There has been a lot of interest, among folks trying to save money, in using 35mm photo lenses rather than cine lenses, which tend to cost literally a couple of dozen times as much.

Why are cine lenses so much more expensive? A lot of it comes down to simple volume. I’ve read that Cooke sells something like 250 zoom lenses a year. Nikon probably sells that many zooms every day. Before breakfast. I’d also suspect that cinematography lenses are built far past what a budget user would consider the point of diminishing returns. When the engineers at Cooke or Zeiss or Angenieux look at a design and realize they can make it a tiny bit better by spending $5000 more, they probably do it. Their traditional customers have very deep pockets, and are willing to pay to get the absolute best stuff that anyone knows how to make.

Photo lenses clearly have the resolving power to handle 4K — they’re used all the time with photo cameras that have more resolution than a Red One. And individual photos tend to get examined more closely than individual frames in movies, so they clearly manage to hold up pretty well.

With that said, however, there are some significant material differences between cine and photo lenses. Here’s a quick rundown on the issues with using photo lenses in cinematography:

1. Breathing; that is, small changes in focal length when racking focus. Cine lens makers try to design this out, since it can make in-shot focus racking look odd. Photo lens makers mostly don’t bother. However, there are some photo lenses don’t breath much. Evan Grant’s lens testing over on Reduser.net has turned up a few.

2. Accuracy of barrel markings for focus. Cine are individually tested and tweaked, and their barrel markings are placed based on how they actually perform. Photo lenses don’t go through this process, and barrel markings might be a little off on some units. In these cases, it might be necessary to establish focus by eye and then use marks on a follow focus, or to just figure out how far off the barrel markings are and take that into account when setting focus.

3. Distance between barrel markings. Most photo lenses these days are designed with auto focus cameras in mind. In such a case, you actually want to have very little distance between focus barrel markings, as it leads to faster auto focusing. When you’re pulling focus by hand while looking at the barrel markings, in contrast, you clearly want those barrel markings to be as far apart as possible, so you can make more accurate adjustments.

4. With zooms, a lot of photo lenses don’t maintain the same f-stop throughout their zoom range, which would be a major hassle on-set. Particularly because you often don’t even have an easy way of knowing what stop a lens is at at a given focal length, it the aperture ring markings say it’s open all the way. (A photo camera will tell you, though its electronics. A cine camera doesn’t know how to talk to those electronics.) Higher end photo zooms do generally maintain f-stop, though.

5. A similar issue, with primes. If you want five primes between, say between 18 and 100mm, that all open up to the same stop, I don’t think anyone in the photo lens world offers that. Also, as far as I know, nobody in the photo lens world sells prime sets that have been tested and tweaked to match for color, sharpness, etc.

All of that said… anyone who has used a digital SLR camera knows it should be quite possible to produce a good looking image with photo lenses on Red. Unlike some folks out there, I’m not trying to tell people they shouldn’t bother buying the camera if they can’t afford to drop lots of money on cine glass. You can save a lot of money using photo lenses, and some people will evaluate the above trade-offs and validly conclude that it’s worth it.

Another option, of course, is Red’s glass. This is the route we’ll almost certainly be taking. Prices are maybe 4-5 times what prices for photo lenses would be… but it appears to be real cine glass, and prices are still far below what you’d pay Cooke, Zeiss or Angenieux. I suspect what’s going on with Red’s lens pricing is basically what’s going on with their camera pricing. They’re changing something closer to the actual material cost, because they believe there’s a market beyond the traditional deep-pocket customers, and they’re shooting for lower margins but with much higher volumes. (In light of the 250 zooms/year number for Cooke, consider the implications of the fact that if Red’s production schedule plays out the way they’ve said, Red will be selling 1000 cameras per month at the beginning of next year. There’s going to be a vastly larger market for cine lenses once that happens.)

This entry was posted on Thursday, April 26th, 2007 at 12:45 pm and is filed under Lenses. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.