the camera woud be ideal, the functional equivalent of a double cable release would be acceptable.</p>

 

<p>Another way of thinking of it is as a reversed action DOF preview lever.</p>