What Does a Professional Look for in a Digital SLR?

Some posters on Usenet wanted to know just exactly what a professional looks for in the selection of a Digital SLR. This is a work in progress, so please be patient. I rushed this out after becoming aware that some people had no idea of what constituted a professional level camera.

Lenses

Full line of both Professional and Amateur Lenses
A professional will usually shoot with professional lenses, but on occasion may use an amateur level lens if it's a rarely used focal length that does not justify the purchase of a very expensive professional lens. This requirement effectively limits professional digital cameras to those bodies  that can accept Canon or Nikon lenses (all professional digital SLRs on the market, other than medium format, can accept Nikon or Canon lenses).

Accessory Availability

These are some of the accessories that will be available for professional level digital SLRs. Many are also available for lower level cameras.

Communications

High Speed Communications (IEEE 1394 or USB 2.0)
During a professional shoot, the professional may want to download the contents of the memory card without removing it. A high speed serial link is very important. All newer professional models include high speed communications.

Direct Connection to Computer
This allows continuous shooting as images are transferred directly to the host computer. This is a useful feature in studios.

LCD Display Information

Histogram Shows All Three RGB Channels
A histogram which shows all three channels (RGB) is a very useful professional feature. The Nikon D2X and D2H/HS, the Canon EOS-1Ds Mark II and EOS-1D Mark II, and the Fuji S3 Pro, feature an RGB Histogram (the older Nikon D1X, the Canon EOS-1D and EOS-1Ds, and the Fuji S2 Pro, do not have this feature). Lower end cameras usually have only a luminance histogram, though Sigma did implement an RGB histogram on the SD9 and SD10.

It is safe to say that no professional digital SLR, in current production, does not have a histogram that is capable of showing all three RGB channels (on the other hand, the presence of this feature does not automatically make a camera into a professional level model).

Large, High Resolution, LCD (2.0" minimum)
Smaller LCDs are a pain in the butt when you want to do in-camera processing, or look at histograms.

Image Quality

Noise
Noise levels must be acceptably low, even at higher ISO settings. It is not acceptable to avoid the higher ISO speeds due to excessive noise. This is an area that really separates the men from the boys.

Color Purity and Accuracy  at all ISO speeds
On some cameras, color accuracy is fine at ISO 100, but suffers at higher ISO speeds. The colors should match the subject, without a lot of post-processing, even at higher ISO speeds.

Resolution
Does it produce images with sufficient resolution? This varies by photographer. A photographer who specializes in large portraits will need higher resolution than a sports photographer. Normally, no one would consider a digital SLR with less than 8 megapixels to be professional level. However, the Nikon D2HS is an exception.

Aliasing/Moiré
Images from digital cameras naturally have jagged edges. Anti-aliasing smoothes out the rough edges, at the expense of making the images appear less sharp. RAW images will usually not have anti-aliasing applied, so the professional can apply the desired amount of anti-aliasing using the post-processing software. However, some amateur cameras, such as the Nikon D70, use a softening filter in front of the sensor, which does some anti-aliasing, even on RAW images.

I haven't included sensor size explicitly, but the image quality is often directly related to the sensor size, because the larger the sensor, the larger the pixels can be for a given resolution, and lower-noise and better color accuracy fall out automatically from this.

Flash

Flash Sync Speed
Flash sync speed is the maximum shutter speed where the shutter and the flash are synchronized. Slow flash sync limits your ability to use fill flash. Do not go below a sync speed of 1/250 second. The Nikon D70, while not a professional camera, has the ability to go to 1/500 second, because it uses an electronic shutter for high speed operation.

Flash Exposure Compensation Control
You should be able to manually increase or decrease the flash exposure compensation.

Evaluative Flash Metering
There are differences between flash metering on film and digital cameras because the way a digital camera sensor reflects light is different from how film reflects light. Both Canon and Nikon have made changes to how they determine flash illumination for proper exposure. Furthermore, not all flash attachments will work properly with digital bodies. For the Canon 20D, EOS-1D Mark II, and EOS-1Ds Mark II, the best flash to use is the Speedlite 580EX (see http://www.photo.net/equipment/canon/580ex/ for a good explanation of the advantages of this flash)

Automatic Operation

Auto Focus System
Despite what many people believe, most professionals usually use auto-focus. The quality of the auto-focus system is a crucial feature. Here are some features to look for:

Automatic White Balance
Automatic white balance should work well under "normal" conditions. Automatic white balance works by the camera looking at the scene and trying to figure out the areas that are actually supposed to be white.

Most professional digital SLRs let you choose from a menu of conditions in order to "help" the automatic white balance. Conditions include 'Incandescent,' 'Fluorescent,' 'Sunlight,' 'Cloudy,' ''Tungsten,' 'Shade,' 'Overcast,' and 'Flash.' This is kind of like "semi-automatic" mode.

Manual Controls

Custom Function Controls
Look for the Following Custom Functions (these vary by camera, many are included on prosumer and consumer cameras as well):

White Balance Control
There should be a way to set the white balance using a card. All professional and amateur digital SLRs have this feature. You should be able to save your own custom settings.

Accurate In-Camera Exposure Metering
Professional level cameras will usually have better in-camera metering.

Good In-Camera Image Processing
When you don't have access to a computer, you may still want to adjust sharpness, color saturation, and other image parameters.

LCD Screen (Bright, Accurate, Zoomable)
The quality of the LCD screen (number of pixels, resolution, and the ability to zoom in and out), will determine how easy it is to do in-camera processing.

Performance

"Shoot Priority"
This is a strange term, but it relates to whether or not the camera is ready to shoot, even when other activities are occurring. For example, can you interrupt reviewing an image to shoot more images, without delay?

Shutter Lag
The shutter lag should not be more than 40ms. It is usually settable to different values. Sometimes, a higher shutter lag is desirable.

Maximum Shutter Speed
Anything less than 1/8000 second is unacceptable.

Frame Rate (Frames per Second)
The frame rate is dependent on the internal processor, and the buffer write speed. A portrait photographer may not care about a high frame rate, while a sports photographer will require it. For example, the Nikon D2Hs has a relatively low resolution sensor (4.1 megapixel) but it is intended for photojournalists and sports/action photographers that need the high frame rate, and that don't care about high resolution portraits.

Buffer Size (Burst Depth)
The maximum frame rate can only be sustained for a short time. The camera will have internal buffering to store frames, while it dumps them to the slower Compact Flash memory. Again, A portrait photographer may not care about a large buffer, while a sports photographer will require it.

Power Consumption/Battery Life
You should get at least 1000 shots per battery, at normal temperature.

Orientation Sensor
Does the camera automatically switch from portrait to landscape mode?

Quality

Construction
 Can the camera withstand continuous use and rough handling? Is the lens mount on the body metal or plastic. Is the body made out of cheap plastic, polycarbonate, or magnesium.

There are differences in the ruggedness and longevity between consumer-level cameras and professional-level cameras. The body material, the number of shutter cycles, the lens mount material, all play a part in the ruggedness and longevity of the product. Even when two cameras can take the same quality of photos, there can be big differences in how each stands up to continuous use and abuse. A good analogy is the difference between consumer-quality appliances and commercial quality appliances. A commercial washing machine will not get your clothes any cleaner than a consumer washing machine, but the commercial machine can handle continuous use and abuse, while a consumer machine could not handle 15-20 loads per day, every day, for very long.

Temperature Ratings & Weather Resistance
Can the camera withstand harsh climatic conditions?

Shutter Release Cycles
Look for a rating of at least 150,000 release cycles, with 200,000 being better.

Ergonomics

Controls (buttons, dials, etc.) can be easily manipulated. Size and weight of camera are acceptable.

RAW and JPEG Support

All digital SLRs support both RAW mode and JPEG mode. In RAW mode, the internal processing of the camera is not used, and the raw data is written directly to the memory card for post-processing on a computer. RAW mode almost always results in better quality than a JPEG processed internally, and flaws be more easily corrected with a RAW image processed outside the camera.

Still, JPEG mode is often used, even by professionals. JPEG results are often sufficient, if the camera and sensor are of good quality, and you can store many more JPEG images on a memory card. The camera should offer selectable compression ratios.

Workflow

Software--Excellent  RAW processing software (Included or After-Market)

Adobe Photoshop now supports most RAW formats, so even if the included software doesn't include the capabilities listed above, they are still available.

Minimal Post-Processing

There should not be extensive manual post-processing necessary. There are some lower-end cameras, such as the Sigma SD-10, which require extensive post processing in order to obtain satisfactory results. A professional that does high volumes of photographs cannot afford to spend hours per picture correcting the results.

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