Prime WA vs. wide end of a WA zoom

After numerous comments regarding the superior sharpness of a 15mm FE over wide angle zoom lenses, I just purchased a Sigma 15mm FE for my full frame 1Ds MkII. Now I'm wondering under what circumstances I might still prefer to take a WA zoom (16-35mm or 17-40mm). It seems to me that I'd choose the 15mm if I'm just planning to shoot reef scenes, but that the zoom might be better for big critters (sharks, mantas, etc.), because I could still zoom in when they aren't near enough.

Can those of you with more extensive experience show examples (or just explain) when you choose to use a fixed WA lens (like the 15mm with full frame cameras, or maybe a 10mm on a cropped sensor camera) vs. a WA zoom (e.g., 16-35mm for full frame, 10-22mm for cropped...)? I think this might be an issue of interest to lots of people...

Well you do not allways need 180 degrees.

Big animals, dolphins, sharks, turtles, divers usually work better on a less wide lens as most of the time, they do not allow you to shoot them from 6" away.

To me, the only WA zoom advantage is just the flexibility to have longer focal length available. If I don’t need it, I always prefer the fisheye prime. My fisheye has not 180° due to the smaller imaging chip. But I would use it the same way with 180°, when I can get close enough and won’t shoot sharks, etc..

Julian

I choose fixed primes for a simple reason, I concentrate a lot more in composition and finding subjects when I am using a fixed focal lenght lens. When I dive with, say the 17-55 I look for everything from real wide to big fish, and I am sure sometimes I miss both. So I think my best wide angle (and macro) shots are with fixed lenses.

Not to say that I never use a zoom, I do, and sometimes they are very useful, especially for large animals as William said.

Interestingly, unlike Rocha, I think the composition of my shots has improved since I switched to using a w/a zoom for w/a. For years I shot all w/a with a 20 mm prime (on my old F801s film housing). When I moved to the fuji S2, I also bought a 11-24 mm zoom.

The difference for me, I think, is being able to change framing quickly without having to move forward or backwards. Particularly when shooting w/a with fish in the scene, as there may not be time to frame properly with a prime lens before the subject swims away or changes position, esp. if it's necessary to approach too close to its comfort zone. I do use the 10.5 prime a lot, more and more actually, but I haven't used the 20 mm prime (which would be the equivalent of a 30 mm on my rig now anyway) for a long time.

As per Rocha's comment, when diving with a 12-24 mm (as opposed to the 17-55 or a lens with a larger zoom range), one is still very focused on finding the right wide-angle subject, but it can be useful to be able to quickly zoom in and out to get the subject in the frame the right way.

Frogfish

This is a great topic and I hope more people using both continue to post - I wanted to add that with the 12mp bodies comming out, you will be able to crop with higher quality. If that prime lens is just too wide take the shot anyway you will be able to crop and still have a quality shot. Same with the zoom also but this factor will really help to favor the primes.

I've just been using a 20mm Canon fixed focal behind a smallish dome and found that it is pretty reasonable. Corner sharpness is not bad, if not perfect, and despite the lens not being an 'L' series lens, and one that doesn't enjoy the best of reputations topside, it still turned out some very acceptable results. I'm still trying to sort out whether I prefer this, the 24mm f/1.4 or 17~40mm f/4 lens. I am not a great user of fisheyes and at the moment am erring towards the 20 and 24 lenses.

This is because of:

Optical quality, corner sharpness, size and ease of use of the smaller ports and last but not least, because I personally prefer working with a fixed focal length lens!

At the end of the day you do have to decide what you like working with for yourself after due consideration of the pros and cons of each, of course.

As a side (but related) topic, is there any consensus as to whether fixed or zoom WA is better for over/unders, or does it make no difference (i.e., it's just dependent on the quality of the lens)?

Hi Bruce,

It seems to me that a fixed focal length lens will kill a zoom anytime. It's easier to get a good lens design if you only have to make it work at one focal length I suppose. Add to this that many fixed lenses are a LOT faster, whereas most zooms top out at f2.8 Shooting an f1.4 prime at f2.8 means you're literally two stops from "wide open."

Cheers

James

As a side (but related) topic, is there any consensus as to whether fixed or zoom WA is better for over/unders, or does it make no difference (i.e., it's just dependent on the quality of the lens)?

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I shoot a lot of split level under overs and always use a 180 degree fisheye.

Only very occasionally will I use other lenses for these shots.

Alex

For split shots I want max. possible DOF and a wide field of view. That's why I prefer the Sigma 10-20mm @10mm for split shots. My 15mm fisheye has roughly the same field of view but DOF is smaller due to the higher focal length. However, both lenses are not wide enough for my taste. Did I mention that I am a poor Canon user without a 10mm 180° fisheye lens for 1.6 crop? The lens I would like to use for split shots isn't available at the moment ... .

Julian

It seems to me that a fixed focal length lens will kill a zoom anytime.  It's easier to get a good lens design if you only have to make it work at one focal length I suppose.  Add to this that many fixed lenses are a LOT faster, whereas most zooms top out at f2.8  Shooting an f1.4 prime at f2.8 means you're literally two stops from "wide open."

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James,

Playing devil's advocate...with an actual example, I have Canon's 16-35mm L lens, which is f2.8, and I just bought a Sigma 15mm FE, which is also f2.8. So at the wide end, there's no speed advantage in that case (whereas the 15mm f2.8 has a definite speed advantage over my 17-40mm f4.0 L). So speed is definitely one factor.

But what I "hear" you saying is that even when you're comparing two lenses of equal speed, the fixed lens is still likely superior simply because (assuming both are well-made) the more straigtforward design of a prime lens makes it "better?"

I realize that this all assumes a person is shooting both lenses at roughly the same focal length (i.e., it isn't addressing the added flexibility of a zoom), but it is an important issue nonetheless. If good primes are simply "better" than good zooms, then in cases where you are diving to specificallly photograph something that can't swim away (e.g., a reef scene, a wreck, etc., rather than sharks, manta, etc.), would you not always choose a fixed rather than a zoom?

difference between primes and zooms is very small compared to what superior image quality fisheyes deliver behind a dome glass. wideangle corners are poor compared to fisheyes, especially with open aperture. I would rather concentrate the question on fisheye vs. rectilinear instead of zooms vs. primes.

Julian

Hmmmm. Not all fixed focals are actually better than zooms! Many zooms are far newer designs and sometimes exceed older fixed focal designs in terms of their 'quality' - whether this shows up significantly underwater is something else! Nikon's 28~105 has a reputation of being as good as their 28mm fixed lens at 28mm - though I've never put them side by side I can vouch for my copy of that zoom being an excellent lens.

What is more significant is that the performance of zooms can often only be optimised at one focal length and very wide zooms often have soft corners when their field of view exceeds 90 degrees which worsens if they are not optimised at the wider end.

Regarding fisheye and rectilinear lenses, in my opinion (and it is only my opinion) they require a very different approach - I personally like to use 80~90 degree field of view fixed focal length lenses because I like their characteristics and enjoy the discipline that they impose on my photography. I've used various wide zooms (17~35, 12~24, 17~40) and both 15 & 16mm fisheyes, but still enjoy and prefer 20 and 24mm fixed lenses.

So these lenses are those that I use most. Fortunately other people have other preferences - the world would be an exceedingly dull place if convergent evolution drew us all to the same conclusions over everything!