Wow, that's much more stringent than the example I gave, and worse, it's needlessly stringent for a 12 MP camera.
Again, no argument...
Wrong. As photosite density increases, the number of f/stops available on a lens that will support a desired print resolution at an anticipated enlargement factor will decrease. In choosing a sensor size for any given number of Megapixels, as you increase the pixel density (shrink the sensor), you'll find yourself having to decrease your enlargement factor to maintain a desired print resolution, or you'll have to decrease your desired print resolution to maintain a given enlargement factor.
Mike, I think Emil is talking about a given sensor size and increasing photosite density by increasing the number of photosites not by shrinking the sensor size, in which case the diffraction effect is a constant for a given enlargement size for a given size of sensor up to approximately the apertures and number of MP he stated with some extra breathing room as you point out.
Maybe a bit overstated, but essentially correct. By itself, photosite density tells you nothing. In combination with another parameter, such as pixel count or sensor size it begins to give you some information, but by and large, the same information in the old fashioned form of pixel count and sensor size is more useful and easier to understand.
This is tripe. Which f-numbers you can use depends entirely on how you wish to use them. For most people, one important consideration is output image resolution, so the size of the sensor is critical, since that determines the magnification, and therefore the rendered size of the CoC.
[snip]
I was going to make a point by point refutation, but there are so many false axioms and misarguments, there's not much point. The main one concerns the idea that somehow one is forced to make prints at a given size for a pixel count. (well, actually, you are more confused than that, for how would you ever be encouraged to print at a given size by a pixel density?). Mainly, I suspect that this notion of yours is based not on a misunderstanding of physics, but by a lack of understanding of basic photographic technique. There are quite a few situations where, pictorially, one would want to use the peak definition of a lens. Not least landscapes. I see everywhere that landscape photography goes with small apertures. Not in my book, it doesn't. Differential focus is one of the main tools in providing 'pop' to a landscape. When you do this, you need to shoot with a good prime, around f/4 or 5.6 (on a FF camera) and I guarantee, you make a good quality large print, and you'll see the difference in detail between the primary subject and the background at infinity. It's enough to make it stand out. But here's the rub. In most landscape situations, with that primary subject a good few metres away, the background is imaged with a CoC still smaller than if you stopped the whole down to f/11. By limiting yourself to f/11 or smaller, or by using a camera incapable of rendering detail above the f/11 level, your reducing the whole lot to the same level of resolution, whichever aperture you select.
If you are serious about higher ISO's then you need a camera with a larger sensor than 4/3. For a given print size, pixel density has little impact on image noise. Sensor size certainly does.
I'm talking about the effects of diffraction here. Of COURSE you can use any f-Number available on the lens if you have no concern for diffraction.
If have no specific print resolution at which you desire to record subject detail, then fine, make any size print you wish from any number of available pixels.
It isn't the pixel density that determines the print size - I never said that.
You can't possibly find anything I've written here that mandates the use of any specific technique. The scope of my discussion has been limited to the impact of diffraction on print resolution. When someone writes about DoF, do you expect them to list every possible situation where one might want to compromise DoF? The scope of my discussion is limited to the effect of diffraction and its relationship with enlargement factor and desired print resolution.
Wow! You're in the wrong thread...
Thank you for sharing that with us. It doesn't contradict a thing I've written.
That's a good idea...
Diffraction occurs at every f-stop on your lens, it is simply that at larger apertures, resolution tends to be limited more by aberrations than diffraction. So this point is nonsensical. You are concern with diffraction (or at least need to understand how it works) at every f-number.
The phrase 'encouraged to print at a given size by the pixel density' was a direct quote from you. You might not have meant it, but you said it. And actually, the whole basis of your argument, and one of the false axioms, is that pixel density of necessity determines the scale at which you print, since you assume printing pixel for pixel at 360dpi. So actually print size in your world is determined by sensor size divided by count. Hey, that's the reciprocal of pixel density.
Except the technique of always printing pixel for pixel at 360 dpi.
Haven't checked your sums, in any case, and I can't remember what N is in any case. However, the simple argument that your case is wrong is that it precludes the possibility of having resolution in reserve so that you can, when the situation demands open up the lens to optimum aperture and print larger. Your definition of 'usable' f-stops is so limited as to be useless.
Why, because I actually take some photographs now and then?
Except that, had I followed your advice, and selected a camera where the resolution maxed out at f/11 or so, I wouldn't have had the opportunity to utilise the additional resolution a f/5.6, the sharpness of my major subject would have been levelled down to exactly the same as the background and I'd have lost the 'pop' I was aiming for. DoF effects don't have to be extreme to be useful.
Mike, given that your equation showing the limits of aperture for a given print size, resolution, and enlargement (I haven't checked the math but it makes sense that such a relationship exists), at no point in your equation is the photosite density actually stated, therefore photosite density is not a variable.
I was responding to your contention that I had implied some apertures can never be used under any circumstances. I pointed out that my discussion is limited to the effects of diffraction on aperture selection and now you're telling me that's "nonsensical"?
Please provide us with the date and time stamp where I wrote that.
That's generous of you, but you're still mistaken.
I've never said that, either. Maybe you actually are in a different thread and don't know it. You need to support your claims of what I did or didn't say by giving us references.
I chose 5 lp/mm arbitrarily as an example of how to use the formula I've provided.
Simply taking the reciprocal of pixel density does not account for losses induced by the Bayer algorithm and anti-aliasing filter common to CMOS sensors.
Where did I write that one should always print at 360 dpi? Go find it. Happy hunting...
That's the easy way out...
Read my posts in this thread. N, as used in that formula, is the f-Number at which diffraction will begin to inhibit a desired print resolution in lp/mm, at an anticipated enlargement factor. Sound familiar?
Nothing in the above statement refutes anything I've said.
I'm only talking about diffraction here. You're absolutely welcome to use any stop on your lens if you don't give a hoot about diffraction inhibiting a desired print resolution.
No, because the above statement is off-topic. I'm talking about the impact of diffraction. I'm not writing a dissertation on all the factors one should take into account when shooting landscapes or any other subject matter.
I never gave the advice you claim I gave. Find it. Quote it. It doesn't exist.
Photosite density is not a variable for determining the f-Number (N) at which diffraction will begin to inhibit a desired print resolution at an anticipated enlargement factor.
I never said that we have to print at 360 dpi, except under the one, highly qualified, example scenario where a shooter actually desires to resolve subject detail at a resolution of 5 lp/mm in the print after enlargement.
That statement doesn't refute anything I've written. If you make like-sized prints from like-sized sensors, the limits of resolution imposed by diffraction will be identical for any given f-Number. But if the guy with more MP decides to make a LARGER print, to take advantage of all or some of those extra pixels, he will be increasing the enlargement factor and thus reducing print resolution if he insists on using the same f-Number and sensor size.
I've only made one claim regarding photosite density: As photosite density increases, the number of stops that will support a desired resolution at a given print size will be decrease.
I never said that.
Ditto
I haven't.
