Here's a couple of choice items that don't merit full columns of their own.
Post Exposure is free
After 15 years, my book Post Exposure has finally gone out of print—an excellent run. Both I and Focal Press are very happy to have created this book.
The rights have reverted to me. At this time I haven't decided whether to massively rewrite the book to incorporate digital photography and printing, or to write an entirely new book on that subject.
In any case, such a book is a good year off.
In the meantime, I've decided to give Post Exposure away, in PDF form. The PDF is identical to the published book, save that it's missing the 16-page color signature (I didn't do the layout files for that). Sorry, you'll just have to use your imagination. Also, it's just a "dumb" Acrobat file—no internal links or any cool stuff like that.
But, hey, you can't beat the price.
You can get it by going to my website and clicking on the book cover image at the lower right.
I only ask one thing of you: Please don't redistribute the file. Don't post it to your own site, don't torrent it, don't give a copy to friends. If someone you know would like a copy, send them a link to http://ctein.com.
That's not asking too much, is it?
Now we know how high ISOs can go
About a month back I wrote "Photography at the Speed of Light" in which I asked the question of how fast digital sensors could really get. When would we hit the brick wall of absolute physical limits of photon counting statistics that can't be surpassed?
I wasn't up to the challenge of doing the photometry, but one of our readers, Nick Condon, was. He's posted his answer online.
For those of you who don't want to wade through the technical work, the conclusion is that image quality comparable to the Nikon D3S at ISO 6400 is theoretically achievable at ISO 100,000. We've got about four more stops to go before we hit the wall. But, please, read his analysis before commenting on the answer here. Of course any first-principles analysis assumes an absolutely perfect system, so the real world answer might be a stop lower. Conversely, it assumes no nonclassical tricks played with detection or statistics, so the real world answer might be a stop higher. But at least we know what the ballpark looks like.
While such high ISOs would never be what you'd use routinely, they will have one advantage over more conventional ones. You're collecting so few photons (and, hence, photoelectrons) that you never have to worry about saturating the pixel in any decent sized sensor. Blown-out highlights become a non-problem.
One can turn the problem on its head to answer another interesting question: how small a sensor could the ideal camera have and deliver current D3S image quality? The answer is about 1/4-scale, comparable to the sensors in compact digital cameras.
Important caveat: while Nick is a real optical scientist and doesn't just "play one on TV" like me, and while he has shown the analysis to his colleagues, none of us are experts in the specific area of photometry. It is possible there is some mistake buried in the math or the assumptions. If one of you readers does photometry professionally and would care to take the time to give Nick's work a review, we'd both really appreciate it.
If you do have any technical criticisms of his analysis, please do not post them here as comments; TOP cannot serve as a technical debate forum. Instead, e-mail your remarks directly to Nick (condon [dot] photography [at] gmail [dot] com) if you want them to be private, or post them to his blog if you want them to be public. (And, if you care to, cc them to me—ctein [at] pobox [dot] com.) If any conclusions change substantially, I'll write a follow-up to this follow-up.
Ctein's regular weekly column appears on Wednesdays.
Note: Links in this post may be to our affiliates; sales through affiliate links may benefit this site. More...
Original contents copyright 2011 by Michael C. Johnston and/or the bylined author. All Rights Reserved.
Featured Comment by Ben: "Just dipped into the PDF for the first time and found it to be very interesting and well written. Perhaps this is the justification I need to buy a Kindle...but where's the TOP link to Amazon to buy one? ;) I have some reading to do...."
Mike replies: "Uh, same place it's always been—in the right-hand sidebar, under "PORTALS," second item from the top, where it says "Please Help Support This Site—Use Our AMAZON LINKS." If you can't find it, please do let me know.
Featured Comment by Semilog: "Ctein, wow. After 15 years out of the darkroom, last month I bought ('stole' is only slightly too strong a descriptor) a used Leitz V35 enlarger and I've just re-started in the darkroom. I've read about half of your PDF now, and it's just incredibly useful, refreshing things I used to know and filled with useful bits that I did not know. There really should be a PayPal donation link on the download page. Thank you so much for sharing this."