Lens Mod FAQ

I receive dozens of emails everyday and I want to respond to them all but sometimes it just isn’t possible. I’m not a trade secret kind of guy. I like to spread knowledge and educate as many people as I can. So here is a quick little FAQ in regards to lens modification and a few other common questions I am asked… Frequently.

EDIT: THIS POST IS OUTDATED AND MAY NO LONGER BE ACCURATE. PLEASE CONTACT DUCLOS LENSES FOR CURRENT INFO

1) What lenses work well for motion picture?

2) I have a bunch of still lenses. Can they be converted to work for cinema?

3) What is a Cine-Mod?

4) Can my lens be Cine-Modded?

5) What lenses are well suited for a Cine-Mod?

6) Can the mount on my lens be changed?

7) I have Nikon lenses. Can the focus be reversed?

8] The focus throw of my still lenses is short, can it be expanded?

9) Can lens breathing be corrected?

10) Can my lens be re-housed for cinema use? What is the cost?

11) Can my lens be converted to PL mount?

1) What lenses work well for motion picture? Obviously cine lenses work best for motion picture. The glass used in still lenses works well, but isn’t always suited for motion. Still lenses tend to breathe, the image is not stable and “jumps” when focused or zoomed. There are some still lenses that work well such as full manual lenses like Nikon AIS, Leica R, or Zeiss ZF. These lenses are built very well and eliminate some of the flaws of modern auto focus lenses. There are many other characteristics to consider. Like, does the lens telescope when you zoom? This can create problems with a mattebox. Internal focus lenses are a much better option. Most auto focus lenses lack a hard stop at the end of focus travel and will not work well for marking distances with a follow focus.

2) I have a bunch of still lenses. Can they be converted to work for cinema? There are certain measures that can be taken to help still lenses get close to cinema lenses. It all boils down to usability. You can modify your lenses with a Cine-Mod and it will help quite a bit. Simple add-ons and minor modifications can go a long way.

3) What is a Cine-Mod? A Cine-Mod is a procedure that Duclos Lenses performs. The standard cine-mod consists of a three part process including a solid, seamless delrin focus gear, de-clicking the aperture for smooth movement, and an 80mm step up ring for clamp on accessories, all of which are customizable to suit the users needs. It makes still photo lenses more suitable for motion picture use.

4) Can my lens be Cine-Modded? Most still lenses can receive the Cine-Mod. As long as there is a surface to attach the focus gear, and a threaded front ring, it is usually possible. Some modern lenses do not have a manual aperture ring and cannot be de-clicked.

5) What lenses are well suited for a Cine-Mod? The lenses that benefit most from the Cine-Mod are full manual lenses with longer focus throw and metal housings such as Nikon Ais, Leica R, and Zeiss ZF. Auto focus lenses will still have a relatively short focus throw and possibly no aperture ring.

6) Can the mount on my lens be changed? Certain lens mounts can be easily adapted. Over the years people have made adaptors for many styles of mounts. Nikon to Canon. B to PL. Etc. But some lenses cannot be easily changed. For example, Putting a hard PL mount on a Nikon lens is very difficult and usually requires re-engineering most of the lens to accommodate a PL mount usually costing more than a PL mount lens in the first place. Another common lens conversion would be the Russian OCT 19 to PL. People love the look of the old Russian Lomo lenses. These can usually be converted easily but the cost is high and the build quality of Lomo lenses is not advantageous.

7) I have Nikon lenses. Can the focus be reversed? Not really… Reversing the focus direction requires hours and hours of design and engineering. It basically requires designing and building a new focus mechanism. In short, yes it can be done… But to 99% of shooters, the cost is prohibitive. The simplest solution is a focus reversing gear that goes between the lens and a follow focus or simply a follow focus that allows for reversed travel.

8] The focus throw of my still lenses is short, can it be expanded? Sometimes this can be done by using specific gears on a follow focus unit. But extending the travel within the lens would again require re-engineering the focus mechanics. This also is cost prohibitive. It would be cheaper to simply purchase a proper cine lens with the appropriate focus travel.

9) Can lens breathing be corrected? No. Breathing is a characteristic that is considered when the lens is designed. Most still lenses breath simply because it doesn’t matter since you don’t focus as you take a still photo. Cine lens designs take this into consideration and compensate for it. This is a major part of the cost difference between still and cine lenses.

10) Can my lens be rehoused for cinema use? What is the cost? Re-housing lenses is a very long, expensive, and involved process. Duclos Lenses spends months and months on a single design in order to achieve a lens that works as well as it can for cinema use. While there are many still lenses that are great for shooting stills, most are just not suitable for a complete re-house. Duclos Lenses tries to accommodate users with lens features such as focal length, max aperture, size and weight, that are not available from other manufacturers. There is a very specific set of criteria that must be met in order to consider a lens for re-housing. Very few lenses meet this criteria. It’s almost always more expensive to rehouse a single still photo lens for cinema use than it is to purchase a new cinema lens.

11) Can my lens be converted to PL mount? Changing the mount on a lens is a very involved process. Specific measurements that are critical to optical performance must be maintained. The distance from a PL mount flange to the sensor is 52mm. This means that within that distance, the glass itself must be placed at the given distance from the manufacturer. For example, a Nikon mount lens has a flange depth of 46.5mm. This distance can’t be changed because it is relative to the optical design. So the glass must stay in the same place while giving the PL mount 52mm of distance to the sensor. This can usually be accomplished by rehousing a lens and designing the rear housing from scratch with this goal in mind. If you’re thinking about re-housing your lens, read the previous question (10).

EDIT: THIS POST IS OUTDATED AND MAY NO LONGER BE ACCURATE. PLEASE CONTACT DUCLOS LENSES FOR CURRENT INFO