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Does crop factor have to be applied to aperture & ISO? (Is the Panny 35-100 f2.8 really f2.8?)

Discussion in 'This or That? (MFT only)' started by sigamy, Aug 2, 2014.

  1. sigamy

    sigamy Mu-43 Regular

    134
    Dec 4, 2012
    Can someone explain this to me like I'm a six year old?

    Tony Northrup is saying that crop factor must also be applied to aperture when comparing FF, APS-C and MFT cameras. In another video's comments he says that the Panny 35-100 f/2.8 is equivalent to a f/5.6 on full frame.

    A lot of folks in the comments are making counter arguments, calling Tony stupid, saying things like "f/2.8 is f/2.8"...

    https://www.youtube.com/watch?v=DtDotqLx6nA
     
  2. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Not this again...

    What he is saying applies only if you are trying to re-create a specific look from a specific sized sensor. The 35-100 is an f2.8 (the physical size of the aperture goes from 12.5mm-35.7mm (rounded slightly)). It gives the same exposure as any other camera having the same ISO and shutter speed with a lens at f2.8, regardless of sensor size. What he has done is start with a single property that differs from each size sensor, then work backwards to make the math work out. Where this breaks down is that modern m4/3 sensors outresolve older 35mm sensors at the same ISO, so the noise arguement falls apart.

    Do a search and find several threads on this. It is primarily click-bait.
     
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  3. phigmov

    phigmov Mu-43 Hall of Famer

    Apr 4, 2010
    This type of thing has cropped (get it?) up several times before (almost monthly if not more frequently).

    Without trying to sound snarkey, these types of articles/videos are effectively click-bait (this one in particular has appeared before) - they encourage revenue clicks through posting something contentious.

    Ultimately, m43 takes pictures (the forums image threads are full of thousands of happy campers shooting great pics!) and fills a market segment (in the same way as all other formats (bigger or smaller) do) - enjoy what you have and use it whenever you can to get the images you enjoy.
     
    • Like Like x 1
  4. sigamy

    sigamy Mu-43 Regular

    134
    Dec 4, 2012
    Thanks for the quick replies. You are both right, I should have searched first.

    Tony seems like a straightforward guy so I didn't even think about click-bait. But now I see he has books and videos to sell, so...

    I love my GH3 for both stills and short films.
     
  5. nstelemark

    nstelemark Mu-43 Hall of Famer

    May 28, 2013
    Halifax, Nova Scotia Canada
    Larry
    This is a well balanced and accurate explanation:

    http://admiringlight.com/blog/full-frame-equivalence-and-why-it-doesnt-matter/

    Tony Northrup is trying to drive an audience to his product. If you only want to control depth of field via aperture and this is the only thing that matters in the photos you take then you want the largest sensor you can get. This is where all the supposed "full frame" vendors are cheating everyone. Full frame is not 24x36, you want something much larger to achieve optimum shallow depth of field, say at least 6x7 which is 56x70!
     
    • Like Like x 1
  6. Dalton

    Dalton Mu-43 Veteran

    329
    Jan 24, 2010
    Portland, Oregon USA
    Dan Ferrall
    Does crop factor have to be applied to aperture & ISO? (Is the Panny 35-100 ...

    Tony Northrup doesn't give a damn about "crop factor." Tony Northrup is baiting you to stir up activity for his web site so people will "click thru" advertisements on his web site which will make him money in the process. The guy knows that this topic has been hashed to death previously and he knows how much controversy lays within the topic. Any time you see his name in a thread somewhere just ignore him. He could care less about photography. His goal is to bait you to ho to his site and allow him to cash his advertiser vendor checks.

    A given exposure for a particular scene will require the same ISO/aperture/shutter speed settings for all sensor sizes. Just pick any old light meter and try and find a reference to imaging sensor size. There isn't any such reference. The crop factor/exposure argument is well beyond tired. The horse is dead. The fat lady has sung.

    If you want to talk lenses, depth of field, focal length, angle of view, and influence of aperture then that is a whole different discussion entirely.
    Dan
     
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  7. zlatko-photo

    zlatko-photo Mu-43 Veteran

    228
    Jan 8, 2014
    F/2.8 is f/2.8, regardless of camera or crop factor. Aperture is aperture, not a measure of depth of field for a crop factor. That's why a light meter doesn't need to know the crop factor (or sensor or film size) when it measures the light and gives you the aperture for a given ISO and shutter speed. He is confused because he seems to think an f-stop is a measure of depth of field.

    Those lenses are labeled correctly. It's up to the photographer to know the differences in depth of field the format they're using. It's not up to Panasonic to mislabel their 35-100/2.8 lens as f/5.6 because that's the depth of field in another format. A maximum aperture label on a lens is a not a claim about depth of field equivalence in any other format. Never has been! This is really basic stuff, and he should be embarrassed about spreading ignorance on the subject.
     
    • Like Like x 6
  8. Replytoken

    Replytoken Mu-43 Hall of Famer

    May 7, 2012
    Puget Sound
    Ken
    Ignore the scary man on the screen. You will only get nightmares watching him, full frame ones no less! Simple as that. :biggrin:

    --Ken
     
  9. zlatko-photo

    zlatko-photo Mu-43 Veteran

    228
    Jan 8, 2014
    Sorry, but FF vendors aren't "cheating" anyone. That is absurd. Really, this point about larger formats and shallow depth of field is known to anyone who is not an absolute beginner in photography. If someone feels cheated by FF vendors, they probably feel cheated when they learn that the Star Wars movies are fiction and not reality.
     
    • Like Like x 1
  10. broody

    broody Mu-43 Veteran

    388
    Sep 8, 2013
    A funny thing about equivalence. It is indeed true that on a M43 sensor, the DoF for any given aperture is equivalent to what you get stopping down 2 stops in FF.
    It is also true that in theory, ISO on a M43 sensor should be 2 stops noisier than the equivalent ISO on FF (indeed, ISO 6400 on a FF sensor looks about as clean as ISO 1600 on M43).

    However! What most people don't actually consider, is that for a given "equivalent exposure" on M43 and FF, the M43 sensor is *more* efficient than the 35mm one when it comes to Dynamic Range, by about 1-1.5 stops. By the logic of 'equivalence', an ISO 200 shot at F/2 on M43 is equivalent to an F/4, ISO 800 shot on FF. However, if you look at the DR curve for modern M43 sensors, ISO 200 on M43 is clearly ahead from ISO 800 on FF... And the same holds for all other 'equivalent' ISOs. While people love to claim that FF is better because there are some apertures and ISOs for which M43 can have no equivalent, whenever you talk about equivalence, keep in mind that the equivalent exposure with FF gear would be a little behind in IQ all things considered, all while being a lot heavier...
     
  11. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Guys, I think the OP has gotten enough of an answer to understand. Now each new thread bumps it to the top, and the cycle starts over...

    Can we just let this die?
     
    • Like Like x 2
  12. drd1135

    drd1135 Zen Snapshooter

    Mar 17, 2011
    Southwest Virginia
    Steve
    OK. :tongue:
     
  13. STR

    STR Mu-43 Veteran

    222
    May 16, 2013
    I disagree.The whole "total light collected" stuff is utterly worthless and they dedicated a whole page to it. A sensor isn't one big bucket collecting every photon that falls into it. It's a lot of tiny buckets (of varying sizes, depending on model, and is independent of sensor size) which leak at varying rates (due to sensor tech). Some of the "photon rain" lands outside the buckets and is never recorded.

    As a sidenote, look at their demo on page 4, the four thirds image looks cleaner than the full frame! I'm not going to say that's typical, but if you have an older FF camera, yes, there is a possibility it will be outperformed by a newer sensor. Sensor design (pixel size) and sensor tech (2014's finest vs the best 2005 had to offer) are both more important than crop factor.
     
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  14. RobWatson

    RobWatson Mu-43 Hall of Famer

    Seems crop factor get applied everywhere except price! Wheres my crop factor refund/rebate?
     
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  15. drd1135

    drd1135 Zen Snapshooter

    Mar 17, 2011
    Southwest Virginia
    Steve
    Never a good topic for calm discussion but here goes. You need to show the FF and mu43 images at the same size and resolution such as 2000 x 1500. You also need to assume that you can use the whole image, so the lens on the mu43 body must have half the FL of the FF body. In this case both images reflect the total amount of light collected by the sensor. Either the FF has bigger light cups (same number of MP) and less noise or the FF has the same size cups and more MP. In the latter case, the sampling of more MP can be used to reduce noise. Exposure is the same but noise is affected.

    Edit: Let me add that this simply reflects my understanding of the issue. I have been wrong on occasion.
     
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  16. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    How about we tell it like this, historically…or should that be hysterically?

    Back in the 1930s there was an influential group of photographers called the F/64 group because, you guessed it, they used F/64 a lot. Ever seen a 35mm film camera lens, or a "full frame" digital sensor lens that stopped down to F/64? No, for a good reason. The results look bad because of diffraction, yet the F/64 group produced wonderfully sharp, absolutely stunning images. Why? Because they used view cameras with 8" x 10" negative sizes and similar, so that was their "sensor size" and they needed to stop down to F/64 to get the depth of field they wanted, and with a negative that size they could do that without running into problems with diffraction. At F/2.8 or faster they had virtually no depth of field at all. F/2.8 on a view camera that size makes F/1.4 on a full frame sensor look like it's got a lot of depth of field, Those full frame guys don't know what "shallow" depth of field is if they think that's what you get at F/1.4 with their lenses.

    So, what happened between then and now. Smaller negative/sensor sizes let the landscape photographers get enough depth of field for their needs at far larger apertures than F/64 so they could ditch tripods and shoot hand held for a lot of their work, and get to more remote locations because they didn't need to drive their gear into the shooting location in a car, and other photographers started chasing super fast lenses to get the shallow depth of field that the view camera people used to get at F/5.6 or so.

    And what's it all about in the end? Reaching an acceptable compromise between a camera/lens combination that delivers the kind of image you want and a camera/lens combination that delivers on the convenience issues that let you carry around no more than you want to and shoot the way you want to.

    People who shoot M43 need to learn to care about the comments of those who think full frame is the holy grail as much as the people who shoot full frame care about the comments of those who thought an 8" x 10" view camera was the holy grail. The view camera guys spent years telling the 35mm film guys that they were using a toy format, that it would never deliver professional quality work, and that it would never catch on. Dinosaurs do that to predators and the predators eventually eat the dinosaurs, and as they do so and the dinosaur gene pool weakens the dinosaurs become smaller. The full frame guys are this era's descendants of the dinosaur gene pool and those using smaller formats are their descendants and the next generations dinosaurs. This discussion has been going on in one form or another for a century or more and the only thing worth saying is that it isn't going away.

    Forget equivalence as a way of proving that bigger is better. Pick the camera and lens that lets you get the shot you want and get it the way you want to work. There are always compromises to be made so pick the ones you want to make. That's what the full frame guys did and what they're doing now is saying to smaller sensor guys "Don't do what I did, do what I say." Well, we're doing what they did and for the same reasons that they did it. Because we can get the results and get them with a lot more convenient way of working, and we can even get some results that they couldn't, just like they could get results that the view camera guys couldn't. Photojournalism really became the profession it became because 35mm film cameras were small enough and convenient enough to work with so that photographers could get reportage photos that were simply impossible to get before. Smaller sensors are starting to do that to the full frame guys.

    The only thing we need to know about the holy grail when it comes to formats is that the holy grail is shrinking. It always has, it always will.
     
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  17. nstelemark

    nstelemark Mu-43 Hall of Famer

    May 28, 2013
    Halifax, Nova Scotia Canada
    Larry
    Since we aren't letting this die :tongue:.

    Of course the FF vendors aren't cheating anyone, but cheating by the m43 vendors is the whole premise of Tony Northrup's video. It is ironic that the comment that the FF vendors are cheating leads to a
    statement. And there is further irony that Tony Northrup does not take Nikon to task for totally omitting the DOF discussion in their FX vs DX page:

    http://www.nikonusa.com/en/Learn-And-Explore/Article/g588ouey/the-dx-and-fx-formats.html
     
  18. zlatko-photo

    zlatko-photo Mu-43 Veteran

    228
    Jan 8, 2014
    I was responding to your statement — "This is where all the supposed 'full frame' vendors are cheating everyone." I agree that the FF vendors aren't cheating. But the m43 vendors aren't cheating either.

    No one is cheating anyone by virtue of f/2.8 aperture labels on lenses. F-stops have an old and established meaning which is understood by manufacturers and photographers. The only way that Tony Northrup can allege "cheating" by m4/3 vendors is by pretending that his own mixed up definition (based on DOF equivalence) is the one they should have been using all along.

    Tony Northrup might as well apply his investigatory prowess and educational enthusiasm to illuminate similar instances of "cheating", such as:
    1. How Atlas Vendors Cheat You: where he reveals that countries in Latin America don't actually speak ancient Latin.
    2. How Soda Vendors Cheat You: where he reveals that a 16 oz. soda does not actually weigh 16 ounces.
    3. How Advertisers Cheat You: where he reveals that advertisers sometimes use actors to deliver messages.
    4. Etc.
    :smile::wink:
     
    • Like Like x 1
  19. ptan55

    ptan55 Mu-43 Regular

    45
    Dec 18, 2011
    Amherst, NY
    I am not a fan of the Tony Northrup videos.
    I am still trying to figure out if he is dumbing down his videos to the point that it confuses people, or he is just dumb.