Accurately comparing FF vs APS-C sensor performance? An open discussion.

Started Apr 8, 2013 | Discussions thread
VirtualMirage
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Re: Nonsense
In reply to Klipsen, Apr 14, 2013

Klipsen wrote:

Practice what you preach 

We are all guilty.  Just some more than others.

That's the pot calling the kettle Black.

It is easy to label much of anything that, especially in these forums.

That one statement when looked upon just by itself can be considered that.  But when you put together everything else that it is based around, then not so much.  I am the one that is being accused of fabrication, which is not the case.  I am not calling them a liar or someone that is making stuff up, only one that is stuck looking at a small portion of the bigger picture.  A part of the picture which I feel is not valid in my original observation.

No, DoF is not a mathematical formula - you only use formulas to get an approximate idea of what the DoF will be. The mere fact that the CoC is an arbitrary value means you cannot claim to have a patent on the truth about DoF.

How granular do you want to get?

We might as well then throw this in along with the circumference of a circle and pi.  At some point you have to determine where to stop counting and just round to the nearest number so as to finally get to the point while still remaining valid.

They can! There is no fixed value for the CoC.

There may not be a fixed value, but there is an accepted value for what is used when determining depth of field across different size formats that provide a high level of accuracy.  This accepted standard is d/1500, which is the diagonal measurement of the image format by 1500.  1730 used to also be used, but 1500 became the more widely accepted value.  The results, why not identical, were close enough to be similar.  Most DoF calculations done today for photography follow the 1500 guideline.

There is more to it than what I can explain, but this is a good read:

http://en.wikipedia.org/wiki/Circle_of_confusion

DoF is a concept, not a formula.

It may be considered a concept, but that doesn't make it any less valid.  A lot of mathematics is based around concepts.  Determining DoF is a concept that has been accepted to be measured through a set of standardized formulas.  When applied in 'normal' situations, your results can be highly accurate.  And these results are used to determine DoF.  So I am not wrong here.

What baffles me is why does it seem like some of you think I am trying to rewrite the book on DoF and that my claims are false?

All my values and results are taken using accepted practices for determining DoF and is but only one part of the larger equation in my observation.  If you don't like the results, then disprove the formulas and write your own to be published.  In the meantime, disprove me.  Don't give me just a "your wrong" answer.  Give me results, give me examples, show me differently for the scenario that I laid out.  Show me that I am wrong, which also makes pretty much every other DoF calculator out there wrong as well.  And if you feel the calculators are wrong, then take it up with the people that made them.

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Paul

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