Nikon D100 vs Sony A99

The Nikon D100 and the Sony Alpha SLT-A99 are two digital cameras that were announced, respectively, in February 2002 and September 2012. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (D100) and a full frame (A99) sensor. The Nikon has a resolution of 6 megapixels, whereas the Sony provides 24 MP.

Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Headline Specifications

Nikon D100		Sony A99
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Sony A mount lenses
6 MP – APS-C sensor		24 MP – Full Frame sensor
no Video		1080/60p Video
ISO 200-800 (200 - 1,600)		ISO 100-25,600
Optical viewfinder		Electronic viewfinder (2359k dots)
1.8" LCD – 118k dots		3.0" LCD – 1229k dots
Fixed screen (not touch-sensitive)		Fully flexible screen (no touchscreen)
3 shutter flaps per second		6 shutter flaps per second
Lens stabilization only		In-body stabilization
not weather sealed		Weathersealed body
370 shots per battery charge		500 shots per battery charge
144 x 116 x 81 mm, 780 g		147 x 111 x 78 mm, 812 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D100 and the Sony Alpha SLT-A99? Which one should you buy? Read on to find out how these two cameras compare with respect to their body size, their imaging sensors, their shooting features, their input-output connections, and their reception by expert reviewers.

Body comparison

The physical size and weight of the Nikon D100 and the Sony A99 are illustrated in the side-by-side display below. The two cameras are presented according to their relative size. Three consecutive perspectives from the front, the top, and the back are available. All width, height and depth measures are rounded to the nearest millimeter.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A99 is somewhat smaller (2 percent) than the Nikon D100. However, the A99 is slightly heavier (4 percent) than the D100. It is noteworthy in this context that the A99 is splash and dust-proof, while the D100 does not feature any corresponding weather-sealing.

The above size and weight comparisons are to some extent incomplete since they do not consider the interchangeable lenses that both of these cameras require. Hence, you might want to study and compare the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.

Concerning battery life, the D100 gets 370 shots out of its Nikon EN-EL3 battery, while the A99 can take 500 images on a single charge of its Sony NP-FM500H power pack.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price (USD)	Street Price
1.		Nikon D100	144 mm	116 mm	81 mm	780 g	370	n	Feb 2002	1,999	ebay.com
2.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	2,799	ebay.com
3.		Canon 10D	150 mm	107 mm	75 mm	850 g	500	n	Feb 2003	1,999	ebay.com
4.		Nikon D1X	157 mm	153 mm	85 mm	1100 g	1200	Y	Feb 2001	5,999	ebay.com
5.		Nikon D40	124 mm	94 mm	64 mm	522 g	470	n	Nov 2006	499	ebay.com
6.		Nikon D50	133 mm	102 mm	76 mm	620 g	400	n	Apr 2005	749	ebay.com
7.		Nikon D70	140 mm	111 mm	78 mm	679 g	400	n	Jan 2004	999	ebay.com
8.		Nikon D70s	140 mm	111 mm	78 mm	679 g	500	n	Apr 2005	899	ebay.com
9.		Nikon D80	132 mm	103 mm	77 mm	668 g	600	n	Aug 2006	999	ebay.com
10.		Nikon D90	132 mm	103 mm	77 mm	703 g	850	n	Aug 2008	1,299	ebay.com
11.		Nikon D200	147 mm	113 mm	74 mm	920 g	400	Y	Nov 2005	1,699	ebay.com
12.		Nikon D300	147 mm	114 mm	74 mm	925 g	1000	Y	Aug 2007	1,799	ebay.com
13.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
14.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	1,399	ebay.com
15.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	3,199	ebay.com
16.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	1,999	ebay.com
17.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	2,999	ebay.com
Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.
Convert to Imperial

Any camera decision will obviously take relative prices into account. The retail prices at the time of the camera’s release place the model in the market relative to other models in the producer’s line-up and the competition. The D100 was launched at a markedly lower price (by 29 percent) than the A99, which puts it into a different market segment. Usually, retail prices stay at first close to the launch price, but after several months, discounts become available. Later in the product cycle and, in particular, when the replacement model is about to appear, further discounting and stock clearance sales often push the camera price considerably down. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.

Sensor comparison

The size of the imaging sensor is a crucial determinant of image quality. A large sensor will tend to have larger individual pixels that provide better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixel-units in a sensor of the same technological generation. Moreover, a large sensor camera will give the photographer more control over depth-of-field in the image and, thus, the ability to better isolate a subject from the background. On the downside, larger sensors tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Nikon D100 features an APS-C sensor and the Sony A99 a full frame sensor. The sensor area in the A99 is 130 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 24MP, the A99 offers a higher resolution than the D100 (6MP), but the A99 has smaller individual pixels (pixel pitch of 5.96μm versus 7.85μm for the D100). Yet, the A99 is a much more recent model (by 10 years and 6 months) than the D100, and its sensor will have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units.

The resolution advantage of the Sony A99 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A99 for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Nikon D100 are 15 x 10 inches or 38.2 x 25.4 cm for good quality, 12 x 8 inches or 30.6 x 20.3 cm for very good quality, and 10 x 6.7 inches or 25.5 x 16.9 cm for excellent quality prints.

The Nikon D100 has a native sensitivity range from ISO 200 to ISO 800, which can be extended to ISO 200-1600. The corresponding ISO settings for the Sony Alpha SLT-A99 are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-25600.

In terms of underlying technology, the D100 is build around a CCD sensor, while the A99 uses a CMOS imager. Both cameras use a Bayer filter for capturing RGB colors on a square grid of photosensors. This arrangement is found in most digital cameras.

For many cameras, data on sensor performance has been reported by DXO Mark. This service is based on lab testing and assigns an overall score to each camera sensor, as well as ratings for dynamic range ("DXO Landscape"), color depth ("DXO Portrait"), and low-light sensitivity ("DXO Sports"). The table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.

Sensor Characteristics

		Camera Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Nikon D100	APS-C	6.0	3008	2000	none	20.4	9.9	394	48
2.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
3.		Canon 10D	APS-C	6.3	3072	2048	none	21.1	10.9	571	57
4.		Nikon D1X	APS-C	5.9	3008	1960	none	..	..	..	..
5.		Nikon D40	APS-C	6.0	3008	2000	none	21.0	11.0	561	56
6.		Nikon D50	APS-C	6.0	3008	2000	none	20.9	10.8	560	55
7.		Nikon D70	APS-C	6.0	3008	2000	none	20.4	10.3	529	50
8.		Nikon D70s	APS-C	6.0	3008	2000	none	20.4	10.3	529	50
9.		Nikon D80	APS-C	10.0	3872	2592	none	22.1	11.2	524	61
10.		Nikon D90	APS-C	12.2	4288	2848	720/24p	22.7	12.5	977	73
11.		Nikon D200	APS-C	10.0	3872	2592	none	22.3	11.5	583	64
12.		Nikon D300	APS-C	12.2	4288	2848	none	22.1	12.0	679	67
13.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
14.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
15.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
16.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
17.		Sony A900	Full Frame	24.4	6048	4032	none	23.7	12.3	1431	79
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras are not only capable of taking still images, but can also record movies. The A99 indeed provides for movie recording, while the D100 does not. The highest resolution format that the A99 can use is 1080/60p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A99 has an electronic viewfinder (2359k dots), while the D100 has an optical one. Both systems have their advantages, with the electronic viewfinder making it possible to project supplementary shooting information into the framing view, whereas the optical viewfinder offers lag-free viewing and a very clear framing image. The viewfinder in the A99 offers a wider field of view (100%) than the one in the D100 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the A99 has a higher magnification (0.71x vs 0.53x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Nikon D100 and Sony A99 in connection with corresponding information for a sample of similar cameras.

Core Features

		Camera Model	Viewfinder (Type or 000 dots)	Control Panel (yes/no)	LCD Specifications (inch/000 dots)	LCD Attach- ment	Touch Screen (yes/no)	Max Shutter Speed *	Max Shutter Flaps *	Built-in Flash (yes/no)	Built-in Image Stab
1.		Nikon D100	optical	Y	1.8 / 118	fixed	n	1/4000s	3.0/s	Y	n
2.		Sony A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/s	n	Y
3.		Canon 10D	optical	Y	1.8 / 118	fixed	n	1/4000s	3.0/s	Y	n
4.		Nikon D1X	optical	Y	2.0 / 120	fixed	n	1/16000s	3.0/s	n	n
5.		Nikon D40	optical	n	2.5 / 230	fixed	n	1/4000s	2.5/s	Y	n
6.		Nikon D50	optical	n	2.0 / 130	fixed	n	1/4000s	2.5/s	Y	n
7.		Nikon D70	optical	n	1.8 / 130	fixed	n	1/8000s	3.0/s	Y	n
8.		Nikon D70s	optical	n	2.0 / 130	fixed	n	1/8000s	3.0/s	Y	n
9.		Nikon D80	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
10.		Nikon D90	optical	Y	3.0 / 920	fixed	n	1/4000s	4.5/s	Y	n
11.		Nikon D200	optical	Y	2.5 / 230	fixed	n	1/8000s	5.0/s	Y	n
12.		Nikon D300	optical	Y	3.0 / 922	fixed	n	1/8000s	6.0/s	Y	n
13.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
14.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
15.		Sony A99 II	2400	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	n	Y
16.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
17.		Sony A900	optical	Y	3.0 / 922	fixed	n	1/8000s	5.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One difference between the cameras concerns the presence of an on-board flash. The D100 has one, while the A99 does not. While the built-in flash of the D100 is not very powerful, it can at times be useful as a fill-in light.

The D100 writes its imaging data to Compact Flash cards, while the A99 uses SDXC or Memory Stick PRO Duo cards. The A99 features dual card slots, which can be very useful in case a memory card fails. In contrast, the D100 only has one slot.

Connectivity comparison

For some imaging applications, the extent to which a camera can communicate with its environment can be an important aspect in the camera decision process. The table below provides an overview of the connectivity of the Nikon D100 and Sony Alpha SLT-A99 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.

Input-Output Connections

		Camera Model	Hotshoe Port	Internal Mic / Speaker	Microphone Port	Headphone Port	HDMI Port	USB Port	WiFi Support	NFC Support	Bluetooth Support
1.		Nikon D100	Y	- / -	-	-	-	1.1	-	-	-
2.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
3.		Canon 10D	Y	- / -	-	-	-	1.1	-	-	-
4.		Nikon D1X	Y	- / -	-	-	-	FW	-	-	-
5.		Nikon D40	Y	- / -	-	-	-	2.0	-	-	-
6.		Nikon D50	Y	- / -	-	-	-	2.0	-	-	-
7.		Nikon D70	Y	- / -	-	-	-	1.0	-	-	-
8.		Nikon D70s	Y	- / -	-	-	-	2.0	-	-	-
9.		Nikon D80	Y	- / -	-	-	-	2.0	-	-	-
10.		Nikon D90	Y	mono / mono	-	-	mini	2.0	-	-	-
11.		Nikon D200	Y	- / -	-	-	-	2.0	-	-	-
12.		Nikon D300	Y	- / -	-	-	mini	2.0	-	-	-
13.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
14.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
15.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
16.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-
17.		Sony A900	Y	- / -	-	-	mini	2.0	-	-	-

Studio photographers will appreciate that the Sony A99 (unlike the D100) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Travel and landscape photographers will find it useful that the A99 has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.

Both the D100 and the A99 have been discontinued, but can regularly be found used on ebay. The D100 was replaced by the Nikon D200, while the A99 was followed by the Sony A99. Further information on the features and operation of the D100 and A99 can be found, respectively, in the Nikon D100 Manual (free pdf) or the online Sony A99 Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Nikon D100 or the Sony A99 – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.

Reasons to prefer the Nikon D100:

• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (29 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in February 2002).

Advantages of the Sony Alpha SLT-A99:

• More detail: Has more megapixels (24 vs 6MP), which boosts linear resolution by 100%.
• Better image quality: Is equipped with a larger and more technologically advanced sensor.
• Richer colors: The sensor size advantage translates into images with better, more accurate colors.
• More dynamic range: Larger sensor captures a wider spectrum of light and dark details.
• Better low-light sensitivity: Larger sensor produces good images even in poorly lit environments.
• Broader imaging potential: Can capture not only stills but also 1080/60p video.
• More framing info: Has an electronic viewfinder that displays shooting data.
• More complete view: Has a viewfinder with a larger field of view (100% vs 95%).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.71x vs 0.53x).
• Larger screen: Has a bigger rear LCD (3.0" vs 1.8") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (1229k vs 118k dots).
• More flexible LCD: Has a full-flex screen for odd-angle shots in portrait or landscape orientation.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (6 vs 3 flaps/sec) to capture the decisive moment.
• Longer lasting: Gets more shots (500 versus 370) out of a single battery charge.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• Faster data transfer: Supports a more advanced USB protocol (2.0 vs 1.1).
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• More modern: Reflects 10 years and 6 months of technical progress since the D100 launch.

If the count of relative strengths (bullet points above) is taken as a measure, the A99 is the clear winner of the contest (23 : 4 points). However, the relative importance of the various individual camera aspects will vary according to personal preferences and needs, so that you might like to apply corresponding weights to the particular features before making a decision on a new camera. A professional wildlife photographer will view the differences between cameras in a way that diverges from the perspective of a family photog, and a person interested in architecture has distinct needs from a sports shooter. Hence, the decision which camera is best and worth buying is often a very personal one.

How about other alternatives? Do the specifications of the Nikon D100 and the Sony A99 place the cameras among the top in their class? Find out in the latest Best DSLR Camera listing whether the two cameras rank among the cream of the crop.

In any case, while the comparison of technical specifications can provide a useful overview of the capabilities of different cameras, it remains incomplete and does no justice, for example, to the way the D100 or the A99 perform in practice. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.

Expert reviews

This is where reviews by experts come in. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], digitalcameraworld [DCW], dpreview [DPR], ephotozine [EPZ], photographyblog [PB]). As can be seen, the professional reviewers agree in many cases on the quality of different cameras, but sometimes their assessments diverge, reinforcing the earlier point that a camera decision is often a very personal choice.

Expert Camera Reviews

		Camera   Model	AP   score	CL   score	DCW   score	DPR   score	EPZ   score	PB   score	Camera Launch	Launch Price (USD)	Street Price
1.		Nikon D100	..	..	..	+ +	o	..	Feb 2002	1,999	ebay.com
2.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	2,799	ebay.com
3.		Canon 10D	..	..	..	+ +	..	..	Feb 2003	1,999	ebay.com
4.		Nikon D1X	..	..	..	+ +	..	..	Feb 2001	5,999	ebay.com
5.		Nikon D40	..	81/100	..	+ +	o	4.5/5	Nov 2006	499	ebay.com
6.		Nikon D50	..	78/100	..	+ +	4/5	4.5/5	Apr 2005	749	ebay.com
7.		Nikon D70	..	..	..	+ +	..	..	Jan 2004	999	ebay.com
8.		Nikon D70s	..	..	..	..	..	5/5	Apr 2005	899	ebay.com
9.		Nikon D80	..	+	..	+ +	o	4.5/5	Aug 2006	999	ebay.com
10.		Nikon D90	..	+ +	..	+ +	4/5	4.5/5	Aug 2008	1,299	ebay.com
11.		Nikon D200	..	+ +	..	+ +	o	..	Nov 2005	1,699	ebay.com
12.		Nikon D300	..	+ +	..	+ +	5/5	4.5/5	Aug 2007	1,799	ebay.com
13.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
14.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	1,399	ebay.com
15.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	3,199	ebay.com
16.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	1,999	ebay.com
17.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	2,999	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. Also, please note that some of the review sites have changed their methodology and reporting over time.

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Other camera comparisons

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