philaret

<p>Martin, I am not a frequent visitor to this forum, so I hope you will excuse me if I repeat what somebody already said elsewhere. With all due respect, you are deluding yourself by thinking that cameras of the kind you mention are useful for presentation quality results. But you have made your point with the examples, in that the upper one can be cleared with a noise reduction software to a decent look, while the other is totally hopeless. Unless this meeting was unique, you would do yourself a better service by re-shooting this group with a DSLR, better light, correct exposure and correct white balance. As all those are off-mark in this image AT THE SAME TIME, trying to to make those right in software will reveal even more noise than is currently apparent. BTW, the program that you hate is nearly the only one capable of handling images in the LAB color space, and Dan Margulis in his books many years ago suggested a simple but useful trick to reduce noise which is "blur the chroma channels, sharpen the luminosity channel" (in LAB, that is). Here is what can be done in a couple of minutes to your upper image.</p>

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I am afraid that at this point I am just going to repeat one of the previous posters, but here is my two cents.

After 6 books on digital photography I can say that in 2008 there is really nothing in film that cannot be

replicated in digital (or surpassed), with proper hardware, software and knowledge. But I'd wish those Photoshop

book authors were more considerable of the reader and do not repeat each other so much on basic things that often

take the first third of every book. From digital speak, a film is just another "pre-set". However, a compact

digital camera is another pre-set (or two). To be more in control of your digital image, you need a camera with

RAW capture and face a steep learning curve with potentially not the best teachers around cluttering the horizon.

However, if one is not prepared to spend that much money on new hardware, or that much time on learning digital

exposure, white balance and RAW processing, what happens, is that "we go back to what we know....I am going back

to black" (Amy Winehouse song).

Teresa, there was a thread on the same topic in 2004:

 

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=009ZDV

 

which had to be stopped by the moderator because it escalated to a near-fight between Bill Troop, one of the authors of "The Film Developing Cookbook" and a former Kodak employee. The whole idea behind a stable stop bath (as put by Troop, who is a proponent of all-alkaline process) is that it should be buffered and have a pH indicator dye to show that it is exhausted. From the 2004 discussion it was clear that if there was a difference between using a water (or no rinse at all) and an acid rinse, it was only in the lifetime of the fixer. I personally do not see a point in deviations from the film manufacturer's recommendation if a film is going to be scanned.

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.

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.

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?

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. ;-(

This is an undisputable point, Mark. Slamming down mirror lenses should begin with "...but they do not have an iris", not with anything else previously mentioned. Some of them did, but as a general rule they do not have one. However, stopping down in Alan's shot, as I said, may not really salvage the situation. And, what if you got a lens with a 6-blade iris?

It is not clear, Jean-Jacques, if your experience refers to using a Rubinar on a DSLR or on film, but obviously certain point are the same. And, so that Shun, Mark and others do not think I am an unconditional adept of mirror lenses, I should add that using a mirror lens at 'macro' distances is THE biggest problem IMO (3m is 'macro' for a 500mm lens!). Since stalking some insects is difficult with a typical 100mm macro (+1.4X TC), on a full-frame DSLR is conserned (or film), I once got a 300mm Rubinar and tried it at short distances. Well, the donuts are the worst obstruction in this range. While you can shoot a dragonfly at a considerable distance, even in those places where you cannot physically get closer, you get a really weird looking image wherein tiny dohnuts line up every bright area, while there is little or no background problem. However, getting small animals completely in focus at close distances can be a challenge for any lens, since it can be tough to choose a spot over which to align an autofocus sensor and choose the right depth of field. I did not use the other Rubinars except the 300mm, but they are better built than some of the plastic Japanese mirror lenses and sharper/contrastier than they are. However, Rubinars are a by-product of the Lytkarino optical factory making large telescopes and there is little hope they will be optimized for digital sensors, while pricier mirrors may well be optimized in the future. Finally, IMHO Alan's image would not look good with any lens stopped to the same F-stop. The background is bright and really distracting unless you have one of those 500 F/4s. But then at F/4 the whole bird may not be in focus ;-). A powerful flash may be in order to isolate the bird from the background. With the risk of being slammed again for low quality, here a 2-minute fix for Alan's image.

Shun, I mentioned Contax because this looks like your favorite system and because you said: "Today, most major brands don't bother to make them [mirror lenses] any more because people are accostumed to the higher standards from AF now." A hint that you may not be entirely accurate even for your favorite system. Tamron still makes an umptienth version of their mirror lens, which received only positive marks in this discussion. If you can find their 350/5.6, it is even better. My purpose was to collect opinions from people who actually shoot with mirror lenses, so that we could identify the 'lemons' and pinpoint the good ones. It is you who imply that I am trying to push my point of view by deceiving the public with appropriately scaled images, or worse, that my standards of quality are too low. When I scaled a 8 megapixel image to 1024 pixel on the long side, it is not enough for you to judge the sharpness! If you have time, go to http://www.photographyreview.com/, find reviews on Zeiss Mirotar 500/8.0 and wonder how different they are. Unfortunately, they are not about digital. -My- purpose was to find it about the performance of specific lenses with digital sensors. I think we succeeded in collecting a few benchmarks that people can use in the future. More would be very welcome. BTW, their prices, Jeff H, spread all the way from $50 to your 500/4 refractor price and do not exactly correlate with the quality. Finally, I do not find a 20D viewfinder image dim, even at F/9. But it is small and with a certain kind of vision problem this can be difficult. I sure miss the autofocus with the Tamron, but I am waiting for my chipped EOS to M42 adapter (thanks to Bob Atkins who pointed us to it) and hope to improve on what I get right now.

There is nothing in my post, Mark, that identifies Shun as a bad photographer. My statement is not 'condescending', but it is 'classifying' to the same extent he is trying to say I am convinced mirror lens is a way to go. Now, I recall Shun's portrait is obscured by a Contax 645. What about Zeiss Mirotars? "Carl Zeiss Mirotar T* 500mm f4.5, one of the fastest ultra-telephoto lenses in the world today. This lens design has totally eliminated chromatic aberrations so prevalent in conventional high-speed lenses of this class..." Granted, this lens is neither cheap nor small, but do you have doubts it is a quality optics? The last of them, the 500mm, I believe, was re-designed only 2 years ago. Any 'condescending' comments about Zeiss?

Well, first off, I am indeed completely in Douglas camp. And, not to sound offensive, Shun, I now know what kind of photographer you are. You made your choice 20 years ago. ;-) With the risk of being trivial, sharpness is not only something to be demonstrated 'on the pixel level'. I am happy you requested that. That identifies you with a certain crowd. Another point of view is that sharpness is not only a characteristic of a lens, it is also an illusion and sharpening algorithms use this feature. Much like special effects in movies use other illusions of the eye. We will go off topic if we start arguing that sharpening of a scanned film image does not do the same job as sharpening of a digital image. What I really wanted to demonstrate with the latest image is that the illusion of acceptable sharpness can be achieved with a mirror lens image. Probably because its rays hit the digital sensor at the right angle. Which makes it more usable than before. You cannot do this with an old expensive wide angle lens. For digital sensors these will have to be designed from scratch. And finally, I believe photography is about creating an image that is appealing to yourself, to other people and ultimately to a market. That is associated with a lot of rejects! All the time. Fortunately, as Douglas mentioned, we do not have to pay a huge price for them anymore.

Here is the larger version of the doves:

 

http://img71.imageshack.us/img71/184/img0061ap6.jpg

 

However, opinions indeed differ whether out of focus shapes ruin the image or not, as I said in my original posting. Besides, obstructing foreground shapes are rather difficult to remove by postprocessing, while with the background it is fairly easy using 'Gaussian blur'in Photoshop. I was tempted to do this, but I think it is more informative to show the image as it was taken.

Thank you, David, for giving and example of two different mirror lenses. Running on a mediocre mirror lens is not that uncommon and you are not safe with a DSLR here. I have been thinking for a day whether I should comment on Shun's latest post about '20 year old frustration' and a 'warning'. I believe 20 years ago the first autofocus SLR was just out, the Minolta Maxxum 7000, and autofocus was still more of a curiosity. And I am not sure if there was any decent color film with ASA 800+ at that time. I got my Tamron 500mm between '93 and '95 and it took me a couple of years to master this lens and understand its shortcomings. For a while I mostly shot black and white, because I had full control over film speed and contrast. But then came the films with flat crystal technology and life became somewhat easier. At this point of the discussion I feel compelled to present another image which I got today walking around a nearby provincial park. Cloudy day, grey doves with not a lot of contrasty detail to focus on, sitting in the shade amidst a lot of branches...I think everybody would agree that this is a tough situation to focus both manually and automatically. I took several shots in succession using that 'focus float' technique, I also bracketed exposure. One is here for you to judge. With film, you would stand more than a 50% chance ending up with a weak image. No postprocessing except downsizing, but camera image controls (contrast, sharpness and saturation) were set to max.<div></div>

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'.

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.

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?

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?

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></div>