Nikon D40X vs Sony A99

The Nikon D40X and the Sony Alpha SLT-A99 are two digital cameras that were revealed to the public, respectively, in March 2007 and September 2012. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (D40X) and a full frame (A99) sensor. The Nikon has a resolution of 10 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 D40X		Sony A99
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Sony A mount lenses
10 MP – APS-C sensor		24 MP – Full Frame sensor
no Video		1080/60p Video
ISO 100-1,600 (100 - 3,200)		ISO 100-25,600
Optical viewfinder		Electronic viewfinder (2359k dots)
2.5" LCD – 230k 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
520 shots per battery charge		500 shots per battery charge
124 x 94 x 64 mm, 522 g		147 x 111 x 78 mm, 812 g

Check D40X offers at
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Check A99 offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D40X 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 side-by-side display below illustrates the physical size and weight of the Nikon D40X and the Sony A99. The two cameras are presented according to their relative size. Three consecutive views from the front, the top, and the rear side are shown. All width, height and depth dimensions are rounded to the nearest millimeter.

The D40X can be obtained in two different colors (black, silver), while the A99 is only available in black.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A99 is notably larger (40 percent) than the Nikon D40X. Moreover, the A99 is substantially heavier (56 percent) than the D40X. It is noteworthy in this context that the A99 is splash and dust-proof, while the D40X 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 D40X gets 520 shots out of its Nikon EN-EL9 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. In case you want to display and compare another camera duo, you can use the CAM-parator app to select your camera combination among a large number of options.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price	Street Price
1.		Nikon D40X	124 mm	94 mm	64 mm	522 g	520	n	Mar 2007	EUR 699	ebay.com
2.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	EUR 2 799	ebay.com
3.		Canon 400D	127 mm	84 mm	65 mm	556 g	370	n	Aug 2006	EUR 799	ebay.com
4.		Canon 450D	129 mm	98 mm	62 mm	524 g	500	n	Jan 2008	EUR 699	ebay.com
5.		Nikon D40	124 mm	94 mm	64 mm	522 g	470	n	Nov 2006	EUR 499	ebay.com
6.		Nikon D60	126 mm	94 mm	64 mm	522 g	500	n	Jan 2008	EUR 499	ebay.com
7.		Nikon D90	132 mm	103 mm	77 mm	703 g	850	n	Aug 2008	EUR 1 189	ebay.com
8.		Nikon D3000	126 mm	97 mm	64 mm	536 g	500	n	Jul 2009	EUR 539	ebay.com
9.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	EUR 549	ebay.com
10.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	EUR 699	ebay.com
11.		Olympus E-420	130 mm	91 mm	53 mm	440 g	500	n	Mar 2008	EUR 499	ebay.com
12.		Panasonic L10	135 mm	96 mm	78 mm	556 g	450	n	Aug 2007	EUR 599	ebay.com
13.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	EUR 5 299	ebay.com
14.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	EUR 1 299	ebay.com
15.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	EUR 3 599	ebay.com
16.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	EUR 1 999	ebay.com
17.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	EUR 2 799	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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The D40X was launched at a markedly lower price (by 74 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.

Sensor comparison

The size of the sensor inside a digital camera is one of the key determinants of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels in a sensor of the same technological generation. Further, a large sensor camera will give the photographer additional creative options when using shallow depth-of-field to isolate a subject from its background. On the downside, larger sensors are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Nikon D40X features an APS-C sensor and the Sony A99 a full frame sensor. The sensor area in the A99 is 128 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 D40X (10MP), but the A99 has smaller individual pixels (pixel pitch of 5.96μm versus 6.11μm for the D40X). Yet, the A99 is a much more recent model (by 5 years and 6 months) than the D40X, 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 D40X are 19.4 x 13 inches or 49.2 x 32.9 cm for good quality, 15.5 x 10.4 inches or 39.3 x 26.3 cm for very good quality, and 12.9 x 8.6 inches or 32.8 x 21.9 cm for excellent quality prints.

The Nikon D40X has a native sensitivity range from ISO 100 to ISO 1600, which can be extended to ISO 100-3200. 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 D40X 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 assesses and scores the color depth ("DXO Portrait"), dynamic range ("DXO Landscape"), and low-light sensitivity ("DXO Sports") of camera sensors, and also publishes an overall camera score. Of the two cameras under consideration, the A99 offers substantially better image quality than the D40X (overall score 26 points higher). The advantage is based on 2.6 bits higher color depth, 2.6 EV in additional dynamic range, and 1.6 stops in additional low light sensitivity. The adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-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 D40X	APS-C	10.0	3872	2592	none	22.4	11.4	516	63
2.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
3.		Canon 400D	APS-C	10.1	3888	2592	none	22.1	11.0	664	62
4.		Canon 450D	APS-C	12.2	4272	2848	none	21.9	10.8	692	61
5.		Nikon D40	APS-C	6.0	3008	2000	none	21.0	11.0	561	56
6.		Nikon D60	APS-C	10.0	3872	2592	none	22.5	11.4	562	65
7.		Nikon D90	APS-C	12.2	4288	2848	720/24p	22.7	12.5	977	73
8.		Nikon D3000	APS-C	10.0	3872	2592	none	22.3	11.1	563	62
9.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
10.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
11.		Olympus E-420	Four Thirds	10.0	3648	2736	none	21.5	10.4	527	56
12.		Panasonic L10	Four Thirds	10.0	3648	2736	none	21.3	10.8	429	55
13.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
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

Many modern cameras cannot only take still pictures, but also record videos. The A99 indeed provides for movie recording, while the D40X 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 range of features. For example, the A99 has an electronic viewfinder (2359k dots), while the D40X 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 D40X (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 adjacent table lists some of the other core features of the Nikon D40X and Sony A99 along with similar information for a selection of comparators.

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 D40X	optical	n	2.5 / 230	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 400D	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
4.		Canon 450D	optical	n	3.0 / 230	fixed	n	1/4000s	3.5/s	Y	n
5.		Nikon D40	optical	n	2.5 / 230	fixed	n	1/4000s	2.5/s	Y	n
6.		Nikon D60	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
7.		Nikon D90	optical	Y	3.0 / 920	fixed	n	1/4000s	4.5/s	Y	n
8.		Nikon D3000	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
9.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
10.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
11.		Olympus E-420	optical	n	2.7 / 215	fixed	n	1/4000s	3.5/s	Y	n
12.		Panasonic L10	optical	n	2.5 / 207	swivel	n	1/4000s	3.0/s	Y	n
13.		Sony A9	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 D40X has one, while the A99 does not. While the built-in flash of the D40X is not very powerful, it can at times be useful as a fill-in light.

The D40X writes its imaging data to SDHC 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 D40X only has one slot. The A99 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the D40X cannot take advantage of Ultra High Speed SD cards.

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 D40X 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 D40X	Y	- / -	-	-	-	2.0	-	-	-
2.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
3.		Canon 400D	Y	- / -	-	-	-	2.0	-	-	-
4.		Canon 450D	Y	- / -	-	-	mini	2.0	-	-	-
5.		Nikon D40	Y	- / -	-	-	-	2.0	-	-	-
6.		Nikon D60	Y	- / -	-	-	-	2.0	-	-	-
7.		Nikon D90	Y	mono / mono	-	-	mini	2.0	-	-	-
8.		Nikon D3000	Y	- / -	-	-	-	2.0	-	-	-
9.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
10.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
11.		Olympus E-420	Y	- / -	-	-	-	2.0	-	-	-
12.		Panasonic L10	Y	- / -	-	-	-	2.0	-	-	-
13.		Sony A9	Y	stereo / mono	Y	Y	micro	2.0	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 D40X) 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 D40X and the A99 have been discontinued, but can regularly be found used on ebay. The D40X was replaced by the Nikon D60 , while the A99 was followed by the Sony A99. Further information on the features and operation of the D40X and A99 can be found, respectively, in the Nikon D40X Manual (free pdf) or the online Sony A99 Manual.

Review summary

So what conclusions can be drawn? Is the Nikon D40X better than the Sony A99 or vice versa? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Nikon D40X:

• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• More compact: Is smaller (124x94mm vs 147x111mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 290g or 36 percent) and hence easier to carry around.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (74 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in March 2007).

Advantages of the Sony Alpha SLT-A99:

• More detail: Has more megapixels (24 vs 10MP), which boosts linear resolution by 55%.
• Better image quality: Scores substantially higher (26 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.6 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (2.6 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (1.6 stops ISO advantage).
• 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).
• Easier setting verification: Features a control panel on top to check shooting parameters.
• Larger screen: Has a bigger rear LCD (3.0" vs 2.5") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (1229k vs 230k 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.
• 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.
• 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.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Reflects 5 years and 6 months of technical progress since the D40X launch.

If the number of relative strengths (bullet points above) is taken as a guide, the A99 is the clear winner of the contest (23 : 6 points). However, the pertinence of the various camera strengths will differ across photographers, so that you might want to weigh individual camera traits according to their importance for your own imaging needs before making a camera decision. 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 D40X 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 the spec-sheets of cameras can offer a general idea of their imaging potential, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the D40X or the A99. At times, user reviews, such as those published at amazon, address these issues in a useful manner, but such feedback is on many occasions incomplete, inconsistent, and unreliable.

Expert reviews

This is why hands-on reviews by experts are important. The table below provides a synthesis of the camera assessments of some of the best known photo-gear 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	Street Price
1.		Nikon D40X	..	79/100	..	+ +	4/5	4/5	Mar 2007	EUR 699	ebay.com
2.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	EUR 2 799	ebay.com
3.		Canon 400D	..	+ +	..	+ +	o	4/5	Aug 2006	EUR 799	ebay.com
4.		Canon 450D	..	+ +	..	+ +	4/5	4.5/5	Jan 2008	EUR 699	ebay.com
5.		Nikon D40	..	81/100	..	+ +	o	4.5/5	Nov 2006	EUR 499	ebay.com
6.		Nikon D60	..	80/100	..	+ +	4/5	4.5/5	Jan 2008	EUR 499	ebay.com
7.		Nikon D90	..	+ +	..	+ +	4/5	4.5/5	Aug 2008	EUR 1 189	ebay.com
8.		Nikon D3000	..	+	..	72/100	4/5	4.5/5	Jul 2009	EUR 539	ebay.com
9.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	EUR 549	ebay.com
10.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	EUR 699	ebay.com
11.		Olympus E-420	..	85/100	..	+ +	4/5	4.5/5	Mar 2008	EUR 499	ebay.com
12.		Panasonic L10	..	85/100	..	+	3.5/5	4/5	Aug 2007	EUR 599	ebay.com
13.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	EUR 5 299	ebay.com
14.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	EUR 1 299	ebay.com
15.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	EUR 3 599	ebay.com
16.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	EUR 1 999	ebay.com
17.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	EUR 2 799	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The assessments were made in relation to similar cameras of the same technological generation. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparisons of ratings among very different cameras or across long time periods have little meaning. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

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Other camera comparisons

Did this review help to inform your camera decision process? If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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