I'd like to know if anyone has any advice or experience they can share about using a pair of zoom lenses that have overlapping focal lengths; or a pair of zoom lenses that have adjacent focal lengths.
I've narrowed down my next big lens purchase to a couple choices, one of which has a focal length range that overlaps a lens I already have and one that has a focal length range that sits next to it. I can compare all their technical attributes through available review sites, but I don't have any experience with the overlapping-vs-complementary question and have read very little about it online.
The overlapping lens neatly encompasses my favorite focal lengths, but I'm concerned that if I buy it I'll use it to the exclusion of my current lens and as a result I'll grow to hate it because it means I leave a great lens in my bag or at home. On the other hand, I fear that if I buy the complementary lens I'll have to change lenses for every other picture. (Obviously there are a lot of pros to each, but its those cons as well as the ones that I don't know about that keep worrying me, so I have a hard time comparing them since I have no experience with this.)
I'd love to know why you chose to go one way or the other, and what you thought after you used the lenses for a while.
Edit 2011-02-10: A couple answers mentioned the common weakness of lenses at the edges of their focal length ranges, which I think is the killer reason to get overlapping lenses. After reading the rest of the answers, though, I see that I wasn't very clear in my question, and I think that using real lenses in my example was a bad idea. Here's my attempt to clarify my question:
Suppose I have a DSLR whose sensor has some unknown crop factor. I currently have a 20-45mm lens, and after trying some other lenses in the 20-200mm range I come to the conclusion that my favorite pictures are all in the 25-70mm range. After investigating lenses I narrow down my choice to two lenses, a 35-85mm lens and a 45-85mm lens. So the lenses in question look like this:
1 2 3 4 6 8 2 0 0 0 0 0 0mm ==#====.====#====.====#====.== +----.----#+ | current | +----.-----+ +-.----#----.--+ | sweet spot | +-.----#----.--+ +-#----.----#+ | proposed | +-#----.----#+ +---.----#+ |proposed | +---.----#+
Clearly there's no do-it-all lens, but one, out of many, of the differences between the two lenses I am choosing from is that one overlaps my current lens and the other one doesn't. I research both proposed lenses, let's call them Lens A and Lens B, and I rank all their attributes, like this:
| Score Feature | Weight | Lens A | Lens B --------------+--------+--------+--------- Max Aperture | 5 | 5 | 4 Size/Weight | 4 | 3 | 4 IS/VR/OS | 2 | 4 | 5 AF speed | 3 | 4 | 3 Full-time MF | 4 | 5 | 4 Brand | 1 | 3 | 5 Sharpness | 4 | 4 | 4 Flare | 1 | 3 | 5 CA | 5 | 4 | 5 Other stuff...| | | Price | 4 | 1 | 2 Overlapping | ? | ? | ?
Now, I'm asking you to help me answer those three question marks. Is it better or worse to have overlapping ranges, and how important is that. Once I know which option is better, I can give the two lenses their rankings (probably '1' and '5' to indicate they are on opposite ends of the spectrum) and then I can weight the subject based on how important I think that is. Obviously these are somewhat subjective questions, but unlike everything else in the table, there has been very little written about this subject online, that I've found, so I don't have a lot of opinions to draw from. That's where you come in :)
(And please don't overanalyze the table, the numbers are all made up.)