Nikon D40 vs Pentax K-S1

The Nikon D40 and the Pentax K-S1 are two digital cameras that were announced, respectively, in November 2006 and August 2014. Both are DSLR (Digital Single Lens Reflex) cameras that are equipped with an APS-C sensor. The Nikon has a resolution of 6 megapixels, whereas the Pentax provides 20 MP.

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

Headline Specifications

Nikon D40		Pentax K-S1
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Pentax K mount lenses
6 MP – APS-C sensor		20 MP – APS-C sensor
no Video		1080/30p Video
ISO 200-1,600 (200 - 3,200)		ISO 100-51,200
Optical viewfinder		Optical viewfinder
2.5" LCD – 230k dots		3.0" LCD – 921k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
2.5 shutter flaps per second		5.4 shutter flaps per second
Lens stabilization only		In-body stabilization
470 shots per battery charge		410 shots per battery charge
124 x 94 x 64 mm, 522 g		121 x 93 x 70 mm, 558 g

Check D40 offers at
ebay.com
Check K-S1 offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D40 and the Pentax K-S1? 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 D40 and the Pentax K-S1. 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 size dimensions are rounded to the nearest millimeter.

The K-S1 can be obtained in four different colors (black, grey, orange, white), while the D40 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 Pentax K-S1 is somewhat smaller (3 percent) than the Nikon D40. However, the K-S1 is markedly heavier (7 percent) than the D40. In this context, it is worth noting that neither the D40 nor the K-S1 are weather-sealed.

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 D40 gets 470 shots out of its Nikon EN-EL9 battery, while the K-S1 can take 410 images on a single charge of its Pentax D-LI109 power pack.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price	Street Price
1.		Nikon D40	124 mm	94 mm	64 mm	522 g	470	n	Nov 2006	US$ 499	ebay.com
2.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	US$ 749	ebay.com
3.		Nikon D40X	124 mm	94 mm	64 mm	522 g	520	n	Mar 2007	US$ 729	ebay.com
4.		Nikon D50	133 mm	102 mm	76 mm	620 g	400	n	Apr 2005	US$ 749	ebay.com
5.		Nikon D70s	140 mm	111 mm	78 mm	679 g	500	n	Apr 2005	US$ 899	ebay.com
6.		Nikon D80	132 mm	103 mm	77 mm	668 g	600	n	Aug 2006	US$ 999	ebay.com
7.		Nikon D3000	126 mm	97 mm	64 mm	536 g	500	n	Jul 2009	US$ 599	ebay.com
8.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	US$ 599	ebay.com
9.		Nikon D3200	125 mm	96 mm	77 mm	505 g	540	n	Apr 2012	US$ 599	ebay.com
10.		Nikon D3300	124 mm	98 mm	76 mm	430 g	700	n	Jan 2014	US$ 499	ebay.com
11.		Nikon D3400	124 mm	98 mm	76 mm	445 g	1200	n	Aug 2016	US$ 499	ebay.com
12.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	US$ 799	ebay.com
13.		Panasonic L10	135 mm	96 mm	78 mm	556 g	450	n	Aug 2007	US$ 599	ebay.com
14.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	US$ 1 299	ebay.com
15.		Pentax K-500	130 mm	97 mm	71 mm	646 g	710	n	Jun 2013	US$ 549	ebay.com
16.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	US$ 749	ebay.com
17.		Sony A68	143 mm	104 mm	81 mm	610 g	540	n	Nov 2015	US$ 699	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 manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The D40 was launched at a markedly lower price (by 33 percent) than the K-S1, 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. All other things equal, a large sensor will have larger individual pixel-units that offer better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixels in a sensor of the same technological generation. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to isolate a subject from the background. On the downside, larger sensors are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Both cameras under consideration feature an APS-C sensor, but their sensors differ slightly in size. The sensor area in the K-S1 is 1 percent smaller. They nevertheless have the same format factor of 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Despite having a slightly smaller sensor, the K-S1 offers a higher resolution of 20 megapixels, compared with 6 MP of the D40. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 4.28μm versus 7.85μm for the D40). However, it should be noted that the K-S1 is much more recent (by 7 years and 9 months) than the D40, and its sensor will have benefitted from technological advances during this time that make it possible to gather light more efficiently. Coming back to sensor resolution, it should be mentioned that the K-S1 has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Pentax K-S1 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the K-S1 for good quality output (200 dots per inch) amounts to 27.4 x 18.2 inches or 69.5 x 46.3 cm, for very good quality (250 dpi) 21.9 x 14.6 inches or 55.6 x 37.1 cm, and for excellent quality (300 dpi) 18.2 x 12.2 inches or 46.3 x 30.9 cm. The corresponding values for the Nikon D40 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 D40 has a native sensitivity range from ISO 200 to ISO 1600, which can be extended to ISO 200-3200. The corresponding ISO settings for the Pentax K-S1 are ISO 100 to ISO 51200 (no boost).

In terms of underlying technology, the D40 is build around a CCD sensor, while the K-S1 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. This service determines an overall sensor rating, as well as sub-scores for low-light sensitivity ("DXO Sports"), dynamic range ("DXO Landscape"), and color depth ("DXO Portrait"). Of the two cameras under consideration, the K-S1 offers substantially better image quality than the D40 (overall score 22 points higher). The advantage is based on 2.5 bits higher color depth, 2 EV in additional dynamic range, and 0.9 stops in additional low light sensitivity. 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 D40	APS-C	6.0	3008	2000	none	21.0	11.0	561	56
2.		Pentax K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
3.		Nikon D40X	APS-C	10.0	3872	2592	none	22.4	11.4	516	63
4.		Nikon D50	APS-C	6.0	3008	2000	none	20.9	10.8	560	55
5.		Nikon D70s	APS-C	6.0	3008	2000	none	20.4	10.3	529	50
6.		Nikon D80	APS-C	10.0	3872	2592	none	22.1	11.2	524	61
7.		Nikon D3000	APS-C	10.0	3872	2592	none	22.3	11.1	563	62
8.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
9.		Nikon D3200	APS-C	24.1	6016	4000	1080/30p	24.1	13.2	1131	81
10.		Nikon D3300	APS-C	24.0	6000	4000	1080/60p	24.3	12.8	1385	82
11.		Nikon D3400	APS-C	24.0	6000	4000	1080/60p	24.8	13.9	1192	86
12.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
13.		Panasonic L10	Four Thirds	10.0	3648	2736	none	21.3	10.8	429	55
14.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
15.		Pentax K-500	APS-C	16.1	4928	3264	1080/30p	23.7	13.1	1087	79
16.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
17.		Sony A68	APS-C	24.0	6000	4000	1080/60i	24.1	13.5	701	79
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras cannot only take still pictures, but also record videos. The K-S1 indeed provides for movie recording, while the D40 does not. The highest resolution format that the K-S1 can use is 1080/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. The D40 and the K-S1 are similar in the sense that both have an optical viewfinder. The latter is useful for getting a clear image for framing even in brightly lit environments. The viewfinder in the K-S1 offers a wider field of view (100%) than the one in the D40 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the K-S1 has a higher magnification (0.63x 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 D40 and Pentax K-S1 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 D40	optical	n	2.5 / 230	fixed	n	1/4000s	2.5/s	Y	n
2.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
3.		Nikon D40X	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
4.		Nikon D50	optical	n	2.0 / 130	fixed	n	1/4000s	2.5/s	Y	n
5.		Nikon D70s	optical	n	2.0 / 130	fixed	n	1/8000s	3.0/s	Y	n
6.		Nikon D80	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
7.		Nikon D3000	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
8.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
9.		Nikon D3200	optical	n	3.0 / 921	fixed	n	1/4000s	4.0/s	Y	n
10.		Nikon D3300	optical	n	3.0 / 921	fixed	n	1/4000s	5.0/s	Y	n
11.		Nikon D3400	optical	n	3.0 / 921	fixed	n	1/4000s	5.0/s	Y	n
12.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
13.		Panasonic L10	optical	n	2.5 / 207	swivel	n	1/4000s	3.0/s	Y	n
14.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
15.		Pentax K-500	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
16.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
17.		Sony A68	1440	Y	2.7 / 460	tilting	n	1/4000s	8.0/s	Y	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the K-S1 and the D40 is in-body image stabilization (IBIS). The K-S1 reduces the risk of handshake-induced blur with all attached lenses, while the D40 offers no blur reduction with lenses that themselves do not provide optical image stabilization.

The D40 writes its imaging data to SDHC cards, while the K-S1 uses SDXC cards. The K-S1 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the D40 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 D40 and Pentax K-S1 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 D40	Y	- / -	-	-	-	2.0	-	-	-
2.		Pentax K-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
3.		Nikon D40X	Y	- / -	-	-	-	2.0	-	-	-
4.		Nikon D50	Y	- / -	-	-	-	2.0	-	-	-
5.		Nikon D70s	Y	- / -	-	-	-	2.0	-	-	-
6.		Nikon D80	Y	- / -	-	-	-	2.0	-	-	-
7.		Nikon D3000	Y	- / -	-	-	-	2.0	-	-	-
8.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
9.		Nikon D3200	Y	mono / mono	Y	-	mini	2.0	-	-	-
10.		Nikon D3300	Y	mono / mono	Y	-	mini	2.0	-	-	-
11.		Nikon D3400	Y	mono / mono	-	-	mini	2.0	-	-	Y
12.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
13.		Panasonic L10	Y	- / -	-	-	-	2.0	-	-	-
14.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
15.		Pentax K-500	Y	mono / mono	-	-	-	2.0	-	-	-
16.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
17.		Sony A68	Y	stereo / mono	Y	-	micro	2.0	-	-	-

Both the D40 and the K-S1 have been discontinued, but can regularly be found used on ebay. The D40 was replaced by the Nikon D40X, while the K-S1 was followed by the Pentax K-S2. Further information on the features and operation of the D40 and K-S1 can be found, respectively, in the Nikon D40 Manual (free pdf) or the online Pentax K-S1 Manual.

Review summary

So what is the bottom line? Is the Nikon D40 better than the Pentax K-S1 or vice versa? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the Nikon D40:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Longer lasting: Can take more shots (470 versus 410) on a single battery charge.
• More affordable: Was introduced into a lower priced category (33 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in November 2006).

Arguments in favor of the Pentax K-S1:

• More detail: Has more megapixels (20 vs 6MP), which boosts linear resolution by 82%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores substantially higher (22 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.5 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (2 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (0.9 stops ISO advantage).
• Broader imaging potential: Can capture not only stills but also 1080/30p video.
• 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 (0.63x vs 0.53x).
• 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 (921k vs 230k dots).
• Faster shutter: Has higher mechanical shutter speed (1/6000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (5.4 vs 2.5 flaps/sec) to capture the decisive moment.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Reflects 7 years and 9 months of technical progress since the D40 launch.

If the count of individual advantages (bullet points above) is taken as a guide, the K-S1 is the clear winner of the contest (16 : 4 points). However, the relevance of individual strengths will vary across photographers, so that you might want to apply your own weighing scheme to the summary points when reflecting and deciding on a new camera. A professional wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro 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 D40 and the Pentax K-S1 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 says little about, for example, the shooting experience and imaging performance of the D40 and the K-S1 in practical situations. 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 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	Street Price
1.		Nikon D40	..	81/100	..	+ +	o	4.5/5	Nov 2006	US$ 499	ebay.com
2.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	US$ 749	ebay.com
3.		Nikon D40X	..	79/100	..	+ +	4/5	4/5	Mar 2007	US$ 729	ebay.com
4.		Nikon D50	..	78/100	..	+ +	4/5	4.5/5	Apr 2005	US$ 749	ebay.com
5.		Nikon D70s	..	..	..	..	..	5/5	Apr 2005	US$ 899	ebay.com
6.		Nikon D80	..	+	..	+ +	o	4.5/5	Aug 2006	US$ 999	ebay.com
7.		Nikon D3000	..	+	..	72/100	4/5	4.5/5	Jul 2009	US$ 599	ebay.com
8.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	US$ 599	ebay.com
9.		Nikon D3200	5/5	+ +	..	73/100	4.5/5	4.5/5	Apr 2012	US$ 599	ebay.com
10.		Nikon D3300	3/5	+	..	77/100	4.5/5	4.5/5	Jan 2014	US$ 499	ebay.com
11.		Nikon D3400	4/5	+	4/5	76/100	4/5	4.5/5	Aug 2016	US$ 499	ebay.com
12.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	US$ 799	ebay.com
13.		Panasonic L10	..	85/100	..	+	3.5/5	4/5	Aug 2007	US$ 599	ebay.com
14.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	US$ 1 299	ebay.com
15.		Pentax K-500	..	..	..	..	4.5/5	4.5/5	Jun 2013	US$ 549	ebay.com
16.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	US$ 749	ebay.com
17.		Sony A68	3/5	..	..	..	4/5	4/5	Nov 2015	US$ 699	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. 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, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

Check D40 offers at
ebay.com
Check K-S1 offers at
ebay.com

Other camera comparisons

Did this review help to inform your camera decision process? In case you would like to check on the differences and similarities of other camera models, just use the search menu 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.

~

Check D40 offers at
ebay.com
Check K-S1 offers at
ebay.com

Did you notice an error on this page? If so, please get in touch, so that we can correct the information.