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

Started Apr 8, 2013 | Discussions thread
Re: You misunderstand

OldClicker wrote:

You're making this up.  Look at these definitions of DoF.

http://www.dofmaster.com/dof_defined.html

"...which appears to be in sharp focus."

"...appear reasonably sharp (according to the standards of sharpness required for the particular photograph and the degree of enlargement of the negative)."

"...distances within which objects are imaged with acceptable sharpness."

"...which will also be acceptably sharp."

DoF is not a mathematical formula; it is a perceived value.  You can mathematically model DoF any way you like, but you cannot use a model to evaluate the influence of a variable if your model ignores that variable.

Wow, seriously?  Are you listening to yourself?

I am not making it up, you are only choosing to grab information that only appeals to you without looking at the whole picture.

DoF is not a mathematical formula?  You've got to be kidding.  Let me take you to the same site you are trying to school me with:

http://www.dofmaster.com/equations.html

Also look here:

http://en.wikipedia.org/wiki/Depth_of_field#Derivation_of_the_DOF_formulas

and here:

http://en.wikipedia.org/wiki/Depth_of_field#DOF_formulas

There you will find the formulas for hyperfocal distance, near distance of acceptable sharpness, and far distance of acceptable sharpness and more.  If we didn't have formulas, there would be no calculators.  With no formulas, there would be no standard acceptance and people would then be able to make up whatever they want as being the DoF.

So yes, DoF is a mathematical formula.  Within that is what appears sharp.  Because of these formulas we can determine how DoF can differ across formats and equivalent focal lengths.  From within that is where you determine your perceived value of sharpness.

So before you label me as a fibber or someone that has a wild fascination of making stuff up that isn't true, make sure you have all your facts before bringing them to the table.

For many that are curious about depth of field, they will use DoF calculators and formulas.  Since that is what they will use or will be taught in a photography class, that is what I will base my model off of since it will better apply to them.  For those that choose to only "eyeball" it, then this should be of no interest to you.

If you have a better way, then do your own work and show it.  But don't smear my work unless you have something to back it up with or improve upon it.  So far, you have come up short in refuting it.  Your only crutch you are using to argue against me with is what is seen by your perception versus what is measured.

Your perception may be different from mine or from everyone elses, it doesn't make it fact.  I would not create a model based on just one person's perception since it would then not be applicable to anyone else.  I can, however, build a model that is based on real numbers and real formulas for a realistic situation in which your perception and majority of others would fall within. Remember, my model is not stating where exactly the absolute peak of sharpness is, only the range at which it falls within (ie, DoF).

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Paul

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