300mm f4...5 star review.

[Dave in Wales]

https://photographylife.com/reviews/olympus-300mm-f-4-is-pro

[blackfox]

the only point I disagree with is the fact he doubles everything up and says the lens is the same as a 600mm F8 ... no its not its F4 on a 2x crop sensor the aperture remains the same

[Dave in Wales]

the only point I disagree with is the fact he doubles everything up and says the lens is the same as a 600mm F8 ... no its not its F4 on a 2x crop sensor the aperture remains the same

Two stops light loss with TC-2...........https://robinwong.blogspot.com/2019/...converter.html

However, there is a compromise when it comes to lens brightness, we lose 2 stops of light, that means instead of F4 wide open, we get F8.

[blackfox]

Go back to where he refers to the bare 300mm as equal to a 600mm f8 dave .. it’s obvious that adding the 2x will give f8 that wasn’t my point

[drmarkf]

A good 50% of the back archive on dpreview must be taken up with the World's keyboard warriors getting heated about that particular non-issue, paragraph after angry paragraph

[R99C99]

Not that I want to stoke up any further arguments, but I must admit, as a new(ish) m4/3 user I totally understand the 2x focal length equivalency. But I definitely don't understand what the supposed doubling of the aperture to some kind of equivalent means or if its even 'a thing'.

[blackfox]

its been discussed many times on various platforms ,its a constant whatever crop factor your camera uses the F stop is as written on the lens .. or you would with tele convertors be at the limits of credibility

[Miketoll]

As Jeff says the the F stop is a property of the lens. An F4 is always an F4 whatever the size of the sensor.
I think the so called doubling of the aperture thing comes from the fact that because of the smaller sensor size the apparent DOF is greater for a given shot by two stops compared to the same shot taken on a FF camera.ie a shot taken on the Olly 300 f4 at f4 has the same exposure as the same shot taken on a FF 600 f4 at f4 but looks like a FF 600mm shot taken at f8 as far as DOF is concerned.

[RobEW]

For general photographic purposes, when dependent on ambient light, the important characteristic of the lens, for the purposes of getting the right exposure and shutter speed and ISO, is the F stop as written on the lens. Especially with fast moving subjects and poor light, you want wide aperture lenses to keep the shutter speed sufficiently high and the ISA sufficiently low so as not to have motion blur or noise.

However, studio portrait photographers with complex lighting rigs (steady or flash) have a different viewpoint. They have as much light as they like, and can select a fast shutter speed and low ISO so as to have no problems with motion blur or noise. BUT they are incredibly keen on having low depth of field, to create the out of focus backgrounds which are currently so fashionable. Depth of field depends on both aperture and crop factor, and so they informally think of a F/4 lens on a 4/3 sensor as being the "equivalent" of an F8 on full frame. For these people, the reason to invest in a wide aperture lens is to create low depth of field, not to avoid motion blur or noise, and so they think and speak accordingly.

[tmp]

that's how I figure it as well. Tony Northrup actually did a pretty good video on this not long ago.
light gathering is f/4.
DOF at f/4 on m4/3 is same as DOF of f/8 on FF....and I do appreciate m4/3's doubled DOF 98% of the time. the other 2% is inconsequential.

[RobEW]

YEs, for macro, extra DOF is definitely a good thing.

1960s photography publications used to argue that wide aperture lenses are sometimes necessary to get in sufficient light, and a downside of them is the low depth of field. Somehow in the last few decades, out of focus backgrounds (in portrait photography at least) have been elevated from being a sad necessity to being artistic. It perhaps started as making virtue out of necessity but is now the prevailing aesthetic in certain circles.