More T1i...DOF control with Canon EF/EF-S lens at DVinfo.net

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Old August 25th, 2009, 05:32 PM   #1
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More T1i...DOF control with Canon EF/EF-S lens

If you've seen my other video, you got a look at using an older manual Nikkor lens (with adapter, of course), a 50mm F1.8 for shallow DOF and selective focus. Looked real good, too.

Well despite no built in manual control in video mode, you can still use "fast" Canon EF and EF-S lenses (like the 50mm F1.8 or the 50mm F1.4 for exceptional DOF control. There is a way of setting the aperture manually.

Check out this video, the fence behind the model was only about 3 feet away.

Shallow DOF on T1i with Canon EF/EF-S lenses on Vimeo
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Old September 9th, 2009, 09:56 PM   #2
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One step left out...

If going for maximum aperture follow the steps in the video as shown, but if what you want is an aperture smaller than max there is one more step not shown in the video. Press and hold the DOF prevue button while depressing the lens lock button and turning the lens barrel slightly.

If the DOF prevue button is not held in until the lens is "unlocked", the aperture will remain "wide open".

It seems that when I tested the procedure to see if it worked, I never tried anything but maximum aperture.

Sheesh! I guess we all just need to buy the 7D now.

Where's that hammer to smash my piggy bank?
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Old September 12th, 2009, 07:57 PM   #3
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Quote:
Originally Posted by Bruce Foreman View Post
Where's that hammer to smash my piggy bank?
I have a hammer... but no piggy bank...wanna trade? lol
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Old September 13th, 2009, 04:10 PM   #4
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If you use manual lenses, can't you set shutter and iso in manual photo mode then switch to video? Will it not preserve the settings?
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Old September 13th, 2009, 06:31 PM   #5
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Gerald,

No matter what you have set in manual, av, tv, or any other mode on the T1i, when you switch to "movie" (video) mode the camera goes into full auto.

The only reason the DOF button, lens "unlock" button, and slight "twist" the lens barrel method with EF/EF-S lenses works is because you have "broken" the electrical connections in the lens mount (by turning the lens barrel contacts out of alignment) so the lens and camera can no longer communicate. Aperture remains at what was last physically "activated" and cannot be changed until the lens is "locked" back in place again and the contacts make connection.

The camera remains in control of ISO and shutter because nothing you do on the lens directly changes those, but they do adjust to the amount of light the physical aperture lets in. As near as I can tell, the camera will try to adjust ISO as necessary to try to keep the shutter as close to 1/50th as possible as slower shutter speed values can cause excessive blur in individual frames and the faster values can cause a "strobing" like effect on anything in motion.

With your Nikon lenses (as long as they have an aperture ring) they neither have the Canon compatible contacts nor does the physical adapter ring used to mount them so there is no communication with the Canon camera body at all (unless your adapter ring has a focus confirmation connection). So you manually select the desired aperture on the aperture ring and as with the method of physically selecting aperture with the Canon EF/EF-S lenses, the T1i sets ISO and shutter according to the amount of light coming in through the lens.

Using manual focus Nikkors is the simpler way to effect manual aperture control because you simply set what you want on the aperture ring while already in "movie" mode as compared with the change to AV or Man, press 2 buttons, twist the lens barrel a bit, and then switch to "movie" mode.

The one thing you may have to watch with your Nikkor's is the adapter ring may allow some degree of "back focus" past infinity. Mine does. Just the same for "night work" I will prefer to use the 50mm F1.8 Nikkor (I also have the Canon 50mm F1.8 EF lens) because on the last night tests I ran, I wound up using anything from F1.8 to F4 depending on how much light there was and the visual effect I wanted. It was much simpler to just start turning the aperture ring.

A further degree of control in video mode is the capability to lock exposure and bias exposure up to 2 stops over and as much as 2 stops under what the camera sets. The ISO button becomes the exposure lock in "movie" mode and the "lock" stays in effect until you either "lock" on another scene or turn the camera off then back on. Exposure bias is done by pressing the AV button and turning the control wheel by the shutter release. You can adjust the bias either with the exposure locked or unlocked.

Typically I "lock" exposure because I do not want the overall brightness changing as I follow motion or pan.

Yes, I like others, am "drooling" over the idea of the Canon 7D. But then again, it costs a lot more than our T1i's and I've just had mine a few months. And what we've got is a tad more flexible than Canon designed.
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