zoom vs primes

[WhereDreamsAreBorn]

I am sure this will sound absolutely stupid to all the cinematography professionals on here, but not everyone knows everything and i would like someone to explain to me what the differences are exactly.

For instance if there is a 85mm prime, could you not use a zoom lens like the 70-200mm zoom. And achieve the same shot.

(by the way i am not talking about 'zooming in' during a shot, as i personally hate that. But before you press record).

 

[morgan_moore]

Say with this 85 the fastest you can get as a zoom is 2.8

with a prime you can get 1.2

So a prime can give you more speed

COnsider that some lenses are a little wooly wide open your 2.8 ould have a operational range F4 and below - thats a lot slower than f2 on a slightly stopped down prime

At the wide end you will see often more distortion and barrelling with zoom lenses than primes

Of couse primes - slow you down not just changing the lens - but possibly realigning the FF and maybe making other adjustments

ON my EX1/Letus I found primes to be required because I always needed more light

On my 5d I find zooms fine because the large chip means that F2 is just not enough DOF

on my 7d finding a decent wide angle is a problem full stop and at the longer end it can benefit from F2.8 or f2

IMO a 50 1.4 is so cheap its a must have - other primes take more thinking about

Some zooms (my nikkor 20-35 for instance) have poor minimum focus distance too - worth checking that out

For RnG primes are a pain and a zoom is nearly a must

Artistically zooms can create lazyness in composition of course that is you not the technology - my 16-50 (7d) I tend to use on 16, 24 or 50 ONLY

On a Fulframe chip I have tended to go 20mm prime, 50prime 70-200 which is obviously a mix

S

 

[Cassius]

A lot of people say primes give you better image quality, and to an extent I agree. But for short zooms made in the last decade I think they're fine.

 

[Huy Vu]

Good zooms are more expensive than a few decent primes, that's what it usually comes down to.

 

[blazer003]

Primes: Cheaper for faster (wider aperture) lenses. Wider aperture = less light needed for a good exposure and shallower depth of field.
Zooms: More flexible as you can achieve different focal lengths. More expensive, and won't match the fastest primes.

To answer your second question, yes. Essentially you could get the same shot from an 85mm as a 70-200mm zoom as long as lighting was good and you have a high quality zoom lens.