lens question

[Charles Talbott Jr]

I feel silly just asking this, but if I'm using a good, sharp zoom lens (let's say a 10-100mm)and I set it on the 10mm, is that going to give me the same look as using a 10mm prime lens? Again, if it's set somewhere else on the lens, say 50mm, is that consistent with a 50mm prime? If so, why would anyone use anything but a great zoom? If not, what type of differences would I see between the primes and the zoom? Thanks for the help.

[Mike Simpson]

In theory they will look the same. However, there is some inaccuracy in markings sometimes. But probably more importantly, there is a spot on the 10-100 that will look just like 50mm prime (it just might be more like 52mm or something).

 

The difference is that primes are lighter, and tend have smaller aperture settings.

 

A good example is canon's still photography line. canon makes a 24-70mm zoom. Its max aperture is a 2.8, but its very sharp and looks great. However, the 50mm prime opens to 1.4, so you can get alot more light out of it, and if they are both set to 2.8, the prime is sharper. This will be generally true of most prime/zoom relationships.

[Guest Glen Alexander]

I feel silly just asking this, but if I'm using a good, sharp zoom lens (let's say a 10-100mm)and I set it on the 10mm, is that going to give me the same look as using a 10mm prime lens? Again, if it's set somewhere else on the lens, say 50mm, is that consistent with a 50mm prime? If so, why would anyone use anything but a great zoom? If not, what type of differences would I see between the primes and the zoom? Thanks for the help.

 

Go with primes every time. Forget about zooms.

[Andrew Koch]

All things being equal (by this I mean a zoom lens and a prime lens in the same league of quality) The prime lens is usually sharper. It is also most likely going to be faster. The zoom's widest aperture might be 2.8 whereas a Zeiss Superspeed Prime lens opens up to a T-Stop of 1.3. Zoom lenses also have more glass elements making them more prone to flare. The other issue is that zooms breath more when changing focus. When racking back and forth between two subjects, a zoom lens that breathes a lot will zoom in and out as you shift the focus (particularly noticeable on the wider focal lengths). I have not tested this, but I have been told that prime lenses give better shadow detail in low lit scenes, not just because of their speed, but because of the way they handle contrast. Apparently the added glass elements in zooms effects the lenses ability to see into the shadows. I would love to hear any opinions on this. Many zooms also have a farther minimum focusing distance. The Zeiss 10-100mm has a minimum of 5 feet if I recall. This can be difficult for work in small spaces.

 

Zooms do have an obvious advantage. You can do a zoom in. Both prime lenses and zoom lenses have their place and choosing one or the other depends on the project (creative reasons, technical reasons, budgetary reasons, etc...)

[Adrian Sierkowski]

I feel I should chime if you're on a bad budget or are doing a run/gun style shoot, zoom might be quite useful, when used as a variable prime. I'm talking about if you have the choice between a larger lighting packge or a differant set of lenses... personally I'd tend towards the lighting package.

Zooms are of course, almost standard on documentary shoots as they give you the ability to re frame more quickly (zoom in to a new shot, lock it and roll)

[Malik Sajid]

Thats quite information for a student like me who have always this question in mind.

 

I have never used prime lenses(we are given cannon XL 1, and DSR 450p for our class projects), always used zoom lenses.

 

well......isn't there any possibility in Prime Lenses, where we can move a bit just to adjust the frame. If Primes are fixed means we cant compose a frame according to our own? Taking a closeup on 70mm prime, we will not be able to adjust the frame?

I hope you got what i mean.

[Ira Ratner]

You adjust the frame by moving your tripod. If you want to get closer while the camera is shooting, you put your tripod on a dolly with wheels and move it.

[Charles Talbott Jr]

Thanks, guys. So...essentially, primes are usually sharper (given the same aperature setting under the same conditions), have better minimum focus distance, and better under low light conditions (because you can open up the lens more). Does that sum it up well, or am I missing something?

 

Thanks again for the info.

[Andrew Koch]

Don't forget that prime lenses breath less than zooms (in many cases they don't appear to breath at all)

[Charles Talbott Jr]

Thanks, Andrew. That's a good point also.

[Steve Absalom]

Don't forget that prime lenses breath less than zooms (in many cases they don't appear to breath at all)

What does "breath" mean in regard to a lens?

[Malik Sajid]

When doing a rack focus(or in a differntial shot), changing focus from one foreground object to the other background object(or vice versa), shifting the focus causes the lens to zoom in or out slightly, thats the breathing.

 

Correct me if i m wrong.