D7100 1.3x crop - Is it my math or...

Started Jun 17, 2013 | Questions
Suhas Sudhakar Kulkarni
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D7100 1.3x crop - Is it my math or...
Jun 17, 2013

Nikon claims on their website that 1.3x crop gives 15.4 MP image.

http://imaging.nikon.com/lineup/dslr/d7100/features01.htm#a10

However, If I calculate:

1.3x1.3=1.69

24/1.69=14.20MP approx.

Which one is correct?

Also 1.5x1.3 would give total crop of 1.95x and not 2x as specified by Nikon.

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Suhas
website: photo.net/photos/suhaskulkarni

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Nikon D7100
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BirgerH
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Re: D7100 1.3x crop - Is it my math or...
In reply to Suhas Sudhakar Kulkarni, Jun 17, 2013

Suhas Sudhakar Kulkarni wrote:

Nikon claims on their website that 1.3x crop gives 15.4 MP image.

http://imaging.nikon.com/lineup/dslr/d7100/features01.htm#a10

However, If I calculate:

1.3x1.3=1.69

24/1.69=14.20MP approx.

Which one is correct?

Also 1.5x1.3 would give total crop of 1.95x and not 2x as specified by Nikon.

-- hide signature --

Suhas
website: photo.net/photos/suhaskulkarni

Because:

1.5 crop is not exactly 1.5 crop. With the D7100 it is 1.53518 if you use the relation of 24 x 36mm.

1.3 crop is not exactly 1.3 crop. In relation to 24 x 36 mm it is 1.91744 (aprox. 2)

The "1.3" crop will then be the square root of the Square of 1.9744 divided by the Square of 1.53518, which wil be 1.2490, aprox. 1.3

And then you got aprox. 15.4 MP (24/1.249/1.249).

Thats the math - but why bother - go use it.

BirgerH.

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BirgerH
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Re: D7100 1.3x crop - Is it my math or...
In reply to BirgerH, Jun 17, 2013

BirgerH wrote:

Suhas Sudhakar Kulkarni wrote:

Nikon claims on their website that 1.3x crop gives 15.4 MP image.

http://imaging.nikon.com/lineup/dslr/d7100/features01.htm#a10

However, If I calculate:

1.3x1.3=1.69

24/1.69=14.20MP approx.

Which one is correct?

Also 1.5x1.3 would give total crop of 1.95x and not 2x as specified by Nikon.

-- hide signature --

Suhas
website: photo.net/photos/suhaskulkarni

Because:

1.5 crop is not exactly 1.5 crop. With the D7100 it is 1.53518 if you use the relation of 24 x 36mm.

1.3 crop is not exactly 1.3 crop. In relation to 24 x 36 mm it is 1.91744 (aprox. 2)

The "1.3" crop will then be the square root of the Square of 1.9744 divided by the Square of 1.53518, which wil be 1.2490, aprox. 1.3

And then you got aprox. 15.4 MP (24/1.249/1.249).

Thats the math - but why bother - go use it.

BirgerH.

Sorry, missed a 1 in "Square 1.91744"

 BirgerH's gear list:BirgerH's gear list
Nikon D90 Nikon D7000 Nikon AF Nikkor 85mm f/1.8D Tamron SP AF 11-18mm F/4.5-5.6 Di II LD Aspherical (IF) Tamron AF 18-200mm F/3.5-6.3 XR Di II LD Aspherical (IF) Macro +14 more
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Suhas Sudhakar Kulkarni
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Re: D7100 1.3x crop - Is it my math or...
In reply to BirgerH, Jun 17, 2013

Thanks, that explains. So it is actually 1.917.. crop from full frame and not 2x crop.

Why bother?? Just out of curiosity, I was comparing with Sony smart teleconverter which gives you 2x crop with 12MP image (on A65 / A77).

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Suhas
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lock
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not even that
In reply to Suhas Sudhakar Kulkarni, Jun 17, 2013

Look at the hor and vert. Number of pixels. It is a factor of 1.25.

Lock

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BirgerH
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Re: not even that
In reply to lock, Jun 17, 2013

lock wrote:

Look at the hor and vert. Number of pixels. It is a factor of 1.25.

Lock

Okay - didn't do that.

It makes a different of size-crop and pixel-crop. Still I can't see any real problem if you want to make Photos.

The D7100 has this extra Facility of cropping - go use it or do not. Math will not give you better Pictures.

BirgerH.

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lock
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Of course!
In reply to BirgerH, Jun 17, 2013

By all means, use it.

Lock

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BirgerH
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Re: not even that
In reply to lock, Jun 17, 2013

A factor of 1.25 is in my eyes very close to a factor of 1.249.

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jimoyer
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Re: D7100 1.3x crop - Is it my math or...
In reply to Suhas Sudhakar Kulkarni, Jun 17, 2013

This thread makes my eyes bleed......

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Red5TX
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Re: D7100 1.3x crop - Is it my math or...
In reply to Suhas Sudhakar Kulkarni, Jun 17, 2013

Suhas Sudhakar Kulkarni wrote:

Thanks, that explains. So it is actually 1.917.. crop from full frame and not 2x crop.

Why bother??

Because in crop mode the autofocus points cover virtually the entire frame.

And if you shoot in jpeg + crop, you have (I believe) unlimited buffer depth. There are limited circumstances where those two factors (full af coverage and limitless buffer) might be very handy in combination.

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Erik the Red
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Re: D7100 1.3x crop - Is it my math or...
In reply to Red5TX, Jun 19, 2013

4800 x 3200 = 15,360,000 pixels, for what it's worth.

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