Timings & File Sizes

The D70 proved to be an extremely fast camera, Nikon has clearly taken large steps to ensure that in use this camera feels and responds just like a film SLR, and they've achieved that. Startup delay is nonexistent with the camera ready to shoot at the instant the power switch is turned to On. Shutter release lag simply isn't there, the camera responds to your slightest input and the shutter just opens when you depress the button, as you would expect.

Thanks to newly a designed buffering system, extremely fast image processing and blistering Compact Flash interface (with the right CF cards) storage times are so short to be of almost no consequence. The D70 literally wipes the floor with the competition for continuous shooting capability, indeed you'll need to spend significantly more to find a digital SLR which is any faster. Kudos Nikon, the D70 sets a new benchmark at its price point.

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 3008 x 2000 Fine JPEG (approx. 2.2 MB per image).

The media used for these tests were:

• 2 GB SanDisk Ultra II Type I Compact Flash card
• 1 GB IBM Microdrive Type II Compact Flash card
• 4 GB Lexar Pro 40x Type II Compact Flash card (FAT32)

Action	Details	Time, seconds (SanDisk)	Time, seconds (Microdrive)	Time, seconds (Lexar Pro)
Power: Off to On		0.0	0.0	0.0
Power: On to Off *1		0.0	0.0	0.0
Record: Review *2	JPEG / RAW	0.9	0.9	0.9
Record: Enter play mode *3	JPEG / RAW	1.0	1.2	1.3
Play: Image to Image *4	JPEG / RAW	0.5	1.3	0.5
Play: Thumbnail view 2 x 2		0.5	1.5	0.5
Play: Thumbnail view 3 x 3		0.7	1.3	0.8
Play: Magnify		0.9	1.3	0.9

Low Light Auto Focus

This test is designed to measure the minimum amount of light under which the camera can still focus. The focus target is our lens distortion test chart (shown here on the right), camera is positioned exactly 2 m (6.6 ft) away.

Light levels are gradually dropped until the camera can no longer focus. Before the shutter release is half pressed the lens is manually focused to the closest subject distance (typically 0.5 m) to "throw the focus out". This test target is the optimum type of subject for most AF systems (as it has a vertical line at its center).

AF assist lamp

The D70 has a white light AF assist lamp which is by default enabled and can be disabled via custom function 22.

The D70's auto focus proved impressive in good light and equally as good in low light situations. The AF assist lamp had an average working range (around 3 m) but didn't have a negative impact on focus times. Without the AF assist lamp the camera managed to focus in very dim lit situations in under three seconds.

Continuous shooting mode

One thing we picked up on very quickly in our D70 preview was the D70's impressive continuous shooting capability which comes about from a fast shutter, fast processor, good buffer usage and fast Compact Flash throughput.

Smart buffering

In my D2H review I talked about 'Smart buffering' (my own name for it), the ability for the camera to use its buffer in the same way a multitasking computer operating system would use RAM, to buffer the RAW data and temporarily store the converted output data (JPEG or NEF) before being written to the Compact Flash card. This technique has the advantage of freeing up Buffer space as quickly as possible and not being bottlenecked by the Compact Flash card or interface.

The diagram below was created for my D2H review, having observed the way the D70 operates I am fairly confident that it is a fair representation of what goes on inside this camera too.

Approximate image processing sequence:

1. Record data as it comes off the image sensor, unprocessed data (approx. 8.7 MB per shot)
2. Store this unprocessed data in the buffer
3. Take unprocessed data from the buffer, convert to image file format (JPEG, NEF, etc.)
4. Store this processed image file in the buffer ready for writing
5. Write output JPEG / NEF image files from buffer to CF card

The important thing to understand here is that steps 3 and 5 are happening in parallel, the image processing engine (step 3) is constantly freeing up buffer space for new shots to be stored. This means that you do not necessarily have to wait for the entire burst of frames to be written to the CF card before there is enough space to take another full burst.

Something the D70 does significantly differently than previous Nikon digital SLR's is that it allows you to keep taking images continuously after the initial burst of shots, it does not limit you to a certain number of frames and require you to re-press the shutter release.

Measuring frame rate

We used a new approach to measuring frame rate on the D70, very simply we made an audio recording of the camera shooting continuously in each of the image modes and then analyzed this using our own proprietary software to produce a graph of frame rate versus time. The card used for these tests was the 2 GB SanDisk Ultra II, image shot was our standard resolution chart at ISO 200, shutter release button was depressed for 40 seconds each time. The results were:

* By 'continuous' we mean until the Compact Flash card is full.

The graph below represents the average frame rate at each 'stage' of the camera's buffer usage as identified by the measured frame rate (in reality the actual frame rate fluctuates slightly from one frame to the next).

File Write Timing

Timings shown below are the time taken for the camera to process and "flush" the image out to the storage media (the amount of time the CF compartment light is on). This timing would hardly ever impact on your usage of the camera because (a) it's so fast and (b) the D70 continues to process images in the buffer and write data out to the storage media in parallel to you composing (and taking) the next shot.

The media used for these tests were:

• 2 GB SanDisk Ultra II Type I Compact Flash card
• 1 GB IBM Microdrive Type II Compact Flash card
• 4 GB Lexar Pro 40x Type II Compact Flash card (FAT32)

An extremely impressive performance, but expected after the results from our continuous shooting tests.

Actual throughput

To measure the maximum potential throughput of the D70 with various cards we simply shot a burst of four RAW images (total size around 22 MB) and timed how long the CF activity lamp was lit. The actual total file size was measured from each card and divided by the time take to produce a throughput figure. As you can see from the results below the combination of the 2 GB SanDisk Ultra II and the D70 produced some pretty amazing results, just under 4 MB/sec. The results below are almost identical to the D2H.

Card	Throughput (Burst of 4 RAW images)
2 GB SanDisk Ultra II Type I	4,039 KB/sec
4 GB Lexar Pro 40x Type II	3,045 KB/sec
1 GB IBM Microdrive Type II	1,652 KB/sec
1 GB Viking Type I	982 KB/sec

Battery life

The EN-EL3 Lithium-Ion battery in the D70 has a capacity of 1400 mAh at 7.4 V (10.3 Wh), in our experience the battery lasted well and we never found ourselves with even a low battery warning after a decent shooting session (several hours). Note that the D70 can also be powered by three CR2 type Lithium (non-rechargeable) batteries using the supplied battery cradle.

Nikon state battery life as the following (taken from the D70 manual):

Example 1

Zoom Nikkor AF-S DX 18–70 mm f/3.5–4.5G IF ED lens; continuous shooting mode; continuous-servo autofocus; image quality set to JPEG Basic; image size set to M; shutter speed 1/250 sec; shutter-release pressed half way for three seconds and focus cycled from infinity to minimum range three times with each shot; after six shots, monitor turned on for five seconds and then turned off; cycle repeated once exposure meters have turned off.

Number of shots (EN-EL3): 2000
Number of shots (CR2): 560

Example 2

AF-S DX 18–70 mm f/3.5–5.6G IF ED lens; single-frame shooting mode; single-servo autofocus; image quality set to JPEG Normal; image size set to L; shutter speed 1/250 sec; shutter-release pressed half way for five seconds and focus cycled from infinity to minimum range once with each shot; built-in Speedlight fired at full power with every other shot; AF-assist illuminator lights when Speedlight is used; cycle repeated once exposure meters have turned off; camera turned off for one second with every ten shots.

Number of shots (EN-EL3): 400
Number of shots (CR2): 160