Ultra-Wide Zooms

One of the problems with Digital Single-Lens Reflex cameras (DSLRs) with the usual APS-size sensor, is that because of the "digital multiplier" effect from the smaller sensor the focal length of any lens is, in effect, half again as long as it would be on a full-frame DSLR or film SLR. That means that an 18mm lens, for example, which was considered a really wide angle lens on a film camera, is effectively a 27mm lens on an APS-sensor DSLR. A 28mm lens, wide-angle on film, is 42mm on APS - nearly a normal lens.

In recent years zoom lenses have become available which have a low end of 12mm, which is equivalent to the 18mm full frame wide angle. I've had a Tokina 12-24mm for several years. This picture was taken at 12mm on that zoom:



I gave my old wide zoom lens to my daughter-in-law when she and my son visited on New Years Eve, and replaced it with a new Nikon 10-24mm zoom. I have to say that I really like it. The lens is light and smooth operating, and seems quite sharp.

The difference between 10mm and 12mm at the low end doesn't seem like much, but it really is a big difference in terms of angle of view - 99 degrees vs 85 degrees horizontal, and 76 degrees vs 66 degrees vertical.

These are the first pictures I took with the new lens - They were taken from only a few inches away from Natasha, and you can see the exaggeration of scale which such proximity at such a wide angle causes:





Of course, that distortion makes this something less than desirable as a portrait lens...

For comparison, this is a series of pictures taken at the 18mm "short" end of the typical kit zoom, 12mm and 10mm:

18mm:


12mm:


10mm:


In my earlier Camera Corner thread, "What are those numbers on lenses?", I compared various focal lengths from a constant distance-to-subject position. Here is the same comparison, shot today:

18mm:


12mm:


10mm:


The constant-distance comparison shows how the various lenses can be used to include more of the world in the frame, which is what most people use wide-angle lenses for. However, it's even better to use wide angle lenses to emphasize a foreground element by optically throwing the background further away, in effect - the reverse of the distance compression effect you get with very long telephoto lenses.

To see this, I've shot three pictures keeping a constant size for for the subject on the image by moving toward the subject as I zoom. You can see how much more background is brought in, and how much further it seems from the subject stuffed bunny:

18mm:


12mm:


10mm:


Bottom line: I think I'm going to use this lens a lot. If you like very wide-angle lenses, the 10mm focal length is about the best you can do today before you get into exotica like "fisheye" lenses, and personally I don't like the distortion a fisheye lens introduces.

I don't do digital speak very well...all my experience is in film, but 10-24mm lens sounds extreme. I didn't realize that focal length in a digital lens is different than a a lens on a film camera. The most verstile lens I had on my SLR was a 35-70mm. I really wanted a 28-70mm, but the price difference was too much for me at the time. The first thing I did when I got my Canon A-1 was to store the 50mm lens away and put my 35-70mm zoom on.

majorv said:

I don't do digital speak very well...all my experience is in film, but 10-24mm lens sounds extreme. I didn't realize that focal length in a digital lens is different than a a lens on a film camera.

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A 10mm lens would be extreme in a film camera - on an APS-sensor digital like the D7000, it's the equivalent of a 15mm in film. Of course, that's pretty wide, too. The widest lens I had when I was using film was 18mm.

The lens isn't any different in a digital camera than in a film camera, its focal length really is what it is. Because the sensor in the digital camera is smaller, it uses only the middle part of the image, roughly of 2/3 the area of the 35mm film frame.



If you had a lens which put that same 2/3 of the frame as a full frame 35mm image, it would have to be half again longer - hence the 1.5 "digital focal length multiplier".



I could put the 10-24mm zoom on my film Nikon and it would work fine as the 10-24mm zoom that it is - but only in a circular area in the middle of the film frame. Because it's optimized for a digital sensor, the edges of the frame, outside the digital sensor area, would be darker or maybe even black around a circular image area.



I should also point out that some of the most expensive digital SLR cameras - like the Nikon D600, D800, or D3 - have sensors which are the size of a full 35mm frame. On these cameras, the lens would work exactly as it does on a film camera. Of course, if the lens is one of those intended for APS sensors, you'll get the vignetting I've simulated in the example, unless the camera is programmed to just use the APS-sized part of the sensor (which is how Nikon full-frame DSLRs work). That's why the lenses intended for full-frame DSLRs and film SLRs are more expensive, because they have to maintain the image all the way to the edge of the 35mm frame.

In the Nikon line, APS-sensor digital lenses have a "DX" in the number. So, the 10-24mm zoom I just got is called a "10-24mm f/3.5-4.5G ED AF-S DX". Translating this gobbledegook out, in case anyone is interested:

• 10-24mm is the focal length range, obviously
• f/3.5-4.5 means that the amount of light through the lens (f/stop) varies as you zoom. The most expensive zooms maintain their f/stop constant as you zoom.
  
• G means that there is no mechanical f/stop ring on the lens, so if you want to manually set the f/stop you have to do it through the camera. This is only of interest if you own an older camera which doesn't have the electronic f/stop setting capability.
  
• ED means that the lens uses some "magic" glass with "extended dispersion" capability, which is mostly of advertising interest. Basically, it's how they get such a wide lens in such a small package.
  
• AF means the lens is autofocus and has a CPU chip in the lens. That means it will work with any Nikon camera which requires electronic lens information feedback. The more expensive Nikons - D300 / D7000 and up - can use mechanical feedback from the older "AI" lenses to get information like focal length, maximum f/stop, current f/stop setting, etc, from the lens. Most lower-cost Nikon DSLRs and some of the later Nikon film cameras required that the CPU chip in the lens send this information to the camera electronically.
• -S means that the autofocus is done through a motor in the lens, so this lens can be used with the lower-line Nikon cameras like the D3200 which require the motor because there is no focus motor in the camera body.
• DX means that it's optimized for APS-sensor digital cameras
  

Okay, so it's possible to put certain digital lenses on a film camera and it would work okay. I would assume that the reverse probably isn't true though...putting a lens from a film camera onto a DSLR and have it work correctly.

I don't see myself ever buying a digital SLR...they are soo much more expensive than film SLRs were. If I did, though, it would sure help if I didn't have to buy lenses all over again...that is, assuming they even have the same mount.

majorv said:

Okay, so it's possible to put certain digital lenses on a film camera and it would work okay. I would assume that the reverse probably isn't true though...putting a lens from a film camera onto a DSLR and have it work correctly. ... it would sure help if I didn't have to buy lenses all over again...that is, assuming they even have the same mount.

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In many brands lenses intended for film cameras will work fine on DSLRs - if the DSLR has the APS sensor, you'll get the digital multiplier effect, otherwise full-frame DSLRs will work with film lenses exactly as a film camera would. Of course, that's so long as the camera manufacturer didn't change the mount when they went to digital. I'm most familiar with Nikons, since that's what I've owned for thirty-plus years, and in that line the differences are less digital vs film, than electronic vs mechanical lens operation. All Nikon lenses made since the early 1970's will physically fit on any Nikon SLR (with a few very exotic exceptions). However, not all of the features of the camera will necessarily be available, depending on the camera and the lens.

• AI lenses (manual lenses made since the mid-1970's) will work completely with the prosumer and professional DSLRs (D300/D7000/D600-800/D3) and the more expensive film Nikons. With all other DSLRs and some of the later film Nikons, the camera exposure metering won't work with AI lenses, although you could use them in fully manual mode. Obviously the AI manual lenses can't autofocus on any camera. Many of the pre-70's non-AI lenses will work, too, depending on the camera and the lens, but you have to be careful with a really old lens - some pre-70's lenses had to be modified to fit on some Nikon SLRs and DSLRs, or they would break off a mechanical metering pin on the camera. Once the mount was modified, the lens would work just like any other AI-type lens.
• AF lenses (those with a CPU in the lens and autofocus capability) will meter with any Nikon DSLR or film camera (although "G" series lenses lack the aperture ring, so they may not work properly with older film cameras). AF lenses (without the -S suffix) will not autofocus on some of Nikon's less expensive DLSRs.
• AF-S lenses will work completely on all Nikon DSLRs and later Nikon film SLRs with autofocus. Earlier film Nikons will work with any AF-S lens which has the aperture ring (i.e. not "G" series).
• DX lenses (that is, lenses optimized for APS-sensor DSLRs) will still work with full-frame DSLRs and film Nikons, although as I said above the DX lenses may vignette. All DX lenses are AF or AF-S, and most are G, so the oldest Nikon film cameras might have problems with metering.

DSLRs actually aren't that expensive these days, allowing for inflation over the years. The new entry-level Nikon DSLRs are cheaper with a lens than the mechanical camera bodies were when I got my first Nikon film SLR in 1982. If you've got compatible lenses, you may find that a DSLR body is relatively cheap.

I got a new camera body (aT4i upgrade from an XTi) for Christmas, and a new computer over the weekend after the unfortunate apparent death of my prior computer so I really don't need to be buying more stuff right now, but now you've got me shopping for lenses!

I'll have to do a little homework, I guess. I originally had a Canon AE-1, which got stolen. I then picked up a used A-1, which I still have. Since I have several lenses - zoom and telephoto - I'll just have to see if Canon still uses the bayonet mount and if the 70's-80's made lenses will work with their DSLR.

A question for you Mike, is your sole interest and experience in 35mm or did you ever delve into other formats?

majorv said:

A question for you Mike, is your sole interest and experience in 35mm or did you ever delve into other formats?

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I've tried all sorts over the years. I started with several 120 roll-film cameras, a folding old Kodak, a Fuji Twin-Lens Reflex and a Konica 6x7cm rangefinder. I still have a 2 1/4 x 3 1/4" Speed Graphic, although they haven't made sheet film for it in decades. I just keep it because it's neat. Scone thought it was neat, too...



In 35mm, I had several Pentax SLRs, both screw-mount and bayonet, but then my Pentaxes were stolen and I switched to Nikon because that's what all my friends had. I had a bunch of different Nikon film cameras (and still have an 8008) before I switched to digital SLRs.