Prime vs. Zoom

I have the Canon 17-55 f2.8 zoom, and am thinking about getting another lens -- fixed focal length. Part of the motivation is size, but another part of the motivation is that I've repeatedly seen it written that prime lenses have better IQ than "all but the best" zooms. I'm wondering whether the 17-55 f2.8 is considered a good enough zoom to be competitive with primes or not. The lens I'm considering is Canon's 50mm f1.4. At comparable aperatures, based on the slrgear.com data, it looks like the 50mm is clearly superior. How does this bear our from those who have both lenses?

The 17-55 f/2.8 is one of canon's best zoom, L or otherwise. Oh, if you don't agree with that and it hurts your 24-70's feelings then check out the review sites like digitalpicture, etc.

Anyway, I wouldn't focus on IQ of the primes vs. the zooms, but more what the prime will give you. With the 50 f/1.4, you get a much much faster lens, and the DOF will be totally different. In print, the images probably won't be any different from an IQ standpoint. Don't buy the lens expecting you will start getting amazing pictures. You can do that already with the zoom.

I agree with the coment above.

If you can't get sharp images from your 17-55 IS, either your lens is busted, or you are doing something wrong.

If however, you are looking to do something that you can't do with your current lens (get the paper thin DOF of f/1.4 with nice out of focus background, Freeze action in low light, put your camera+lens into your coat pocket...) then by all means, go for the prime! You just have to chose the prime that supports whatever it is that you are looking for.

What photos do you want to make that you can't with your current gear?

If "sharp" is the answer, then get your current gear looked at by a shop first! it should be plenty sharp.

D

Sorry to be the voice of impulse and lack of fully fleshed out reason, but if you've never shot with a prime you should really get one, but only one with a nice, big aperture. Having a small, great IQ prime like the 50/1.4 will open up new doors in creativity and portability. Or the 35/2. Or the 28/1.8. Or the 85/1.8. Any fast prime is fun to have, especially if you haven't used one.

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Guv said:

Sorry to be the voice of impulse and lack of fully fleshed out
reason, but if you've never shot with a prime you should really get
one, but only one with a nice, big aperture. Having a small, great
IQ prime like the 50/1.4 will open up new doors in creativity and
portability.

Click to expand...

Yes they can be fun, if you can live with a sliver of your subject being in focus. Maybe the poster should start with a cheap $80.00 50 f1.8 and see if an aperture like this is pleasing to him. I personally find extremely fast apertures don't usually provide the depth of field that I like, but yes... sometimes it's needed just to get the shot. But don't ever think that in 2009 you can't get very sharp pictures from a good zoom.

Generally speaking prime lenses are no longer sharper than good zoom lenses, or at least they are so darn close that it's irrelevant. Although fixed focal length (I don't like the term prime because it implies optical superiority) lenses do have the advantage of shooting in low light with PAPER thin depth of field and foot zooming. This is just my opinion though and what I like.

Guv said:

Or the 35/2. Or the 28/1.8. Or the 85/1.8. Any fast
prime is fun to have, especially if you haven't used one.

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Click to expand...

--
'The truth is rarely pure and never simple' Oscar Wilde

I use both, and both have their advantages and disadvantages.

For me it is not a matter of "prime vs. zoom" but a matter of "prime AND zoom."

The sharpest lens I own is a prime, but sometimes it makes a lot more sense to shoot a particular subject with a zoom. There are a ton of reasons for this, but let me mention one. If, for example, your composition frames perfectly (subject, foreground, background) with a 50mm focal length, in general the 50mm prime will produce a sharper image than the 50mm FL on even a very good zoom. However, if the shot does not frame exactly at 50mm but instead requires, say, 60mm you can "crop in camera" with the zoom (and retain full resolution) but you'll have to crop in post with the prime and lose some resolution. The latter counteracts at least some of the increased resolution of the prime.

OK, one more. What do you do with your photographs? If you share them on the web or perhaps print no larger than letter size the differences in sharpness are entirely moot.

What the heck... a third one. When you shoot, do you always use a tripod, carefully compose and focus, use MLU and a remote release? If so, and you print large, the lens could be a "limiting" factor and you might see a difference. If you shoot handheld or are otherwise a bit more "spontaneous" in your shooting, the lens sharpness will matter little in the end.

Dan

GrahamRobinson said:

I have the Canon 17-55 f2.8 zoom, and am thinking about getting
another lens -- fixed focal length. Part of the motivation is size,
but another part of the motivation is that I've repeatedly seen it
written that prime lenses have better IQ than "all but the best"
zooms. I'm wondering whether the 17-55 f2.8 is considered a good
enough zoom to be competitive with primes or not. The lens I'm
considering is Canon's 50mm f1.4. At comparable aperatures, based on
the slrgear.com data, it looks like the 50mm is clearly superior.
How does this bear our from those who have both lenses?

Click to expand...

--
---
G Dan Mitchell - SF Bay Area, California, USA
Blog & Gallery: http://www.gdanmitchell.com/
IM: gdanmitchell

Gear List: Cup, spoon, watch, shoes (size 12), socks, credit card, eyes, scotch tape, chewing gum.

springbock said:

Guv said:

Yes they can be fun, if you can live with a sliver of your subject

Click to expand...

being in focus.

Click to expand...

That's been my concern in moving to a prime or a macro lens. I currently have the 24-105L and the 100-400L. I'm thinking a 100 2.8 Macro would round me off nicely, but I'm concerned about my novice ability to work with the razor thin DOF.

One question...isn't the razor thin DOF only an issue at the widest apertures on these fast prime/macro lenses, or is it present throughout the entire range of the lens.

As an example, does the DOF differ significantly between a 50/1.2 and a 50/4 if they are both shot at f11???

crumbs said:

I'm thinking a 100 2.8
Macro would round me off nicely, but I'm concerned about my novice
ability to work with the razor thin DOF.

Click to expand...

Macros are not usually shot wide open. I typically stop down to f/11-16 and shoot with flash. DOF is usually smaller than I would like, but it's a different problem than what you're referring to.

--
http://jackandkelly.zenfolio.com/
30D, 40D, 10-22mm, 28-135mm, 50mm/1.8II, 60mm macro
Adapted: Nikkor 50mm/1.4, Kiron 28mm/2.0

I have gone back and forth with this myself, and am on the verge of going prime. All I can do is share my thought process.

If you wish to fill the frame and never crop, a zoom has real advantages, as cropping with your feet is often impossible. There could be a road, or cliff or fence preventing it.

On the other hand, if you wish to print large and have stunning image quality to the very corner, a prime is usually better. This has been my experience in the 17-70 range. I am pretty happy with my 70-200.

This corner issue is probably more critical for lenses at 50mm and below where you may have subject matter from 5 feet to infinity and that framing element in the lower left corner needs to be sharp. I think thats why my 70-200 works for me, you don't use this focal length in that manner, or at least I don't.

Also, if you shot people or other subjects where the critical part of the image is in the center, I think most L zooms will work. Of course if you need faster than f2.8 you need a prime.

However, by that same token, you can use a prime to shot people and crop out a lot of the image. I shot this Christmas with a 35 and 50. The quality even after heavy crop was very pleasing.

When I went to 21mpixels, I found that I can crop the image and still have enough pixels for a high quality print. This makes primes more viable. If you have say a 24mm,35mm and 50mm, at the wide end, you will never have to crop excessively and may have more really high quality pixels left than if you were using a zoom lens perfectly framed.

So thats my story. Just wish I had something a bit wider than 24 to choose in the primes. 14 is wider than I need. 18 or even 21 would be nice.

I should note that I am a landscape tripod cable release MLU sort of guy, so weigh that.

-
http://www.pbase.com/roserus/root

Ben

crumbs said:

As an example, does the DOF differ significantly between a 50/1.2 and
a 50/4 if they are both shot at f11???

Click to expand...

If you shoot both at f/11 there is NO difference in DOF.

People refer to thin DOF on prime lenses because that's what you get when you use a large aperture (i.e. f/1.4) that is simply not available on zoom lenses. The widest any Canon zooms go is f/2.8 AFAIK.

On crop, many good zooms offer more than adequate quality, with excellent centers wide open and sharp images corner to corner around f 5.6- f8. So the difference in quality is not big enough to justify using a prime, you use a prime because it is better wide open and because it opens more (more than f2) for increased low light capability and smaller DOF.

On FF, you need a prime in order to achieve maximum corner sharpness. Great zooms like 16-35 17-40 24-70 still have some traces of corner softness, no matter how much you stop down, while cheaper primes like 35mm f2, 50mm f 1.8 or 85mm f 1.8 achieve tack sharp frames stopped down around f 5.5 - f 8.
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A great prime for a crop camera is the 35L btw. I bought one for my 40D, and it is sharp corner to corner, wide open at f1.4. I have used it extensively for night and indoors photography wide open.

On my 5Dii, this lens is only sharp in the centre when wide open, but remains my lens of choice indoors or in low light, where the focal length suits.

I used the lens because of the speed used it wide open a lot.
Could be a bit sharper at 1.4 but 2.0 is great.

The L zooms are as sharp or even sharper, but not faster.

L primes are really really good. But instead of buying a L 85 1:1.2 you could rent the lens at rentalservice for 10-25 bugs per day. Will not buy this lens, because the situations you "need" a 1.2 85mm instead of a 1.8 85mm are rare.

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crumbs said:

springbock said:

Guv said:

Yes they can be fun, if you can live with a sliver of your subject

Click to expand...

being in focus.

Click to expand...

That's been my concern in moving to a prime or a macro lens. I
currently have the 24-105L and the 100-400L. I'm thinking a 100 2.8
Macro would round me off nicely, but I'm concerned about my novice
ability to work with the razor thin DOF.

Click to expand...

But that is the fun of a prime! photos shot at faster then f/2 just have a different feel . Thin DOF is a powerful tool for intimate portraiture. Check out this tread for a few casual examples:

http://forums.dpreview.com/forums/read.asp?forum=1029&message=30651635

crumbs said:

One question...isn't the razor thin DOF only an issue at the widest
apertures on these fast prime/macro lenses, or is it present
throughout the entire range of the lens.

As an example, does the DOF differ significantly between a 50/1.2 and
a 50/4 if they are both shot at f11???

Click to expand...

The DOF is controlled by aperture, subject distance and focal length. at the same aperture and distance they will have the same DOF. The point is simply that the zoom can't be set to f/1.2, and thus doesn't have the option of such a shallow dof.

So, yes, you can always use a prime stopped down for the same DOF, and probably better IQ at the same aperture, but that won't fundamentally change the image nearly as much as if you try experimenting with it wide open.

and don't worry so much about your novice ability... that is what experimentation is for, and today's cameras handle most of the hard parts. Just set the camera to Aperture priority, set it to the widest aperture you have, set center focus point, put the center point over the eye, half press, recompose, and shoot.



Have fun! Try the thrifty fifty just for the experience! also, one of the smallest and lightest lenses Canon makes, and Excellent IQ at f/2.8 or smaller aperture, and lots of fun at faster settings!

D

I agree 100% another thing to consider is that the 50 equals the long end of your zoom. If you want some to approximate the wide end of your zoom you'll want either the 20mm f2.8 or the 14mm L.

jack

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http://pa.photoshelter.com/user/kurtzjack

All very helpful responses, thanks. Truth is I think my existing zoom is very sharp, though I've often found you don't know a sharper image can exist until you see it. The responses confirm my suspicion that there likely isn't a great difference in sharpness.

Size is one motivating factor. The 17-55 is heavy and big. I mostly shoot at 55, so the 50 is a good approximation. I would lose the ability to open up, which I do do sometimes, but I could live with it (and use the 17-55 when I couldn't). I did some thinking about where I'd most want to be if fixed, and I think it's 50.

The narrower DOF is another attraction, and I think it would be fun to experiment with.

We'll see where this goes...