[pinhole-discussion] focal plane shutter theory (Slit Scan Shutters)
Murray had said "I would like to understand (actually, analyze) the operation of a focal plane shutter, for the purpose of building one for sheet film. I want to get a grasp on calculating exposure duration as a function of slit width and linear speed, I guess (or direction to what I should be thinking about)." All shall be revealed, grasshopper... Head on over to the incredible Andrew Davidhazy site from RIT: http://www.rit.edu/~andpph/articles.html And note the Slit Scan Photography article here: http://www.rit.edu/~andpph/text-slit-scan.html (as well as many more on Slit Scan) A big ol' slab of juicy math awaits: http://www.rit.edu/~andpph/text-strip-basics.html IMHO, this is one of the greatest sources of creative energy I have ever found on the web when it comes to innovative camera designs and very, very exciting results. FYI, Andrew Davidhazy is from the School of Photographic Arts and Sciences, Imaging and Photographic Technology, Rochester Institute of Technology. The guy is truly amazing. I may quit my job and go back to school there, but for the wife, son, mortgage, etc... And, FYI, he is WWPD#1 Image #26 and WWPD#2 Image #81. Michael Georgoff San Jose, CA (FYI: An incredible nude here, done with a peripheral slit scan device: http://www.rit.edu/~andpph/photofile-misc/periphoto-barbs-4.jpg)
[pinhole-discussion] More on Scanners...
See, I just knew that the twice-or-three-times-as-expensive Epsons would be suggested! Not that you're wrong about them, just that I am "resource challenged" at present... (What about Canonscan scanners? Anyone use 'em?) While pondering flatbed scanners that will also do 35mm transparencies, I happened to mention to a guy off-list that I might rather get a standard flatbed scanner and figure out some way to turn off the internal light source and use an external light source for transparency scans (which is all that a flatbed with a transparency adaptor seems to do anyway, as far as I can see). They guy I was exchanging email with said "Many standard flatbed scanners allow you to turn off the internal light by selecting transparency in the Software (TWAIN driver). You can then cut a piece of cardboard to fit over the scanner with a hole cut to the slide size and then place a light over the slide." This, I did not know. I was all set to grab my screwdrivers, soldering iron, Dremel and a switch... and here it might be doable in software. Has anyone out there done this? Anyone use the TWAIN transparency mode to turn off internal illumination and then light transparencies or negs with external illumination? I figure there's be enough nuts & bolts hackers, geeks and general DIY kinda folks on this this that someone may have tried this... Thanks, Michael Georgoff San Jose, CA
[pinhole-discussion] Epson Perfection 1250 Photo Flatbed Scanner
Anyone have any direct experience with an Epson Perfection 1250 Photo Flatbed Scanner? It comes with a "35mm Slide Adapter Unit" which is basically a small handheld light source. (Sure, I'd like to get the Perfection 1650 Photo Scanner, but that's twice the cost. The 1250 is admittedly the low end... ) Most of what I want to scan is flat relfective stuff like photo prints, but I do have slides and negatives that I'd like to have the ability to scan. If you have experience with an Epson Perfection 1250 Photo Flatbed Scanner, let me know. Thanks, Michael Georgoff San Jose, CA
[pinhole-discussion] Flashing with Bulbs
Mark Power (mpo...@coventry.ac.uk) asked about flashbulbs... 1. See http://www.flashbulbs.com/index.shtml (Cress Photo, "THE WORLD'S LARGEST FLASHBULB DEALER" and "The Preeminent EXPERTS", according to them, located in New Jersey. 2. Mark said (of bulbs) "Unfortunately, at least here in the UK, they're no longer available." See http://www.meggaflash.com/ These guys have got some very serious bulbs, guide numbers in the 300's... And they are in the Republic of Ireland (which is closer to the UK than New Jersey, I think). Happy Flashing! Michael Georgoff San Jose, CA
[pinhole-discussion] WWPD Gallery On Line: Thanks!
Every time I hit the WWPD Gallery to see what's new, there are always a few more images that are absolutely amazing. Very, very well done! Thanks to all who organized and publicized, thanks to all who made and submitted great images, thanks for all who worked to do the excellent web site... thanks, thanks, and more thanks! Michael Georgoff San Jose, CA
[pinhole-discussion] Thanks: Beginning Paper!
Big thanks to Guillermo, Jean, George and Richard for information and suggestions on getting started with paper! Regards, Michael Georgoff San Jose, CA
[pinhole-discussion] Beginning Paper?
Can anyone recommend a good printing paper to start with for paper negative work? I've only ever done pinhole onto negative film and had it lab processed. Any recommendations for a fast, easy to use "beginner" paper, and some clues for ASA speed of recommended papers? (And why are there no "positive" papers??) Thanks, Michael Georgoff Still Learning in San Jose, CA
[pinhole-discussion] Hardware or Art?
I found this somewhere a long time ago, figured it was appropriate now: "This reminds me of a true story of a famous photographer, who was well known for his amazing portrait shots who was commissioned to photograph a famous newspaper reporter. The photographer took the reporter's portrait and when he saw it a few days later, exclaimed how great it was and how easy it must have been to take with such an expensive camera. The photographer returned the compliment by mentioning how easy it must be to write great stories with that expensive typewriter!" Regards, MG
[pinhole-discussion] New Georgoff Images
Greetings, After months of lurking and a some great off-list email exchanges with many of you, I now have some images to share: http://www.p at ???/discussion/upload/images/georgoffpinhole1.jpg http://www.p at ???/discussion/upload/images/georgoffpinhole2.jpg http://www.p at ???/discussion/upload/images/georgoffpinhole3.jpg http://www.p at ???/discussion/upload/images/georgoffpinhole4.jpg These were done with a handmade .010" pinhole in .003" thick brass, mounted in a body cap used on an old Chinon (K-mount) 35mm camera, ended up at f/181. I shot Kodak Gold negative film, had 4x6 prints done at a local discount store, scannned 'em and here you go. Comments welcome on list or off. Thanks, Michael Georgoff San Jose, CA georg...@trendmicro.com
[pinhole-discussion] Pinhole Day
I nominate Lord Rayleigh's birthday, November 12, 1842. Michael Georgoff San Jose, CA
[pinhole-discussion] Pinhole Day?
I nominate Lord Rayleigh's birthday, November 12, 1842. Michael Georgoff San Jose, CA
[pinhole-discussion] Dr. Scott Williams Coffee Developer
Regarding Coffee Developer, I did exchange email back in April with Dr.
Scott Williams. It seemed pretty simple with Coffee, Baking Soda, and
Potassium Hydroxide ("added to pH 9.0"). Being chemically clueless, I
thought I'd ask him a few questions.
Dr. Williams said:
> ... We used real potassium hydroxide. As it turns out,
> you would have to use the "old" formulation of Drano,
> one where the active ingredient is sodium or potassium
> hydroxide. The new formulation does not contain this
> active ingredient in useful amounts
>
> On another note, we later found that mint leave extract
> - boiled extract from one store package of fresh mint
> leaves - works better than coffee and can be activated by
> just using sodium bicarbonate (again about a tablespoon
> full per liter) - much safer.
I did learn later that Potassium Hydroxide is also known as Caustic Potash
("Chemical compound with formula KOH. Pure potassium hydroxide forms white,
deliquescent crystals. For commercial and laboratory use it is usually in
the form of white pellets. A strong base, it dissolves readily in water,
giving off much heat and forming a strongly alkaline, caustic solution. It
is commonly called caustic potash. It closely resembles sodium hydroxide in
its chemical properties and has similar uses.")
Genuine Potassium Hydroxide is available from www.bostick-sullivan.com, but
if anyone comes up with any substitutions for Potassium Hydroxide, let me
know (as I am still chemically clueless). Off-list replies welcome.
Regards,
Michael Georgoff
San Jose, CA
georg...@trendmicro.com
