Forgotten in its old age

by Aditya

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I have read comments in multiple places, both on photo.SE and elsewhere, that superzoom lenses are not good and that most people will be better served by buying two zoom lenses, each spanning a smaller zoom range.

Specifically, I own the Sony NEX-5R, with the 35mm Sony F1.8 and the 19mm Sigma F2.8. I'm trying to decide whether to buy a superzoom lens, specifically, the Sony 18-200, as opposed to a non-superzoom lens like the Sony 16-50 or the Sony 18-105.

From DXOMark, the 18-200 has a perceptual megapixel score of 5 megapixels, while the 16-50 has a score of 7 megapixels. This seems like a small difference. Why do superzooms have a bad reputation? For comparison, the 35mm prime has a score of 11 megapixels.

Even 5 megapixels is not a significantly higher resolution than my 15-inch Retina Macbook Pro (5.05 megapixels) or my 30 inch monitor (3.9 megapixels). So it looks like I'm not going to notice the supposedly worse performance of the superzoom. I don't pixel-peep or print out my photos.

Note that I'm not looking for the Nth degree of optical performance here. I wouldn't pay hundreds of dollars for a small difference in performance (F1.4 vs F1.8, for example), or inconvenience myself by carrying and changing between two zoom lenses instead of one superzoom lens, if the differences were not visible to most people.

Is this analysis and conclusion correct?

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7 is 40% more than 5. It's a huge difference but if you don't look at your photos, you wont notice! –  Itai Jan 2 at 2:16
    
I understand what you've written here -- the logic makes sense -- however your conclusion seems at complete odds with what DXOMark is saying: the prime is very good; the zooms are mediocre and poor. I have trouble believing anyone wouldn't notice the difference between "very good" and "poor" lenses. –  Dan Wolfgang Jan 2 at 2:29
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Itai, when you said "if you don't look at your photos", did you mean look at them zoomed in on the computer? Dan, under what circumstances would I notice the difference between the "good", "mediocre" and "poor" lenses? Only when I crop? –  Kartick Vaddadi Jan 2 at 3:52
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I think it will help to take a look at What characteristics make a good lens good?. An extreme zoom lens requires a lot of design compromise in areas beyond resolution and sharpness. –  mattdm Jan 2 at 4:33
    
I actually did take a look before, Matt, and briefly glanced through it again. You were kind enough to point this out to me in the context of another of my questions. But what's missing for me is an understanding of how much these factors matter. I don't care about distortion to the extent it can be corrected automatically in camera and in LR. I don't remember being upset about the quality of the bokeh, or the edge sharpness, or the flare in many of my photos. So, yes, these are the factors, but how much do they matter in practice for a layman like me (not expert with equipment costing $3000)? –  Kartick Vaddadi Jan 2 at 5:24

2 Answers 2

up vote 16 down vote accepted

I'm going to go all contrarian here. That is, against the protestations of photographic craftsmen, and against my own nature, I have to say that the value of a lens, any lens, lies not in its absolute, measurable qualities, but in what it does for your photography. And that means that the ends and aims of the photographer matter when deciding whether or not a particular lens is "good enough".

That 5MP sounds horrible to a lot of us. (So does the 7MP of the 16-50.) But it's enough for a good 6" x 9" print or a very acceptable 7-1/2" x 11-1/4" by anybody's standards. You can get away with a larger print if it's going to be viewed from anything more than arms' length. It' certainly good enough for a 1080P screen, and you'd need to pay close attention to notice anything amiss on a 4K screen. And those are pretty hard limits — the option to print large on glossy or lustre paper and examine your work close-up, filling your insides with a warm sense of pride in a job well done isn't quite there. For most of the people wrapped up in photography as a serious hobby (or, often, as a business), that sours things quite a bit.

The fact remains, though, that these "horrible" lenses can be perfectly adequate for a lot of people's ordinary use cases. You can shoot for the screen; you can shoot for the book-sized print (six by nines on twelve-inch-square pages is a lovely format); you can shoot for the larger canvas print (where minute detail is going to be lost in the texture of the ground anyway). And, you know, that's sometimes good enough. (Unless things have changed in the last couple of weeks, National Geographic still has a 6MP minimum standard. It's not that they don't want larger files, but that 6MP is good enough for a double gatefold at their format, provided that there are no other problems with the picture.)

So, yes — the lens is a horrible one. It causes you to "waste" precious pixels. And that matters if you had any plans to use all of those pixels. But if you're shooting to share online, shooting for the web, shooting for an album — basically, if you're not shooting for gallery prints or display ads and have no plans to expose yourself to gearheads online — and the lens allows you to go places and take pictures, then it's probably good enough. And coupled with the NEX 6, it's a lot better than the compact superzoom alternative.

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Agreed on most of that but generally for the cost of a Super zoom you can get multiple lenses to cover the range better. It's only worth it If you need the single lens to be your only lens for some reason. –  AJ Henderson Jan 2 at 4:53
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Thanks, AJ. I've heard this argument before, but keeping in mind that I'm a layman rather than an expert with thousands of dollars worth of photographic equipment, why suffer the inconvenience of swapping lenses for a unnoticeable improvement in quality? Am I missing something? –  Kartick Vaddadi Jan 2 at 5:19
    
@KartickVaddadi Everything Stan says is correct except for one small detail: You do look at your photos more critically than your question implies. All anyone has to do is read the questions you've asked here in the last couple of months. You're not worried about the difference in resolution between the 18-200 and the 35 prime yet you agonize over photo.stackexchange.com/questions/45426/… ? Or photo.stackexchange.com/questions/46009/… ? –  Michael Clark Jan 2 at 7:55
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I just want to make sure I don't end up spending close to a thousand dollars or accumulate too many or too big lenses when something simpler will do the job. If it helps, this is like someone asking me what I think of a $500 Dell laptop. I may say it's "horrible", but that might be the right choice for them. So I just have to dig in a little deeper and try to understand what does and doesn't matter to me. Thanks for your help. –  Kartick Vaddadi Jan 2 at 8:23
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One other clarification: I may have asked questions about minutiae like median blending, but that's only because I don't know how much each aspect affects the final photo. Thanks again. In other words, I asked about minutiae not because I'm interested in minutiae, but because I didn't know it's minutiae :) –  Kartick Vaddadi Jan 2 at 8:38

The 16-50 isn't particularly great either from the sound of it, but that doesn't mean that the 18-200 isn't pretty mediocre. I mean, not being able to shoot more than 5mp of meaningful photo with the lens is not very good. I'd say that is more an example of proving the point.

You can find bad lenses in any category, but until you can show me a good super-zoom, it still doesn't mean they are a good investment.

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Unfortunately, DXOMark doesn't seem to have the numbers for other Sony E-mount zooms, like the 18-55, 55-210, 18-105, or the 18-200 (non-LE version). When you say 5MP is pretty bad, do you have cropping in mind? Otherwise, how does it help to have higher resolution than my monitor can display? –  Kartick Vaddadi Jan 2 at 3:49
    
I could compare lenses from other APS-C mounts, like Sony A-mount, or Canon or Nikon, but that will mean comparing lenses with different bodies, which sounds like an apples and oranges comparison. Please let me know if I'm wrong. Note that I don't want to compare two Canon lenses, or two Nikon lenses, because I won't be buying them. I'd also flip your "show me a good super-zoom" question around, and ask, "Is there a non-superzoom zoom lens for the E-mount that's noticeably better than the aforementioned superzoom?" If not, I might as well buy the superzoom, right? –  Kartick Vaddadi Jan 2 at 3:56
    
If you only plan to view on screen then you'll never need more than 3 megapixels, so you'd be OK with either, but it would be limiting your camera if you do decide to print any ever. I also don't know about other lenses for that camera. It may be possible that they don't make any lenses for it that fully utilize its sensor, though that would be rather unfortunate. –  AJ Henderson Jan 2 at 4:57
    
It's also not apples to oranges to compare any lenses. The camera body doesn't impact lens performance. Resolution of a lens is just its ability to sharply resolve points of light. Ie, what the smallest thing you could see through it is. –  AJ Henderson Jan 2 at 4:59
    
Understood. In any case, I don't want to compare a lens that's not for the E-mount, since I'm not buying that. –  Kartick Vaddadi Jan 4 at 7:20

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