Alley in Pisa, Italy

by Lars Kotthoff

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There seems to be a preference for to have the

  • 18 mm - 55 mm
  • 55 mm - 250 mm

lenses, but no mention of why they're better than a single 18-200mm. Could someone please explain why the two separate are better than the one combined, and if anyone has quantified this difference?

(I'm curious about Canon in particular.)

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3 Answers 3

  1. Image quality. The wider the range of focal lengths on one lens, the more design compromises are made and the more correction must be applied deal with things like geometric distortion, chromatic aberration, and light fall off in the corners.

  2. Aperture. Even though the EF-S 18-200mm f/3.5-5.6 has the same maximum aperture of f/5.6 as the EF-S 55-250mm f/4-5.6 IS II at each lenses respective maximum focal length, the 18-200 is slower for most of the range they share in common. The 18-200 is at f/4 by 28mm, f/4.5 at 45mm, f/5 at 55mm, and f/5.6 from 80mm on up. The 55-250, on the other hand, doesn't reach f/4.5 until 74mm, f/5 until 96mm, and f/5.6 until 154mm.

  3. Price. Depending on where you buy, the kit with the EF-S 18-55mm f/3.5-5.6 IS II rarely costs much more than the body only for the cameras it is offered with. I have seen occasions, usually during camera+lens rebate promotions where the kit was actually cheaper than the body only! The current difference at amazon.com for a T4i body is $16 less than the kit. So the 18-55 costs very little. The EF-S 55-250mm f/4-5.6 IS II goes for about $300 in U.S. stores, but you can get it from amazon.com for $174. The EF-S 18-200mm f/3.5-5.6 IS sells for around $700 in the stores and $569 on amazon.com. The 18-55 & 55-250 will run you around $190 more than a T4i body. That's $379 cheaper than the 18-200. The Sigma Sigma 18-250mm f/3.5-6.3 DC OS HSM IF is even slower than the Canon 18-200, costs $349 and performs about the same or worse than the Canon 18-200.

The-Digital-Picture reviews the EF-S 18-200mm f/3.5-5.6 IS lens here, the Sigma 18-250mm f/3.5-6.3 DC OS HSM here, and the EF-S 55-250mm f/4-5.6 IS II here.

DxO Mark has all the quantification you could want of theses three lenses.

Here's a screen grab comparing the Canon 18-200, Canon 55-250, and Sigma 18-250. The charts show sharpness at maximum focal length and aperture of each lens. Green is sharper, yellow is in between, and red is less sharp.

Screen grab

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1  
So you really do pay substantially more for a lesser product if you go with the 18-200mm than the two lenses 18-55mm and 55-250mm –  Evan Carroll May 3 '13 at 8:45
4  
Unless the portability of only one lens is the most important feature to you. –  Michael Clark May 3 '13 at 9:37
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A smaller zoom range means fewer compromises in the optical design and usually better quality. It's better to have a boat and a car and use them where appropriate than to have some sort of boatcar that doesn't do either job as well.

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BUT BUT BOATCAR! –  Peng Tuck Kwok May 3 '13 at 9:03
2  
And so a new term enters the discipline of photography. "Dude, that lens is a total boatcar, why did you buy it?!". Not to be confused with bokeh, of course. –  ElendilTheTall Jun 24 at 10:56
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Although the two answers are correct, I would like to chime in with a slight different opinion --- notice that I am not a professional by any means.

I used to have the to kit lenses for my Sony Alpha 55 (18-55 and 55-200) and switched to a new configuration where I have a 18-250 and a couple of nice, sharp primes (a 35/1.8 and a 105/3.2 macro).

I have probably lost a bit of sharpness by switching the two zooms with the new one, but I really am much more comfortable with this set-up. I have a lens that cover a lot of focal range and get the work done for small prints, the web and for the family snapshots. It let me switch from a moderate wide angle to a nice zoom --- got that squirrel stealing a nut to my daughter while I was photographing the view of a lake.

And when I see something more worth a good photo, that I probably would want to print and enlarge, I use the primes, that are much better to what the two kit zoom could ever delivery.

If you like a bit of humor about this theme, read John's Shermann take on "18-300 is bad".

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