Fujifilm GFX 100 vs Pentax 645D

The Fujifilm GFX 100 and the Pentax 645D are two professional cameras that were revealed to the public, respectively, in May 2019 and March 2010. The GFX 100 is a mirrorless interchangeable lens camera, while the 645D is a DSLR. Both cameras are equipped with a medium format sensor. The Fujifilm has a resolution of 101.8 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

Fujifilm GFX 100		Pentax 645D
Mirrorless system camera		Digital single lens reflex
Fujifilm G mount lenses		Pentax 645 mount lenses
101.8 MP – Medium Format sensor		39.5 MP – Medium Format sensor
4K/30p Video		no Video
ISO 100-12,800 (50 - 102,400)		ISO 100-1,600
Viewfinder optional		Optical viewfinder
3.2" LCD – 2360k dots		3.0" LCD – 921k dots
Fully flexible touchscreen		Fixed screen (not touch-sensitive)
5 shutter flaps per second		1.1 shutter flaps per second
In-body stabilization		Lens stabilization only
Weathersealed body		Weathersealed body
800 shots per battery charge		800 shots per battery charge
156 x 144 x 75 mm, 1320 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 Fujifilm GFX 100 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

The physical size and weight of the Fujifilm GFX 100 and the Pentax 645D 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 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 notably smaller (19 percent) than the Fujifilm GFX 100. However, the 645D is markedly heavier (12 percent) than the GFX 100. In this context, it is worth noting that both cameras are splash and dust-proof and can, hence, be used in inclement weather conditions or harsh environments.

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.

As can be seen in the images above, the GFX 100 has a battery grip built in. This facilitates image-taking in portrait orientation and gives it additional battery power. The power pack in the GFX 100 can be charged via the USB port, so that it is not always necessary to take the battery charger along when travelling.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. 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 (USD)	Street Price
1.		Fujifilm GFX 100	156 mm	144 mm	75 mm	1320 g	800	Y	May 2019	9,999	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.		Fujifilm GFX 50R	161 mm	97 mm	66 mm	775 g	400	Y	Sep 2018	4,499	ebay.com
6.		Fujifilm GFX 50S	148 mm	94 mm	91 mm	740 g	400	Y	Sep 2016	6,499	ebay.com
7.		Fujifilm GFX 50S II	150 mm	104 mm	87 mm	900 g	440	Y	Sep 2021	3,999	amazon.com
8.		Fujifilm GFX 100 II	152 mm	117 mm	99 mm	1030 g	540	Y	Sep 2023	7,499	amazon.com
9.		Fujifilm GFX 100S	150 mm	104 mm	87 mm	900 g	460	Y	Jan 2021	5,999	amazon.com
10.		Fujifilm X-H1	140 mm	97 mm	86 mm	673 g	310	Y	Feb 2018	1,899	ebay.com
11.		Fujifilm XP140	110 mm	71 mm	28 mm	207 g	240	Y	Feb 2019	229	ebay.com
12.		Hasselblad X2D 100C	149 mm	106 mm	75 mm	895 g	420	Y	Sep 2022	8,199	amazon.com
13.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
14.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
15.		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

The price is, of course, an important factor in any camera decision. The manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. 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 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. 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 tend to be associated with larger, more expensive camera bodies and lenses.

Both cameras under consideration feature a medium format sensor, but their sensors differ slightly in size. The sensor area in the 645D is 1 percent bigger. They nevertheless have the same format factor of 0.79. Both cameras feature a native aspect ratio (sensor width to sensor height) of 4:3.

Despite having a slightly smaller sensor, the Fujifilm GFX 100 offers a higher resolution of 101.8 megapixels, compared with 39.5 MP of the Pentax 645D. 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 3.76μm versus 6.06μm for the 645D). However, it should be noted that the GFX 100 is much more recent (by 9 years and 2 months) than the 645D, 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 neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.

The resolution advantage of the Fujifilm GFX 100 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the GFX 100 for good quality output (200 dots per inch) amounts to 58.2 x 43.7 inches or 147.9 x 110.9 cm, for very good quality (250 dpi) 46.6 x 34.9 inches or 118.3 x 88.8 cm, and for excellent quality (300 dpi) 38.8 x 29.1 inches or 98.6 x 74 cm. The corresponding values for the Pentax 645D are 36.3 x 27.2 inches or 92.3 x 69.1 cm for good quality, 29.1 x 21.8 inches or 73.8 x 55.3 cm for very good quality, and 24.2 x 18.1 inches or 61.5 x 46.1 cm for excellent quality prints.

The GFX 100 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Fujifilm GFX 100 has a native sensitivity range from ISO 100 to ISO 12800, which can be extended to ISO 50-102400. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).

In terms of underlying technology, the GFX 100 is build around a BSI-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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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.		Fujifilm GFX 100	Medium Format	101.8	11648	8736	4K/30p	25.7	14.5	3227	99
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.		Fujifilm GFX 50R	Medium Format	51.1	8256	6192	1080/30p	25.7	14.4	3169	98
6.		Fujifilm GFX 50S	Medium Format	51.1	8256	6192	1080/30p	25.4	14.1	2977	96
7.		Fujifilm GFX 50S II	Medium Format	51.1	8256	6192	1080/30p	25.9	14.8	3456	100
8.		Fujifilm GFX 100 II	Medium Format	101.8	11648	8736	8K/30p	25.9	15.0	3651	101
9.		Fujifilm GFX 100S	Medium Format	101.8	11648	8736	4K/30p	25.8	14.7	3391	100
10.		Fujifilm X-H1	APS-C	24.0	6000	4000	4K/30p	24.0	13.3	1806	82
11.		Fujifilm XP140	1/2.3	15.9	4608	3456	4K/15p	20.7	12.2	1102	52
12.		Hasselblad X2D 100C	Medium Format	102.1	11656	8762	none	25.9	14.9	3550	101
13.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
14.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
15.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
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 also of capturing video footage. The GFX 100 indeed provides movie recording capabilities, while the 645D does not. The highest resolution format that the GFX 100 can use is 4K/30p.

Feature comparison

Beyond 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 GFX 100 relies on live view and the rear LCD for framing. That said, the GFX 100 can be equipped with an optional viewfinder – the EVF-GFX2. The following table reports on some other key feature differences and similarities of the Fujifilm GFX 100, 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.		Fujifilm GFX 100	optional	Y	3.2 / 2360	full-flex	Y	1/4000s	5.0/s	n	Y
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.		Fujifilm GFX 50R	3690	n	3.2 / 2360	tilting	Y	1/4000s	3.0/s	n	n
6.		Fujifilm GFX 50S	optional	Y	3.2 / 2360	full-flex	Y	1/4000s	3.0/s	n	n
7.		Fujifilm GFX 50S II	3690	Y	3.2 / 2360	full-flex	Y	1/4000s	3.0/s	n	Y
8.		Fujifilm GFX 100 II	9440	Y	3.2 / 2360	full-flex	Y	1/4000s	8.0/s	n	Y
9.		Fujifilm GFX 100S	3690	Y	3.2 / 2360	full-flex	Y	1/4000s	5.0/s	n	Y
10.		Fujifilm X-H1	3690	Y	3.0 / 1040	full-flex	Y	1/8000s	14.0/s	n	Y
11.		Fujifilm XP140	none	n	3.0 / 920	fixed	n	1/2000s	10.0/s	Y	Y
12.		Hasselblad X2D 100C	5760	Y	3.6 / 2360	tilting	Y	1/4000s	3.3/s	n	Y
13.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
14.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
15.		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 feature that differentiates the GFX 100 and the 645D is in-body image stabilization (IBIS). The GFX 100 reduces the risk of handshake-induced blur with all attached lenses, while the 645D offers no blur reduction with lenses that themselves do not provide optical image stabilization.

The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the GFX 100 is one of those camera that have an additional electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).

The Fujifilm GFX 100 and the Pentax 645D both have 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 GFX 100 and the 645D write their files to SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. The GFX 100 supports UHS-II cards (on both slots), 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 Fujifilm GFX 100 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.		Fujifilm GFX 100	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
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.		Fujifilm GFX 50R	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
6.		Fujifilm GFX 50S	Y	stereo / mono	Y	Y	micro	3.0	Y	-	-
7.		Fujifilm GFX 50S II	Y	stereo / mono	Y	Y	micro	3.2	Y	-	-
8.		Fujifilm GFX 100 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
9.		Fujifilm GFX 100S	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
10.		Fujifilm X-H1	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
11.		Fujifilm XP140	-	mono / mono	-	-	micro	2.0	Y	-	Y
12.		Hasselblad X2D 100C	Y	stereo / mono	-	-	-	3.2	Y	-	-
13.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
14.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
15.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-

It is notable that the GFX 100 offers wifi support, while the 645D does not. Wifi can be a very convenient means to transfer image data to an off-camera location.

Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.

Both the GFX 100 and the 645D have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the GFX 100 was followed by the Fujifilm GFX 100 II. Further information on the features and operation of the GFX 100 and 645D can be found, respectively, in the Fujifilm GFX 100 Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So how do things add up? Which of the two cameras – the Fujifilm GFX 100 or the Pentax 645D – 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.

Arguments in favor of the Fujifilm GFX 100:

• More detail: Offers more megapixels (101.8 vs 39.5MP) with a 60% higher linear resolution.
• Broader imaging potential: Can record not only still images but also 4K/30p movies.
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (2360k vs 921k dots).
• More flexible LCD: Has a full-flex screen for odd-angle shots in portrait or landscape orientation.
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster burst: Shoots at higher frequency (5 vs 1.1 flaps/sec) to capture the decisive moment.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• Less heavy: Is lighter (by 160g or 11 percent) and hence easier to carry around.
• More portrait friendly: Features an integrated vertical grip for easier portrait shooting.
• Easier travel charging: Can be conveniently charged via its USB port.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
• Faster data transfer: Supports a more advanced USB protocol (3.1 vs 2.0).
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• Faster buffer clearing: Supports Ultra High Speed (UHS-II) SDXC cards on both slots.
• More modern: Reflects 9 years and 2 months of technical progress since the 645D launch.

Reasons to prefer the Pentax 645D:

• Easier framing: Has an optical viewfinder for image composition and settings control.
• More compact: Is smaller (156x117mm vs 156x144mm) and will fit more readily into a bag.
• More heavily discounted: Has been around for much longer (launched in March 2010).

If the count of individual advantages (bullet points above) is taken as a guide, the GFX 100 is the clear winner of the match-up (19 : 3 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 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 Fujifilm GFX 100 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the GFX 100 or the 645D. 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 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.		Fujifilm GFX 100	4.5/5	+ +	4.8/5	90/100	5/5	4.5/5	May 2019	9,999	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.		Fujifilm GFX 50R	5/5	..	5/5	84/100	4.5/5	4.5/5	Sep 2018	4,499	ebay.com
6.		Fujifilm GFX 50S	..	..	4.5/5	85/100	5/5	4.5/5	Sep 2016	6,499	ebay.com
7.		Fujifilm GFX 50S II	5/5	..	5/5	87/100	..	5/5	Sep 2021	3,999	amazon.com
8.		Fujifilm GFX 100 II	5/5	+	5/5	..	..	4.5/5	Sep 2023	7,499	amazon.com
9.		Fujifilm GFX 100S	5/5	+ +	5/5	90/100	5/5	5/5	Jan 2021	5,999	amazon.com
10.		Fujifilm X-H1	..	+	5/5	86/100	4.5/5	4.5/5	Feb 2018	1,899	ebay.com
11.		Fujifilm XP140	..	+	..	..	3.5/5	4/5	Feb 2019	229	ebay.com
12.		Hasselblad X2D 100C	4/5	..	5/5	..	..	..	Sep 2022	8,199	amazon.com
13.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
14.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
15.		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.

Care should be taken when interpreting the review scores above, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. Thus, a score needs to be put into the context of the launch date and the launch price 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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