Digital SLRs bring lens quandary

The digital era has given camera buyers abundant new choices. But changes that came with higher-end models called digital SLRs have also imposed new lens complexities and compatibility issues buyers hadn't bargained for.

On the one hand, the engineers behind single-lens reflex cameras, now unleashed from the constraints of 35mm film, can match the image sensors at the heart of digital SLRs to different cost and engineering priorities. On the other hand, because the size of those sensors therefore varies, the same type of lens often produces different results when comparing one digital SLR to another--or to 35mm film SLRs. In one situation, lenses are not just different, but actually incompatible as well.

Consumers, who have shown a strong appetite for digital SLRs and the cameras' accompanying high-quality images, are grasping the new rules. But no one denies there's a learning curve to demystify the details.

Take the case of Jesse Warren, an English teacher and avid photo hobbyist in Shenzhen, China. He concluded that, with lens compatibility issues in mind, he'd be wise to avoid Canon EF-S lenses that work only on small-sensor SLRs and to stick to the EF models that follow the older standard.

"After asking around for a few weeks, I came to fully understand the details of lens focal length and compatibility," he said. "I am very concerned, which is why I will probably invest in EF lenses."

Manufacturers are unrepentant about the newly fluid situation. "Standards always lead to something that makes life easier for the consumers, but it also limits creativity" for camera designers, said Darin Pepple, marketing manager for Fujifilm. "You have to weigh both sides."

On traditional film SLR cameras, a lens with a 50mm focal length closely approximates the optics of a human eye. But smaller sensors on most digital SLRs mean that a 50mm lens has a narrower field of view, which leads to light from a smaller angle hitting the sensor (see graphic). As a result, for example, the image of a car that shows completely on a 35mm film SLR might be missing the bumpers when viewed with a digital SLR using the same lens.

A conversion factor is used to describe new-era cameras in old-era terms.

For example, on a Nikon or Fujifilm, a 50mm lens shows the same field of view as a 75mm lens on a film SLR and therefore has a 1.5x conversion factor. On an Olympus or Panasonic, a 50mm lens works like an old-school 100mm lens. And for digital SLR market leader Canon, the equivalent is 80mm for consumer models, 65mm for its midrange line and an unchanged 50mm for top-of-the-line models with "full-frame" sensors.

The issue isn't likely to fluster experienced photographers. But now that digital SLRs cost less than $650--not much more than high-end point-and-shoot cameras--a new generation of less sophisticated buyers is arriving in the market.

Electronics manufacturing issues triggered the change. Although full-frame sensors preserve compatibility with film SLR cameras and produce cleaner images, they're more expensive and consume more battery power. Canon must make full-frame sensors by joining several smaller ones.

"You definitely have an entirely disruptive situation as the silicon guys drive the technology," said analyst Jeff Clark of Current Analysis.

Even as computing technology remakes the camera business and film becomes a relic, the film frame standard endures as a reference point to compare photographic equipment. The 35mm camera standard prevails for describing the lenses even of simple point-and-shoot cameras that lack interchangeable lenses.

New wrinkles for old standard
For decades, photography fans preferred 35mm film SLR cameras for their balance of size, image quality, film cost and the attraction of interchangeable lenses. By attaching different lenses to the same camera, people can photograph everything from wide crowd pictures to distant birds. Enthusiasts and professionals accumulated lens collections to span the range and fit special circumstances.

The 35mm label derives from the size of the film, 35mm wide with a negative measuring 36mm by 24mm. SLR refers to a reflex mirror that reflects light from the lens directly into the viewfinder, then snaps out of the way to expose the film. The design means the photographer sees the same image that appears on the image sensor, even when employing different lenses.

The narrower field of view on many digital SLRs boosts telephoto lenses, those with long focal lengths. For example, a 200mm lens on a film SLR works like a 300mm lens on a Nikon digital SLR or a 320mm lens on a consumer-level Canon competitor.

"The 1.6x factor on the focal length has, for my main subject of railways, been a bonus," said Chris Millner, an English photo buff and deputy editor of The Railway Magazine.

[menty666]

No problems here

I'll be the first to admit I'm clueless about cameras, but I upgraded from a Nikon Coolpix 2100 to a Panasonic/Lumix FZ-30 and can shoot a decent picture. There's enough range of presets and customizable settings that I can do simple point and shoot images of my baby and later if I want to I can learn more about aperature and shutter settings to take some nice outdoor shots. Yes, it was an expensive upgrade (look it up for yourself at B&H) but given the pictures we've gotten so far it was worth it. No odd cropping, great clarity...Maybe if I shot for a living I'd be more peeved but for me, it's a fantastic camera. Great job Panasonic. I'm glad to know that the Olympus lenses might work with my camera too. I'll have to ask at one of the local shops about it.

[lmasanti]

on 35 mm...

[quote]
The 35mm label derives from the size of the film negative, about
36mm by 24mm.
[/quote]
The "35 mm" tag refers to the width of the film.
The film lies horizontally. The 24 mm height plus the holes to
move the film add up to 35 mm.
This cames from the movies: the films are 35 or 70 mm width,
and it was cheaper to use the same film.

[markdoiron]

Odd Aspect Ratios are Problem

Odd aspect ratios (ie, 4:3) are a problem for me. That's because I crop in the camera. There's little buffer for further cropping of the digital image before printing. When a viewfinder shows an image and I release the shutter, I expect that the entirety of the image will show up in the final print. Not so for the typical 4x6 print. It's annoying to end up with chopped off heads and feet. Sure, these oddball aspect ratios may be more suitable for other print sizes. But, at the end of the day, the vast majority of prints will end up in photo albums and frames that are designed to accomodate a 4x6" print. 3:2 aspect ratio fits. 4:3 is problematic.

mark d.

[PolarUpgrade]

Sensors in many "35mm" cameras are APS dimensions!

This problem as described by the author relates to 35mm digital SLRs in consumer product ranges tending to use sensors that are the smallish APS-size, not 35mm size. This effectively means a change in effective focal length when a lens designed for a true 35mm film camera is used on a "35mm" APS-sensored digital camera.

Personally, I have long-wondered by U.S. federal regulators have not barred the use of "35mm" with respect to such cameras, as they produce an APS-sized image for all practical purposes.

APS stands for Advanced Photo System. It was a revision of 35mm film using automated exposure-date-storing cartridges and a smaller more efficient film dimension. APS film was blindsided by low-cost digital, but clever camera makers appear to have stuck to the format, essentially stuffing it inside "35mm" digital SLRs shells.

Not all "35mm" SLRs use APS-sized sensors; some have sensors that cover the entire 35mm film gate and do not present lens issues. Such cameras are usually much more expensive.

[Dachi]

I am going back to film.

I went to digital for most of the same reason as everyone else, but after using a slew of crappy sub-$400 cameras that are only good at taking pictures in optimal conditions I have decided to back to using a film camera.

Megapixels are the _only_ measurement of performance used on the low end so manufacturers cut all the corners they can to post high MP values.

The cheap digitals tend to use small CCD censors like say 5mm x 4mm for a 1/2.7" sensor compared to 36mmx24mm for film (35mm) cameras. (You can look your camera up here http://www.dpreview.com/learn/?/key=sensor_sizes )
The result is often poor color depth and and grainy (image noise) or blurry photos in low lighting due to high ISO settings and slow shutter speeds needed to capture a picture in low lighting on such a small sensor.

The cheapy digitals perform terrible in low lighting, you will get _much_ better photos in these conditions with an $8 disposable film camera. The low end digitals can produce as much noise at ISO 200 as the digital SLR's produce at ISO 800 or 1600.

The digital SLR's have much better sensors but they also cost $800+ compared to a decent film SLR that can be had for only about $200 (the cost of a crappy digital)

I went in a camera shop in CA last year and test drove a $450 Nikon (Digital), taking pictures in their store with the flash on my pictures of a moving subject (my 5 year old) were still visibly blurred even on the 4" LCD screen.

Slower start time of digital means I miss lots of good (spontaneous) shots, so my pictures always look posed.

There is a cost to having film developed, but after you add the cost of the digital camera(s), mem card, photo printer etc. it is no cheaper. I have owned a few digitals all of which were really bad.

2 digitals (2x$200) + mem card ($40) + photo printer ($200) = $640

Having film developed is not that expensive and you get better quality and, *gasp* you may still have them after your next Windows problem.

It is nice to have digitized pics to email or touch up etc. but most modern labs should be able to give you digital copies of your exposures on a CD.

After having $8 disposable 35mm cameras constantly put my last range of digital cameras to shame I have decided to just get a 35mm SLR for my next camera.

It is a toss up between the "Canon - EOS Rebel K2" ($220) or the "Nikon N75" ($250), both come with lens. I really like the Nikon but either of them will outperform almost every sub $800 digital on the market.

[dargon19888]

Lame Story...

Ok,

This is really a snooze fest when it comes to digital cameras.

Anyone who's shot digital will know this. Note that its a moot point. Just look at the digital back to see what you got. If you don't like it, delete and reshoot.

I purchased a D70 a year prior to a once in a lifetime trip to South Africa. Sure I could have waited and gotten a higher pixel count, but then I probably would have muffed some of the shots.

The moral of the story...
1) Get two lenses. A wide angle and then a zoom telephoto.
2) Purchase the camera early if you're buying it for an event.
3) Learn the ins and outs of your camera so that you know what to do.

4) If you're going digital, go SLR. Even though the camera phone can have a large megapixel count, the image won't be as nice as a SLR.

Of course, I'm saving up for a DX2 or the next generation. The higher the pixel count, the better the image and the larger the blow up. Also my existing lenses will work with the newer body.

-G

[Razzl]

New standards needed

I noticed this problem very early on and thought that the photo industry should bypass it with a new standard: describe lenses by their field of view. For instance: a "20" lense would be a lense which can take an image in a 20-degree arc and impose it on the receiving plate. That narrow field would make it a telephoto lense. A "140" lense would capture an arc of 140 degrees and would be considered and extreme wideangle. It wouldn't require any translation to understand what type of lense it is and the size of the hardware would be irrelevant.

As for the light-gathering qualities described by the F-stop numbers, those were always specific to each lense and described by the manufacturer and could still be used. Again, however, it might be more efficient to migrate to the EV numbering system used on cinematography lenses so that there is no longer a translation factor from film. The EV numbers idicated a sliding ratio of capture speed/aperture numbers that are universal and easily understood with practice.

[doon41]

Give me my full frame!

Like many digital photo users, I have a number of classic and valuable lenses for my older Nikon SLRs. I want to be able to use these, especially the wide angle lenses, on a new digital SLR. So far, the only choice I have is the discontinued Kodak DCS Pro cameras. Does Nikon really think I am going to buy new lenses and a D2X while they smugly laugh at my decades of investment in older Nikon lenses? Dammit! Give us full frame sensors!

[ruykava]

good story for seriously novice people.. oh well

i suppose everything said here is correct. it's just that, while i don't even consider myself an advanced amatuer, i've known about this since... erm... the first digital SLRs came out many, many, many years ago.

it's also not as if there's a danger to buying EF-S (for Canon) lenses. it has been made clear that the 1.6 crop factor is to stay except on the top range. today, "digital" lenses are designed to compensate for the crop factor if you really need wide angle. this is not going to change anytime soon.

concerns about images vignetting at the margins )as suggested by some comments), because the lenses aren't full sized are also unfounded as the lenses are designed with that in mind. if anything, digital SLRs are much more forgiving on lousier lenses because they crop out the edges where it is most challenging, optically, to produce good quality images.

overall, nothing wrong with the article, just a bit duuuh, i suppose.. just wondering how it is made to look like a breaking story.. is cnet running out of ideas?

[psulonen]

Do your research, CNet!

A basically good-intentioned article, but way too many factual errors, some of which are really annoying and persistent myths.

(1) The 50 mm lens does not approximate the optics of the human eye in any meaningful sense of the word. A lens that would do that would be something like a circular fisheye smeared with Vaseline and a big ol' black spot in the rear element. The 50 on a 35 mm camera does produce images that look "natural," but so does any lens between about 35 and about 135 mm. This effect has more to do with conventions in Western art than human physiology.

(2) Canon's full-frame sensors are not made by joining several smaller ones. (This would be impossible to do with current technology without leaving a "blind" seam where the chips are joined.) They do use a stepper in the manufacturing process, which is probably what's confusing the author. Look it up if you're interested.

(3) Portrait lenses and millimeters: an 85 on 1.5x performs exactly like a 128 mm on 35 mm, if you stop the 128 mm down one stop more. This is still a pretty good FL for tight portraits. It seems the gent they interviewed doesn't understand how perspective works either -- surprisingly many professional photographers don't. IOW, if you want portraits that look like they were shot on an 85 on 35 mm film, use something around 50 mm on 1.5x. If you want portraits that look like you used a 135 on 35 mm, use something around 85.

(4) Ultra-wides. Actually, rectilinear 12 mm lenses exist for the 35 mm format, and they don't cost anywhere near as much as a car. Look up the Voigtländer Heliar 12 mm 1:5.6, and the Sigma EX 12-24/4.5-5.6 HSM for various SLR systems. Almost every SLR format has a 14 mm 1:2.8 lens available too.

[mjd420nova]

SLR

Until the specific problem of focal length and
depth of field are addressed, I'll stick with
film SLR's and scan those I want into my system.
I worked with many digital types and manufacturers, and none have satisfied my needs.
The real problem seems to be that the lens has
too sharp a focus and too narrow a depth of
field. When taking photos of large groups, it
is impossible to get everyone in focus. Can't
this be cured with proper lens construction??

[tank2000]

Get a clue

Seriously, CNET, I know you're great with computer-related stuff, but your writers are a little clueless when it comes to DSLR and other camera-related news.

I won't repeat the innacuracies already mentioned here, but what I will say is that the confusion is really only with experienced film SLR users switching over to a DSLR, since these film SLR users most likely already have money invested in some lenses which they intend to reuse when upgrading to a DSLR.

If you're a novice buying in to a DSLR system, you're not going to care whether an 18mm lens is equivalent to a 27mm with a 1.5x crop factor DSLR or not. They won't be confused because that's all they've known.

In fact your article doesn't show that novices are going to be confused -- it in fact shows that professionals are the ones confused -- not only about the crop factor but also about perspective and its equivalent.

[memo06dic]

Bad, Lame, Outdated Story

Very bad story.

[mr e]

Pentax

It's a pity that you choose to ignore or overlook Pentax in your discussion of DSLRs, because Pentax offer something the others don't, namely backwards compatibility with just about every SLR camera lens (manual and autofocus) they ever made. As is well known, Pentax have always made very high quality optics, so this backwards compatibility is a real plus for anyone wanting to buy quality lenses relatively cheaply second-hand or to utilise their old film lenses on a digital body. Not only that, assuming Pentax don't change the lens mount - which seems highly unlikely given their current policy - these lenses should adapt perfectly to the full-frame sensors which will eventually be used on Pentax DSLRs at some point in the future.

I have to say that much as I liked the old Olympus SLRs, I can't help feeling that the 4/3 system will be a flop. Apart from the waste of printing paper, incompatibility with frame and mount sizes etc, it is an 'ugly' format. I've used it and find it strangely unsatisfactory, whereas the standard 35mm or square image ratios just seem right somehow. The 4/3 system is neither fish nor fowl, and I almost always find myself cropping images to 35mm or square when I use it.

[don509]

Good story, silly title

When I was in High School I got my first 35mm SLR. I got a manual Nikkormat and I had to learn how to use it to take great pictures. I've had a number of cameras since then and now I use the Canon Rebel XT and I'm loving it, just as I would the Nikon D70, etc... There is a learning process that one goes through to gain proficiency learning the workings of the tool is part of the pleasure. The 1.6 differential is not a problem, it's a characteristic that one takes into account when using a tool properly.

[W.BURROWES]

Digital SLR Cameras

Very informative article on this subject, although, I have heard that the CCD sensors on digital SLR Cameras can get easily polluted with dust etc when changing lenses, that can lead to expensive professional CCD cleaning?

[W.BURROWES]

Digital SLRs bring lens quandry

Very informative article on this subject, although, I have heard that the CCD sensors on digital SLR Cameras can get easily polluted with dust etc when changing lenses, that can lead to expensive professional CCD cleaning?

[jowct]

Tempest in a teapot

While the "quandry" is accurately described arithmetically, it is a non-issue for the simple reason that today's zooms are very often equal or better than prime lenses--if you don't see what you want, turn the ring! And the latitude digital processing provides totally trumps film which, although a wonderful memory, has become an anacronism nonetheless.

[gary85739]

instant gratification[you can see the pix NOW]!

other than that, digital photography is little more than a Photoshop induced joke!

once again, Madison Ave have brainwashed the public into thinking faster is some how better than quality!!

while the upper end digital camera constantly tout how they are "as good as 35mm", well, medium or large format photographers know 35mm is mediocre at best!!!

there is some hope with the Foveon sensor:

http://www.sigma-photo.com/cameras/cameras_cameras_details.asp?id=3256

other than that, most dslr's are little more than dust collecting plastic junk...

while digital cams are GREAT for point n shoot, no real photographer[NO, 35mm is not real, maybe with a Leica, thats about it]

[anothered]

Why do we think things are "forever"

We should try to enjoy and use techology for what it is. Sure, to keep the price of D-SLRs (NOT "35mm" D-SLR) down, it was probably and is cheaper for the manufacturer to come up with "specialized" wide lenses or zooms to offset the magnification factor. This why you see these digital only lenses like the Canon's EF-S or Nikon's DX only in the lower ranges where it more needed. In fact a camera like Canon's 5D with it full frame sensor can actually show a lens' weakness in edge sharpness if it's less than professional quality. I seen many people hang onto old lenses waiting for a D-SLR to come along. Sure all those Minolta Maxxum lenses you paid so much for years ago but you didn't want to spend for a new Canon Digital Rebel or Nikon N50 system which would have given you newer lens technology and smaller lighter lenses for a similar price of a Maxxum 7D body. New is new, if it works with you old stuff great but don't knock it if it doesn't.