Canon 75-300 and 100-300 lenses

Canon made (or make) 3 basic "300mm telephoto zooms", the 75-300, 100-300 and 100-300L. At one time or another, I've used all of them, so I think I'm in a reasonable position to make a comparison.

There's also a new lens, the EF70-300/4.5-5.6 DO IS USM which was introduced in April 2004 and I'll make a few comments on that at the end of this article.

EF100-300/5.6L

The EF100-300/5.6L is the only lens in this group which uses fluorite or UD elements (it has one of each) to achieve "apochromatic" status. It's an old lens, introduced very early on in EOS history (1987). It was dropped from the Canon lineup around 2000. No USM, no full time manual focus, rotating front element, push-pull zoom, no tripod mount. It's a constant f5.6, which means it's a stop or so slower than the other lenses at the short end.

It's sharp at 100mm and the sharpness holds up well (though does drop a bit) at 300mm. This was one of the first EOS lenses I owned and I was fairly happy with it until I bought the 300/4L. The 300/4 was not only nicer to use (USM, no rotating front element, full time manual focus, tripod mount), but is also a stop faster and sharper! I sold the 100-300/5.6L shortly afterwards.

Overall the 100-300/5.6L is a decent lens from an optical standpoint, but the ergonomics leave something to be desired. I don't really know why Canon didn't upgraded it A 100-300/4-5.6L with USM and tripod mount could be a winner for those who need a sharp zoom. Perhaps the new 100-400/4.5-5.6L IS fills that gap, but at a significantly higher cost than the 100-300/5.6L

EF100-300/4.5-5.6 USM

This is Canon's mid range consumer zoom of the trio. It's a current design with a ring USM, full time manual focus and a non-rotating front element. Focus operation is silent and fast, as you would expect. Optically it's pretty good at the short end, dropping to OK at 300mm. Clearly a couple of notches down on the 300/4L and a notch down on the 100-300/5.6L at 300mm. If you want real resolution numbers, at 300mm and on Kodachrome 25 at f5.6, the 300/4 resolves around 80 lp/mm, the 100-300/5.6L about 70 lp/mm and the 100-3004.5-5.6 about 60 lp/mm, all under optimal conditions and in the center of the image.

EF75-300/4-5.6 (II, USM, IS)

The 75-300 is available in 3 flavors. The "II" uses a micro motor (not USM). The USM uses a USM motor (no big surprise), but not a ring USM. It uses a micro USM, so it doesn't have full time manual focus. It's not silent either, though it's pretty quiet. I'm not quite sure just what the advantage over the "II" is. Maybe it's slightly quieter? Maybe it's slightly faster focusing ?(I never compared them directly). It costs $20-$30 more, which isn't really a lot. Personally I wouldn't worry about which version to get too much. If your budget is real tight, get the "II", if not, get the USM.

The front element rotates in both versions and optically they are identical. The lens formula is very similar to the 100-300USM, but you get a little more zoom range. At 75mm it's very sharp. It will resolve 80+ lp/mm on Kodachrome 25 in the center of the frame at f5.6. The edge is a little softer, but still OK. At 300mm as far as I can tell the resolution is the same as the 100-300USM. In the 100-300mm range, there's very little difference in the optical performance of any of the 75-300 lenses and the 100-300 USM.

The 75-300/4-5.6USM is also available in an image stabilized (IS) version. This lens has built in gyros and a system which corrects for unsteadiness when hand held. Typically this enables the user to get sharp images with a 2 stop slower shutter than the non-IS lens. So if you think you can hand hold a 300mm lens at 1/350 and get sharp images, then you should be able to hand hold the IS lens at 1/90 and get equally sharp images. Very useful if you don't use a tripod or you are shooting from a moving boat or an airplane for example. The optically performance of this lens appears to be very similar to the non-IS version despite the extra elements needed for the IS function. I tested the two side by side and saw no significant difference.

What to buy?

If you need an IS lens because you shoot in low light or with slow film and you refuse to use a tripod, then there's only one choice. If you want the best possible optics in a zoom, get the 100-300/5.6L, though personally I'd get the 300/4L if you intend to shoot much at 300mm. If you want the ring USM, full time manual focus, a non-rotating front element, silent operation and fast AF, get the 100-300USM. If you really need the extra range 75-100mm or have a VERY limited budget, get the 75-300. The II if you can't afford the USM, the USM if you can!

Here's an image sample of a small part of two slides (Sensia 100), one shot with a 300/4L at f5.6, one shot with a 75-300 IS zoom at 300mm and f5.6. The scan is shown full size at a resolution of 4000dpi. I think this shows the 75-300 isn't as bad as some people claim, especially when viewing scanned images. The 300/4L image is noticeably sharper under a good 10x loupe, but 4000dpi isn't enough to fully show the difference.

NEW!! 70-300/4.5-5.6 DO IS USM - In 2004 Canon announced a new lens using their diffractive optics technology. It's a 70-300 lens which is about the same size and shape as the 28-135 zoom. They claim the diffractive optics give "substantially superior image quality and chromatic aberration correction compared to previous conventional 75-300mm designs. The bad news is the price of around $1300.