So why are adapters necessary?

HBlack

HBlack

Underage Member
Sorry for the question, I've just never been able to understand this.

Some DSLRs have a crop factor because the sensor is smaller than full frame 35mm. So why doesn't the same apply for video camera?
 
As I understand, it doesn't apply because the distance behind the rear lens element to the actual imager isn't the same. Some DSLRs have smaller chips, but they are at the correct distance behind 35mm glass to work properly, but since they are smaller, you don't get 35mm size framing, but you go get 35mm DOF.
 
Ah, right, I guess the fact that it's going through the camera's glass causes it. Embarrassed I didn't figure that out on my own.
 
I was under the impression all SLRS had the same DOF with the same lenses, regardless of sensor size?
 
i believe that is incorrect, olympus has a 2x crop because of their sensor size and they do not get as shallow DOF with lenses as a result. People are moving up to full frame cameras with the assumption that they will get more depth of field, and i believe that is the case.
 
Nope.

A 50mm lens has a set DoF for any given f-stop and focus distance. If you put in on a 1.5x crop DSLR (for instance) it will have the Field of View of a 75mm lens but the Depth of Field will remain the same.
 
Exactly... A 50mm lens at a given fstop and "focus distance" produces always the same DOF no matter what camera (sensor size) you are using. If the sensor gets smaller the FOV gets smaller and vice versa. To get the same FOV with a SLR camera that doesn't have a full size 35mm sensor than with a camera that has a full size sensor, you need a shorter focal lenght --> shallower DOF
 
ya, i guess thats what it was, the equivalent focal length debate. Never mind my ignorance on depth of field.
 
Thanks Will for explaining that clearly, I always thought the crop factor was the reason DoF was smaller on camcorders and DSLRs! This sheds a lot of light on DoF for me, it's pretty logical when you think about it.

And cord, didn't you mean a short focal length = greater DoF to get the same FoV at a 35mm focal length equivalent?

I should not read these forum when just waking up... I need coffee!
 
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