DOF and Anamorphic

Hans Moleman

Hans Moleman

Carbonite Member
Howdy,

I'm the proud new owner of the LA7200 anamorphic adapter which i ordered about a week or two ago.

My DVX is still shipping, so I had a question.

I've heard that the adapter makes the dof more shallow, is this true?

and if so, is it a noticable difference?

good dof on miniDV is hard to get, and i'm wondering if my new baby is going to enhance that much.
 
Partially, but not really correct. An anamorphic adapter like the LA7200 requires that you stop the camera down in order to get both the horizontal and vertical planes of the adapter within the focus range. This usually results in more minimum depth of field than if you were not using the adapter.

It is true that the two focal planes will not have the same depth of field (one will be at and before the critical focus point, the other at and behind the same point) but this isn't likely to be perceived as shallower (just different) depth of field.

The best tool that you can get to use with your adapter is a great focus chart. Then just be certain to focus for both horizontal and vertical at the critical distance and then set the cameras focus to the mean of the two (and of course stop the camera down far enough to be certain that both are within the depth of field that you will have for a given aperture and zoom combination).

Composition and framing will be your strongest tool when using the adapter, and if done correctly, can give you great results.

Have fun with the new toys.
 
thanks. two things:

lol, "stopping down" means to open the iris up more? I never had the term defined for me

and can you link me to a good focus chart?
 
Actually, just the oppsite. Stopping down is to close the aperture (larger number, smaller opening).

I just put a focus chart up on my web site, you can down load it from the following URL:

http://www.museelectronics.com/cvp_focus_chart.pdf

Its a PDF so just right click and save the file to your machine. Then, using a good laser printer, make a few of these on decent stock and keep them with you when you shoot. I have one on the back of our slate so its a simple matter for the 1st AC to flip the slate over just prior to calling the scene so that we can get proper focus.
 
HEH its the same focus chart I have been using khmuse.

Is Barrys book coming with your DVX? If not you must get it. It has a section dedicated to the ana lense and getting the best result from it. It has some conversion charts that are really invaluable when shooting with this lense.

Getting shallow DOF requires you to zoom in as much as possible and have the aperture more open. The ana lense works against this in principle insofar as to achieve proper focus at a closer zoom means you need to stop down a lot (as khmuse stated). To be able to open the lense and achieve proper focus means you can not zoom as far. So either way you go your working against one of the principles of shallow DOF: zoom in and open aperture (or as Barrys dvd puts it - f2.8 and z99 on the dvx).

In my current shoot I will be removing the lense and shooting squeeze in one small sequence so I can make full use of the shallowest DOF the dvx can deliver without a mini 35.
 
ncje said:
the shallowest DOF the dvx can deliver without a mini 35.
Click to expand...

What about lenses? (I mean one single lens - not a converter or objective...)

e.g. when I use macro lenses for photography, the DOF is reduced on only some few centimeters. With some lenses even focussing is NOT POSSIBLE, but you have to arrange the camera after the lenses focus.

I wonder now: is there no similar lens that could be used for shallow DOF?
 
A macro lens won't really help you achieve shallow DOF unless the object is extremely close to the camera. This might work in some situations, but isn't likely to be useful much of the time.

The only other technique that I can offer is the idea of shifting the critical focus point in front of your main subject so that it/they are just at the limit of the DOF the particular zoom/aperture combination yields. With this approach, your background will be further from the critical focus point and will be further softened compared to the mean focus method.

When using the anamorphic adapter, composition and lighting will be your best tools. Just like a shallow DOF can reduce the backgrounds impact on a scene, so can denying the background light (or intentionally allowing it to blow out). Whatever causes the viewers eye to ignore the background accomplishes the same thing. Too many users here think that shallow DOF is the only tool to use. Rather its just the easiest one, not the only one.
 
With the anamorphic adapter, you'll be dealing with a much deeper depth of focus than without one. You can get some softness possibly in some backgrounds, but don't count on using a shallow DOF as a storytelling device.

khmuse could not be more right, you'll have to use depth cues of other kinds. Not a huge problem, though, since a lot of the most beautiful movies ever used deep focus photography. I personally use DOF as a depth cue (as well as backlighting) because I'm cheap and they're the two simpliest ways to make an image pop. They're also probably the least creative and least artisitic. Camera movement and art design are better but trickier.
 
khmuse said:
A macro lens won't really help you achieve shallow DOF unless the object is extremely close to the camera. This might work in some situations, but isn't likely to be useful much of the time.
Click to expand...

This was only an example - some macro lenses permit a distance up to 1 m (!) with a DOF of ONLY SOME millimeters or centimeters (!)and let's imagine a lens that permits a distance of only 2 m, that's not so much more than the macro lens and it would be enough for many shooting situations. I mentioned the example of a macro-lens because it is reality for extremly shallow DOF - but I'm imagining ANY kind of lens for shallow DOF - best would be WITHOUT magnifiying the image of course and with a longer distance than of the macro lenses....

Let's say: a lens that locks the focus of the camera on a certain distance and doesn't permit too much space within this distance BUT the gain is a very shallow DOF.

Perhaps the more a lens magnifies, the shallower the DOF is.... and that would mean, that I won't find what I am looking for - unless it is a macro lens and that means: not more than 1 m of distance :(
 
lol - Policar, are you referring your "what" to me? lol

Sorry, I'm neither english native, nor do I manage to bring my idea to "paper"... :

Short: is there any "optic" to screw in front of the lens to reduce the DOF?

Answer 1: YES - it's the macro lens
Answer 2: (missing - looking for....)
Answer 3: 35mm-Adapter (I don't want that one)
 
cici said:
Perhaps the more a lens magnifies, the shallower the DOF is.... and that would mean, that I won't find what I am looking for - unless it is a macro lens and that means: not more than 1 m of distance :(
Click to expand...

That is exactly the behavior of any lens.
 
Perhaps a group of 1 convex and 1 concave lens could do that.... Or will the shallow DOF of the convex lens be destroyed again by the concave lens? I'm sure it will.... But I'm also very sure, there is another solution than a 35mm Adapter just for a very shallow DOF! - Perhaps some compendium&lens construction...
 
There are plenty of factors which affect the depth of focus but they can pretty much be narrowed down to two things:

The size of the aperture opening. How close you are to the subject.

The size of the aperture measured in f-stops is related to the focal length. So when you're shooting at 50mm, f1.4 has as large an aperture as 100mm at f2.8. The largest the aperture on the dvx gets is f2.8 at 45mm, but you can't use the anamorphic adapter at that focal length or zoom setting anyhow.

If you're making a movie about ants, a macro lens is a good way to ensure a shallow depth of focus, simply because the ants need to be so close to the camera to fill the frame. But if you film a person that close to the camera, then you're shooting a one by one inch square on his/her face. If you decide to fix that by using a wider lens, then you've shrunk your aperture because it's related to the focal length, so the depth of focus is actually deeper.

If you're very sure that there's another solution besides a 35mm adapter (or a camera with larger CCDs, build one.) Honestly, it would probably be easier to build a shrink-ray and shrink your talent to the size of ants.
 
Aside from a focus screen approach, there isn't much that can be done with a fixed lens camera. With a detachable lens camera, one could in theory use a lens that had an extremely large aperture opening (small f-stop) and a very long focal length to achieve a shallower DOF. While possible, there are practical limits to what can be achieved.
 
When using the anamorphic adapter, composition and lighting will be your best tools. Just like a shallow DOF can reduce the backgrounds impact on a scene, so can denying the background light (or intentionally allowing it to blow out). Whatever causes the viewers eye to ignore the background accomplishes the same thing. Too many users here think that shallow DOF is the only tool to use. Rather its just the easiest one, not the only one.
Click to expand...

In agreeance with khmuse again.... i find another tool is to use some mixed lighting so in some shots the background appears to have a somewhat different colour and contrast. Not everyones cup of tea though, but I am rather partial to the effect it gives.
 
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