Digital Lenses

[Ashim]

Hello,

 

Just wanted to know whether the Digital camera Lenses are designed essentially for a smaller focal plane

( a 2/3'' CMOS sensor vs a 35mm film) or there any other factors that detrmine the existence of these lenses

for digital acquisition.

 

Can one use a 35mm camera lens on a digital camera with a 2/3'' sensor... Some say this is not possible because of the Image circle the 35mm format lens will create... Kindly Post.

 

Thanks

 

Ashim

Edited October 23, 2006 by Ashim

[Patrizio De Sica]

Digital lenses? It sounds strange...

[Ashim]

I mean lenses designed for digital cameras...

[Brian Drysdale]

Sony Cinealta cameras have 3 CCDs mounted on an optical block which splits the light into RGB. Most high end video cameras have this arrangement, although there are also a few single sensor cameras like the D20.

 

Lenses used on the 3 CCD cameras have to optically compensate for the block, that makes them slightly different to film lenses. However, you can mount film lenses on single sensor cameras without any problems - 16mm film lenses would be a good match for a 2/3" single sensor camera.

[Chris Burke]

I mean lenses designed for digital cameras...

 

 

I am sure that someone else with loads more experience than I will respond, but I'll give it a try just the same: The 35mm lenses can be used via an adapter. They are big enough and will handle the resolution just fine. But with the added cost of an adapter why not just use the digi primes? I have never used them, I shoot almost exclusively film, but I suspect that they will give you the very best image you are going to get from the camera they are attached to. This is provided that all esle is equal.

 

Now, the cost of renting the digi primes is quite high and whether it delivers an image that is proportionately better than shooting with an HD zoom is another question entirely. If you are strapped for cash, using a zoom may be the way to go.

 

Chris

[John Ealer]

There's a lot of generational baggage with 3-CCD cameras...It tracks all the way back to when cameras still used vacuum tubes. The sensors are actually at slightly different focal planes, and the lens has to compensate to avoid serious color fringing. (Apparently it was deemed early on in the development of color TV that it would be cheaper or easier to make the adjustment in the lens than in the optic block) If you're using really long lenses or very deep stops and thus have significant depth of focus, a film lens would theoretically be fine, but what fun is it to shoot at f16 at 300mm all the time?

 

[Certainly the sensor size is different between 35mm and 2/3", but that in and of itself wouldn't make the lenses incompatible...in the same way that 35mm PL lenses can be used on 16mm PL cameras...]

 

The DigiPrimes and DigiZooms are great lenses with excellent characteristics all around, since they were designed from the ground up with cinema applications in mind (instead of EFP and ENG), they're optimized for image quality - not for weight or ease of single person operation. Other digital cinema lenses and zooms from Canon and Fujinon share similar characteristics, but to my eye aren't up to the same level as the Zeiss products.

 

EFP and ENG zoom lenses have inferior characteristics (ramping, breathing, portholing etc) but are lighter and designed for use without an assistant. They're ideal when you have to move fast in doc environments.

 

Most of the adaptor systems to use film primes on digital cameras use a relay system that focuses the film lens on an oscilatting ground glass. The video camera is then focused on the ground glass and records that image. The significant advantage of these relay-based systems is 35mm-like Depth of Field. The disadvantages are light-loss (up to a couple stops), speed of use (the systems are cumbersome and awkward), and reliability. In the toss-up column is the softness in the image created by the ground glass. It can look filmic with texture, or just soft...

 

J