wide angle lenses and shape of sensor

[40mm f/2]

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Reading the Sony A7 tread I became again aware of the problems of WA lenses: strong vignetting, lateral color shift and low edge resolution. Leica seems to do better (especially M9) but it has inherently the same problems. Digital corrections help but sacrifice DR at the image periphery. More extreme retro focus lens designs with flatter incidence angles improve the performance especially for the Sony A7® but with the penalty of size and weight. Leica S WA lenses are very bulky and still have a much better image quality in the center compared to the edge.

Micro lens offset on the sensor can improve the performance but is optimal only for a specific angle (I guess this explains why Leica M is better in WA and Sony in tele range - different design compromises).

I came across two small blurbs which which I found very interesting for WA photography. both use a spherical image surface (optical fiber array projecting on a flat sensor):

Miniature wide angle lens under development at UCSD: Digital Photography Review

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What I can see the incidence angle is always 90º and spherical lens corrections are not necessary.

Besides light field photography this not flat sensor technology is something which could be not done with film. Obviously the sensor shape has to be produced to a specific lens but I would not mind a WA specific camera.

[TomB_tx]

I came across two small blurbs which which I found very interesting for WA photography. both use a spherical image surface (optical fiber array projecting on a flat sensor):

What I can see the incidence angle is always 90º and spherical lens corrections are not necessary.

Besides light field photography this not flat sensor technology is something which could be not done with film. Obviously the sensor shape has to be produced to a specific lens but I would not mind a WA specific camera.

The simple Kodak Brownie box cameras I had in the 1950s used a curved film gate so they could use a simple lens and not correct for flat field. Curving the film in the long dimension stiffened it in the short dimension, so no pressure plate was needed. Cheap and effective.

The curved sensor construction is novel, but the concept is old.

[luigi bertolotti]

The simple Kodak Brownie box cameras I had in the 1950s used a curved film gate so they could use a simple lens and not correct for flat field. Curving the film in the long dimension stiffened it in the short dimension, so no pressure plate was needed. Cheap and effective.

The curved sensor construction is novel, but the concept is old.

 

True : apart the Brownie (interesting, btw... I didn't knew of it) curved film has been used for decades in high-level astrophotography : I think that the concept of deforming the sensor matrix can be one of the technologies that will appear in the future : by logic, the first practical implementation in "normal" cameras could be in the MF Digital backs... or, even early, in the similar devices for aerophotography/surveying (in which wide angle coverage with no distortion and CA is critical and VALUABLE : to a certain extent, you can cover the same area with less flight mileage/hours, a costly factor)

[40mm f/2]

As far as I understand it the curvature of the sensor most match a specific lens - so MF digital backs may be not the optimal starting point for this technology. One sensor technology at least Sony and Fuji/Panasonic is hinting at are organic sensors and these are made with a vapor deposition technique which can be applied to a curved surface or on a substrate which can be bent.

[luigi bertolotti]

As far as I understand it the curvature of the sensor most match a specific lens - so MF digital backs may be not the optimal starting point for this technology. One sensor technology at least Sony and Fuji/Panasonic is hinting at are organic sensors and these are made with a vapor deposition technique which can be applied to a curved surface or on a substrate which can be bent.

 

That's true... but in the MF market lenses' providers are more "free" of restrictions... I think that if Dalsa or someone else would make a curved sensor, someone like Schneider could make a series of Super Angulons (3 or 4 focals) designed to have a "standard" field curvature focal-indipendent (of course, other factors like dependancy from focus distance must be taken into account... but it's their job to afford designinig tasks... )

[Torontoamateur]

The size of the millions of receptors makes the difference. The finer the size of each receptor the more the vignetting. If you want to use wide on a digital then use a lower resolution sensor at the present time.

[plewislambert]

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If you want to use wide on a digital then use a lower resolution sensor at the present time"

 

I have been using a 20mm AF Nikkor and a 17mm manual Tokina on adapters on my M9. Neither lens suffers from heavy vignetting or shaded edge colours. Both lenses have a long back focus to clear the moving mirrors of the slrs for which they were designed and the rays leaving the lens in the direction of the edges of the sensor do so at a much less acute angle than those produced by my 12mm CV, whose rear element is very close to the sensor and which suffers both faults so needs Cornerfix.

As an aside, the 12mm lens covers such an amazingly wide angle that often the edges need to be cropped in the interests of composition, so the defects mentioned don't appear in the finished picture.

I hope this adds light to the subject.

Philip

[plewislambert]

The simple Kodak Brownie box cameras I had in the 1950s used a curved film gate so they could use a simple lens and not correct for flat field. Curving the film in the long dimension stiffened it in the short dimension, so no pressure plate was needed. Cheap and effective. "

 

I wish my Kodak Brownie had been this advanced. I did not know what a sharp 6x4 enlargement was until I upgraded in 1952 to an Ensign Ranger Special!

The next technical advance was to buy a Weston......

 

Colour transparencies followed on a 35mm Ilford. I haven't bothered with monochrome since then.

 

M9 is best.

Philip

[algrove]

Philip

Try a Monochrom M at a Leica Akademie just for the fun of it and bring back nostalgia.

[Guest larryking6458]

I had in the 1950s used a curved film gate so they could use a simple lens and not correct for flat field. Curving the film in the long dimension stiffened it in the short dimension, so no pressure plate was needed. Cheap and effective.