Panasonic GX1 vs Pentax 645D

The Panasonic Lumix DMC-GX1 and the Pentax 645D are two digital cameras that were announced, respectively, in November 2011 and March 2010. The GX1 is a mirrorless interchangeable lens camera, while the 645D is a DSLR. The cameras are based on a Four Thirds (GX1) and a medium format (645D) sensor. The Panasonic has a resolution of 15.8 megapixels, whereas the Pentax provides 39.5 MP.

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

Headline Specifications

Panasonic GX1		Pentax 645D
Mirrorless system camera		Digital single lens reflex
Micro Four Thirds lenses		Pentax 645 mount lenses
15.8 MP – Four Thirds sensor		39.5 MP – Medium Format sensor
1080/60p Video		no Video
ISO 160-12,800		ISO 100-1,600
Viewfinder optional		Optical viewfinder
3.0" LCD – 460k dots		3.0" LCD – 921k dots
Fixed touchscreen		Fixed screen (not touch-sensitive)
4.2 shutter flaps per second		1.1 shutter flaps per second
not weather sealed		Weathersealed body
320 shots per battery charge		800 shots per battery charge
116 x 68 x 39 mm, 318 g		156 x 117 x 119 mm, 1480 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Panasonic Lumix DMC-GX1 and the Pentax 645D? 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

An illustration of the physical size and weight of the Panasonic GX1 and the Pentax 645D is provided in the side-by-side display below. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All width, height and depth dimensions 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 Pentax 645D is considerably larger (131 percent) than the Panasonic GX1. Moreover, the 645D is substantially heavier (365 percent) than the GX1. It is noteworthy in this context that the 645D is splash and dust-proof, while the GX1 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 GX1 gets 320 shots out of its Panasonic DMW-BLD10 battery, while the 645D can take 800 images on a single charge of its Pentax D-LI90 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 (USD)	Street Price
1.		Panasonic GX1	116 mm	68 mm	39 mm	318 g	320	n	Nov 2011	699	ebay.com
2.		Pentax 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	ebay.com
3.		Canon 1D Mark IV	156 mm	157 mm	80 mm	1230 g	1500	Y	Oct 2009	4,999	ebay.com
4.		Canon 1D X	158 mm	168 mm	83 mm	1551 g	1120	Y	Oct 2011	6,799	ebay.com
5.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
6.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
7.		Panasonic G2	124 mm	84 mm	74 mm	428 g	360	n	Mar 2010	599	ebay.com
8.		Panasonic G3	115 mm	84 mm	47 mm	336 g	270	n	May 2011	599	ebay.com
9.		Panasonic G5	120 mm	83 mm	71 mm	396 g	320	n	Jul 2012	599	ebay.com
10.		Panasonic G6	122 mm	85 mm	71 mm	390 g	340	n	Apr 2013	599	ebay.com
11.		Panasonic GF1	119 mm	71 mm	36 mm	385 g	380	n	Sep 2009	749	ebay.com
12.		Panasonic GF2	113 mm	68 mm	33 mm	310 g	300	n	Nov 2010	549	ebay.com
13.		Panasonic GF3	108 mm	67 mm	32 mm	264 g	300	n	Jun 2011	549	ebay.com
14.		Panasonic GF5	108 mm	67 mm	37 mm	267 g	360	n	Apr 2012	499	ebay.com
15.		Panasonic GH2	124 mm	90 mm	76 mm	442 g	330	n	Sep 2010	899	ebay.com
16.		Panasonic GM1	99 mm	55 mm	30 mm	204 g	230	n	Oct 2013	749	ebay.com
17.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	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 GX1 was launched at a markedly lower price (by 93 percent) than the 645D, which puts it into a different market segment. Normally, street prices remain initially close to the MSRP, but after a couple of months, the first discounts appear. 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 imaging sensor is at the core of digital cameras and its size is one of the main determining factors 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.

Of the two cameras under consideration, the Panasonic GX1 features a Four Thirds sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 545 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 0.79. Both cameras feature a native aspect ratio (sensor width to sensor height) of 4:3.

With 39.5MP, the 645D offers a higher resolution than the GX1 (15.8MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 3.77μm for the GX1) due to its larger sensor. However, the GX1 is a somewhat more recent model (by 1 year and 7 months) than the 645D, and its sensor might have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units. Coming back to sensor resolution, it should be mentioned that the 645D has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Pentax 645D implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the 645D for good quality output (200 dots per inch) amounts to 36.3 x 27.2 inches or 92.3 x 69.1 cm, for very good quality (250 dpi) 29.1 x 21.8 inches or 73.8 x 55.3 cm, and for excellent quality (300 dpi) 24.2 x 18.1 inches or 61.5 x 46.1 cm. The corresponding values for the Panasonic GX1 are 23 x 17.2 inches or 58.3 x 43.8 cm for good quality, 18.4 x 13.8 inches or 46.7 x 35 cm for very good quality, and 15.3 x 11.5 inches or 38.9 x 29.2 cm for excellent quality prints.

The Panasonic Lumix DMC-GX1 has a native sensitivity range from ISO 160 to ISO 12800. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).

In terms of underlying technology, the GX1 is build around a CMOS sensor, while the 645D uses a CCD 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.

Consistent information on actual sensor performance is available from DXO Mark for many cameras. 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 645D offers substantially better image quality than the GX1 (overall score 27 points higher). The advantage is based on 3.8 bits higher color depth, 2 EV in additional dynamic range, and 0.8 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.		Panasonic GX1	Four Thirds	15.8	4592	3448	1080/60p	20.8	10.6	703	55
2.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
3.		Canon 1D Mark IV	APS-H	16.0	4896	3264	1080/30p	22.8	12.0	1320	74
4.		Canon 1D X	Full Frame	17.9	5184	3456	1080/30p	23.8	11.8	2786	82
5.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
6.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
7.		Panasonic G2	Four Thirds	12.0	4000	3000	720/30p	21.2	10.3	493	53
8.		Panasonic G3	Four Thirds	15.8	4592	3448	1080/60i	21.0	10.6	667	56
9.		Panasonic G5	Four Thirds	15.9	4608	3456	1080/60p	21.4	11.6	618	61
10.		Panasonic G6	Four Thirds	15.9	4608	3456	1080/60p	21.3	11.5	639	61
11.		Panasonic GF1	Four Thirds	12.0	4000	3000	720/30p	21.2	10.3	513	54
12.		Panasonic GF2	Four Thirds	12.0	4000	3000	1080/60i	21.2	10.3	506	54
13.		Panasonic GF3	Four Thirds	12.0	4000	3000	1080/60i	20.6	10.1	459	50
14.		Panasonic GF5	Four Thirds	12.0	4000	3000	1080/60i	20.5	10.0	573	50
15.		Panasonic GH2	Four Thirds	15.9	4608	3456	1080/60i	21.2	11.3	655	60
16.		Panasonic GM1	Four Thirds	15.8	4592	3448	1080/60i	22.3	11.7	660	66
17.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101

Many modern cameras are not only capable of taking still images, but can also record movies. The GX1 indeed provides movie recording capabilities, while the 645D does not. The highest resolution format that the GX1 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 645D has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the GX1 relies on live view and the rear LCD for framing. That said, the GX1 can be equipped with an optional viewfinder – the DMW-LVF2. The following table reports on some other key feature differences and similarities of the Panasonic GX1, the Pentax 645D, and comparable 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.		Panasonic GX1	optional	n	3.0 / 460	fixed	Y	1/4000s	4.2/s	Y	n
2.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
3.		Canon 1D Mark IV	optical	Y	3.0 / 920	fixed	n	1/8000s	10.0/s	n	n
4.		Canon 1D X	optical	Y	3.2 / 1040	fixed	n	1/8000s	14.0/s	n	n
5.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
6.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
7.		Panasonic G2	1440	n	3.0 / 460	swivel	Y	1/4000s	2.6/s	Y	n
8.		Panasonic G3	1440	n	3.0 / 460	swivel	Y	1/4000s	4.0/s	Y	n
9.		Panasonic G5	1440	n	3.0 / 920	swivel	Y	1/4000s	6.0/s	Y	n
10.		Panasonic G6	1440	n	3.0 / 1036	swivel	Y	1/4000s	7.0/s	Y	n
11.		Panasonic GF1	optional	n	3.0 / 460	fixed	n	1/4000s	3.0/s	Y	n
12.		Panasonic GF2	optional	n	3.0 / 460	fixed	Y	1/4000s	2.6/s	Y	n
13.		Panasonic GF3	none	n	3.0 / 460	fixed	Y	1/4000s	3.2/s	Y	n
14.		Panasonic GF5	none	n	3.0 / 920	fixed	Y	1/4000s	4.0/s	Y	n
15.		Panasonic GH2	1534	n	3.0 / 460	swivel	n	1/4000s	3.0/s	Y	n
16.		Panasonic GM1	none	n	3.0 / 1036	fixed	Y	1/500s	5.0/s	Y	n
17.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
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 GX1 has one, while the 645D does not. While the built-in flash of the GX1 is not very powerful, it can at times be useful as a fill-in light.

The Pentax 645D has an intervalometer built-in. This enables the photographer to capture time lapse sequences, such as flower blooming, a sunset or moon rise, without purchasing an external camera trigger and related software.

Concerning the storage of imaging data, both the GX1 and the 645D write their files to SDXC cards. The 645D features dual card slots, which can be very useful in case a memory card fails. In contrast, the GX1 only has one slot. The GX1 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the 645D 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 Panasonic Lumix DMC-GX1 and Pentax 645D 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.		Panasonic GX1	Y	stereo / mono	-	-	mini	2.0	-	-	-
2.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-
3.		Canon 1D Mark IV	Y	stereo / -	Y	-	mini	2.0	-	-	-
4.		Canon 1D X	Y	mono / -	Y	-	mini	2.0	-	-	-
5.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
6.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
7.		Panasonic G2	Y	stereo / mono	-	-	mini	2.0	-	-	-
8.		Panasonic G3	Y	stereo / mono	-	-	mini	2.0	-	-	-
9.		Panasonic G5	Y	stereo / mono	-	-	mini	2.0	-	-	-
10.		Panasonic G6	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
11.		Panasonic GF1	Y	mono / mono	-	-	mini	2.0	-	-	-
12.		Panasonic GF2	Y	stereo / mono	-	-	mini	2.0	-	-	-
13.		Panasonic GF3	-	stereo / mono	-	-	mini	2.0	-	-	-
14.		Panasonic GF5	-	stereo / mono	-	-	mini	2.0	-	-	-
15.		Panasonic GH2	Y	stereo / mono	Y	-	mini	2.0	-	-	-
16.		Panasonic GM1	-	stereo / mono	-	-	micro	2.0	Y	-	-
17.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-

Studio photographers will appreciate that the Pentax 645D (unlike the GX1) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the GX1 and the 645D have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the GX1 was followed by the Panasonic GX7. Further information on the features and operation of the GX1 and 645D can be found, respectively, in the Panasonic GX1 Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So how do things add up? Is the Panasonic GX1 better than the Pentax 645D or vice versa? A synthesis of the relative strong points of each of the models is listed below.

Reasons to prefer the Panasonic Lumix DMC-GX1:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Broader imaging potential: Can record not only still images but also 1080/60p movies.
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster burst: Shoots at higher frequency (4.2 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (116x68mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 1162g or 79 percent) and hence easier to carry around.
• More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More affordable: Was introduced into a lower priced category (93 percent cheaper at launch).
• More modern: Is somewhat more recent (announced 1 year and 7 months after the 645D).

Arguments in favor of the Pentax 645D:

• More detail: Has more megapixels (39.5 vs 15.8MP), which boosts linear resolution by 58%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores substantially higher (27 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (3.8 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 (0.8 stops ISO advantage).
• Easier framing: Has an optical viewfinder for image composition and settings control.
• Easier setting verification: Features a control panel on top to check shooting parameters.
• More detailed LCD: Has a higher resolution rear screen (921k vs 460k dots).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Gets more shots (800 versus 320) out of a single battery charge.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• 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 heavily discounted: Has been on the market for longer (launched in March 2010).

If the number of relative strengths (bullet points above) is taken as a guide, the 645D is the clear winner of the contest (15 : 11 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 sports photographer will view the differences between cameras in a way that diverges from the perspective of a street photog, and a person interested in family portraits has distinct needs from a landscape 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 Panasonic GX1 and the Pentax 645D place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera and Best DSLR Camera listings 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 says little about, for example, the shooting experience and imaging performance of the GX1 and the 645D in practical situations. 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 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 (USD)	Street Price
1.		Panasonic GX1	3/5	+	..	77/100	4.5/5	4.5/5	Nov 2011	699	ebay.com
2.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
3.		Canon 1D Mark IV	5/5	..	..	89/100	..	..	Oct 2009	4,999	ebay.com
4.		Canon 1D X	5/5	..	..	..	4.5/5	4.5/5	Oct 2011	6,799	ebay.com
5.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
6.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
7.		Panasonic G2	..	..	..	72/100	4/5	4.5/5	Mar 2010	599	ebay.com
8.		Panasonic G3	3/5	+ +	..	75/100	4.5/5	5/5	May 2011	599	ebay.com
9.		Panasonic G5	3/5	+ +	..	..	4.5/5	4.5/5	Jul 2012	599	ebay.com
10.		Panasonic G6	4/5	+ +	..	..	5/5	4.5/5	Apr 2013	599	ebay.com
11.		Panasonic GF1	..	85/100	..	69/100	4.5/5	4.5/5	Sep 2009	749	ebay.com
12.		Panasonic GF2	3/5	82/100	..	70/100	4.5/5	4.5/5	Nov 2010	549	ebay.com
13.		Panasonic GF3	3/5	82/100	..	71/100	4.5/5	4/5	Jun 2011	549	ebay.com
14.		Panasonic GF5	3/5	..	..	..	4.5/5	4.5/5	Apr 2012	499	ebay.com
15.		Panasonic GH2	5/5	+ +	..	79/100	4.5/5	5/5	Sep 2010	899	ebay.com
16.		Panasonic GM1	3/5	+	..	78/100	5/5	4.5/5	Oct 2013	749	ebay.com
17.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date have little meaning. It should also be noted that some of the review sites have over time altered the way they render their verdicts.

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Other camera comparisons

Did this review help to inform your camera decision process? In case you are interested in seeing how other cameras pair up, just make a corresponding selection in the search boxes below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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