Thank you for bringing objective measurement to the difficult question of tripod evaluation. There's nothing more satisfying than the ka-snick of a camera firing when it's solidly attached to a vibration-free tripod so thanks for helping us find out which ones deliver.
You're a genius for figuring out that vibration measuring system! I hope you patented it.
Erick L: Total light on sensor affecting noise doesn't make sense to me. Don't smaller sensors appear more noisy simply because the image needs to be enlarged more, noise included?
Seems to me that saying a FF sensor has less noise because it gathers more light is akin to saying a telephoto lens "compresses perspective".
Correct, but that's not what these people are talking about. For them, lens equivalence is a BUYING tool. It's NOT a shooting tool. It's a metric to make intelligent choices about tradeoffs to reduce the size and weight of the equipment you carry. And forget exposure—this is mainly about depth of field.
Thom Hogan has a useful article on equivalence http://www.sansmirror.com/articles/pick-a-size.html
"The simple fact is that there are looks you can't get with small formats that you can with large formats, and vice versa. The trick is to pick the right tool for the right job, and therefore to understand the underlying differences of your tools… You may make hundreds of decisions to get a single good photograph, and one of them is to choose the right tool for the job….People want small, light, inexpensive, high image quality, flexible, robust…But there's a simple fact of life: the more things you require from a tool, the more compromised and/or expensive it is."
wansai: while applaud dpreview for doing this article, i have the distinct impression all it is doing is confusing more ppl than it is helping.
camera settings for any exposure of a scene is done for your respective sensor/camera. it's not useful to consider its equivalence, only what focal length/reach do you want, how are you framing it and what settings on THIS camera do i need to get the exposure.
equivalence is purely academic and is being used almost entirely by fanbois to support either of their cases for superiority.
when taking a shot, what does it matter what the Ff ewuivalence is? here, now, my camera, i need my f stopped to x to get a certain amount of dof. i need the iso and shutter to be set at xx. i expose.
that's all that matters.
Here's the question that all this raises for me....does noise increase at a linear rate with exposure time or does it stay the same and only is affected by ISO? Lets say your sensor introduced 1 unit of noise when you take a shot at f/8 ISO 100 and 1/100. So what happens in low light levels when the shutter needs to stay open for 1/2 second or 1 minute? Do we still get that 1 unit of noise at ISO 100? Or does something else come into play like heat-induced noise?
mostlyboringphotog: @DPR/Richard,May I make a modest proposal:Instead of simply "Equivalent Aperture or F-stop" can we use "DOF Equivalent Aperture or F-Stop)".
After annoying Sven umpteen time, sorry that it took 141 post and 5 days to come up with this modest proposal but I'm not known to be swift.
To all those who would think but that's what is implied in the Equivalent F-stop, remember that F/2 is NOT equivalent F/4 for brightness in any format. No such corollary for Equivalent FL, which makes it less controversial.This proposal is not for the forum posters who know all this already.
Thanks again all, particularly Sven, GB and Richard for engaging me.
That is the best idea I've heard in this entire discussion. Stick to the one point that people agree on and forget about trying to convert people on the others.
No one is going to change their mind, and trying to argue one side or the other just perpetuates the cycle of trolling and flaming, trolling and flaming.
Compromise is what adults do when they realize that they're not going to agree on everything; it's time for both DPR staff and readers to grow up.
This is one of those great simple innovations that you can't appreciate unless you've watched $5000 worth of camera and lens on what you thought was a carefully propped monopod start sliding slowly toward the concrete.A great, low-tech way to add stability to an inherently unstable piece of equipment. Bravo.
rfsIII: There must be an professor of imaging science out there somewhere who can be hired by DPR to write a nice counterpoint article that will untangle this topic and bring sanity to what is essentially a holy war between two under-informed camps. I would start at http://www.rit.edu/cos/optics-rit and work westward from there.
There is nothing simple about optical science especially at the level we're discussing. But I get the point. For whatever reason you're not going to reveal the name of anyone in your circle who has the academic or professional credentials to back up this theory of yours. I surrender. Live long and prosper.
The problem is that the equivalence evangelists don't work in the field of optics or sensor design so it is impossible for them—or us—to know what gaps there are in their theories.
For instance, yes, on a single-element lens, I would imagine you might get the same amount of light. But what about a double Gauss? Or a 15-element 24-70 with 11 lens groups? There's a lot going on in that tube that they're not accounting for.
The other thing that makes me skeptical of their idea is that they attack those who raise questions about it. It's something we see frequently here in America where arguments are won by out-shouting your opponent rather than by weight of logic and fact.
And despite the protestations by the supporters we still haven't heard anyone with even a bachelor's degree in a relevant field come forward and endorse this theory. That's what makes me think that perhaps there's a gaping hole somewhere and it may in fact be this "total light" concept as mentioned by nigelht, above
This is my point. No one involved in promulgating this theory has said anything about their relevant scientific or engineering credentials. Supporters just keep saying it's common sense. I haven't seen a single mathematical proof.It's a nice thought experiment and it may be completely true, but right now it lacks the real-world input from people working in the field to make it something that should be spread on the front page of an important website like DPR.
I'm no physicist, but I know that you guys are leaving out the fact that resolution is a tradeoff between diffraction and aberration. A wider aperture means more optical aberrations (which are themselves a form of "noise") which is just as deleterious if not more so than diffraction. You are also ignoring new sensor technology that is coming close to eliminating the problem of noise from smaller pixels.
We live in a world of science, theories should not be set forth as facts without rigorous evaluation by qualified experts.
There must be an professor of imaging science out there somewhere who can be hired by DPR to write a nice counterpoint article that will untangle this topic and bring sanity to what is essentially a holy war between two under-informed camps. I would start at http://www.rit.edu/cos/optics-rit and work westward from there.
JPdeJ: In response to sb. below. The human eye - 50 degrees and standard lens on 35mm?Most humans have the functional use of two eyes with a significant distance relative to sensor size and optics.That means horizontally we see differently than vertically.Image processing in the brain helps us and sometimes fools us.The angle of view is the conscious part of _male_ (=tunnel) vision.
My first wide-angle lens (28mm on 24x36) seemed an eye opener. After some time I needed 24mm. Then I moved to 20mm on 24x36. After 10,000 conscious shots, I noticed a sudden change and it seemed all lenses "narrower" than 180..220 degrees were actually a limitation. The male tunnel had gone. Through learning. Neuronal connections, etc.
Or, "standard" or "normal" are so relative.
Great point about the vertical axis. But I'm with you, wide angle is better especially when you can contrast close subject with distant background.
Bodhi Dharma Zen: To put it in other words. MARKETING people are (professional) liars. They would push a lens as being "2.8" when, in reality, their light sensitivity is a lot less (depending of course of the relative size between sensor and lenses)... There should be LAWS to guarantee that marketing people should be limited to stating FACTS in RELATION to an approved standard.
All lensmakers overstate the aperture. If you read lens reviews most lenses labeled f/2.8 are actually around f/3.2. But if you're metering through the lens it doesn't make any difference the meter is reading the actual light. If you're using a handheld meter, then it's a problem.
ThePhilips: DPR, you should have started with historical fact that 135 film format, aka "Full Frame", started its life as a crop, literally.
All these formats are crops of the crops of the crops. None of them is "full".
The de facto standard for stills in the film era was 8x10; when I started working in the mid-90s the standard was 4x5, which slowly morphed to 2 1/4 square, then 645 and then medium-format digital backs and finally 35mm digital. It wasn't really until the 60s that 35mm became the standard even for news photographers.
rfsIII: Thanks for legitimizing one man's crackpot theory. You have set photographic understanding back by 150 years and made life harder for photography teachers everywhere.What you guys are ignoring is that f-stop also controls overall performance of the lens. Most lenses are sharpest at their middle apertures—there's no "equivalence" for that law of optical engineering. The image from a cropped sensor camera is not going to be as sharp across the frame at f/2.8 as one from a large-sensor camera is at f/5.6.
What really bugs me about this whole story is that it is not up to the usual standards of DPR journalism. The writer naively buys into the nomenclature and conclusions of the "lens equivalence" crowd and doesn't engage his own critical faculties nor does he interview qualified optical or imaging scientists to probe anything about their assertions. It's as if he were writing about people who think the earth is flat and didn't bother to talk to an astronomer or a geographer. I think the editors of DPR do a great job of keeping their distance from Amazon, so they're clearly people of strong character and high intellect, but for this story they allowed themselves to be seduced into becoming the blushing, star-struck cheerleaders for a group with a somewhat questionable understanding of physics.
So, Mr. Butler, now that you have spent your day off posting answers to the comments for this story you know first-hand what people mean when they say "no good deed goes unpunished."
I want to know when they're going to make an adapter so I can use this as a back for my 4x5 view camera.
My point is that this whole equivalence argument has lots of internal validity, but no external validity. In other words, it's great for choosing which camera to buy, but can interfere with intelligent choices once you're out in the field—such as which f/stop to use. F/stop is a parameter that affects sharpness, exposure, and to an extent depth of field, but DOF is better manipulated by changing the focal length or the subject-camera-background relationship. In addition, it makes teaching the exposure triangle even more difficult than it already is because it advances the incorrect notion that somehow the amount of light gathered depends on the area of the sensor. Yes, if light were water and the sensor was a bucket that would be true. But capturing an image at a given light level, the sensor doesn't care how big it is. That's why with t-stop calibrated lenses, you don't need to change your ISO or shutter speed when changing lenses or moving a lens from one size sensor to another.
bartjeej: Good article, I'm sure the issue will become clearer for a lot of folks.
One request though; could you PLEASE not contribute to the already much too pervasive myth that the word 'bokeh' only refers to the quality of the blur and not the quantity? It simply means blur, and you can have lots or little blur/bokeh just like you can have pleasant or unpleasant blur/bokeh. 'The quality of the blur' would be 'boke(h)-aji'. Just a little pet pieve of mine :)
Because it also carries the meaning of unclear or confused, In some parts of Japan, bokeh is an insult equivalent to "idiot."
nerd2: In addition to this article, smaller format has other issues too:
-Smaller sensor requires faster lens for the same DOF-Smaller sensor requires smaller pixel pitch for the same resolution-Smaller sensor requires sharper lens for the same resolution-Smaller sensor has lower diffraction limit due to the higher pixel pitch
So you have to use faster, sharper lens that is good enough at wide open (you cannot stop down too much due to diffraction) to make up for the smaller sensor size. It was somehow justified 10 years ago when sensor prices were sky high, but now sensor prices are cheap enough.
And there is no reason FF camera cannot be shrunk down. Pentax *ist film SLR was only 335gr with mirror and pentamirror! (Yes, it was FF DSLR)
Sorry nerd2, you would lose that bet. The 12-35 and 35-200 f/2 4/3rds lenses from olympus are unbelievably sharp and of course they cost even more than their Nikon and Canon equivalents, if I remember correctly they were about $2500 each when the price of the Canons and Nikons were under $2000.
gtstone: The title of this article took me back to 1966-1967 when I took workshops with Minor White. One of his big themes was the concept of "equivalence" (or sometimes "equivalents") where he would show us image after image of clouds and try to get us to understand that the image of a cloud-scape was "equivalent" to a feeling he wanted to convey. Similarly sea-scapes and rocks.
Here's a link about this:http://jnevins.com/whitereading.htm
He never talked about photographic technique: he had lab assistants to help us with that. What he wanted to talk in about in class was how we would respond to a print (as opposed to "react").
Another frequent theme was pre-visualization: you don't look for something interesting to photograph, you look for something that will make an interesting photograph. You look around and pre-visualize what a print of what you see before you would look like considering all the steps to get there. I often wonder what he would have done with with Photoshop!
You are correct, it is ungrammatical, but that's the word those geniuses used so we pay honor to them by using it as well.
OldScotch: On page 3, you state: >"As you can see, the amount of depth-of-field depends on sensor size."
That's not quite accurate, the depth-of-field varies because the focal length has changed, not directly with the sensor size.
But is a tomato a fruit or a vegetable?