Sigma fp vs Sony A9 III

The Sigma fp and the Sony Alpha A9 III are two digital cameras that were revealed to the public, respectively, in July 2019 and November 2023. Both the fp and the A9 III are mirrorless interchangeable lens cameras that are equipped with a full frame sensor. Both cameras offer a resolution of 24 megapixels.

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

Headline Specifications

Sigma fp		Sony A9 III
Mirrorless system camera		Mirrorless system camera
Leica L mount lenses		Sony E mount lenses
24 MP – Full Frame sensor		24 MP – Full Frame sensor
4K/30p Video		4K/120p Video
ISO 100-25,600 (6 - 102,400)		ISO 250-25,600 (125 - 51,200)
Viewfinder optional		Electronic viewfinder (9440k dots)
3.2" LCD – 2100k dots		3.2" LCD – 2100k dots
Fixed touchscreen		Fully flexible touchscreen
12 shutter flaps per second		120 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		Weathersealed body
280 shots per battery charge		530 shots per battery charge
113 x 70 x 45 mm, 422 g		136 x 97 x 83 mm, 702 g

Check fp price at
amazon.com
Check A9 III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Sigma fp and the Sony Alpha A9 III? 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 Sigma fp and the Sony A9 III is provided 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 A9 III is considerably larger (67 percent) than the Sigma fp. Moreover, the A9 III is substantially heavier (66 percent) than the fp. 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.

Concerning battery life, the fp gets 280 shots out of its Sigma BP-51 battery, while the A9 III can take 530 images on a single charge of its Sony NP-FZ100 power pack. The battery packs of both cameras can be charged via USB, which can be very convenient when travelling.

The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. 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.		Sigma fp	113 mm	70 mm	45 mm	422 g	280	Y	Jul 2019	US$ 1 899	amazon.com
2.		Sony A9 III	136 mm	97 mm	83 mm	702 g	530	Y	Nov 2023	US$ 5 999	amazon.com
3.		Fujifilm X-Pro3	141 mm	83 mm	46 mm	497 g	440	Y	Oct 2019	US$ 1 799	amazon.com
4.		Leica SL	147 mm	104 mm	39 mm	847 g	400	Y	Oct 2015	US$ 7 449	ebay.com
5.		Nikon D780	144 mm	116 mm	76 mm	840 g	2260	Y	Jan 2020	US$ 2 299	amazon.com
6.		Panasonic S1	149 mm	110 mm	97 mm	1017 g	400	Y	Feb 2019	US$ 2 499	amazon.com
7.		Panasonic S1H	151 mm	114 mm	110 mm	1052 g	400	Y	May 2019	US$ 3 999	amazon.com
8.		Panasonic S5	133 mm	98 mm	82 mm	714 g	440	Y	Sep 2020	US$ 1 999	amazon.com
9.		Panasonic TS7	117 mm	76 mm	37 mm	319 g	300	Y	May 2018	US$ 449	ebay.com
10.		Sigma fp L	113 mm	70 mm	45 mm	427 g	240	Y	Mar 2021	US$ 2 499	amazon.com
11.		Sony A1	129 mm	97 mm	81 mm	737 g	530	Y	Jan 2021	US$ 6 499	amazon.com
12.		Sony A7	127 mm	94 mm	48 mm	474 g	340	Y	Oct 2013	US$ 1 699	ebay.com
13.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	US$ 1 999	ebay.com
14.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	US$ 1 999	amazon.com
15.		Sony A7C	124 mm	71 mm	60 mm	509 g	740	Y	Sep 2020	US$ 1 799	amazon.com
16.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	US$ 4 499	ebay.com
17.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	US$ 4 499	amazon.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 naturally be influenced heavily by the price. 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 fp was launched at a markedly lower price (by 68 percent) than the A9 III, 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.

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. 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. 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 associated with larger, more expensive camera bodies and lenses.

Both cameras under consideration feature a full frame sensor, but their sensors differ slightly in size. The sensor area in the A9 III is 1 percent smaller. They nevertheless have the same format factor of 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Even though the fp has a slightly larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the fp has a lower pixel density and larger individual pixels (with a pixel pitch of 5.98μm versus 5.94μm for the A9 III), which gives it a potential advantage in terms of light gathering capacity. It should, however, be noted that the A9 III is much more recent (by 4 years and 3 months) than the fp, and its sensor will have benefitted from technological advances during this time that at least partly compensate for the smaller pixel size. Coming back to sensor resolution, it should be mentioned that the fp has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The A9 III has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Sigma fp has a native sensitivity range from ISO 100 to ISO 25600, which can be extended to ISO 6-102400. The corresponding ISO settings for the Sony Alpha A9 III are ISO 250 to ISO 25600, with the possibility to increase the ISO range to 125-51200.

In terms of underlying technology, the fp is build around a BSI-CMOS sensor, while the A9 III uses a Stacked 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"). The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.

Sensor Characteristics

		Camera Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Sigma fp	Full Frame	24.0	6000	4000	4K/30p	25.2	14.2	2829	94
2.		Sony A9 III	Full Frame	24.0	6000	4000	4K/120p	25.4	14.7	3243	96
3.		Fujifilm X-Pro3	APS-C	26.0	6240	4160	4K/30p	24.1	13.6	1968	84
4.		Leica SL	Full Frame	24.0	6000	4000	4K/30p	25.0	13.4	1821	88
5.		Nikon D780	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	2877	95
6.		Panasonic S1	Full Frame	24.0	6000	4000	4K/60p	25.2	14.5	3333	95
7.		Panasonic S1H	Full Frame	24.0	6000	4000	6K/30p	25.2	14.2	2805	94
8.		Panasonic S5	Full Frame	24.0	6000	4000	4K/60p	25.1	14.5	2697	94
9.		Panasonic TS7	1/2.3	20.2	5184	3888	4K/30p	20.6	12.1	1028	51
10.		Sigma fp L	Full Frame	60.2	9520	6328	4K/30p	25.3	14.4	3001	96
11.		Sony A1	Full Frame	49.8	8640	5760	8k/30p	25.9	14.5	3163	98
12.		Sony A7	Full Frame	24.0	6000	4000	1080/60p	24.8	14.2	2248	90
13.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
14.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
15.		Sony A7C	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3407	95
16.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
17.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
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 two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the A9 III provides a faster frame rate than the fp. It can shoot movie footage at 4K/120p, while the Sigma is limited to 4K/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the A9 III has an electronic viewfinder (9440k dots), which can be very helpful when shooting in bright sunlight. In contrast, the fp relies on live view and the rear LCD for framing. That said, the fp can be equipped with an optional viewfinder – the EVF-11. The following table reports on some other key feature differences and similarities of the Sigma fp, the Sony A9 III, 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.		Sigma fp	optional	n	3.2 / 2100	fixed	Y	1/8000s	12.0/s	n	n
2.		Sony A9 III	9440	n	3.2 / 2100	full-flex	Y	1/80000s	120.0/s	n	Y
3.		Fujifilm X-Pro3	3690	n	3.0 / 1620	tilting	Y	1/8000s	8.0/s	n	n
4.		Leica SL	4400	Y	3.0 / 1040	fixed	Y	1/8000s	11.0/s	n	n
5.		Nikon D780	optical	Y	3.2 / 2359	tilting	Y	1/8000s	12.0/s	n	n
6.		Panasonic S1	5760	Y	3.2 / 2100	full-flex	Y	1/8000s	9.0/s	n	Y
7.		Panasonic S1H	5760	Y	3.2 / 2330	swivel	Y	1/8000s	9.0/s	n	Y
8.		Panasonic S5	2360	n	3.0 / 1840	swivel	Y	1/8000s	7.0/s	n	Y
9.		Panasonic TS7	1170	n	3.0 / 1040	fixed	n	1/1300s	10.0/s	Y	Y
10.		Sigma fp L	optional	n	3.2 / 2100	fixed	Y	1/8000s	10.0/s	n	n
11.		Sony A1	9437	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
12.		Sony A7	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	n
13.		Sony A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
14.		Sony A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
15.		Sony A7C	2360	n	3.0 / 922	swivel	Y	1/4000s	10.0/s	n	Y
16.		Sony A9	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
17.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the A9 III and the fp is in-body image stabilization (IBIS). The A9 III reduces the risk of handshake-induced blur with all attached lenses, while the fp 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, both cameras under consideration feature an 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 Sigma fp and the Sony A9 III 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.

The fp writes its imaging data to SDXC cards, while the A9 III uses CFexpress (type A) or SDXC cards. The A9 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the fp only has one slot. Both cameras support UHS-II cards, which provide for Ultra High Speed data transfer of up to 312 MB/s.

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 Sigma fp and Sony Alpha A9 III 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.		Sigma fp	Y	stereo / mono	Y	-	micro	3.1	-	-	-
2.		Sony A9 III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Fujifilm X-Pro3	Y	stereo / mono	Y	-	-	3.1	Y	-	Y
4.		Leica SL	Y	stereo / mono	Y	Y	full	3.0	Y	-	-
5.		Nikon D780	Y	stereo / mono	Y	Y	mini	3.1	Y	-	Y
6.		Panasonic S1	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
7.		Panasonic S1H	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
8.		Panasonic S5	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
9.		Panasonic TS7	-	stereo / mono	-	-	micro	2.0	Y	-	-
10.		Sigma fp L	Y	stereo / mono	Y	Y	micro	3.2	Y	-	-
11.		Sony A1	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
12.		Sony A7	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
13.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
14.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A7C	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
16.		Sony A9	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
17.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y

It is notable that the A9 III offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the fp does not provide wifi capability.

Studio photographers will appreciate that the Sony A9 III (unlike the fp) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the fp and the A9 III are recent models that are part of the current product line-up. The A9 III replaced the earlier Sony A9 II, while the fp does not have a direct predecessor. Further information on the features and operation of the fp and A9 III can be found, respectively, in the Sigma fp Manual (free pdf) or the online Sony A9 III Manual.

Review summary

So what is the bottom line? Is the Sigma fp better than the Sony A9 III or vice versa? A synthesis of the relative strong points of each of the models is listed below.

Reasons to prefer the Sigma fp:

• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• More compact: Is smaller (113x70mm vs 136x97mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 280g or 40 percent) and hence easier to carry around.
• More affordable: Was introduced into a lower priced category (68 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in July 2019).

Arguments in favor of the Sony Alpha A9 III:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better video: Provides higher movie framerates (4K/120p versus 4K/30p).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• Easier framing: Has an electronic viewfinder for image composition and settings control.
• 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 (1/80000s vs 1/8000s) to freeze action.
• Faster burst: Shoots at higher frequency (120 vs 12 flaps/sec) to capture the decisive moment.
• Longer lasting: Gets more shots (530 versus 280) out of a single battery charge.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Faster data transfer: Supports a more advanced USB protocol (3.2 vs 3.1).
• 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.
• 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 4 years and 3 months of technical progress since the fp launch.

If the number of relative strengths (bullet points above) is taken as a guide, the A9 III is the clear winner of the contest (18 : 5 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 Sigma fp and the Sony A9 III place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens 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 partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the fp or the A9 III. 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 expert reviews 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.		Sigma fp	4/5	..	4/5	..	4/5	4.5/5	Jul 2019	US$ 1 899	amazon.com
2.		Sony A9 III	4.5/5	..	..	..	..	..	Nov 2023	US$ 5 999	amazon.com
3.		Fujifilm X-Pro3	4/5	+	4/5	85/100	4/5	..	Oct 2019	US$ 1 799	amazon.com
4.		Leica SL	4/5	..	4/5	84/100	4.5/5	4/5	Oct 2015	US$ 7 449	ebay.com
5.		Nikon D780	5/5	..	5/5	87/100	4.5/5	4.5/5	Jan 2020	US$ 2 299	amazon.com
6.		Panasonic S1	4.5/5	+ +	4.5/5	88/100	4.5/5	4/5	Feb 2019	US$ 2 499	amazon.com
7.		Panasonic S1H	..	..	4/5	90/100	..	..	May 2019	US$ 3 999	amazon.com
8.		Panasonic S5	4.5/5	+ +	4.5/5	88/100	4.5/5	4.5/5	Sep 2020	US$ 1 999	amazon.com
9.		Panasonic TS7	..	+	..	..	..	3.5/5	May 2018	US$ 449	ebay.com
10.		Sigma fp L	4/5	..	4/5	..	4/5	4/5	Mar 2021	US$ 2 499	amazon.com
11.		Sony A1	5/5	o	4.5/5	93/100	4.5/5	5/5	Jan 2021	US$ 6 499	amazon.com
12.		Sony A7	5/5	+ +	..	80/100	5/5	5/5	Oct 2013	US$ 1 699	ebay.com
13.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	US$ 1 999	ebay.com
14.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	US$ 1 999	amazon.com
15.		Sony A7C	3.5/5	..	3.5/5	86/100	4/5	4/5	Sep 2020	US$ 1 799	amazon.com
16.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	US$ 4 499	ebay.com
17.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	US$ 4 499	amazon.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated 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. Hence, a score should always be seen in the context of the camera's market launch date and its price, and comparisons of ratings among very different cameras or across long time periods have little meaning. Also, please note that some of the review sites have changed their methodology and reporting over time.

Check fp price at
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Check A9 III price at
amazon.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.

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