Does Crop Factor Affect Aperture?

[lennon33x]

I'm not really sure about this. If this is true, then wouldn't it apply to all lenses when it comes to crop factor vs ff?

It would be interesting to see if someone tested this out & posted it here

 

[lennon33x]

After re-reading it, I think it is essentially comparing the difference between 1.8 and 2.8 on aps-c to full frame. The FF offers greater light sensitivity, and at the two comparative apertures, are probably equal.

What I mean is this:
The histogram of the same image/setup on a FF camera at 2.8 should be equal to 1.8 on a CF camera. The reason it's probably occurring is bc of the greater light sensitivity of FF.

I can test this theory out tomorrow. My coworker has the old T3 I sold her and I'll shoot the same setup (ISO/shutter speed) with the same lens and I'll let you know what happens

 

[astroNikon]

per your other question ... crop vs FF for working distance can be seen here
http://www.thephotoforum.com/forum/...rence-between-full-frame-cropped-sensors.html


With the aperture, The theory, as I'm assuming is this:
a crop camera uses a smaller area than a FF while using a FF lens
Thus, it's not taking in all the light that a 1.8 or 2.8 lens takes in on a FF camera .. it's using less of the projected image area. So if you cut out the extra light that isn't being used (as in the above link) then a 1.8 aperture is really the same amount of light gathering as a 2.8 lens.

That is what I assume the above review meant.
I can actually test that theory .... we'll see if I have time later on.

a crop specific lens, if I understand it correctly, can use less glass etc as it only has to project an image large enough for a crop sensor. If you use a crop lens on a FF camera then you get black/vingetting heavily around the edges as the image is not large enough to cover the entire FF sensor.

 

[timor]

Aperture is about intensity of the light on every square millimeter of sensor or film and size of the medium have no influence on that. It is not about "gathering" the light, it is about transmission. If the light meter is showing f8 at 1/100 of a second with ISO 100, it applies to any size of the camera and sensor and lens in any combination.

 

[lennon33x]

So I tested this out with a 1.8 lens on both my 5D and my old T3. Same distance, ISO, shutter speed. I looked at this histograms, and it appears that at 2.8, the 5D FF captures less highlights and more shadows, and at 1.8 on the T3, more highlights. I'm not sure that Sigma is really boasting anything about a lens, but more about theory of wider apertures.