Using anamorphic lenses can be very easy or very difficult. Here is an article designed to shed light on some obstacles you might face when setting up an anamorphic system for your DSLR. [Note: I'm working on adding images and diagrams to this post, I hope to have them up soon]
The Anamorphic Optical Chain
The conventional setup goes like this: DSLR, then taking lens, then anamorphic lens, then diopter (optional). If you have a heavy anamorphic lens, you may want to use a lens clamp to clamp the anamorphic lens to your taking lens. Also, you may choose to support your anamorphic lens via a tripod collar or lens support system. Here are some diagrams of typical anamorphic setups:
Attaching an Anamorphic Lens Directly to Your Taking Lens
Some anamorphic lenses have rear thread diameters that make it easy to attach the lens directly to your taking lens. If the diameters don’t match, you can buy a step down or step up ring. For instance, the Sankor 16C has a 40.5mm rear thread, to attach it directly to my 52mm taking lens thread I would need a 52mm to 40.5mm step down ring. Similarly, I could use a Redstan clamp to clamp the anamorphic lens to my taking lens.
Attaching Heavy Anamorphic Lenses
My Schneider anamorphic lens weighs about 571 grams. Attaching this lens directly to my taking lenses would be preposterous because something would most likely end up breaking (either the anamorphic lens would fall off, or the taking lens would get damaged). The rule of thumb here is be smart. If you are shooting with a cheap plastic Canon as your taking lens, you probably won’t want to mount much weight onto it. I have a vintage Olympus 50mm 1.4 that I directly attach a Sankor 16c to. I have attached the Sankor directly to my Canon 50mm 1.4 but I felt that was too much stress for the Canon. I did not bother trying to attach it directly to my Canon 50mm 1.8 (the built quality of the 50mm 1.8 is awful).
When a lens is too heavy, use additional support. The Velbon SPT-1 is my weapon of choice. It is fairly light weight, and allows me to use a tripod collar for my anamorphic lenses. You can also use a rail system. Rail systems are very popular for filmmakers because they allow you to build a custom rig; follow focusing, barn doors, lens supports, etc…
Does Your Lens Have Internal or External Focusing?
Before you attach your anamorphic lens to your taking lens figure out whether or not the front element of your taking lens moves inward or outward when focusing. Simply manually focus your lens across its focusing range (from up close to infinity). If you odn’t notice any movement, then your lens focuses internally and you are good to go. If your lens moves inward or outward while focusing you must be careful when attaching your anamorphic lens because you do not want your taking lens to hit the anamorphic lens while you focus.
Here is a picture of my Canon 50mm 1.8 with a Schneider anamorphic mounted in front of it. Notice I have a gap in between the two lenses. This is to give my Canon 50mm 1.8 ample room to extend without hitting the Schneider throughout the focusing range .
How to Align an Anamorphic Lens
The best way to align your anamorphic lens is to shine a small focused light strait into your anamorphic lens. Using your viewfinder or LCD screen, you want to rotate the anamorphic lens so that the lens flare is perfectly horizontal. In Live View I use the horizontal line overlay to help align everything. If you don’t align your anamorphic lens your footage will be skewed after you desqueeze it.
Anamorphic Lenses Can Cause Vignetting and Light Loss
Be sure to watch the exposure when you shoot with anamorphic lenses. Generally you will lose a bit of light when you place an anamorphic adapter in front of your taking less. The light loss is not much, maybe one stop of light at worst. A much bigger problem is vignetting. Basically if you shoot too wide, you will experience vignetting. There are two types of vignetting: The most apparent is a darkening of the image (typical vignetting). The second type is soft vignetting (I made this name up). Soft vignetting is when you experience white colored vignetting when the lens is pointed at a bright light source. Here are examples of what I am talking about:
Both of these suck. The dark vignetting is easy to remedy; just get a longer focal length lens. Soft vignetting can be tougher to fix. Going with a longer focal length and stopping down the lens are common solutions.
The Cost of Setting Up an Anamorphic Lens
If you choose a light weight anamorphic lens and attach it directly to a your lens (an internal focusing lens) you don’t have to spend any money on additional gear. If the threads don’t match you will need a clamp (about $50). If your lens moves in and out when it focuses or is not strong enough to hold an anamorphic lens, you will need a support system. My Velbon SPT-1 costs about $70. A Chinese tripod collar should cost about $10. Additional step up/down rings could run you $10. If you want a lens support plus clamps, the clamps will cost you $35 to $50. A rail system usually starts off at about $50 for the cheap stuff, and can easily climb to several hundred dollars. If your anamorphic lens does not have conventional filter threads on the front, and you want to use filters, you will need a clamp. A Redstan style clamp will cost $50.
Or… physically hold the anamorphic lens in front of your taking lens. I shot a whole test video by holding a Singer 16D in front of a vintage Olympus 75-150mm. The video was a bit shaky, and the lenses were not perfectly aligned, but the video still turned out very cinematic and sharp. This is a great way too shoot anamorphic video if you can’t afford to purchase additional support equipment. Plus its a good work out! Holding a DSLR with one hand, and an anamorphic lens with the other hand builds your muscles!