What is a prime lens for?


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ernie1984

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Apr 23, 2006
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#1
hi i have some doubts here, may i know what is a basic function of a prime lens

for eg.

Nikon 50mm F1.8AFD??

any kind pro can explain? thanks
 

cantaresg

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Feb 23, 2007
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#2
I'm not a pro, but here is what I know about prime lenses.

Basically prime lenses are available at certain popular settings, like 50mm, 85mm and 100mm. As such, the focal length is fixed, so you cannot zoom with the lens. Since the lens has dedicated focal length, usually it has a wider aperture and sharper image quality compared to zooms.

But if you ask what is the function of a prime lens, it is used to focus the image onto the sensor/ film, just like any other lens?
 

Rashkae

Senior Member
Nov 28, 2005
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#3
It's basically a lens that is dedicated to getting the sharpest possible image at it's single focal distance. It dosn't need to compromise by trying hard to be good over a long focal range.

And always remember, wikipedia is your friend:

http://en.wikipedia.org/wiki/Prime_lens
 

zac08

Senior Member
Feb 21, 2005
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#5
Prime lenses are the first type to have evolved for the SLR type cameras. Zooms came out after them and have been taking time to evolve such that they are able to compare to the image quality of the primes, some of the high end zooms are as such.
 

ernie1984

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Apr 23, 2006
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#6
am i right to say that prime lens r normally used for taking portrait photo, as the image quality will be better, and it will have a nice blur background due to its aperture size?
 

yyD70S

Senior Member
Dec 25, 2005
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#7
Primes can be used most situations; not just portraits. However, those medium telephoto primes do come in large apertures (f/1.2, f/1.4, f/1.8, & f/2) and they do help a lot in portrait photography.

Compared to zooms -- at and around the same focal length -- they do generally possess better optical quality; not just in terms of sharpness but overall optical quality.
 

posez

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Mar 23, 2007
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#8
Primes can be used most situations; not just portraits. However, those medium telephoto primes do come in large apertures (f/1.2, f/1.4, f/1.8, & f/2) and they do help a lot in portrait photography.

Compared to zooms -- at and around the same focal length -- they do generally possess better optical quality; not just in terms of sharpness but overall optical quality.
Four other benefits that have not been mentioned already -

1. Prime lenses are usually much faster than zooms (larger maximum aperture)
2. They are much smalller and lighter than zooms hence easier to carry around
3. Primes are generally much, much cheaper than zooms that provide the same image quality
4. Most primes have been manufactured for far longer than zooms and have been improved upon over successive generations. Generally, most primes from Canon or Nikkor will be pretty well made as the manufacturers would have decades of experience working on them.
 

angiee

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Apr 5, 2007
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#9
Prime lenses are for people who think zooms are not for them.
 

scenar

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Aug 23, 2005
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#11
Short primes like 35f2 / 50f1.8 / 85f1.8 are great for budget-constrained hobbyist (like me) to experiment with shallow depth of field and shoot in low-light conditions. As mentioned, they are also light and portable.

Excluding olympus (which makes f2 zooms for the 4/3 system), the fastest zoom lens out there is limited to f2.8. They cost a fortune and weigh a ton...

When we get to the longer telephoto primes like the 400f2.8 / 500f4 / 600f4, those are the ONLY lenses (bar the new sigma 200-500f2.8) which give u such a large aperture at the stated focal lengths.
 

Nov 21, 2006
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#12
I have 3 primes...I love them...No intention to buy zoom lens if I don't go oversea this midyear. :D..I use my lens for shooting lor..every thing, anything i like..:D...
 

yyD70S

Senior Member
Dec 25, 2005
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#13
There are exceptions, of course, but it may be beneficial to know that there are slower primes, such as the 50mm f/1.7 or f/1.8, that can be had for a relatively cheap price. A fact, which, of course, I'm sure you already know.



Yeah and Prime Lenses are also VERY good at busting big fat holes in our pockets or bank accounts...
 

ernie1984

New Member
Apr 23, 2006
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#14
comparing a 50mm and a 100mm, issit the 100mm can see subjects further away?

sorry, really a noob here
 

cantaresg

New Member
Feb 23, 2007
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#15
What do you mean that 100mm can see subjects further away? the 50mm lens can see the Moon and stars, and that is certainly very far away.
 

smutpow

New Member
Mar 20, 2007
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#16
100mm is 2x magnification of a 50mm lens. So yes, it can "see further away".

For pre digital, the 50mm lens was a reference to what the naked eye can see and a lot of pre AF cameras came with a 50mm kit lens. But because of cropping factor for digital cameras, the 50mm lens is now a 75mm lens for 1.5x crop, 80mm for 1.6x crop and 100mm lens for a 2x crop.
 

cantaresg

New Member
Feb 23, 2007
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#17
Technically, the 100mm is capable of seeing a smaller object at a larger distance than a 50mm. I'm sorry about this, and I am not trying to be rude. It's just that when I used to conduct stargazing sessions, my most dreaded question was this: How far can the telescope see? This is because a telescope has difficulty "seeing" a candle light that is 1km away, but the eye is just as capable to see stars which are tremendously far away.
 

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