prime lens

julie32 · Jan 2, 2008

hey guys,
why would someone use a prime lens over a zoom lens? Whats the benefit of not being able to zoom in if you want a close up shot at an event or something.
Please explain.
thank you.

usayit · Jan 2, 2008

Zoom lens has a variable focal length. For example Canon 24-105mm f/4L

Prime lens has a single focal length. For example, 50mm f/1.4

Image quality is usually superior for prime lenses due to the simplicity of their design. Zooms provide the convenience of changing the focal length with a simple twist of a ring but their complex design usually requires a bit of a sacrifice in terms of image quality.

Depending on the photographer, you can shoot any close up shot at an event using either a Zoom or Prime lens.

kundalini · Jan 2, 2008

A few more advantages I have found with the primes is the weight, sharpness and compactness. Oh....and not to be dimissed, the fact you have to be creative to get "the shot".

I have 3........well, 4, but not counting a 300mm, they each have a purpose.

Mav · Jan 2, 2008

The biggest advantage of prime lenses is their speed. The quickest zooms will go is f/2.8, but you can get normal and short tele primes at f/2 and f/1.4 which is a ton faster, and lets you shoot with natural light where an f/2.8 would need a flash. They're also ultra-small, ultra-light, and usually pretty affordable except for the more exotic ones. The fixed focal lengths force you to explore different angles and perspectives that you might not have found if you were using a zoom. I think zooms make me lazy, and I like the photos I get that I take with primes more, just because I find the angles and perspectives to be more interesting. The large aperture can also give you a very tight depth of field which is ideal for portrait type photos where you're trying to blur out the background and isolate the subject.

Two quick examples...

Father of the Bride, Nikkor 85mm f/1.8D @ f/1.8 on my D80. That's in a kitchen with an ugly refrigerator and stupid post it notes behind him, but you can hardly tell thanks to the tight depth of field, lol. With a zoom which wouldn't give as tight of a depth of field, more of the background might have been in focus which could have ruined the shot.

My 9 month old teaching herself to stand and balance with my Nikkor 35mm f/2 @ f/2 and 1/30s via natural light and Auto ISO at 560. To pull this off with an f/2.8 zoom, I would have needed iso1120 which would have been a lot noisier. Or with a slow f/3.5-5.6 or f/4 zoom that would have been at about f/4 wide-open, I would have needed over iso2000 which just wouldn't happen short of having a significantly more expensive body. No processing on this one - straight off the camera.

Another from my Nikkor 35mm f/2. This one is at 1/15s, f/2.8, and iso1000. That's my hand in the back, my wife's hand, and then our little girl's. This illustrates the great handling of prime lenses, since I had my D80 with the 35 f2 in the other hand. A much bigger and far clumsier f/2.8 zoom would have made this shot impossible, on top of the fact that they usually don't focus this close. Primes let you get right into your subject without a big honkin' zoom getting in your way.

So yeah, I'm a big prime fan.

As far as sharpness goes, the best professional grade zooms out there will match or beat primes for sharpness these days, but "in most cases" when comparing consumer grade zooms to similarly priced prime lenses, the prime lenses will definitely have better image quality more often than not.

One last one with my 50mm f/1.8 @ f/6.3 in Program Auto mode. This is the sharpest and contrastiest lens I have, and it only cost 100 bucks! LOL Can't beat it!

kundalini · Jan 2, 2008

Those are the three primes I was speaking of. Love 'em.

Mav · Jan 2, 2008

Yup, the 35/50/85 trio is great. :mrgreen: Best of all, if I upgrade to full-frame (the coming Canon 5D competitor) I can still use all of them. Ditto with Canon shooter with Rebels or 20/30/40D's. All of the primes in that length are EF and compatible with the full-frame and 1.3x sensor professional bodies. OTOH, the $1000 EF-S 17-55 f/2.8 IS and $1200 Nikkor 17-55 f/2.8 DX are useless and only work on the 1.6/1.5x crop bodies and you've got to go and sell it.

Sideburns · Jan 2, 2008

Primes are cheaper, faster, and sharper. Usually more contrast as well.

I think I just summed it up quite nicely if I do say so myself.

usayit · Jan 2, 2008

Way to Go Sideburns!

Reach back there and give yourself a pat.

osirus · Jan 2, 2008

i got the nikon 50mm f 1.8 prime for an xmas gift, and love it so far

none of my zooms will open wide enought to let me shoot at this low light.
(me just messing around in the car.. It was darker out than it looks in the pics)
and then a quick pic of my dog.
no lights on in the kitchen,no flash needed.. and i love the DOF

ANDS! · Jan 3, 2008

I thinks its a tad misleading to say that a "zoom" lens cant achieve the same DOF as a prime. They DO make zoom lenses with the same speed across the entire focal length. The pictures may not be as sharp as a single focal lens, but the DOF should be just as shallow.

Sideburns · Jan 3, 2008

ANDS! said:
I thinks its a tad misleading to say that a "zoom" lens cant achieve the same DOF as a prime. They DO make zoom lenses with the same speed across the entire focal length. The pictures may not be as sharp as a single focal lens, but the DOF should be just as shallow.

True, if the aperture and focal length are the same.

I don't think I've ever seen a 1.8 or faster telephoto zoom.

Helen B · Jan 3, 2008

Just as an aside, maximum aperture for zooms depends a lot on format. I have an f/1.1 16-44 mm and an f/1.6 9.5-56 mm zoom but they only cover 16 mm film, which is smaller than a 4/3rds sensor.

Best,
Helen

Mav · Jan 3, 2008

Helen B said:
Just as an aside, maximum aperture for zooms depends a lot on format. I have an f/1.1 16-44 mm and an f/1.6 9.5-56 mm zoom but they only cover 16 mm film, which is smaller than a 4/3rds sensor.

Best,
Helen

Yes, that's true. And I've heard of an f/2 zoom for the 4/3rds system too. The largest aperture zooms I've heard of for Nikon 1.5x / Canon 1.6x cameras is f/2.8.

Mav · Jan 3, 2008

ANDS! said:
I thinks its a tad misleading to say that a "zoom" lens cant achieve the same DOF as a prime. They DO make zoom lenses with the same speed across the entire focal length. The pictures may not be as sharp as a single focal lens, but the DOF should be just as shallow.

They can, but you'll need a much longer lens and a greater working distance to achieve the same DOF that a larger aperture prime will without needing to get so far away. If you're outdoors maybe that would work, but you might not have the space indoors. Comparing focal length to focal length of primes vs zooms, primes will always be capable of tighter depths of field.

A 50mm f/1.8 will give a much tighter DOF than...
A 17-55 f/2.8 @ 50mm and f/2.8, which will give a much tighter DOF than...
An 18-55 f/3.5-5.6 @ 50mm and f/5.6, etc...

julie32 · Jan 3, 2008

Wow!

So helpful, thank you! And Mav, your daughter is adorable. The example with your hands is very helpful to me because prior to that, I wasn't understanding why I couldn't focus very close up....now I get it. Also, the photo of the father of the bride is great. I love the color and the reflection in his eyes... and I never would have known that a fridge was behind him.

Osirus---love your dog!

Have a great thursday--
julie