Re: Primer on photographic exposure, etc.
Re: Primer on photographic exposure, etc.
- Subject: Re: Primer on photographic exposure, etc.
- From: Ben Goren <email@hidden>
- Date: Tue, 21 May 2013 07:30:19 -0700
On May 21, 2013, at 7:13 AM, Iliah Borg <email@hidden> wrote:
> Flat field helps, most certainly. But it is easier to say than to actually do the flat field shot. The rub is in the word "flat" - current grey targets are not flat enough, and color targets are also not flat. So one needs to use DIY methods.
I've actually had very good success in the studio with large sheets of matte fine art paper. If the surface isn't fine enough the texture will still be visible. I think EquaLight is smart enough to deal with this intelligently, but you ideally want to find a paper with a smoother surface (Fabriano Artistico hot press natural watercolor paper is great) or defocus the shot enough to obliterate the texture (which isn't such a bad idea, either). You'll definitely want to profile the chart at the same focus setting as the white card because many lenses (very slightly) change vignetting with focus.
> The regular targets do not contain dark enough patches.
Just yesterday I placed an order for some carbon nanotube samples that will be incorporated into my next chart, in addition to a light trap. I ordered them from NanoLab, Inc., in Massachusetts. Dr. Tom Morgan, their senior researcher, was most helpful in advising me what would have the best chances of success. I'll report back on how it all works out.
Also, glossy colorants can get much darker and saturated than matte. So long as you shoot at a geometry that doesn't cause specular reflections -- easier writ than done -- you can significantly increase the gamut of the chart that way. Of course, if your geometry is such that specular reflections would be a problem but you're using only matte patches...well, even then, your lighting is causing you problems and needs to be fixed (even if the problems aren't as obvious).
Cheers,
b&
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References: | |
| >Re: Primer on photographic exposure, etc. (From: Alex Jamison <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Ben Goren <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Iliah Borg <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Ben Goren <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Iliah Borg <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Lars Borg <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Iliah Borg <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Lars Borg <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Iliah Borg <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Lars Borg <email@hidden>) |
| >Re: Primer on photographic exposure, etc. (From: Iliah Borg <email@hidden>) |