Re: fine art reproduction questions
Re: fine art reproduction questions
- Subject: Re: fine art reproduction questions
- From: Ben Goren <email@hidden>
- Date: Sun, 2 May 2010 12:16:15 -0700
On 2010 May 2, at 10:35 AM, neil snape wrote:
> The reason I said a 50 mm lens is not the right lens to
> use, and yes I know from the beginning you are using a very fine lens for
> copy work is because unless you have absolutely flat surfaces all the
> reflections of the texture will have reflection angles that will be
> detrimental to the copy quality. If you are copying a photographic print or
> very flat art work with careful lighting that is fine.
That may well be why I haven't had any problems with the 50mm CM. I've mostly been shooting watercolors. My mom, predictably my most regular and difficult ``client,'' likes to use cheap paper that curls something fierce, but a couple steel rulers or framing squares along the edges will tame it reasonably well.
As for the lighting, I use four bare strobes (reflector only) placed equally distant about 10' away from the art at a 45o angle. I haven't needed to do the cross-polarization thing yet; I'll burn that bridge when it becomes a problem.
> Yet I am convinced that there are some tricks that can
> give you better results that really do optimise DR with a lower S/N in the
> areas that DSLRs have problems.
See...I haven't found this to be a problem, and I haven't seen any indication that medium format would be fundamentally different.
Unless I'm missing something, even theoretically, the only difference between medium format cameras and high-end DSLRs is the size of the sensor. The sensors themselves are made with the same processes by the same manufacturers. Indeed, it's often the second-tier manufacturers, such as Kodak, making the medium format sensors.
What you get with MF digital over 135 digital is therefore the exact same thing you get with MF film over 135 film: more recording area. And the ``only'' thing that in turn gives you is a smaller capture-to-output enlargement ratio. All of the ``creamy goodness'' you get from MF (and LF, of course), whether film or digital, can directly be attributed to the fact that you're not blowing up the original as much.
(Don't get me worng: the larger formats are indeed greatly superior; I'm just identifying the source of their superiority.)
With that understanding, it should be obvious that, if you keep the levels of magnification the same, the smaller format will have identical quality to a crop from the larger format. That is, an 8" x 10" crop from a 16" x 20" print from 645 will have the same quality as an 8" x 10" print from 135 (within rounding error).
But...if you take two 135 pictures and (skillfully) stitch them together, you've now got a 16" x 20" print that's indistinguishable from what you get with medium format -- precisely because it's the exact same thing. It's a print made with the same magnification (and thus the same levels of visible noise, the same SN ratio, and all the rest).
And, once you start stitching, It's not that much more hassle to (digitally) stitch four exposures than it is two, and get large format quality out of the 135 format DSLR. Or, if you really need it, stitch a few dozen exposures and make 8" x 10" film look like one of those throwaway cardboard film cameras in the impulse aisle in comparison.
(This, of course, assumes lenses of comparable quality, but all the major formats have superlative glass available these days. It *could* be a factor, but it never *should* be a factor.)
> HDR is allows the highest level of
> extraction of the info from the raw processor. It is not limited to only
> high contrast and out of range images.
I still think this is one of those ``in theory, but not in practice'' cases. With the kinds of subject matter we're talking about, the tone curve and color correction that gets applied, and the sensor-to-print magnification involved, I really don't think the human eye is sensitive enough to detect the noise present in a modern DSLR. If you can point to any examples to the contrary, I'd be interested to see them, but I've yet to come across any.
That's not to claim that noise is never a factor, of course; just that, in this particular very limited case, it is, for all practical intents and purposes, invisible.
> Building your own charts could be interesting. If you have the same pigments
> as the art work it'd be optimal.
I originally thought that would be necessary, but my research leads me to think otherwise. Even between hardware-store paints and expensive artist's acrylics, you see the exact same spectral patterns over and over and over again. With enough practice, I'm pretty sure most people could learn to sketch a surprisingly-accurate spectral plot of pretty much any color you'll see.
The paint store favors unsaturated colors whereas the paints artists use also include more saturated, spectrally pure colors. But, aside from the different gamut -- which seems to be as much for fashion reasons as anything else -- there doesn't seem to be anything special about the pigments from any particular source.
(I think I mentioned a couple oddball acrylics I came across that I'll be including in the chart, but I'm pretty sure the local paint store could match them.)
> I am interested in how it goes just the
> same.
So am I!
Sadly, with work schedules and all, it's likely to be another month or two before I'll have time to complete it. But, if it shows promise, I'll post more complete details at that time.
Cheers,
b&
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