Originally posted by northcoastgreg Where did I say it shouldn't matter to anyone because it doesn't matter to me?
You didn't, really, I was using your post as a jumping off point there to address a common theme. A lot of folks do have that attitude, and wander in here (FF forum) to express it in various angry ways.
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Quote: Aperture equivalence is something that seems to have been emphasized only recently. Most of the articles that I've found on it through google were written in the last few years; the oldest mention I could find was Ken Rockwell from 2009. Articles before 2009 that discuss equivalency seem to mostly concentrate on FOV equivalency. I suspect that concern over aperture equivalency arose following the introduction of the Nikon D3, which helped stir up interest in and advocacy of FF to a fever pitch.
I think it is interesting how it evolved on DPR and other forums:
Circa 2002-2004 or so ; Most of the first DSLRs were aps-c (1.5x or 1.6x (Canon),) and people had to learn how to convert the FOV to this new format in their heads, so that when they used their existing 35mm SLR lenses they would know what to expect in terms of this 'new' FOV.
All was well and good, but then a few folks started noticing that something didn't look right, DOF seemed a tad too deep for the same FOV and aperture that they were used to, and there were a few people who actually thought the digital camera was misrepresenting their F-stop
Some folks like Lee Jay, Josepsh Wisniewski, Joseph James and others tried to show them why they weren't imagining things and described the physical reasons why they were seeing what they were seeing. A few articles came from that, with I think
this one being the best and most continually updated.
It seems like it really started to get talked about a lot starting in 2006 when the Canon 5D hit, though, because that body sold in huge numbers and was owned by people who also shot aps-c.
I believe that you mostly still see photography instructors talking about FOV only, and in fact a lot of them probably don't even understand equivalence themselves. It's too bad, but I guess if they're teaching mostly small-aperture shooting like Landscapes it just never comes up much in their day-day. Also, they may never learned to teach in an environment where different formats could share lenses, or perhaps they didn't want to 'confuse' their students, especially if they themselves couldn't fully quantify the effect.
Joseph Wisniewski talks about how he was trying to describe equivalence (FOV and DOF, not just FOV, how the F-stops meant different things to the resulting images too between formats, not just FL) before there was a handy label for it, back in the 80's
The main reason I think it's too bad more people don't understand it is because the whole
reason FF is even better in shot-noise performance than smaller formats is described by equivalence - because the linear aperture of the lens for that same FOV and F-stop on the larger format is larger. ie:
50mm f/2.8 FF => 50 / 2.8 => about 18mm linear aperture (entrance pupil)
33mm f/2.8 aps-c => 33 / 2.8 => about 12mm linear aperture
Taken from the same distance, the above allows the same FOV, and shutter speed, but the larger linear aperture brings a larger
total amount of light to the sensor, which will result in less noise, and the larger linear aperture will also result in less DOF.
The reason it's important to understand is that if you plan to
not accept the more shallow DOF - if you know you won't like it, and will be stopping down a lot -
then you lose that 'noise' advantage.
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I guess I don't like that DOF, I'm going to stop down."
50mm f/4.3 FF => 50 / 4.3 => about 12mm linear aperture. (DOF now the same - but noise advantage gone! Doh!)
Just an example of how knowing about these relationships could help you realize something like that before you make a big purchase!
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---------- Post added 04-17-14 at 01:01 PM ----------
Originally posted by nomadkng which summarizes my whole questioning of this "narrow depth of field is the holy grail" logic. If the model's eye is in focus but not the nose, this is a good image? If one orange but not the banana is in focus, this is a good image?
Is more DOF control at the high-end of the F-stop range a good thing?
This '
one model's eye in focus' is a constant, tired example - doesn't anyone have any imagination, can't anyone think of any shooting scenario that doesn't involved close-in portraiture?
I sometimes feel like the forum world is made up of 1) studio portrait photographers who constantly worry about both eyes in focus and 2) landscape photographers who didn't realize their lenses even opened up wider than f/8
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