Mirror Lenses - a rehabilitation in the digital age?

[philaret]

Thank you, Alan, you did give yourself away. Perhaps understandable since we are so far now from the original question (have to scroll too far back). Slides for projection. Right! I can't agree more. All slide films with 400 ASA or more are crap! If I were to make slides, I'd be hard pressed to pick a mirror lens (well, maybe a Zeiss Mirotar would do). But I was asking about the age of -easy- ASA 1600 shooting, 'photoshopping' and LCD projectors or HDTV. Like it or not, this is the way we are going to show our images. Do mirror lenses deserve a better place in this world? Or do all newbies to DIGITAL telephotography have to go through all those crappy tele-attachments, and 20-year old refractors Ebay is bursting with, because you guys keep saying 'o-oh, crappy bokeh, o-oh, no iris..., start saving toward your 3K lens". Any but the most expensive recently designed refractors (APO, LD, SD etc) have chromatic aberration. Sharpening only makes it worse. In contrast, spherical aberration in mirror lenses is (apparently) correctable by sharpening, and it looks as if 'perceived sharpness', observed under normal conditions, not at 'pixel level' is good even in crappy plastic mirrors. At this end I must confess I love slides. But this year I find it difficult to develop slide films here in Toronto, even buy E6 chemicals, and B&H refuses to export them. ;-(

[jean_jacques_lemaire]

Alexander, my answer about the Rubinar was for both film and digital, but I really start using it when I came to digital, thanks to the ISO button ;)<BR>

Yes, you're totally right about high ISO giving a second life to these lenses. But to keep a decent image, I didn't go above 800ISO with my 350D/RebelXT.<BR><BR>

IMHO, image quality provided by this lens remains constant whatever you used, digital (APS-C) or full 24x36mm surface. Some people even report nice results with 6x6 format!<BR>

Honestly speaking, I think that it will not be a lens you would use forever (because of the "bads" of my previous post), but given its quality/price ratio, you will have a lot of fun with it.<BR>

This was about the Rubinar. A Celestron or Meade may be better optically, due to their newer coating technology, and better mechanics, but I have no "proof" about this.<BR>

<BR>

Now, I own a Sigma 120-300 F/2.8 EX HSM. I think it's a much sharper lens, it has AF, it's 1.5x bigger, twice the weight, but it's much more versatile (combined or not to a TC). Last but not least, 10+ times the price...

[sfcole]

I had a Sigma 600 a few years ago and eventually sold it. It was fun for a while, but eventually

I just didn't use it that much. They're slow and in spite of being small for what they are,

they're still big. Mine hogged a large part of my camera bag. Mirror lenses are a product that

seem like a good idea but that eventually gets forgotten about in the closet, like a $1200

treadmill, or a fancy kitchen gadget for making perfect deep-fried onion rings.

If I were going to invest in a tele lens, I'd go for a good 300 f4 (do they still make those?), and

just crop. The resulting image will probably be better, and the lens will be much more

versatile. My problem was never really absolute sharpness--it was steadiness.

I actually like those donut highlights (of course, I never met a donut I didn't like....):<div></div>

[douglas_greenberg]

I ran across this article online that deals with the possible rebirth of mirror lenses in the digital age:

 

http://www.nobell.org/~gjm/photography/fdadapter/mirror.html

 

Definitely interesting, at least to some of us :)).

[philaret]

Thank you, Douglas, for the link. The author of the article started from the same observation as I did when I started this discussion. Oddly, however, he mentions that Photoshop can fix contrast and saturation but says nothing about sharpness. Furthermore, comparing an old Sigma mirror lens model to a modern L-zoom lens ($1500) is not exactly fair. On a previous topic, the weather has been bad last week, so I did not have a chance to use my chipped M42/EOS adapter that was mentioned before. An interesting detail, though, which was not mentioned in Bob Atkins review is that the adapter has not only the chip but a small pin which tells the camera that a lens is attached. BTW, Chinese and HK versions of such adapters, also currently offered on Ebay, come with a suggestion to place a piece of paper under the body lever to achieve the same effect. Bob's comments about the finish quality of the adapter were, IMHO, somewhat overoptimistic. For my specimen some sandpaper work was necessary to make it mount flawlessly on a Tamron EF TC. Is there already a thread on rebirth of old refractors in M42 mount in the digital age?

[ShunCheung]

Interesting Douglas. I am glad that you provided the link instead of me. Even a cheapo 55-200mm f5.6 zoom (after cropping) provides better results than a 600mm/f8 mirror.

 

That is exactly in line with what I suggested earlier: If you need no more than small prints, which is the limitations for mirror lenses anyway, you are much better off getting a 300mm/f4 and crop. In this digital age, it is much easier to crop in PhotoShop, something we couldn't do with slides before.

[philaret]

Shun and Douglas, actually, I am guilty of not looking closely at the 3 lens comparison at first. Now, the comparison is really not accurate. The shutter speed used for the mirror lens is a lot longer than for the other two, while the focal length and potential camera shake is larger. While it is mentioned that a tripod was used and the best of 3 shots etc, it is still possible that camera shake was not taken care of. The 'cheapo' was used at its best aperture and with a shutter speed not actually requiring a tripod. This picture just shows one of the common flaws of <using> really long lenses, not the quality difference. Also, if you look closely, at the top of the images the sharpness is comparable, while at the bottom the mirror lens image is quite simply out of focus. This measures the ability of an autofocus camera (forced to refocus for each shot) against a person's eye of unspecified age ('... not a poor student anymore'), who apparently did not use manual focus for a while. We had better pictures shown during this discussion.;-). I'd love to see a quality affordable 300/5.6 refractor with LD glass (imagine how small, light and sharp it could be) coming out, but it seems they are not going to happen. Then, surely, I could crop.

[ShunCheung]

You can keep making excuses for mirror lenses for all you want. The bottomline is that if you get a 300mm/f4 AF or even a cheap 55-200 f5.6 zoom, you have the advantage of AF, a larger aperture (so that you can use faster shutter speeds) and in some cases IS/VR. All of those advantages make 500mm/f8 type mirror lenses a very poor choice in the digital age.

 

But if you prefer mirror lenses regardless of the facts in front of you, that is your choice.

[douglas_greenberg]

I provided that comparison web page to liven up the discussion, and to point out that there are no photographic miracles out there :)).

Mirror lenses are not easy to use and are incredibly prone to vibration. Etc.

 

STILL, I can speak from my own experience and assert that I have obtained some very satisfactory results using a mirror lens, particularly in bird photography. In looking over the better photos I've achieved with mirror lenses I ponder whether I could have gotten the same results using a 200mm. setting on a zoom lens and additional enlargement, and I find it hard to believe that I could.

 

Again: if you follow the ebay listings for a while you can find a pretty decent 500mm. or 600mm. mirror lens for under $200. Compare that with even a used, older manual focus good-quality refractive 500mm. lens, which I doubt you'll find for less than around $1500. HUGE difference!!! I still think that given the high ISO settings and fast shutter speeds one can enjoy with DSLR's, it's a worthwhile investment for certain types of photos.

 

And by the way, just to stir the pot further, here's an interesting comparison by Bob Atkins of a Tamron 500mm. mirror lens with a much pricier Canon tele:

 

http://www.photo.net/learn/optics/mirrors/

 

The Tamron aquits itself surprisingly well. The entire discussion in the thread that follows Bob's post is interesting.

[philaret]

Well put, Douglas! Actually I was aware of Bob's article before I started this and I had the Tamron for about 10 years. I think our friend Shun got a little carried away by slamming me down for my alleged mirror lens advocacy, recommending a 55-200. I am sure most people will be disappointed by this lens except for when using it all the time at F/11. But a really good point I could not make, but you did now, is that, surprizingly, in the digital age, the gap between a consumer tele-zoom quality and a serious telephoto <widens>! This is because old and/or cheap refractors are not a solution, their optical flaws are too noticeable on a DSLR, and independent manufacturers like Sigma, Tamron and Tokina are dropping 400mm lenses they once offered, in favor of zooms. I had Tamron 200-400mm before but I sold it as soon as I got a DSLR, because it was not that much better than a mirror at the long end. And the autofocus missed all the time. Out of curiosity, I emailed Tamron USA yesterday and asked about the current situation with mirror lenses. The answer came almost in a second and the person there wrote that those were discontinued some time ago and it was not even certain if a mirror lens would work on a digital (???). I think it has to be put in plain English that people looking at those CZJ Telemegors (a huge but actually a 3-element lens), Russian Tairs (also a lens designed in 1954), and cheap Japanese refractors are on the wrong track and if they want to try bird photography, they should hunt down a Tamron mirror lens, and perhaps, with sufficient dedication present, start saving toward a modern refractor.

[ShunCheung]

Douglas, the comparison is no longer a 500mm mirror vs. a 500mm/f4 tele. I have chosen the latter since 1992 and as far as I am concerned, that debate was over a long time ago.

 

The point is, based on the article you provided, a cheap Canon 55-200mm/f5.6, after cropping, beats a 600mm/f8 mirror by a wide margain. And that zoom is a $200 lens, new:

http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=300600&is=GREY&addedTroughType=search

 

Therefore, any price and weight advantages from the mirror lens you try to claim are gone. You can question the methodology of that tester, but since you introduced that article into the discussion, it'll be up to you to verify it.

 

And I am NOT recommending any cheap 55-200. I would pay a bit more and get a used 300mm/f4 AF, which I am sure is superior to the zoom, as I wouldn't buy a tele slower than f4, anyway.

[douglas_greenberg]

Ok, I'll question the methodology of the tester, ok? His little experiment is hardly the last word, and if that's what people have taken it to be, then I am truly sorry for calling our attention to it.

 

To be honest, I put more stock in the methodology and results of Bob Atkins. I think we all know who he is and that he is very knowledgeable about photography.

 

Ultimately, however, I base my viewpoint upon my experience with my mirror lenses. I am fully aware of how difficult it is to get optimal results with them, but I also have numerous photos that prove to me that they can sometimes produce terrific images. If I had only $200 to spend on a lens for taking bird photos, I would definitely prefer to invest in a good cat lens than to try to use a 55-200mm. zoom. That's just me.

 

It seems to me that this discussion is really reaping diminishing returns. People seem pretty entrenched in their positions. So this is my last comment :)))