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DPReview's Equivalence article

Discussion in 'Back Room' started by Reflector, Jul 7, 2014.

  1. Reflector

    Reflector Mu-43 Hall of Famer

    Aug 31, 2013
    I was hoping people noticed that the sample crops on page 4 appeared the same for everything short of the Nikon 1 V3's 1" sensor with a dense 18MP...
  2. alex66

    alex66 Mu-43 All-Pro Subscribing Member

    Jul 23, 2010
    I would like to thank Art13 for his comments in explaining this, he has done a much better job that I have done. That being said we only have to look at how different generations of cameras have behaved to see how the tech in sensors has improved with regard to 'noise' I have had 3 generations of Nikons D100,200/ D70,80,90 where the D80/200 with the increase in MP from 6-10 made it a noisier cam above its lowest setting the D90 was far improved, yet on every body when I set say 1/60 at f8 200asa the image was the same level of brightness, (Studio lights measured with minolta meter). I get the same with Film, m43 cameras a Canon 5d etc and that is with every film camera from a 35mm to a Deardorf 10x8, a smaller area does not affect the meter reading. Yes it can affect the noise performance but this can be mitigated over time, D200 horrible at 800asa G3 happy to use 1600asa. I do not bother with this aperture equivalence thing, I am a lover of deep deep DOF so with m43 using a lower focal length lens for a given field of view I am happy as and the DOF is according to focal length over angle of view, with a few other things dropped in.
  3. fortwodriver

    fortwodriver Mu-43 Top Veteran

    Nov 15, 2013
    Toronto, Ontario, Canada
    Yeah, my issue was more with one of the DPReview guys saying that F-Stops guarantee brightness, which is completely false. T-Stops guarantee brightness. F-Stops only guarantee a ratio in the opening of the iris for the lens.
    • Like Like x 1
  4. Fri13

    Fri13 Mu-43 Veteran

    Jan 30, 2014
    Theoretically F-stop guarantee the brightness but it doesn't counstillse or lenses inside objective optical quality how little they reflect light or how well they refocus incoming light from previous lens, but it does guarantee light transmission change in same rate regardless of lenses quality.

    T-stop is the guarantee for the light transmission but it doesn't guarantee the iris size so everything related that can't be calculated based T-stop, having same T-stop gives different depth of field in different objectives. T-stop evaluates the lense(s) quality. Both gives different values for two different purposes and limits. Other is meant to control amount of light and depth of field as secondary as shutter speed can be adjusted.
    Other is meant to give possibility to use specific film as film rolling rate is always fixed and doesn't allow faster or slower exposure time per frame.

    Now on digital era we can digitally adjust the exposure per frame to rate of frame rate or higher as we don't need to keep film speed in same. We can get 24 frames a second but each frame exposure time being from 41ms to 0.125ms (1/24-1/8000) without recorded video becoming as slow motion video because we can reject all the information between each frame in 24 frame rate.
    (But still we do process them like with OM-D E-M1 we have 120Hz refresh rate for EVF what means camera captures and shows 120 frames a second at max but can sample smoother video from slower frame rate as well until hitting to 24\30 fps limit camera can capture and exposure correctly with boostings.)

    The F-Stop vs T-Stop value differences is very important in photography when comparing different objectives for same exposure values but otherwise T-stop isn't giving required information for still shots capturing. Others needs steady flow of light and other needs to freeze action from wanted time line.

    Now almost all digital cameras can capture stills and video. But we can not all get objectives what gives both stop values same time as it would cost a lot to even make simple objectives. Glass quality should be so high and lenses polishing etc that we could get both values to be same.
    For videos it doesn't matter so much if objective draws a unsharp image as we can use it in fast action moments in low light or hide it just for movement purposes. But such unsharp objective for landscape photography or even for fast action sport shooting will ruin the photo if wanted to get sharpness.

    One day in future when we can get to situation where we do not need optics, we get the ultimate camera for everything. Digitally cropping the view so you just choose a pre-set angle of views or draw a area as wanted in ratio wanted. No need to white balance or color correct anything as all the data what light gives is captured. No need to focus as we get all the light (lightfield camera) and no need to anything actually than just choose pre-set and camera does everything from tracking target to frame rates, light amounts, colors, sharpness etc. We can then even allow camera to build 3D model and alter camera angles radically like in best CSI episodes where camera looks around corners.

    And then we don't need anymore horry to get correct moment as time traveling is possible as we can capture future or past, even in same time.

    But now the time is little past 6am and I leave a house to take photos with my crappy camera what I can choose now, A7 or E-M1 or why not even feel retro and grab a film camera with B/W film as I can't do anything what theoretically is possible as I don't live to see them applied.
  5. OzRay

    OzRay Mu-43 Hall of Famer

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    Shoe sizes are measured differently around the world. Is there an equivalence? Why are US sizes always listed as being bigger (http://www.i18nguy.com/l10n/shoes.html)? Do US buyers get more shoe for the money than do Australian buyers? Can you stand taller and walk longer in the US shoe vs the Australian shoe? There are so many unknowns and unanswered questions. ;) 
    • Like Like x 1
  6. Fri13

    Fri13 Mu-43 Veteran

    Jan 30, 2014
    I believe you hit the nail with that, now let me ask how it is that shoe size 9 (US size) bought from Germany can be bigger (or smaller) than shoe size 9 (US size) bought in Australia?

    Same thing for other cloths like S, M, L and XL can be that XXL size for Japanese is M for American.
    Or manufacturer A has L smaller than B's L..

    So many important factors to discuss
  7. biomed

    biomed Mu-43 Hall of Famer Subscribing Member

    Aug 22, 2013
    Seattle area
    If this is important to you then OK. I tend to think crop factors deserve the same attention that crop circles do.:biggrin:

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  8. Fri13

    Fri13 Mu-43 Veteran

    Jan 30, 2014
    Crop circles? How do you crop a circle? Like cutting it in three pieces?
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