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Mirror Lenses - a rehabilitation in the digital age?


philaret

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I have read a few threads about mirror lenses which seem to have died away

around 2002. Although it is accepted that mirror lenses can yield excellent

images, for the most part they are believed to be the ones to avoid in favor of

a used regular tele (perhaps with a used teleconconverter). It is usually stated

that you can get an excellent used combo a little under $1000. I believe it is

time to reconsider these opinions with a digital SLR in mind. Indeed, mirror

lenses are much maligned for:

1. Inferior sharpness

2. Low maximum aperture

3. Less saturated colors and lower contrast.

4. Nasty bokeh (although here opinions differ).

Indeed, with film one is forced to use a fast one developed to a higher than

usual gamma and saturation (if you can do it). This is invariably associated

with a drop in quality due to large grain and reduced sharpness of a fast film.

However, things work differently in a digital SLR, where one can use ISO

800-1600, in camera sharpening and increased contrast without such a precipitous

drop in quality as it used to be with even the best film. Should not we

'rehabilitate' the mirror lenses now?<div>00IdpJ-33279784.jpg.c9101efe35a7981cd53cbbb11890f357.jpg</div>

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I use to use the 500/8 Canon FD mirror lens for sports and birds and the like. I liked it.

Didn't like the out-of-focus "donuts" you'd get in some landscape shots. You'd still have

to contend with those in digital, and I'm not sure how such a lens would fare with a FF

sensor. Interesting idea, though.

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Hi Alexander,

 

One of the other problems with mirror lenses is that they are so light that it is tempting to shoot them hand-held. But it's almost impossible to get sharp photos with any 500mm or 1000mm lens that is hand-held!

 

You ask a very interesting question, though. It would be interesting to see if one COULD shoot hand-held if the mirror lens is attached (via a T-mount) to a digital SLR that has body-based image stabilization (such as the new Minolta-based Sony DSLR).

 

Sincerely,

 

Dave

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Mirror lenses can be quite sharp and show good contrast, especially after a little digital tweaking:

 

See http://www.bobatkins.com/photography/tutorials/mirror.html for some comparison shots of a 500/8 mirror lens and a Canon 500/4.5L.

 

What you can't get rid of is the lousy "bokeh" in slightly out of focus areas due to the effects central obstruction. I don't think opinions really do differ on this. Everybody hates it.

 

My tests showed that performance with a TC was pretty bad too, much worse then the Canon lens.

 

Speed isn't so much of an issue with digital and good quality at ISO 800 and even 1600. You can get 500/5.6 mirror lenses if f8 isn't fast enough.

 

I still have my Tamron 500/8 mirror lens. It's so small and light compared with a "real" 500mm f4(.5)L that it has its uses when I have to travel with limited room and an eye on weight.

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I am glad this issue isn't really dead, and there is hope that the lens manufacturers read this. The lens in my example was deliberately the cheapest in my collection, and I like my trusty Tamron 500mm, which happens to have a tripod mount, too. A good point was made about the in-camera stabilization. Minolta, by the way, is the one manufacturer to have made an AF mirror lens and I am wondering if they are going to revive it now. What I was trying to say is that in the digital age we are no longer limited with one and the only film that happens to be loaded in the camera at the time a shot is taken, but with some knowledge, can adjust the camera settings to match the light and the lens. As for the 'donuts' of the image, I believe they can be taken care of, at least in a subset of situations, by a similar algorithm that is used to eliminate 'red eye' and scratches, as well as by applying a Gaussian blur to the entire background. Another point is that most current mirror lenses cover more than a 24x36mm frame (they can be used in medium format with some modification), but perhaps a 1000mm mirror designed specifically for the APS digital frame would not be that huge and could even autofocus?
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I love mirror lenses! I use a Nikkor 500/8 Reflex lens for birding and astrophotography all

the time. Used by itself, it produces some fairly sharp, saturated, contrasty pictures; used

with teleconverters, it becomes an inexpensive super-telephoto. I used to occasionally

shoot Fuji Provia 400F slide film with this lens, but now on a Nikon D80, I use it even more

often; the ability to instantly fine tune exposure on a DSLR makes a mirror lens much more

user-friendly and versatile in a digital world than it was with a film camera. The bokeh

donuts don't really bother me, in part because I've never really had a picture ruined by

them: if you are careful with composition and background lighting, you can avoid the

donuts. This photo (cropped) was shot on a Nikon D80 with Nikkor 500/8 hand-held at

1/640 at ISO 800. If I had used a tripod and a slower shutter speed the photo would be

sharper, but by then the bird would be in the next county (the guy next to me with the

Canon EOS-1DS Mk.II and EF 600/4L USM IS lens on a Wimberly gimbal head and Gitzo

tripod couldn't get this shot in time). I say that DSLRs have given mirror lenses new leases

on life!

 

<a href="http://photobucket.com/" target="_blank"><img WIDTH="400" src="http://

img.photobucket.com/albums/v291/SpeedySub/DSC_0110.jpg" border="0"

alt="Photobucket - Video and Image Hosting"></a>

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As I indicated many posts ago, my Tamron cat lens beat out my Canon and Nikon cats. In the end, however, I wasn't using it frequently enough and so I sold it earlier this year. Now in the long end I'm solely using an old Nikon 300/2.8 manual and Leica 400/6.8 and 560/5.6 manuals. Much heavier than the mirror lenses, but producing more consistently pleasing results. The "bokeh" issue with cats can frequently be minimized by judicious selection of lighting or composition.
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Could it be because there are no mirror lenses with anti-shake, stabilization control? I'm ignorant of such. Inform me!

 

Does Canon use in-camera image stabilzation on any of their still cameras? I use XL-* digital video cameras which perform fairly well with such a feature. Might be interesting if in a still camera, but I have to hear from the Canon pros.

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I have the Minolta 500 AF mirror and a Minolta 5D digital. Maybe I should go out and see what I can achieve hand-held and mounted on a tripod. The lens is very light and when I was using it more on my 600si's I always thought it was very sharp (though the out of focus highlights did tend to be distracting). On my Minolta 5D it would be the equivalent of 750mm/f8. That means either 1/1000th of a second or higher or a tripod. Of course the vibration reduction might buy me a stop or two. I find it works very well with other lenses but I mostly shoot from tripods.
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It's not just out of focus highlights appearing as donuts. It's any part of the background (or foreground) that's somewhat out of focus being very "confused" and patterned.

 

If everything is at infinity, or if you are doing a closeup with a distant background, things can look OK. It's when your subject is 30ft away and your background is 50ft away. Sometimes this can totally ruin an image.

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I absolutely agree that mirror lenses are a worthwhile investment for photographers today who don't want to sink big bucks into large, high quality telephoto lenses. I still own a Tamron 500mm and a Sigma 600mm. mirror lens from the "old days," and I have found them fun to use in the field with my DSLRs. This is even more the case now that I own a D200, since you can set the camera body to meter with non-CPU lenses (formerly I used trial-and-error metering, which with digital really is pretty easy).

 

The big advantage in my experience is that you can set the camera ISO to a very high level and can consequently eliminate to a great extent the camera shake issues that are largely responsible for the reputation of mirror lenses as "unsharp." I have been able to get very good bird photos handheld using my mirror lenses, and this was only rarely the case when I used film.

 

As for color/saturation/contrast issues, the truth is that you can tweak these factors in Photoshop to mitigate these problems.<div>00Ie9d-33284584.jpg.baa0f1e4ffd0999a9643c6780396b920.jpg</div>

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Mirror lenses never died away. They have been built and purchased right up to the present day, and if you can appreciate their unique qualities they're great.

 

I, too, once owned a Canon FD 500/8 mirror lens. It was then, and I believe would still be, the sharpest long lens in my arsenal, if I still owned it. Unfortunately, I couldn't stand the crappy bokeh, so I dumped the lens and put the proceeds toward a 300/2.8. I, for one, will not go there again.

 

You can rehabilitate a three-legged horse all you want, but in the end it'll still lose the race.

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IMO, the problem remains that it is very tough to focus mirror lenses because they are f8 (500mm) or f11 (1000mm) so that you'll have a very dim image in the viewfinder. The fact that the viewfinders on the low-end Canon (D-Rebel family, 10D, 20D and 30D) and Nikon DSLRs (D50, D70) can only make things worse. Regardless of how great your optics is, if you cannot properly focus it, you'll have a lot of problems.

 

20 years ago I bought a Nikon 500mm/f8 mirror, and that is the sigle biggest lens-purchasing mistake I have ever made.

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The thing that made me stop using it in the first place was not the doughnuts (I kind of liked that) it was the strange hard double lines you got from non point light sources. Look at that bird about halfway down the thread. The branch highlights are repeated as a double line. I hate that. If you can frame it right you can't tell it from any other lense, but I hate those double lines.
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It looks as though the main issue with mirror lenses is not sharpness, color or contrast, but generally speaking 'the bokeh', which receives the most of the negative comments. IMHO this is a sign of rehabilitation ;-). There seems to be no second opinions on the statement that DSLRs offer more robustness in using a mirror lens due to a higher quality at high ISO setting. Despite varying the ISO on the fly, it seems that nobody is taking advantage of other in-camera image controls offered by a DSLR. It also seems that the majority is using a 500mm mirror lens. My 'secret agenda' in starting this thread was, among other things, to get opinions on the 1000mm mirrors, where there is little competition (even with a $10K budget, Shun) from the regular tele lenses. Also, the dohnut problem becomes less prominent as the focal length increases. The other question I still have is about the possible changes in construction of future mirror lenses. As I said, most current mirror lenses cover more than the standard 35mm frame. It looks plausible that a smaller secondary mirror would be needed to cover the smaller digital sensor. This would also produce a 'thicker dohnut', perhaps to the point it could be recognised by a local pixel patterning software and eliminated?
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Sure, Shun. These combos are not really a 'competition', they were not meant to be owned by an individual (although there is no rule why you shouldn't). In fact, you do not have to sell a kidney to rent a lens of this class at a profi rental here in Toronto. The longest lens I see listed right now is EF400/2.8 L II USM ($150.00 for a weekend, $600.00 for a week). Add $20/day for a TC. Given that this could have been my film costs, renting is definitely a possibility. However, for the same money I can own the most powerful mirror lens. This is what the buzz is all about.
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Sorry, but I simply don't buy the argument. Over the years I've used several mirror lenses,

from 500 mm to 1400 mm (Questar telescope). The single advantage they had over

regular optics was small size, but that came at a very steep price in image quality. None

of them came

even close to the degree of sharpness possible with a good 500 mm refractive telephoto

(Canon 500/4 IS, in this case). And none were close to the sharpness possible with that

500 mm 'stretched' to 1000mm with 2X converter. The Questar's optics are superb when

used as a telescope and theoretically could probably have achieved good sharpness as a

lens, except for unavoidable problems with camera shake (even with MLU), wind, and

convection cells, which were made worse because its very small aperture (~ f16) precluded

high shutter speeds and introduced diffraction effects.

 

Poor optics are even more problematic with APS and DX-format DSLRS than with film,

because digital sensors mercilessly reveal optical flaws that could be overlooked on film.

 

In addition to the issues with optical quality, all of these mirror lenses yielded positively

obnoxious out-of-focus effects except under restrictive and unusual conditions (e.g.,

plain blue sky as background). The 'doughnut' effect from bright out-of-focus areas was

NOT less obvious with the 1400 mm Questar, although that's partially due to the small

aperture.

 

Lack of aperture control is another big drawback of mirror lenses, at least IMO. I

frequently want the option of stopping down a bit for added DOF -- not possible with any

mirror lens I'm aware of.

 

Finally, a Canon 500/4 + 2X converter yields a 1000/8 combination that is stabilized and

costs less than $6K at current B&H prices.

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Maybe I am fortunate. As I said, back in 1987, I bought a Nikon 500mm/f8 mirror, used it for a couple of years and told myself that I would never used a mirror lens again. In 1992 I bought a 500mm/f4 P and a few years later upgraded to the AF-S version, which I still own today.

 

A used Nikon 500mm/f4 P is not that expensive. There is no auto focus, but neither does any 1000mm/f11 mirror. Your mileage may vary and there are certainly fans of mirror lenses, but to put it bluntly, from my point of view, my photo opportunities are too valuable to be wasted on any mirror lens. In particular, if you are talking about a 1000mm/f11, your problem is worsen in two ways compared to a 500mm/f8: you lose one stop of speed and all your vibration issues are worsen because you double your focal length.

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There's a certain element of talking "apples and oranges" here. I don't think a lot of people would argue that a 500mm. mirror lens is the equal optically of a great big 500mm. f4 refractive tele. The issue is, *for the price difference* (which, even if we are talking old, used, manual focus lenses) is considerable)is the mirror lens a reasonable purchase for a digital photographer?

 

I say, absolutely. The small size and portability are actually huge advantages in many situations. Shun mentions the focusing issues, but the truth is that with digital one can afford to snap several photos to get one shot, i.e., you can shoot several exposures while fiddling with the focus ring. Bokeh issues are real *for some photos* but not others. The truth is that for most people's purposes the very slight difference in resolution between a good mirror lens and a good quality large refractive tele is not all that great, and skillful post-processing can render the difference even smaller.

 

The bottom line (which is important here): one can pick up a good used mirror lens (and in my experience owning both, the Tamron 500 is every bit as good as Nikon's own) for a veritable song. Ebay seems to have a number of very cheaply made mirror lenses listed, but there is also currently a Tamron with a 2x telextender included for less than $200. A steal!

 

Again: if someone is interested in everyday, heavy-duty telephoto work, a mirror lens is certainly not the equal of a larger, faster, refractive lens. But for many people, the objective is occasional use in very particular situations. A mirror lens can get you surprisingly good wildlife and scenic shots in most circumstances, particularly not that digital has made the technical issues easier to cope with. I frequently use my mirror lenses cradled onto a bean bag on a post or other support, and the results are quite acceptably sharp.

 

The original poster asks about 1000mm. lenses. He might consider the Celestron or Meade lenses that are made primarily as "telescopes." Optically these are reputed to be decent, and they are inexpensive. However, keep in mind that the longer the focal length and hence the greater the distance between camera and subject, the more problems will be encountered not only in terms of vibration, but also atmospheric interference (this is true for any kind of tele, of course).<div>00IfO9-33317584.jpg.ed59b256cae4d13471510407f577c8b2.jpg</div>

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Thank you everybody for a very informative exchange of opinions and the images. Particularly Douglas, for a very balanced and thoughtful answer. Perhaps I should have asked "With high ISO capability and all those image controls, don't DSLRs reduce the gap between mirror and high-end refractive lenses?" I think from the posts the answer is a definite yes. I never meant 'close the gap'. In other words, if you have invested in a digital body (which is about half the price of a high end lens), you got an instrument in your hands which allows you to 'squeeze' more from a mirror lens. I particularly like the idea of 'focus braketing'.
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You can easily bracket exposure because if you know it is between f5.6 and f11, you can take a few samples in between. If you don't know where the focus is, how can you bracket the focus? In particular, if you are taking about shooting a bird that can move a little, or a bird standing on a branch that is moving a bit under the wind, you are going to have a lot of problems.

 

Again, I am using some strong words here. My shooting opportunities are valuable. Even though you give me a mirror lens for free, I will not waste my time on one. And I don't even mind any donut-shape out-of-focus highlights. Focusing problems and the slowness of such lenses so that you cannot freeze action are my primary problems with mirror lenses.

 

However, your requirements may be different from mine. If a mirror lens works for you, by all means use it. If you go thru the same learning exercise and frustration I went through 20 years ago, please don't come back and tell us that nobody has warned you about it.

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