# crop factor and light (DPR on Equivalence)



## cid (Jul 7, 2014)

I have just read one veeery interesting article with great comparisions on topic light, max aperture, crop factor and ISO and how do they play together

what-is-equivalence-and-why-should-i-care

(I haven't noticed it being posted here so far)


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## privatebydesign (Jul 7, 2014)

*Re: crop factor and light*

Equivalence is a concept I have been banging on about for a long time and I have posted equivalent images on many occasions, the fact that aperture and iso also have a "crop factor" is so often misunderstood or completely ignored.

But I feel the article is s touch simplistic as I didn't see mention of the key aspect to equivalence, reproduction size. I will still push people towards the grandfather of equivalence articles here: http://www.josephjamesphotography.com/equivalence/ 

And the Wikipedia page here http://en.wikipedia.org/wiki/Depth_of_field simply lays out the three scenarios where where a crop camera can be shown to have more, less, or identical dof to a ff sensor depending on how you are comparing or using it under the section "Relationship of DOF to format size".


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## cid (Jul 7, 2014)

*Re: crop factor and light*



privatebydesign said:


> Equivalence is a concept I have been banging on about for a long time and I have posted equivalent images on many occasions, the fact that aperture and iso also have a "crop factor" is so often misunderstood or completely ignored.
> 
> But I feel the article is s touch simplistic as I didn't see mention of the key aspect to equivalence, reproduction size. I will still push people towards the grandfather of equivalence articles here: http://www.josephjamesphotography.com/equivalence/
> 
> And the Wikipedia page here http://en.wikipedia.org/wiki/Depth_of_field simply lays out the three scenarios where where a crop camera can be shown to have more, less, or identical dof to a ff sensor depending on how you are comparing or using it under the section "Relationship of DOF to format size".



Thanks for sharing, I'll have a look on it after work. Main reason why I shared dpreview article were comparistion shots, so you can see immediately the difference. Yes indeed reproduction size is another aspect of crop size, but I think the focus of this article was in having same composition with different setup ("same" aperture lens vs. different crop factor body)


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## privatebydesign (Jul 7, 2014)

*Re: crop factor and light*

Oh everything helps, I have posted these three images many times here http://www.canonrumors.com/forum/index.php?topic=21071.msg401008#msg401008


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## cid (Jul 7, 2014)

*Re: crop factor and light*

I see, I missed it probably because I'm not too much M-interested :


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## privatebydesign (Jul 7, 2014)

*Re: crop factor and light*

This thread is more relevant!

http://www.canonrumors.com/forum/index.php?topic=15884.0


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## dcm (Jul 7, 2014)

*DPReview on equivalence*

Interesting read.
http://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care


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## distant.star (Jul 7, 2014)

*Re: DPReview on equivalence*



dcm said:


> Interesting read.
> http://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care



Like it or not, that's the first decent thing I've seen them do in years, maybe ever.


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## cid (Jul 8, 2014)

*Re: crop factor and light*



distant.star said:


> dcm said:
> 
> 
> > Interesting read.
> ...



indeed, I like the way it's written, most concepts are very easy understandable


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## Steve Todd (Jul 10, 2014)

*Interesting Read on Equivalence (Sensor Size Comparison)*

I found this on DP Review, it is an interesting read on the often discussed subject here on CR:

http://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care?utm_campaign=internal-link&utm_source=features&utm_medium=sidebar-block-Forums&ref=features


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## privatebydesign (Jul 10, 2014)

*Re: Interesting Read on Equivalence (Sensor Size Comparison)*

Already been covered http://www.canonrumors.com/forum/index.php?topic=21687.msg412310#msg412310


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## Steve Todd (Jul 10, 2014)

*Re: Interesting Read on Equivalence (Sensor Size Comparison)*

Oops! Sorry, missed that one...Senior moment I guess!


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## privatebydesign (Jul 10, 2014)

*Re: Interesting Read on Equivalence (Sensor Size Comparison)*

Hey no worries Steve,

It is a subject I have banged on about for years and one that is still greatly misunderstood by even knowledgeable photographers.

Bottom line, there is not only a focal length crop factor but aperture and iso crop factor too, that is why same generation smaller sensors will never, ever, be able to do what larger sensors can, be that an iPhone, M4/3, APS-C, APS-H and even 135 (FF) when compared to anything larger.


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