A Photographer's Camera    


After having been a hobby photographer for nearly 40 years, and living through the evolution from entirely mechanical film cameras to present day digital equipment, I have a pretty clear idea of what is desirable in a camera, and what isn't, at least for the kind of photography I do. In this article I will explain what features I think a good, modern camera should have, to be liked by long standing photographers. Maybe some manufacturer, established or new, reads this and considers implementing it, or maybe we could even develop such a camera as an open project?

The concept

This should be a digital camera, designed from the ground up to have a logical and practical structure, doing away with things that aren't really needed. It should have highest image quality, a simple and logical user interface, and it should interface to the broadest possible range of existing "accessories" - meaning lenses, flashes, tripods, etc. All interfaces to the outside world should be open-source, so that the camera can act as the core of a multi-brand, universally compatible system.

Basic Layout 

Given that the 35mm film format was the most widely manufactured system in photo history, the largest number of high quality lenses in existence are for this format. It follows that to make best possible use of existing lenses, this camera must have a sensor that is either the same size as a conventional film frame, that is 36x24mm, or some size compatible with it. The sensor must not be smaller, because that would reduce the final image quality. A specially interesting possibility would be a large, square sensor, such as 40x40mm. Standard lenses intended for 36x24mm will vignette the corners of such a big sensor, of course, but the camera electronics can give the user a wide choice of interesting formats, such as square 31x31mm, panoramic 40x16mm,  round 40mm diameter, various oval formats, while the standard format would be 36x24mm. Of course each of the rectangular and oval formats would be available in both horizontal and vertical orientation. The format selection would simply indicate the proper crop in the finder, while the photo would always be taken using the full sensor, and the final cropping would be done in software on the computer. That gives the photographer the chance to second-guess his original choice of format for each photo. And if this large 40x40mm sensor is too expensive or not practical, then a simple, plain 36x24mm sensor should be used. These exist right now, and have existed for several years.

This camera would have no separate finder, of course, nor would it be a reflex camera. Instead it would use the main sensor to get a live finder image, doing away with the mirror box, mirror mechanism, matte screen, pentaprism and some other overhead of a conventional SLR camera. A decision that must be made is whether to use only the LCD screen on the back of the camera as a finder, or add a dedicated "peep-hole" finder with a small LCD and an ocular. Many conventional photographers will probably like the peep-hole finder, as it blocks out stray light and allows to better concentrate on an optically enlarged finder image, while many people who have to wear glasses, and are permanently hampered by eyepoint problems with finders,  will be glad to use just the open LCD screen on the camera's back - as long as it can be seen even in full sunlight!

Maybe a good compromise could be a peep-hole finder with a tiny color LCD inside, and high eyepoint optics, combined with a monochromatic, passive, always-on LCD on the back of the camera. All image viewing, both during shooting and during review, would be done through the finder, while all status indication, setting up and configuration of the camera would use the external LCD. 

Really this matter allows several points of view, and gives room to creative solutions. Those could include fold-out LCDs, passive color displays, and so on. It's probably the area most open to variation in this camera concept.

The main sensor would also be used for exposure measuring and focus sensing. This results in no mirrors, prisms nor other things needed between the lens and the sensor,  which allows putting the lens mount quite close to the sensor. This lens mount would follow an open standard, so that both the maker of the camera and third parties can make and sell lens interfaces that allow mounting a very wide variety of existing and new lenses on this camera. The generous space available between the camera's lens mount, and the seating plane of conventional SLR lenses (typically around 45mm from the focal plane), allows the inclusion of any required interface mechanics and electronics in those lens interfaces. For a start, the camera should be designed, and lens interfaces made available, for all of the more common existing lenses, such as M42, Pentax-K in all its variations, Canon FD and EF, Nikon in all its flavors, and additional interfaces should show up soon. But also lenses can be developed specifically for this camera, to mount directly on it, without using any interface. Such lenses can take advantage of the short distance between the lens seating plane and the sensor, which is a significant advantage in the design of wide and ultra wide angle lenses.

Resolution

To take advantage of even the better conventional 35mm lenses, the sensor should have a pixel pitch of roughly 200 pixels per millimeter. Even more than that is desirable, up to about 300 px/mm, but depending on available technology this could be left for future models. At 200 px/mm, a 40x40mm square sensor would have 64 megapixels, while a 36x24mm crop would have nearly 35 megapixels. That's in line with what currently available sensors (2014) in the best DSLR cameras provide. More than 300 px/mm would be overkill even for pretty good lenses of this format.

Dynamic range should be pushed as high as absolutely possible. At the current state of technology, a full 16 bits of resolution per pixel, with correspondingly very low sensor noise, would be really nice to have!

User interface

The camera would follow the principle of one dedicated knob per function. All often used main controls, such as focus, zoom, aperture, shutter speed and mode, sensitivity, format (if provided), would have their dedicated switch or knob or lever or button. Buttons are acceptable only for functions that toggle between just two or maximally three states, and whose state is obvious. Everything else should have levers or knobs that allow to see in what position they are. Instead the less often used functions could be buried in menus, because it would be highly impractical to provide separate controls for all of them. Still these menus should be well structured and use enough on-screen explanations, to allow using the camera without constantly referring to the manual. It should be possible to learn to use the camera with the help of the manual, and then put that booklet to rest.

The manual focus, aperture and zoom controls would be those of the lenses, when using lenses that have them. Lens mount interfaces for any lenses that don't have an aperture ring, would include such a ring in the interface. Lenses specifically designed for this camera would have these control rings built in, of course.

The shutter speed control should be located where it's easy to get at, like on top, near or around the shutter release button. Other controls can be placed wherever convenient. Given the lack of a pentaprism box, the top of the camera should have plenty room for several of the main controls - maybe even all of them!
  

Exposure control

The camera must provide at least fully manual exposure, and aperture priority automatic exposure. The exposure system should use the main sensor, reading all its surface, either by actually reading each pixel, or by reading a sample pixel in each small area.  The exposure system must have a mode in which it uses the brightest pixel of the whole image as reference, setting exposure so that there will be absolutely no saturated pixels, with the brightest pixel set close to saturation. The camera may also provide a second exposure mode that allows a certain percentage of pixels to saturate, and this percentage should be user-adjustable (via menu). These two modes replace all center weighted, spot, overall, area-selective, and fancy motive-specific weightings, because by recording an image with no saturated pixels, or with a small defined amount of saturated pixels, all further adjustments can be made later in software. But images with too many saturated pixels are always unusable, and images exposed lower than necessary to avoid saturating any pixel just lose image quality, in terms of noise.

In the above paragraph, single-color pixels are meant. The exposure system must check that no individual color is saturated anywhere.

The shutter control wheel could have detents for manual shutter speeds covering the camera's whole range in full steps, plus a long exposure setting in which the shutter remains open while the button is pressed, another long exposure setting in which the shutter opens on one button press and closes on the next press, plus two auto-exposure settings: Aperture priority with no saturated pixels, and aperture priority with some saturated pixels. The latter is useful for example when the scene contains some tiny spots reflecting sunlight, such as rippled water or snow surfaces, and it is desired to avoid strongly darkening the whole image just to keep those tiny spots from saturating.

Metering should be done with the lens stopped down to the value used for shooting, to avoid errors arising from imprecise stopping down after fully-open measurement. The most logical system would be keeping the lens at shooting aperture most of the time, opening it fully only when specifically desired for more precise focusing. This also makes the camera highly compatible with old lenses that didn't have automatic stop-down, and might even eliminate the need for the camera to have any control at all over the lens aperture, simplifying the lens interface! Given that an electronic viewfinder is used, there is no need to keep the lens aperture wide open.
 

Exposure compensation

With my current cameras I find that I need exposure compensation exclusively to correct for the incorrect exposure the cameras do. Most of the time, if the lighting is such that a camera will do incorrect exposures, I prefer switching into manual mode rather than using the exposure compensation control. Consequently I think that an exposure compensation control isn't really necessary, in this camera that would have a no-saturation-based autoexposure system.

Any desired lightening or darkening of images can be done much better during processing in the computer, by gamma changes.

Focusing  

Given the wide differences between legacy lenses in their autofocus systems, and the large stock of high quality manual focus lenses still around, the camera should be aimed mostly at camera-aided manual focusing. In this mode, the user moves the lens focus ring by hand, while watching both the finder image and some sort of focus bar, meter, tool, whatever, displayed along with the image, that shows the quality of focusing as detected by the camera's sensor. The main focusing help might even be simply a strongly magnified spot of the sensor displayed on the finder screen, to let the user judge proper focus. This spot might be movable over the sensor area, or several such spots could be displayed at the same time, covering all zones of the image. For example, there could be a grid of 9 such magnified focusing spots, each of them having a diameter of around one sixth the image height or width, superimposed at regular intervals on the background finder image. By pressing a dedicated button, the camera would be switched between displaying all nine focus spots, or just one in the center, or none.

Any further help the camera can provide to the user during manual focusing is certainly welcome. For example, catch-in focus is very useful for moving targets. Also, if the camera displays a focusing indicator, it is MUCH more useful to have an indicator showing which way one has to focus, and how out of focus the subject is, than one that only shows whether or not the camera thinks the focus is correct.

The camera should also provide a simple electrical autofocus interface on its lens mount, allowing dedicated lenses for this camera to contain autofocus motors, and also allowing lens mount adapters for legacy autofocus lenses to either relay the electrical signals, or include a focus motor in the lens interface adapter, depending on the lens type they are made for.
 

Shutter

If technically feasible without image quality degradation, the camera should not have a mechanical shutter, using electronic shuttering instead. This would provide advantages in terms of cost, reliability, noise, and vibration. If this proves unfeasible, a conventional mechanical focal plane shutter would be used. Of course this shutter would be open most of the time, closing only briefly before and after each exposure, to allow setting up and reading out the sensor in darkness.

Shake reduction

The camera should provide shake reduction, either by mechanically moving the sensor, or by electronically shifting the image on the sensor. Evaluation is required of the cost and quality of each method. Input to the shake reduction system should come from both accelerometers and the image itself. To avoid the need of entering the lens focal length into the camera's software after every lens change and after zooming, during pre-exposure the camera can compare the image shift happening on the sensor, to the acceleration data, to calculate the current compensation factor (and focal length, if desired, to store it along with other image data), and then apply the corrected acceleration data alone during exposure.
 

Flash support

A flash built into the camera is not required. The camera should have both a hot shoe, and an industry-standard connector for an external flash. Both flash interfaces should include openly documented functionality for proper camera-flash integration.  Specifically there should be plain simple on/off signals for flash trigger, flash termination (both of them camera-to-flash) and flash charged (flash-to-camera). Additional signals for more advanced flash functions with dedicated flash units might be added, without deleting the basic signals.

In manual exposure mode, the camera shouldn't send a flash termination signal, so that operation remains fully manual. In auto-exposure mode, the camera should measure received light during the exposure, to terminate the flash at the proper moment. I don't know whether this can be done via the image sensor. If not, a workable solution (better than nothing) would be a photocell measuring overall light reflected off the sensor. This wouldn't prevent the risk of saturating some pixels, but would at least give a reasonable overall exposure.

Remote shutter

The camera should have a plain simple industry standard connector for an external shutter release switch connected by a cable.

Power source

The camera should provide some flexibility regarding the batteries used. It must be able to function using some type of standard batteries, such as AA rechargeables, or perhaps 18650-size lithium cells. The batteries might be housed in a holder attached to the camera, so that different holders can be made for different batteries. The camera should accept a sufficiently wide range of input voltages to accomodate several different battery types. For example, a range of 4.0 to 8.0V would allow the use of 4 to 5 NiMH cells, or two lithium cells. The voltage at which it shuts down to protect the batteries should be user-configurable, and instead of a battery charge indicator reading percentual charge, which is always imprecise, it should simply display the actual battery voltage, to let the photographer judge remaining charge.
 
All battery charging should be done outside the camera.

Processing

Image data should be stored and downloaded in raw form, with no processing altogether. The raw files should include the full data read from the sensor, and any information the camera has, such as the format selected, date and time, camera settings, etc.

In-camera image processing should be limited to the minimum required to feed the viewfinder image, focusing, exposure control, etc.

The lack of internal processing into finished JPG images does away with all need to configure things like contrast, gamma, color rendering, etc. Even white balance doesn't need to be set, and the camera could do completely without it. The user can later select the proper white balance in the external processing software. If photos are shot under special lighting, the user can shoot a photo of a white or gray sheet under that light, and later use it for precise white balancing of the other shots during processing outside the camera.

Data storage

Given the fast development in memory cards and chips, it would be desirable that the camera had an openly specified memory interface protocol and connector, supporting very high memory capacity and speed, and plug-in adapters for the currently available types of memory cards. When standards change and new cards appear, it would then be easy to bring out interface modules to take advantage of them.
 

Video

This being essentially a photo camera, video support is not required. If it is found easy to include video support, at nearly no added cost, it could be done, but under no circumstances should the photo performance of the camera be compromised to support video.

What else is not wanted

Modern cameras tend to sport a long list of "features" that are perfectly useless to most photographers. Among them are "picture modes", lots of tools to alter the colors, and all sorts of automatisms, including some as weird as trying to recognize human faces, and optimizing their rendering. Such features might appeal to a few of the most non-technical beginners in photography, and maybe also to a few old photographers who have become tired of actively defining how their photos will look. For everyone else, though,  they are an offense!

All processing features, such as highlight and lowlight protection, cross-processing, digital filters, etc, of course have no place given that the camera won't internally process the images. HDR capturing is also probably better left out. Instead the sensor and A/D converter should be good enough so the camera doesn't need dynamic range extension through multiple exposure HDR techniques.

Mostly useless gadgets, such as WiFi, Bluetooth, infrared interfaces, GPS, attitude sensor, etc, should be left out, and instead either the price should be reduced accordingly, or the money should be invested in further improving the image quality.

The camera should have no beeper, speaker, bell, gong, nor any other pointless noise-making device. And certainly it shouldn't play creaky pre-recorded shutter noises and the like!!! If at all possible, it should be completely silent. Confirmation that a photo was effectively taken can be given via the LCDs.   Pushbuttons should give clear tactile feedback.

Styling

The camera should be as small, lightweight and unobtrusive as possible. It should have neck strap attachments in forward locations, so that the camera balances reasonable well when fitted with a typical lens. As much as possible it should lie in the hands much like a classical SLR camera did. It doesn't need to look fancy. It doesn't need to look classical. It doesn't need to look modern. And certainly it doesn't need to come in several colors! In fact, how it looks is quite unimportant. Instead it should be practical, compact, solid, and well made. Form should follow function. The camera should sell for its capabilities and quality, not for its looks. 

Business model

A camera like this cannot be used to force a photographer to shelf all of his existing equipment and buy everything anew. It cannot be used either to firmly tie a photographer to a given company, brand, lens mount, etc. So, it shouldn't be sold below production cost, as a lure, to make people buy overpriced accessories. The camera would have to sell on its own merits, for a fair price, that allows the manufacturer to make a reasonable profit, while not preventing too many people from buying it. My firm belief is that such a camera would find enough friends and buyers to be a huge commercial success on its own, without needing the sale of accessories to make it worthwhile to the manufacturer! On the other hand, of course the manufacturer can and should bring out optimized lenses and other accessories, to increase his profits and give us photographers more nice toys, and third party manufacturer can and should do the same!


Any takers?


Update!

I wrote the above several years ago. In the meantime I have been refining my ideas about my dream camera. Most of the fundamental concepts remain the same, while some have become better defined, and a few minor points have changed a little. And during this time Sony brought out its Alpha A7 line, which is presently what comes closest to my desire, but is not close enough for me to go and buy an A7 camera.  A few months ago I was close to doing it, but then I decided that the Sony A7 still lacks too many of the features I want, and has too many features I don't want, and so I decided to keep waiting for some camera I like better.

Today (that's in early 2017), having mostly forgotten the wording of this web page, I sat down and made a point-for-point list of the features I want in a camera. Then I re-read my article above, and found a surprising amount of similarities. Almost if the two things had been written by the same guy! :-)

So, here is my updated list of requirements. Camera manufacturers, pay attention. Or maybe a few of us might get together and engage in developing this camera as an open source, crowd-funded project? Since it has very little mechanics, this seems quite possible. The main problem point would be the image sensor. As far as I know, high performance camera sensors cannot be bought over the counter in any store.

Wanted features for my Dream Camera, as of early 2017:

- Compact and lightweight.

- Full frame sensor with decent resolution (20MP or more) and probably no lowpass filter.

- Mirrorless (to save space and weight, avoid mirror mechanism/slap/noise, etc).

- Electronic shutter, if possible (no vibration, no noise, no wear, less power consumption, faster).

- Simple lens mount with short retrofocus distance, so it accepts all sorts of lenses through adapters. Lens mount could have electric interface for dedicated lenses, but should still operate with manual lenses that have no electrical connections nor mechanical linkages.

- Electronic finder (WYSIWYG, allows keeping lens at shooting aperture all the time).

- Finder mounted in upper left corner, to keep my big nose from getting in the way all the time!!!
 
- One-knob-per-function user interface, at least for the basic functions:
    - Shutter time dial with full range selection in full steps, plus B and  AUTO setting.
    - Sensitivity dial with full range selection in full steps, plus AUTO setting.
    - Aperture ring on lens, with AUTO setting to be used if compatible, otherwise only manual aperture. Any lenses that don't have an aperture ring would need an adapter that has aperture ring.
 
      The above three controls eliminate the need for a manual/ shutter priority/ aperture priority/ sensitivity priority/ program mode dial! The operating mode is determined by which of these three controls are set to AUTO or to fixed values.   

    - Exposure compensation dial, in half steps, with a range of  ±2 or ±3 steps.
    - Combined power and shutter mode switch (Off, single, continuous, 2s, 10s).
    - Focus ring on lens, manual/autofocus switch on lens, if compatible.
    - A few user-configurable buttons. Firmware should allow very wide configurability of these.

- Instead of center-weighted metering, multizone, spot, or whatever, the suggested metering method is to read the full frame and take the brightest pixels, then set exposure to put these to almost full scale. In photography dark areas look acceptable, burned-out areas do not. The individual (single-color) pixels must be taken for this operation, to avoid single-color saturation and consequent color loss and shift. The fact that metering is done with the lens stopped down to shooting aperture prevents stop-down inaccuracy. For special shooting situations, a menu setting could configure the allowed percentage of saturated pixels. Normally this would be zero, but depending on cosmetic quality of the sensor such a setting might be necessary to prevent autoexposure falsing on hot pixels.

- Must have good manual focusing tools. Suggestion: One manual focus tool button next to shutter release button. Brief push brings up circle or rectangle in center of finder, showing center spot at full pixel-for-pixel magnification. Longer push (more than half a second) turns entire finder into mosaic of 9 or even 25 rectangles, each showing its center at full pixel magnification. Short push when focus mag is on turns it off. Optionally magnification rate can be menu-configurable.
An alternate, additional manual focusing tool would use the camera's autofocus sensing system, and display some sort of indication of whether the manually set focus is too long, too short, or right. This should be a smooth linear indication, so that the user basically focuses by aligning a displayed  marker to a reference. This tool should sense just the center spot of the image.
Pentax cameras use a simple indicator that lights when the image is in focus and goes dark when not, and this is very inconvenient to use, because the user never knows to which side the focus is off, and by how much!
 
- Autofocus support can be included, for dedicated lenses, and also for off-brand autofocus lenses through intelligent, motorized adapters that use the camera's protocol. These adapters might be supplied by camera maker for select brands of lenses, or the electronic interface would need to be well documented so that third party manufacturers (including lens makers) could supply them. Alternatively the camera might have no autofocus features, and instead fully specialize on manual focus shooting.

- Image stabilization through mechanical or electronic sensor shifting would be a plus, but not a very important one, due to hassle of entering focal distance of off-brand lenses. Should be included only if impact on size, weight and cost is negligible. One can live without.
   
- A backside mounted monitor might not be needed: The finder can serve in its place, and a simple, small, always-on, segment-based, unlit, monochrome LCD might be used to show camera settings, but this is probably not strictly required due to mechanical dials that show all important settings. Having no monitor, and an eye proximity sensor for the finder, results in battery runtime extension: When no eye is present, both the finder AND the sensor/processing are turned off! Only a very basic, low power microcontroller needs to keep running to monitor user input. So the battery use with the camera on, but the user not looking into the finder, would be very low. Eye sensor sensitivity needs to be adjustable, so that it won't easily trigger on objects near the camera.

- No internal JPG processing needs to be done. Images should be stored in raw format, and the only internal processing required is for very basic viewing in finder. This eliminates the need for many setup items and buttons, including white balance, color rendering, highlight/lowlight compression, lens aberration correction, noise reduction, etc etc etc. All this processing is later done on a computer. The camera is ONLY a photo capturing tool, not a fully featured processing lab! And this should also help save some battery power. Modern memory cards are large and fast, they don't really need sophisticated compression before storage.
  
- No stupid "picture modes", "scene modes", nor any other dumb-down presets should be present. This is a camera for photographers who know what they are doing, not a preprogrammed picture taking automat for completely photo-ignorant people. And not a camera that tries to offer a little appeal to everybody.

- No need to configure camera to crop formats. All photos store all sensor data in raw format. Cropping can be done later on computer.

- It should be possible to copy the entire camera setup/configuration to a file on the memory card, and back, to be edited on a computer  in a more comfortable way than in the camera. This would allow almost limitless configurability, if so desired. And many different configurations suiting different shooting situations or different users could be stored on the computer, on the card, and loaded into the camera on demand. The file format should be a simple text file, that can be edited by any text editor.

- Video functionality is entirely optional. Most photographers never use it.

- Power should be supplied by standard batteries, instead of custom ones. AA size NiMH cells are the most universal option, followed by 18650 size lithium ion cells that allow higher energy density. Four of the former or two of the latter are probably enough to power this camera for at least 1000 shots. Cells and charger are supplied by the user.

- SD card storage is currently the way to go. Room for two SD cards is really not needed. Nor is support for other card formats.

- WiFi, NFC and other fancy connectivity isn't needed. I know many people who use cameras having these features, and never anybody of them uses them! A USB connection using a standard connector is most reliable and universal, and  thus best. Likewise, GPS isn't needed. Better save the cost, space and weight, even if it's not much.

- Built-in flash not required. Both a hot shoe and a sync cable connector should be provided. TTL flash metering isn't very important in digital photography, since test shots can be made and the flash and exposure adjusted, but if connections for flash automation are provided, with simple protocol and clear specifications, it would be a plus.

- A beeper/buzzer can be useful, but MUST be configurable, including the option to completely silence it.

- A color-separated set of histograms is an essential tool that should be included both for setting exposure, and for checking images taken. It could be superimposed on the finder image, or better placed above or below it.
 
- The camera should be put into "play" mode at the touch of one button, and returned to shooting mode by touching the shutter release button.







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