2026-03-16- Light Diffraction

When light rays pass the edge of an opaque material, they tend to bend slightly around the edge of it. This bending, known as diffraction, is due to light acting not as a series of straight rays, but as waves.

The amount of bending is dependent on the wavelength and is different for different colours, as shown in the drawing below. Light passing through a very fine slit appears on a screen a short distance away as a white line with a band of colours on each side. Diffraction also is responsible for the ‘halo’ around the moon and the star-shaped patterns seen when you look at a distant bright light through a window screen.

In photography, diffraction around the edges of a lens diaphragm opening is responsible for the limitation of sharpness improvement when stopping down. Beyond a certain point, the use of smaller aperture no longer increases the sharpness of an image; instead the image actually becomes less sharp. In the same way, the image sharpness of a pinhole camera cannot be improved by making the pinhole smaller beyond a minimum diameter.

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2026-03-14 - History and Evolution of the Kodak Logo

While working as a junior clerk at the Rochester Savings Bank, George Eastman first began commercial production of dry photographic plates in a rented loft of a building in Rochester, New York in April 1880. In the next few years, Eastman became very successful and expanded the company several times. His company started as the Eastman Dry Plate Company in 1881, later became the Eastman Dry Plate and Film Company in 1884, and soon after the Eastman Company in 1889. The last name change occurred in 1892, when the Eastman Kodak Company of New York was organized. The company has been called Eastman Kodak Company ever since. The word "Kodak" was first registered as a trademark in 1888. The letter “K” had been a favorite of Eastman’s, he is quoted as saying, "I devised the name myself. The letter 'K' had been a favorite with me; it seems a strong, incisive sort of letter. It became a question of trying out a great number of combinations of letters that made word...

2026-03-20-Manfrotto monopods

Sometimes collecting is a matter of persistence. The Manfrotto “GRUPPO” 434SSB monopod (shown top) showed up one day at my local thrift store. They had a price tag of $25 on it. I had bought the lower Manfrotto Compact MMC3-01 monopod at the same thrift store for $3. So I asked, “Why so much?” They answered their “expert” had found it sold for $200 on the internet. I find experts—who almost never clerk in the thrift store, so are unreachable—hard to deal with. There is also the matter someone might actually pay them $25 for a 2.27 kg (5 pound) aluminum pole, so I decided to let the Gods-of-Collecting decide if I was going to ever own it. For weeks I would pick it up, check the price tag to see if they had come to their senses, and return it to the shelf. I did try various clerks to see if they would lower the price, but they said they were not authorized to change prices. I plodded on, week after week without much hope. ...

2016-03-19 A Collecting Tale

Our Society—The Edmonton Photographic Historical Society—recently had a valued member pass on. His widow asked us if we wanted to have the left-overs of his collection. The family had taken the cameras they valued for their memories and there were over 80 left-overs. It was arranged we could look at the different items and bid on anything we thought we could use. The bids were to be three digit numbers we chose and if multiple people had bid on the same item then the bid closest to a random selected number would win the item. Now to the main thrust of this story. I had noticed three interrelated items I thought could be remixed to solve some of my problems.There was a spare Pentax-A 50 mm f/2 lens. There was a Pentax P3 camera that for some reason had mounted a Pentax-F 28-80 mm zoom. Then lastly there was a Pentax SF-10 camera with a SMC Pentax 135 mm f/2.5 lens. In an unrelated aside there was also an instruction book for the Pentax SF-10. “Why should all this mat...

Edmonton Photographic Historical Society

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