rchuck1 wrote:
I was given an old Tokina 500mm RMC mirror lens. Two questions. First, a pic of the mounting end is attached. What lens mount is this one? Second, can I get a relatively inexpensive adapter to mount it on my Nikon cameras (D90 and D750), realizing it has limited utility - all manual settings, etc. Thanks for the help.
Chuck
That is almost certainly a "T-mount" lens. Those use easily changed adapters to allow them to be used on a wide variety of camera systems. The "T-mount" simply screws on and the threaded fitting is standardized (42x0.75mm) across all the different system mounts (the T-mount threads ARE NOT the same as M42 screw mount used by early Pentax and others).
T-mounts have come in several versions. The original simply screwed onto the rear of the lens. Some of those have one or more set screws around the perimeter that are tightened to prevent the mount from loosening accidentally. The set screws need to be backed off to remove the mount from the lens. One problem (usually minor) with this design was that often the markings on the lens didn't align properly.
A "T-2" mount solved the problem. This also has set screws, but they serve a different purpose. This mount has both an inner and outer ring. The inner ring screws onto the lens and the outer ring fits onto that. Loosening the set screws allows the lens markings to be properly aligned, then the screws re-tightened. Nearly all T-mounts sold today (and for many years) are this type and are simply referred to as "T-mounts".
Yes, what's shown is a Canon FD "breech" mount... for use on the SLRs prior to the EOS models introduced in 1989 (using "EF" mount). The FD mount was largely interchangeable with a slightly earlier Canon FL mount, with a few compatibility issues (mostly just with specialized lenses and some functionality. Canon FD and FL mount cameras had been sold from the early 1960s up to discontinuation around 1990. Late in production there also were FD"n" or FD "New" lenses, which did away with the breech mount design so the entire lens was rotated to latch it in place, and a button was provided to release it.
Something unusual about the FD/FL/FDn mount was it's short flange to focal plane distance. This is the distance at which the lens is designed to focus and, because it's so short, makes it virtually impossible to adapt for use on other systems that use a longer F to FP distance. Essentially there's no "room" to add an adapter.
But that's not a problem with a T-mount lens, which I suspect is the case here. All you need to do is buy a Nikon F-bayonet T-mount and replace what's on the lens now with that. The lens will then be able to mount onto your cameras. T-mounts are still being made in China and are cheap. Look on eBay and get one, swap it out and give it a try.
It might be necessary to set your camera to "shoot without lens", because there are no electronic contacts or mechanical connections between the lens and the camera (for exposure control, autofocus, etc.). As a result, the camera doesn't "know" a lens is mounted. Some cameras have a menu setting that by default prevents the shutter from being tripped when no lens is on the camera. You'll have to check your camera.
It will be manual focus only. Manual focusing can be a challenge with modern cameras. They are designed with auto focusing lenses in mind and their viewfinders simply don't have some of the manual focus assist features that older cameras' viewfinders had. However, I know Nikon has implemented some manual focus assist features in their cameras over they years. You'll have to check to see what your particular cameras offer.
And as a mirror lens it's probably fixed aperture (f/8?). With most mirror (catadioptric or "reflex") lenses, neutral density filters are used to reduce light passing through, rather than an adjustable aperture. Adding one stop ND filter to an f/8 lens makes for f/16 exposure... a 1.5 stop filter makes f/22... a 2 stop filter f/32 equivalent. These filters only effect exposure. They DO NOT change depth of field effects, the way an actually variable aperture does. Still, most mirror lenses are long telephoto designs that are very capable of strong background blur effects. Below image was done with a Tamron 500mm f/8 mirror lens:
A characteristic of mirror lenses is the "donut" shaped out-of-focus highlights they tend to form. Mirror lens design, with the small reflecting mirror in the center of the front element, is what leads to the "donut" effect. You can see some of this in both the below images. I always felt the Tamrons were somehow less prone to this than other mirror lenses I tried. At least it seemed minor and less objectionable with the Tamrons.
Generally speaking, with this lens you may want to use fully manual M exposure (without Auto ISO). However, you may also be able to use A (aperture priority) auto exposure mode. In this mode you set the ISO and the aperture (which is fixed at f/8, unless you add an ND filter), and the camera then provides auto exposure by selecting a shutter speed for you. Depending upon how it's implemented on your camera, you also may be able to get auto exposure using M with Auto ISO... here you select the shutter speed and the aperture (which is still fixed at f/8), while the camera chooses an ISO that it thinks will make a correct exposure. Check your cameras to see if either of the above AE modes are possible.
You WILL NOT be able to use S (shutter priority AE) or P (program AE). You also won't be able to use any highly automated "scene" modes that your cameras might have (such as "sports", "portrait", "landscape"). All these require the camera be able to change the lens aperture, which cannot be done with this lens.
It's been many years since I used a mirror lens, but they can be fun. They are reasonably compact and affordable for the focal length they provide. I tried a lot of different mirror lenses over the years and ended up using the Tamron 500mm f/8 a lot and Tamron 350mm f/5.6 briefly. (I later ended up buying a more typical non-mirror 300mm lens and 1.5X teleconverter that allowed variable apertures and replaced them both.) I felt the image quality of the Tamron lenses was the best of the ones I'd tried, but I don't recall if the Tokina was among them. I know I tried Sigma and some other brands, before settling on the Tamron (which used their own proprietary "Adaptall" interchangeable mount system, instead of T-mounts... BTW, the "T" in T-mount stands for "Tamron". They invented the interchangeable mount and deliberately didn't patent it, allowing other manufacturers to make lenses using the system. Their later Adaptall system, which survived until approx. the mid-1990s, was patented... but is now widely cloned and also allows mounting on many modern camera systems).
Does that Tokina lens have a tripod mounting ring and foot? I ask because one mistake that a lot of people make is trying to handhold powerful mirror lenses. They don't have in-lens image stabilization and might force you to use fairly slow shutter speeds (or high ISOs) and are very susceptible to "camera shake blur". I learned early on to use a tripod or at least a monopod with my mirror lenses. it makes quite a difference in image quality. Not all of the mirror lenses had tripod mounting rings, but my 500mm Tamron did.
Have fun with that lens!
P.S. I noted above that most mirror lenses use a fixed aperture. The only exception I'm aware of was the Konica Hexanon 1000mm f/11, which used internal Waterhouse stops to provide a series of different aperture choices. Because they originally cost as much as a small car, those are relatively rare and uncommon (and don't have an interchangeable mount to use on other systems). They also made a couple 2000mm prototypes using the same system, but never sold any of them. (Even as a mirror lens, the 2000mm was huge and weighed 35 lb.... I saw one displayed at a photo show in Denver CO in the 1980s.)