is a 35mm the only way?

M

mts4243369

Active member
hey guys, I just had a photographer come to out school the other say with a very very nice camera, (still) with a Sigma telephoto on it and the first thing I noticed about it was the incredably shallow DOF on it...and that set me thinking, if you had like a XL2 for example, and put this lense on it, you still achieve that DOF without a 35mm adapter right? also if there is any other way than a 35mm adapter please share it with me! Thanks guys!

TS
 
Keep in mind that the 35mm still camera has a very large negative area (36mm x 24mm) where the imager of a XL2 is extremely small by comparison (typically less than 5mm x 4mm). The lens is going to "seem" to be much longer on the smaller imager as it would only be seeing a small fraction of the lens coverage. Where it was a telephoto on the 35mm it would act more like a telescope on the XL2.

In answer to your question, yes there are "ways" to achieve shallower DOF on a small imager camera. Use the widest aperture that you can, use the longest focal length that works for your framing and keep the relative distances between your in focus and out of focus subjects as different as possible.
 
ways to get shallow DOF:
35mm adaptor,
Zooming in (fake dof)
film camera

pretty much your only choices
 
khmuse said:
"fake"? are you serious?

I would love to understand why you describe it as fake.
Click to expand...

Me too, as I believe getting a shot this way and clean takes a lot of skill.
 
Zooming in is sometimes referred to as fake DOF because the depth of field, in purley scientific terms, is exactly the same. The bluriness is only magnified by a telephoto lens the same way the size of the shot it. If you look at a blurry photograph from 100 feet away, it will look a lot less blurry then when you are 6 inches from it. Obviously, the photo is just as blurry, it just appears different. Therefore it could thought of as "fake." That says nothing to the skill of a camera operator who can make it work. Nothing fake about that guy.
Peace,

-Harry
 
Mathematically the DOF does not change when you back the camera up and zoom in, but because the focal length of the lens in larger (when zoomed in), the DOF appears to be more shallow. So visually it appears to be more shallow, but mathematically it is the same.

I posted this thread a long time ago... It relates to the original question.

http://www.dvxuser.com/V6/showthread.php?t=71373

EDIT: Harry beat me to it :)
 
Thanks but can you tell me why? In that post you said it was another can of worms. I would really like to know why it appears more shallow. Pretty please? :)
 
Prodigy= said:
Thanks but can you tell me why? In that post you said it was another can of worms. I would really like to know why it appears more shallow. Pretty please? :)
Click to expand...

First off, different focal length lenses have a different field of view. The image below shows examples for a wide, normal, and telephoto lens. The images down the center column show the angle of view. The column at the right shows the field of view (and the resulting image). Each of these was shot from the exact same distance. So you can see that the telephoto essentially "zooms" up on the subject (and the background).

DOF2.jpg



The image below at left was shot with a 28mm lens, 2 feet away from the subject. The image at right was shot with a 135mm lens, 8ft away from the subject. I adjusted the distance so that the size of the girl's head was approximately the same for each image. Notice that the DOF for each is very close to the same (noted below image). Now if you look at the image on the left, you can see that the house and street in the background are slightly out of focus. With the 135mm lens though, the background appears to be extremely out of focus. Notice that because of the narrow angle of view of the telephoto lens (the 135mm) we can only see a much smaller portion of the background. Think of it as taking a small portion of the background from the image at left and blowing it up to fit into the frame. Essentially the telephoto magnifies the portion of the background that is within its field of view. So even though the background is out of focus in both images, and even though the DOF is almost the same... the telephoto lens creates the appearance of a much shorter DOF. Again, think of taking something that is already out of focus, cropping it so that you are only seeing a small portion, and then blowing it up to fit into the original frame. So in a way, the amount that it is out of focus is exaggerated.

DOF.jpg


Now, when you zoom the DVX or HVX in all the way, the focal length isn't that of a telephoto lens (the lens on the DVX is a 4.5mm - 45mm zoom lens). Still though, the same principles hold true. So by backing up and zooming in, you get the appearance of a shorter DOF (though it is technically about the same).

Make sense?

*Keep in mind that the more technical answer has to do with the circle of confusion and the optics of a lens. I'm not sure I could do a good job explaining that though (since I am still trying to understand much of it :))
 
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