Pablo8 Loc: Nottingham UK.

A few years ago (Film only cameras) a theory was banded about, that the film plane in a 35mm camera, should be slightly curved, to get the maximum sharpness edge to edge. Cannot remember if any camera model ever got off the production line with a curved film plane. Anybody know?

Leicaflex Loc: Cymru

John Potter built something seriously awesome: a curve film plane paper negative camera
“I built the curved plane paper negative camera as I liked the idea of creating images in a cinematic style.” is what John Potter tells us about his camera after a conversation about curved film planes. “Because I was using such a long negative, I needed to have a curved plane negative, so that each part of the negative receives the same amount of light falling on to it. With a flat plane negative, the ends of the negative would not get as much light falling onto them because they are so much further away from the source of light / pinhole.” He continues to state that there are no lenses involved.
The idea of the curved film plane isn’t new. Some photographers have been doing it for years and these days there are patents for curved imaging sensors. They tend to get rid of distortion and help with other problems. So, what better way to do this by yourself at home than with a pinhole camera? That’s exactly what John did. Last year, he became really interested in cinematic photography with anamorphic lenses. But if you know anything about anamorphic lenses, they sort of stretch the scene out. Plus, it gets expensive. “…I decided to create a pinhole camera which would provide me with the size of image I desired, namely in a 2.5:1 ratio using 4”x10” paper negatives – the Curved plane 4”x10” pinhole camera.” explains John. “More research and revising my mathematics knowledge later, and I had created a curved plane pinhole camera out of foam board which suited my needs.”
For John, this was a match made in heaven. He already really loved pinhole photography. In fact, he started out by just modifying old cameras. He explains:
“My first pinholes were conversions of old cameras using extension tubes until I came across and old Agfa Isola medium format camera belonging to my dad. I removed the lens and used a piece of aluminium kitchen foil with a pinhole in it. After this, I bought a cheap Coronet Ambassador box camera and converted this in the same way, it was a really easy way to make a robust pinhole camera.
As I read more about pinhole camera, I became interested in building my own camera from scratch and researched the internet for ideas. Using the back of an old medium format camera, I built the JP616 around it using foam board and using aluminium kitchen foil to place the pinhole.”
Eventually, him and his wife built their own darkroom and attended classes on how to develop black and white film yourself at home. He currently uses Fomapan 100.
His current prized camera is called the CP410. It’s made out of some plywood and foam board.
The CP410:
Pinhole: 0.4mm in aluminium kitchen foil
Focal length: 120mm (ish)
F300 rounded down to F256
Calculated horizontal field of view 115 degrees
Calculated vertical field of view 46 degrees.

He continues:
“I love the results from the long exposures required of pinhole cameras because I like the idea of trying to capture the passage of time in a single image rather than freezing time in an instant with much faster exposures. Seeing in the blur of a tree’s movement and the flow of water, something we don’t see while we stand and watch in finite detail. Pinhole images seem to have an aesthetic all their own, not completely sharp, but not necessarily completely out of focus. I had also become a little disillusioned with the seeming necessity for pin sharp detail the digital world seems to crave – here was something I could create from first principles to my own liking and satisfaction. I create my own camera, I take the exposure reading from an old light meter I purchased and adjust this to suit the parameters of my camera. I then develop the film / paper negative and print it to my liking. All my own work!!
Although it might seem quite involve and difficult to use these cameras because of the necessity of working out your own exposures, once you’ve tried it a few times it is really quite easy, you just have a few more things to think about.”

When Sony first announced the RX1, it truly turned the photographic world around, as it was the first fixed-lens compact camera to sport a full-frame 35mm sensor and a fixed 35mm f2 Carl Zeiss lens. A little later, Sony updated the camera with the RX1R, which had basically the same specs as the RX1, but came without an anti-aliasing filter on top of the sensor for improved sharpness.
The internet has been busy speculating on the RX1(R)’s successor’s details for a while, but now Photo Rumours reports that the camera, which might be called the RX2, will come with a faster 35mm f1.8 lens and–more importantly–a new curved sensor. Sony’s curved sensor technology had been reported earlier, but now a patent has been discovered that shows a 35mm f1.8 lens designed specifically for a just such a sensor.

lamiaceae Loc: San Luis Obispo County, CA

I think it is just that, a theory. I worked professionally at a museum for several years and I used a 8x10" B&J View Camera to photograph water color paintings and ink and pencil drawings. I used a vintage Goerz 12" Dagor (pre-Schneider) lens on a more modern shutter. Never had any uneven exposure or sharpness from corner to corner issues. View camera lenses (usually) throw a large enough image circle to avoid "problems". I think the issue is really some 35mm camera and/or lens designers try to go the cheap route and have "narrow" image circles such as "crop factor" lenses or cheap 35mm film lenses (in the past) that have corner distortion (barrel, pincushion), and uneven exposure and sharpness. It takes more glass for better lenses. Also note 4 element OK enlarging lenses vs 6 element excellent ones.

As noted by another UHH'er Pin-Hole cameras have issues that well designed lenses either don't have or can compensate for.

Pablo8 Loc: Nottingham UK.

One of the first projects on a Photographic College Course, was to make a Pinhole camera. Most popular item to use, was a round Biscuit Tin, 10" diameter 4" deep. Paper negative 20" x 4",was curved inside the tin (using the darkroom.) Hole, previously made was opposite the paper. That acted as the lens. Replace the lid on the tin (camera). Long exposure was estimated (guessed). out into the sunshine. Eureeka!! perhaps... Develop the 'negative', back in the darkroom. Just the start of a long exciting journey.

wrangler5 Loc: Missouri

The first few models of Minox cameras pressed the film against the (curved) back end of the lens, which was designed to focus the image on its rear surface. While it made for absolute consistency in the lens-film plane department, any speck of dust that found its way into the back of the lens could end up scratching the film as it was moved from frame to frame - although the advance mechanism released pressure on the film before moving it, clearances were very tight and the film moved against the lens as it advanced.

Sony has reportedly developed a curved digital sensor, although this article suggests that its utility would be somewhat limited http://www.whatdigitalcamera.com/technology_guides/curved-sensors-advanced-technology-guide-60556.

Joe Blow

Question 1:

What is the radius of the curve and is the hypothetical center to the lens (front) or back side?

Question 2:

If the Aperture (pinhole) is 0.4mm and the focal distance is 120mm (4.72"), how does this field of view of 115 H and 46 V come in? Or, how is it calculated?

Maybe it's been too long since I sat in a math class, but I'm thinking it would calculated from the H edges through the edges of the pinhole to the converges of the two sides. (Same for the V)

Thanks in advance.

jerryc41 Loc: Catskill Mts of NY

I think that was because of the curvature of the earth.

classic320

special "curcuit" film cameras also used a curved film plane to maintain a constant film/lens distance as the lens rotated (within the camera) to record large groups or panoramas. The Russian made "Horizont" 120mm comes to mind, and I remember there were 35mm cameras as well.

joer Loc: Colorado/Illinois

I believe the Contax SLR had this feature.

Pablo8 Loc: Nottingham UK.

Thanks for the sensible replies.

GGerard

You might be remembering the Contax RTS III, which had a vacuum back along with a ceramic pressure plate.

http://camerapedia.wikia.com/wiki/Contax_RTS_III

CobblestoneLane Loc: Midwest

On a side note, an astronomical camera, called a Schmidt Camera (https://en.wikipedia.org/wiki/Schmidt_camera), puts the unexposed negative on a curved surface at the telescope's prime focus point/surface. Because of the fast focal ratios used, the focal plane is significantly curved, hence the negative being placed on a curved surface.

This telescope setup allows for fast focal ratios (translated: short exposure times), wide view, and tight focus edge-to-edge (a must for pinpoint, high-contrast subjects like stars) for stellar pictures (pun intended).

Its primary use is for sky surveys where a significant portion of the sky is being looked at or studied.

jwn Loc: SOUTHEAST GEORGIA USA

then the sensor should be round....lens does not give rectangle image.

CobblestoneLane Loc: Midwest

Correct, but a rectangle sensor/film will image a rectangle of that circular lens image. The lens of a typical camera also does not provide a rectangular image; you only get that part of the image that is projected onto the sensor element/film.

Some astronomical sensors are square (same number of pixels on X and Y axes), and so better approximate the coverage of the full round image a lens produces.

Welsh snapper Loc: Wales UK

I have a USSR made 35mm which has a VERY curved film plane. It called the Horizont, its a swing lens panoramic, with a 120° view angle giving a 24X58mm negative. No distortion here.