The last time I used a mirror lens, it was an utter debacle. The Soviet-made Rubinar 1,000mm lens was so tele as to be pretty well useless. The optical quality was poor. And the lens was so old and shoddy that the focus ring detached from the barrel and one of its mirrors simply fell apart mid-shoot. It put me off old mirror lenses for a long time. But here I am, two years later, forgetting lessons learned and shooting another big-honkin’ mirror lens – the Minolta RF Rokkor-X 500mm F/8.
Thankfully, the Minolta Five Hundred avoids every one of the issues that I experienced when reviewing the Rubinar One Thousand. It’s a well-made lens, in line with Minolta’s products in the Rokkor range. It makes pretty nice images when we get everything right (more on this later). And, uh, it didn’t explode in my hands. Big Bonus!
But of course, it’s not a perfect lens (not even close). Nor is it a must-buy. It’s a niche lens in a world in which vintage lenses are a niche within the niche of actual-camera photography. It’s a niche product within a niche segment of a niche hobby. What are the chances that anyone reads this? Well, as I said in 2014 when I started this website, let’s write it anyway!
What is the Minolta RF Rokkor-X 500mm F/8?
Sports and wildlife photographers need long lenses. No getting around that. And for many, 500mm is the perfect focal length. It allows the photographer to get close without being close – useful when the subject is on a far-flung football field or has sharp claws. But 500mm lenses are notoriously large and cumbersome, which is especially troublesome for wildlife photographers out in the field. Here’s where the Minolta RF Rokkor-X 500mm F/8 (and any other catadioptric lens) shines.
Catadioptric lenses are colloquially known as “mirror lenses.” They use a form of the Cassegrain reflector in their design, meaning that the optical assembly uses a primary concave mirror and a secondary convex mirror to multiply the focal length of the lens. This design also has the important benefit of reducing the physical length of the optical assembly. A normal super-tele lens can never be as small or light as an equivalent focal length mirror lens, and that’s the big selling point.
But there are drawbacks when this design is incorporated into a photographic lens. Quite a few drawbacks, actually.
To start, the centrally-mounted mirror assembly precludes inclusion of an adjustable diaphragm. The lens’ aperture is therefore fixed (in the case of the Minolta 500mm at F/8). Adjustments to light pouring in through the lens must be handled via neutral density filters, usually installed at the back element of the lens. This means that anytime we want to adjust light without changing shutter speed we need to remove our lens – not ideal in pressurized shoots.
The fixed aperture combined with the super-long focal length also means that mirror lenses typically have incredibly shallow depth-of-field (more pronounced at closer focus distances). This can make contextual photographs of any subject closer than the horizon a challenge.
Lastly, due to the mirror assembly, out-of-focus elements of a frame can be extremely distracting and even take on a iris-shaped bokeh. For the obvious look, many people call this “donut-bokeh.” Some shooters like the look, some don’t, but it’s distracting in any photo in which the intended subject is anything but the bokeh.
Minolta made a number of mirror lenses throughout their time as an optical powerhouse. During the manual-focus SR-mount period from which today’s lens hails, they offered four – the excellent and much more expensive RF Rokkor-X 250mm F/5.6, the RF Rokkor-X 500mm F/8 reviewed here, the rare and semi-expensive RF Rokkor-X 800mm F8, and the back-breaking and ultra-rare RF Rokkor-X 1600 F/11.
The Minolta 500mm originally released for Minolta’s manual-focus SR-mount and received a revision at some point in its lifespan (this added a slightly longer removable lens hood – I’m not sure if the optical formula was changed, but I doubt it). Later the lens was converted to Minolta’s AF mount when the brand launched their autofocus cameras (incidentally it was the first auto-focus 500mm mirror lens ever made).
It’s an all-metal lens with excellent feel, a generously large focus ring, and beautifully milled components throughout. Filters are attached at the back (39mm filters, with a nice little Minolta wrench for removing them). Angle of view is a stunning 5 degrees (so, tripod for best results). Focus throw is long. Minimum focus distance is 4 meters. Teleconverters can be attached to double or triple the focal length (this makes the lens basically unusable).
True to type, the Minolta RF Rokkor-X 500mm F/8 is a very compact, lightweight, well-made lens. Its focal length is long. It gets close. It feels good. It excels in all of the ways that mirror lenses excel. And to be fair, it struggles in all of the ways that mirror lenses struggle.
Shooting and Image Quality
Those of us unaccustomed to the 500mm focal length (and not many among us is) will experience a significant adjustment period when shooting a lens this long. It’s hard to convey just how close 500mm gets us to our subject. The best way I know to illustrate the point is with, surprise surprise, photos!
The photo below, of an aging, beach-parked Jeep SUV (from a time when the term SUV was new), isn’t what it seems. I saw the old machine sitting there in the sand, the sun shining off its flank, the ocean rippling in the background, a bridge diminishing in the distance. It looked like a promising shot! I framed up with my Sony a7 and the 500mm, and noticing that only the side-view mirror and driver’s door of the truck was in frame, I knew immediately that I’d need to take a few steps back. I backpedaled across a parking lot and framed again. Still too close. I tramped across a sand dune and tried again. Only the middle third of the truck was in shot. I turned and walked further, this time going literally as far as I could go without wading into the Atlantic. I framed the shot for the final time – not far enough. Only half of the truck was in frame. In the end, I took three photos in portrait orientation – the front third, middle, and rear third of the truck – and stitched the three images together in Lightroom. For reference, I’ve also included a photo that I made of just how far away I needed to be to make this shot (which was, remember, three shots stitched together).
The final result is fine. A decent photo. But truthfully it was a pain to make, and an eye-opening example of just how ludicrously close a 500mm lens gets us to our subject. And, if I’m being honest, I believe I could have made a much better photo of this particular scene with something a bit less extreme (I immediately found myself wishing for the Sony FE STF 100mm F/2.8 which I reviewed some time ago).
That feeling followed throughout my time shooting the Minolta 500. Always too close. Always hard to frame. Always a little shaky. Always a bit out of focus. Always wishing I was using a different lens, a different focal length. Portraits are hard to make. I had to stand back so far from my subject that communication had me acting like an old-time landing signal officer from a World War II era aircraft carrier.
Image quality with the Rokkor is decent, compared with other lens types. There’s significant light falloff at the edges of the frame, most noticeable when the subject is on a consistent field of light and color, as in my shots of the moon in daytime. We can see that the sky around the edges of the frame is considerably darker than in the center. There’s no chromatic aberration. Sharpness is pretty good, not great (again, I’m comparing to more “normal” lenses – meaning non-catadioptric lenses and lenses of less extreme focal lengths). Bokeh is extremely busy, even when we’re not seeing iris-shaped specular highlights, an unavoidable characteristic of mirror lens design. Background really must be fairly uniform to create distraction-free subject isolation, a rare luxury.
Focusing can be a real challenge, since depth-of-field is razor thin at any distance closer than infinity. And even focusing to infinity isn’t easy, since the lens was designed to focus past infinity to account for expansion and contraction of the mirror elements based on temperature. Camera shake is a real problem as well, due to the extremely narrow field of view. Yes, this is a lens which demands precise focus, good eyes, and a decent tripod.
Straight out of my digital camera, images are a bit flat and lacking in punch. I punch them up in Lightroom with some slider adjustments to exposure, contrast, clarity, highlights, and shadows. In addition, I’ve adjusted my white balance (something I do with every photo made with my Sony). The final results are a mix of good and pretty good. I don’t think I made a remarkable photo with this lens. None of them stick out to me as incredible works, even judged against my own rather low standards of excellence.
There’s not much else to say. It’s a decent image-maker by the metric of image quality. Not amazing. Not bad. But it’s not really fair to compare images from this mirror lens to more normal, everyday lenses. The real trick of the mirror lens is, of course, that long focal length. When you need a 500mm focal length, no other focal length will do. Teleconverters on better, shorter lenses will diminish those lenses’ image quality to a point that makes these lenses worse than Minolta’s 500mm (at least when we’re measuring vintage lens to vintage lens). So, we need a mirror lens. And measuring the Rokkor mirror-lens against other mirror-lenses is really the only measure that matters.
In contemporary reviews, the Minolta RF Rokkor-X 500mm F/8 measured up well against its competition, landing somewhere directly in the middle of the pack. The German photo magazine, Color Foto, tested this and a number of other mirror-lenses back-to-back in 1980. The Minolta performed better than comparable lenses from Yashica, Sigma, and Tamron. However, it performed poorer than 500mm lenses from Nikon, Canon, and Zeiss.
I enjoyed using the Minolta RF Rokkor-X 500mm F/8. It’s a beautifully-made lens. It feels great in the hands, and allows us to make images that very few other lenses can. However, it is simply too specialized for my use. I’m not a wildlife photographer. Little birds aren’t interesting to me, and large birds have large beaks which frighten me. I’m not really interested in taking photos of sports, and you can only shoot so many shots of the moon before getting bored (approximately five, it seems).
But the Rokkor 500 does present a pretty good value proposition. As far as performance, it’s a middle-of-the-pack lens when compared against its contemporary competition. It’s similarly priced, as well. Not the most expensive vintage mirror lens, and not the cheapest. And I guess something can be said, after my last experience with a mirror lens, for the fact that it didn’t self-destruct.
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