Tuesday, December 25, 2018

from f295: My first camera from a Scotch Box.

f295 was an international discussion forum begun and administered by Tom Persinger. Originally just about pinhole photography, it expanded into all kinds of alternative methods. It was active from 2004 until 2015 but it remains on-line. Recently it disappeared from the web for a few days, and that prompted me to decide to reprise some of my favorites here at Pinholica, for backup if no other reason. 

Bottles of Scotch come inside some pretty well made boxes. I've made cameras out of a Glenlivet box, a Glenmorangie box, and one I made for my son from Macallen as a Worldwide Pinhole Photography Day gift. (He and his best man toasted with a wee dram of Macallen before his wedding the previous autumn).  This is what started it all. Posted under the title "Last of the year," on January 3, 2006.

My wife gave me a bottle of Scotch for Christmas. She said she chose Glenmorangie because she thought the box it came in (3.5" x 12" cylinder) would make the best pinhole camera. How can you pass up a challenge like that? The only matte finished paper I had was already cut into 4" x 5" pieces so I taped three of them together. Two minute exposure (very gloomy day), .49mm pinhole, about f 128 (I took the pinhole off an old workshop camera) A bit of burning and dodging in photoshop to correct for center to edge exposure differential.

I got another Macallan box last night.  Happy Yuletide! Did you get a present in a box you could make a camera out of for Worldwide Pinhole Photography Day?

Friday, December 21, 2018

Pinhole distance role reversal with the Variable Cuboid.

With the first roll through the most recent iteration of the Variable Cuboid, I primarily used the 100mm front for exteriors and the 35mm for interiors.  To do due diligence, this time I switched and used the longer front inside and wide-angle out and about.

I started with a walk around the neighborhood. The Glad Tidings Tabernacle is just around the corner from my house. I've always liked the simplicity of the structure and the large plain windows. Looks like a little bit of curvy film on the right there.

The Centennial Inn assisted-living facility is nearby on Main St. Originally built in 1902 as the Ladies Benevolent Society Home, it looks shocked by my temerity.

I've recently heard a lot of discussion about how the surprise element of seeing what you've actually photographed was one of the delights of pinhole. The bit of curvy film in the church image and the pointy stretched-out corner of the Centennial Inn are some of those impossible-to-really-preview-in-your-head situations. Here's another with our big back yard hydrangea. The camera was actually touching the nearest branches and virtually the whole tree is in the picture. You can barely squeeze between it and the garage but here it looks like there's plenty of room. The garage looks smaller than the shrub. Your brain just won't let you see it like this even though it's kind of what's projected on your eyeballs and they're curved as well. But the pinhole reveals all.

The weather was exceptionally gloomy. Back inside with the 100mm mounted, I pointed the camera at Buddha's corner by natural light and left to go across town to the farmers market, do a little shopping and have lunch. After we got back, I forgot to close the shutter for another 20 minutes.

The gloom persisted. Here's a nice academic study of some silver by artificial light.

Moving on to the glassware. Amazing how still those pull chains on the lamp are. We had lunch a few feet away during the exposure. Check out the refraction of the base of the lamp through the clear decanter.

The sun came out for a while one morning.

I finally decided to defy the gloom, put the 35mm back on and just go out and wait as long as the exposures took.

I've had my eye on this building for some time. It was recently remodeled and houses the alarmingly named marketing agency DealerFire. There's a little walled garden behind the building for employees to hang out in, so I had a nice place to sit and wait 8 minutes for the exposure somewhat out of the wind.

I've been waiting all year to photograph this delicious grid of reflecting windows. The street in front of it and half of downtown was under construction all summer. You can see the plastic covering a ramp they poured just before they finished.

The nifty grid and the fresh concrete were the first thing that caught your eye, right? You may have noticed that I occasionally suffer from curved film. It happens because the film transport in my cameras can be a little tight and you have to loosen the supply a little bit and then take it up on the other side. This can push film out into the image chamber which you may have to retighten around the supply to pull back up against the image plane. I do like perfect grids and I do try to retighten the film but sometimes I forget. It was cold and windy. This is a disaster with a lensed camera but with pinhole it's just kind of funny. I'm afraid to admit that I'm beginning to like these random distortions. I've always avoided curved film planes because to me they stamp a standard look on the composition but this random stuff is kind of fun. I'm not sure what should be done about it. Maybe be more careless winding the film?

The 35mm front has .25mm pinholes. All except the tree were done with the rising pinhole.

The 100mm front has .35mm pinholes. All these were with the on-axis pinhole.

TMax 100 in Rodinal 1:50

Friday, December 7, 2018

Was Lord Rayleigh talking about sharpness?

June 2019. When my university retiree account disappeared with a new change in policy, the pictures I uploaded to this blog while logged into that account disappeared. I'm working on fixing that but it's going to be at least a summer long project. 

This all started because of a comment in the Lensless Podcast Facebook group that a longer distance to the pinhole always results in a reduction in sharpness.

What he means is, according to physics worked out by John William Strutt, 3rd Baron Rayleigh in the 19th century, the farther the pinhole is from the image plane, it will take a relatively larger pinhole in order to minimize diffraction. A bigger hole will result in a loss of sharpness. (Perfection of the pinhole is also a significant variable here. Think of it as a lot of tiny holes on the edge of the pinhole that the photons have to squeeze through.)

I've always preferred a smaller than optimum pinhole for my longer cameras.

Everybody checks Mr. Pinhole’s calculator for the optimal results of these equations, and everybody thinks of this in terms of focus.

That started me on a thought experiment.

These equations predict the formation of an Airy disk around a point of light.

.15mm electron microscope aperture, 24mm from the image plane, about 5m from the subject.

Even the best optics in focus form an Airy disk determined by some algebraic gymnastics on the wavelength of light. The Hubble Space Telescope forms an Airy disk. Billions are spent minimizing them. Even with adaptive optics it’s still there, it’s just very, very small for a perfect 30 meter telescope mirror.

This is different from circle of confusion which is associated with depth of field and focus. With a pinhole aperture, circle of confusion always gets greater with a bigger hole. Diffraction varies on both sides of “optimum.”

The Airy disk is still there out of focus, it’s just more diffuse. With a pinhole, it’s just always there, no focusing is going on. It will vary in brightness and radius as a certain size pinhole moves toward or away from the image plane or from a source, will be least bright at some point and the disk itself will vary in some predictable wavy pattern, always rather less bright than the point itself.

How does this really impact the image?

Think about your average American holiday image.  How many point sources of light are there when you have a decorated tree in the picture? An infinite number of course.  Every point in the image is a source. They all have an Airy disk. You just don’t notice them unless it’s a picture of a mini-light, which is also overexposed anyway, so its Airy disk is going to be a whopper. The Airy disk around each theoretical point of the soft glow of your kid’s dreamy face isn’t probably going to rise to the level of the film’s sensitivity, and if it does, it’s a soft glow, it’s not out of focus. Sharpness is determined by the size of the pinhole. At extremes, diffraction reduces the contrast between all the points and all the the disks to unmanageable levels, and it’s not going to be happy with overexposure.

That's assuming you could get the kid to sit still long enough for a pinhole portrait by the light of the Yule decorations with a smaller than optimum pinhole. Motion blur is something else again and like circle of confusion is determined by light acting like a particle which allows us to make pinhole images. Diffraction is evidence of it’s wavelike behavior that gives pinhole some of its unique quality and also affects all optics. Happy Holidays.

The pinhole holiday is April 28 in 2019.

Sunday, December 2, 2018

From f295: They're responding

f295 was an international discussion forum begun and administered by Tom Persinger. Originally just about pinhole photography, it expanded into all kinds of alternative methods. It was active from 2004 until 2015 but it remains on-line. Recently it disappeared from the web for a few days, and that prompted me to decide to reprise some of my favorites here at Pinholica, for backup if no other reason. 

I recently listened to the Lensless Podcast with Nicole Small speaking about her self portraits and it reminded me of this. Quoting Frank Zappa I had done a post of closeups of vegetables, and followed up a week later with this mostly wordless essay under the title "They're responding" on February 12, 2008.

I can feel it.

About a year later a local art collective organized The Oshkosh Triennial juried show where ten regional artists were featured with six works each and they picked me!  The last picture with the red pepper was one of the images in that exhibition.

These were all done with The Populist, .15mm pinhole 24mm from 24x36mm frame.