# Trying to draw viewfinder sizes on screen



## T-RonX (Mar 28, 2013)

Hi,

I am trying to make a little tool for myself to compare viewfinder sizes. I do get some results but the rectangles seem to be a bit small I think. Probably interpreting some values wrong. Can someone please have a look?

The colors in red are the 6D's sensor size, magnification, viewfinder coverage and aspect ratio respectively.

magni = ((35,8 mm * 23,9 mm) = 855,62 mm2) * .71x = 607,4902 mm2
surface = (magni * 97%) = 589,265494 mm2
edge = sqrt(surface) = 24,274791327630398396804364790437 mm) * 2 = 48,549582655260796793608729580875 mm
aspec_part = edge / (3 + 2) = 9,7099165310521593587217459161749 mm
width = aspec_part * 3 = 29,129749593156478076165237748525 mm
height = aspec_part * 2 = 19,41983306210431871744349183235 mm
width_px =(width * 0,0393700787) = 1,1468405339938635232734500043636 inch * 72 dpi = 83px
height_px = (height * 0,0393700787) = 0,76456035599590901551563333624242 inch * 72 dpi = 55px

Below are the results I get.

Thanks,
Ron


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## jcollett (Mar 28, 2013)

They look small probably due to the same reason big screen TVs look smaller in a big box store like Costco or Sam's Club. The boxes are on a large white area, so they appear smaller. Remember, the actual finders are only about a centimeter away from your eye instead of a few decimeters or feet.


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## sandymandy (Mar 28, 2013)

I wanna see the 1100D one, please


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## T-RonX (Mar 28, 2013)

There you go. If anyone can tell me these calculations are correct I could make a public tool out of this.


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## T-RonX (Mar 28, 2013)

Ok I found a flaw. I assumed my Dell U2410 had 72 dpi, which I guess is from the old analog days, but it actually has 94 dpi. But I'm still not sure if the calculations are correct at all. Anyone?

edit:
update result pic with dpi


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## Leejo (Mar 28, 2013)

The basic width and height appear reasonable in cm (20 by 30 mm).
(without a camera at hand)
The problem appears to be in the representation after that...


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## hsbn (Mar 28, 2013)

You made the math look too complicated.
Take the 6D for example, its sensor size is: 35.8mm x 23.9mm
The viewfinder is 0.71x magnification and 97%
So 
96%x(35.8mm x 0.71) =24.655mm = 0.971 inch x 96 ppi = 93 pixel
96%x(23.9mm x 0.71) =16.459mm = 0.648 inch x 96 ppi = 62 pixel
Most monitor out there got 96ppi.


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## T-RonX (Mar 28, 2013)

I wonder if I calculate the magnification right. Now I'm taking 71% of the total sensor surface. If I try to take 71% of each side of the sensor and then calculate the surface I end up with a tad smaller rectangle.


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