Cinema Lenses vs SLR Lenses

[Zblock]

So I've done a quick search and haven't had my curiosity sufficiently squashed. Can someone explain just what a cinema lens is and how it differs from any regular SLR lens?

For instance. I've got a set of Pentax lenses and I plan on using my camera for a long long time. Would/Should I even bother looking into finding a different set, say a PL mount lens or a set of Zeiss lenses?

Is the difference stupid noticeable or just technically?
Thank,

[Robert Ruffo]

I have direct experience with both.

If you get a super awesome SLR lens, like some Canon Ls, or certain Zeiss primes, sharpness, lack of CA, lack of distortion and color rendition will be excellent. On par with great Cinema lenses. However, Cinema lenses offer three advantages:

1 - Often (though not always) , better light transmission. A low f-stop is not the same as a light transmission rating (a T rating). For example, the T-rating of a Canon 24-70L is quite low, maybe as low as T4 at certain points in the zoom, wide-open (so only 1/4 of light is reaching the sensor/film plate.)

2 - Better mechanics. This manifests itself in more degrees of turning needed to change focus. (although Zeiss primes are meant to be manual, so they are better than most SLR lenses in this regard) and a hard focus stop (which Nikons have but Canon lenses lack - they keep spinning when you reach the end, invalidating the focus marks you made on your FF and wasting precious set time). They also have no hard clicks on their f stops, so a cinema lens could be set to say, f2.09876 or whatever - exactly what you need rather than the next "jump" to a standard f-stop position as on am SLR lens (although companies offer "declicking" of Zeiss SLR lenses for about $400 each.)

3 - Internal focusing. This means the lens front will not move forward and back as you focus, making use of a mattebox more tricky, and it even more importantly means that your image will not zoom in and out much (if at all) as you focus. That said, some SLR lenses do not breathe at all, and some cinema lenses, most notably the cheaper Zeiss line, do breathe a bit. It is easy to test how much a particular SLR lens breathes at a camera store.

The problem with Cinema lenses are that they are extremely expensive and extremely heavy.

If you buy a Birger mount for a Red camera and use Canon lenses, then you are only left with issue '1" above (sometimes) and issue "3" (again only sometimes) - this is why that combo is such a popular solution.

[Dino]

Robert makes good points. Cine lenses also offer matched sets optically, to T-stops match, barrel size matches, length matches, back focus matches.

Distance markings are larger and there are more of them, plus they are properly calibrated for distance.

Of course, they have focus gearing as well.

[Lenilenapi]

Ditto for everything said above. Aside from the fact that a $10-20K lens tends to be better optically the main difference is in the housing so they are easier for focus pulling, have internal focus, and no click stops on the f stop barrel. A number of people retrofit old Nikon primes and rehouse them so they become cinema lenses. In fact early Panavision lenses were often Nikon SLR primes rehoused.

However when you talk about Zeiss superspeeds, those lenses are designed to be sharpest at very wide open apertures unlike most SLR lenses so there is an extra performance boost in low light..
That said on a 35mm adapter cinema lenses usually only cover academy aperture and you get lower DOF with an equivilent Full frame lens.

[Dino]

Lenny,

Did you hear about the new Zeiss prime set that is FF35 and has changeable Canon and PL-Mounts. Wouldn't this be the first PL-Mount FF35 lens set? The set is supposed to be around $20K, which is cheap for PL-Mount!

[Barry_Green]

Well, yes, but actually you could say it's the second PL-mount FF35 lens set. The existing Zeiss Compact Primes were the first. Already on the market and have been for a while.

It's the same lens set, the only difference is that the new announcement is saying that instead of being PL-only, it's an interchangeable PL or Canon EOS mount.

[killamill]

Yes, Barry is right. There´s some more info in the link below.

http://www.fdtimes.com/news/?p=1456

[Dino]

Well, yes, but actually you could say it's the second PL-mount FF35 lens set. The existing Zeiss Compact Primes were the first. Already on the market and have been for a while.


Yeah, I knew that Barry, just checking to see if you were paying attention!:D

The thing I don't like about Zeiss Compact Primes is that lenses are different sizes, weights, speeds. I'm sure that's how the price point is kept lower.

[bwwd]

cinema lenses have longer focus throw what is quite important , you will hit infinity sooner with 50mm SLR lens than with 50mm cinema lens.

[Barry_Green]

Normally that is true, but not as an absolute fixed rule; the focus travel on my ZF 85mm is huge; it seems to go forever. Same with the 100mm.

But those are exceptions; you can also find 50mm lenses that have very short focus throws, and those are difficult to use in a cinema-style shooting environment.

[Dennis Wood]

The Zeiss 100mm macro has a focus throw of just over 360 degrees..it's lenses like that in our kit which suggested our focus rings needed to support full rotation. This is one property I really like (as Leni alludes) with all of our Zeiss ZF (now ZF.2) lenses. All of them have very precise focus throws with postive stops at both near focus and infinity.

Because the ZF lenses essentially have the same optics as the compact primes, gearing up a set is a pretty cost effective alternative at about 1/3 of the price.

[Robert Ruffo]

Normally that is true, but not as an absolute fixed rule; the focus travel on my ZF 85mm is huge; it seems to go forever. Same with the 100mm.

But those are exceptions; you can also find 50mm lenses that have very short focus throws, and those are difficult to use in a cinema-style shooting environment.

None of our Zeiss Zfs are a problem in terms of focus throw, inc. the 50mm. Neither are our canon L lenses when mounted on a Red + Birger - a combo that cost way less, including batteries, than a single Cooke prime.