If primes have better image quality than zooms !!

scottduffy

scottduffy

Messages
3,347
Name
Scott
Edit My Images
Yes
Does this mean cheaper primes will have the same image quality as more expensive zooms? Will the Canon 70-200 f4 L have similar quality to one of the 50mm primes like the f1.8 or f1.4 or does it just mean that the primes in the L series are better than the zooms in the L series but the L series zooms are still better quality than the non L series primes? Hope you follow that gobildegook
 
depends entirely on the lens in question you cannot generalise to the extent you are hoping too, some non L primes will be better than some L zooms and vice versa. Generally the L series primes are about as sharp as you'll get.
 
L series primes are so sharp you can cut your eyes by looking at them too hard :D

in any price bracket a prime is sharper and usually in the bracket above too. My 50mm f1.4 is sharper than my 80-200L @ f2.8 and 4, not tried much higher

however that does reverse sometimes as my 135 F2.8 SF is not all that sharp
 
Generally the L class zooms are very close to good quality primes. As has been pointed out, it would be wrong to generalise but the closer you get to standard (say 50mm), the easier it is to manufacture and the less the difference.

However, there is more to this than meets the eye. Other factors such as the shape of the out of focus area in the pics can be cruder in the cheaper lenses (again thinking in particular the 50mm f/1.8). Also, they may need to be stopped down to a larger f number to a point where there is no advantage in having a faster lens (compared to an L zoom).

And there is build quality, which may be an issue.

Graham
 
Thanks guys. Graham is that why people go on about lovely bokkeh then in some lenses?
 
It depends, and you can only generalise, but when it comes to lens design, the less compromises you have to make, the better you can make it. And obvioulsy, a zoom is a much bigger compromise than a prime with just one fixed focal length.

What tends to happen with primes is that the designer will use the extra scope to give a really big maximum aperture (low f/number) like f/2, f/1.4 or even f/1.2. No zooms go better than f/2.8 (*) and the more affordable ones are around f/4.

Canon L lenses, and other similar premium lenses, are not just really good glass. You pay a lot for the construction, which is much more robust and often weather sealed, plus things like the lens doesn't extend when focusing or zooming is really nice (helps weather sealing too).

* Actually, Olympus makes f/2 zooms but that's because their 4/3rds format is much smaller and that allows them to do other things. Of course, there are downsides to a smaller format ;)
 
scottduffy said:
Will the Canon 70-200 f4 L have similar quality to one of the 50mm primes like the f1.8 or f1.4
Click to expand...

TBH that's a bad question to ask. That zoom is on-par (in IS form particularly) with almost any prime at F4 but there is the compromise - it's F4.

The 50mm F1.8 is nice and sharp but has a cheap 5-bladed diaphram which gives someone ropey bokeh (shape of out-of-focus highlights).

Excluding the zoom above then there are other issues they contend with like light fall-off at the edges at the short end, barrel and pincusion distorition varying across the range, keeping the focus consistently sharp across the range, slow apertures at the long end for cheaper zooms etc etc.
 
My 80-200 af-s is the exception to this rule, its sharper at 85mm f/2.8 than my 85mm f/1.8 prime at f/2.8. And the 85mm prime is SHARP.
 
I have been reading a book by Tom Ang, which I found quite interesting. It mentions that zoom lenses have a sweet spot in their focal range and that anything above or below that sweet spot will very gradually start to lose quality, whereas a prime lens will be calibrated to always be on that sweet spot.

He also mentions the aperture playing a part in quality. Apparently the widest aperture is never the best aperture and the sweet spot aperture is usually 3 or 4 f stops higher in zoom lenses and 2 or 3 f stops higher in prime lenses.
 
Generally speaking, if you can put up with a fixed focal length you'll get more bang for your buck with primes but most of the time you'll need to stop them down 2-3 stops to get to the sweet spot in terms of sharpness. The L series primes are normally the exception to the rule and are generally outstanding at any aperture (though still even sharper when stopped down). Primes also don't suffer from barrel or pincushion distortion in the way zooms do.

It can be a pain having to change lenses in some circumstances so it helps to have two bodies with different primes on.

George.
 
alexisonfire said:
Nikon 80-200 af-s f/2.8 @ 86mm f/2.8
http://www.msphotography.net/random/802008628.jpg

Nikon 85mm f/1.8 @ 85mm f/2.8
http://www.msphotography.net/random/8528.jpg

The 80-200 is crazy, i have no idea how they have made a zoom this sharp.
Click to expand...

Yes, but the zoom is rubbish at f/1.8 ;)

You can talk about sharpness, and edge sharpness, and vignetting, distortion, flare, size, weight, cost etc etc, but the big difference is that primes do low f/numbers, and they do them well, if that's your thing.

For most people, focal length range is a bigger priority, and you can get around the low light problem, at least to a large extent, with IS and the very good high ISO performance cameras give these days. Which only leaves shallow depth of field as the one trick that primes can do, and zooms cannot.
 
HoppyUK said:
Yes, but the zoom is rubbish at f/1.8 ;)

You can talk about sharpness, and edge sharpness, and vignetting, distortion, flare, size, weight, cost etc etc, but the big difference is that primes do low f/numbers, and they do them well, if that's your thing.

For most people, focal length range is a bigger priority, and you can get around the low light problem, at least to a large extent, with IS and the very good high ISO performance cameras give these days. Which only leaves shallow depth of field as the one trick that primes can do, and zooms cannot.
Click to expand...

My only zoom is the 80-200, all my other lens are primes for the very reason you said. I was simply stating that nikon have used witch magic on the 80-200 to make a zoom this sharp :LOL:
 
scottduffy said:
Thanks guys. Graham is that why people go on about lovely bokkeh then in some lenses?
Click to expand...


bokeh is more down to how wide you can go with the aperture. its generally easier to get a fast prime than it is to get a fast zoom, in fact f/2.8 is about the widest you can get with most zooms. an f/1.4 prime set wide open should give stronger bokeh than any zoom @ f/2.8
 
kman said:
bokeh is more down to how wide you can go with the aperture. its generally easier to get a fast prime than it is to get a fast zoom, in fact f/2.8 is about the widest you can get with most zooms. an f/1.4 prime set wide open should give stronger bokeh than any zoom @ f/2.8
Click to expand...

think he means the quality og the bokeh, generally on the cheap as chips 50mm primes its a bit pants as the oof highlights are v boxy, the dearer ones with more aperture blades tend to give a much more even blur
 
I have been reading a book by Tom Ang, which I found quite interesting.


I have a book by Tom Ang in the house too and have been too busy reading the Canon 450d for dummies to read it. I will have a look at it over the weekend. Thanks again
 
kman said:
bokeh is more down to how wide you can go with the aperture. its generally easier to get a fast prime than it is to get a fast zoom, in fact f/2.8 is about the widest you can get with most zooms. an f/1.4 prime set wide open should give stronger bokeh than any zoom @ f/2.8
Click to expand...

Getting the DOF effect is down to the aperture yes, but getting a *pleasing* bokeh is down to the shape and number of the blades...
 
HoppyUK said:
Which only leaves shallow depth of field as the one trick that primes can do, and zooms cannot.
Click to expand...

Is that because you can't get a zoom below with a bigger aperture thanf2.8?

Doesn't f2.8 give you a shallow depth of field though?
 
trapper501 said:
Is that because you can't get a zoom below with a bigger aperture thanf2.8?

Doesn't f2.8 give you a shallow depth of field though?
Click to expand...

F2.8 is shallow but F1.2 is quite a bit shallower... I've even seen an f0.95!
Also remember that the sharpest point is normaller a stop or two down from wide open so on an f2.8 lens you might end up shooting at f4 to get the best clarity.
 
trapper501 said:
Is that because you can't get a zoom below with a bigger aperture thanf2.8?

Doesn't f2.8 give you a shallow depth of field though?
Click to expand...

Yes, zooms can't compete on the mega-shallow depth of field front because f/2.8 is as big as they go. And yes also, for most people f/2.8 is adequate.

For example, if you zoom to 100mm at f/2.8, and focus at 2m for a portrait, depth of field will be 6cm. But if the lens can go two stops bigger to f/1.4, depth of field is cut by half to just 3cm. If you go the other way and close down two stops to f/5.6, depth of field is 13cm (full frame camera).

Those figures are when using a full frame camera. If you're on crop format you get more depth of field, because you would zoom back to a shorter focal length, about 65mm, to get the same framing. The smaller image size gives inherantly more depth of field. The difference is about 1.2 stops. For the same reason, 4/3rds format gives even more depth of filed, 2 stops more than full frame, and the tiny sensors on compact camera deliver so much depth of field that it's often quite hard not to have everything in focus.

Dramatic bokeh is the other thing you get with very low f/numbers, with backgrounds thrown massively out of focus, all soft and blurry in a pretty unique way.

Some people might argue that such shallow depth of field is a bit of a liability and is restricting in low light, when all you want from a low f/number is a higher shutter speed. For those people, the high ISO route with IS or VR is a better way, and it's a heck of a lot cheaper.

But big aperture primes have an enduring appeal to enthusiasts, sometimes against purely logical arguments. It's a unique look. That's the beauty of photography, so many ways, different views, creative options.
 
You must log in or register to reply here.
Back
Top