f/1.8 on m4/3, ASP-C, FF; are they the same?

Started Nov 1, 2010 | Discussions thread
Gao Gao Contributing Member • Posts: 561
Equivalent Values

m4/3 20mm F/1.7 ISO 200, 1/100s

is roughly equivalent to

FF 40mm F/3.4 ISO 800, 1/100s

In terms of angle of view, depth of field, dynamic range, and motion blur. In other words, using the two setups above to shoot the same subject from the same spot should yield near-identical prints (that's what equivalent means, ultimately).

To those who think same F-stop means the same amount of light - no, it's the same amount of light per unit sensor area. Since FF has about 4 times the total area compared with 4/3, it receives 4 times the amount of light. And to those who say mounting a 20/1.7 on a FF and crop - what's the point if you can't visualize your final picture in the viewfinder and the metering is incorrectly weighted for the final picture?

FYI, a few other common 35mm-equivalent value sets,
in focal range, max f-stop range, and ISO speed range:

Canon S90 –
28-105mm F/9-22 ISO 1600-70000

Olympus E-P1 + 14-42 kit -
28-84mm F/7-11 ISO 400-25600

Nikon D90 + 18-105 kit -
27-158mm F/5-8 ISO 200-14000

Canon EOS 5D mkII + 24-105 kit -
24-105mm F/4 ISO 50-25600

Hasselblad H3DII31 + 80 kit -
63mm F/2.2 ISO ISO 60-1000

Peiasdf wrote:

Hi everyone, I do not get why some people said the 20 f/1.7 lens on m4/3 equals to 40 f3.5 on FF so here is the thread asking about it.

If a picture is taken at 20mm, f/1/7, ISO 200, 1/100s on m4/3, will it come out similar (beside DOF) to a 40mm f/1.7, ISO 200, 1/100s picture on a FF?

Some people mentioned m4/3 lens only lets in a quarter the light of a FF lens. So does it mean the camera have to reduce speed by a factor of four to get the correct exposure. It does not make sense to me, as P&S cameras do not require 15 times the exposure.

I am thinking about going from D90 + 35 f/1.8 -> GH2 + 20 f/1.7 for a night out with friends camera but the exposure thing is throwing me off. Maybe I need a Nokton 25 f/0.95?

-- hide signature --

. 。o O o 。 . 。o O o 。 . 。o O o 。 .

Post (hide subjects) Posted by
(unknown member)
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow