Sigma fp vs Sony A7S III

The Sigma fp and the Sony Alpha 7S III are two digital cameras that were officially introduced, respectively, in July 2019 and July 2020. Both the fp and the A7S III are mirrorless interchangeable lens cameras that are equipped with a full frame sensor. The Sigma has a resolution of 24 megapixels, whereas the Sony provides 12 MP.

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

Headline Specifications

Sigma fp		Sony A7S III
Mirrorless system camera		Mirrorless system camera
Leica L mount lenses		Sony E mount lenses
24 MP – Full Frame sensor		12 MP – Full Frame sensor
4K/30p Video		4K/120p Video
ISO 100-25,600 (6 - 102,400)		ISO 80-102,400 (40 - 409,600)
Viewfinder optional		Electronic viewfinder (9440k dots)
3.2" LCD – 2100k dots		3.0" LCD – 1440k dots
Fixed touchscreen		Swivel touchscreen
12 shutter flaps per second		10 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		Weathersealed body
280 shots per battery charge		600 shots per battery charge
113 x 70 x 45 mm, 422 g		127 x 97 x 81 mm, 699 g

Check fp price at
amazon.com
Check A7S 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 7S 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

The side-by-side display below illustrates the physical size and weight of the Sigma fp and the Sony A7S III. 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 Sony A7S III is considerably larger (56 percent) than the Sigma fp. Moreover, the A7S 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 A7S III can take 600 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 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.		Sigma fp	113 mm	70 mm	45 mm	422 g	280	Y	Jul 2019	1,899	amazon.com
2.		Sony A7S III	127 mm	97 mm	81 mm	699 g	600	Y	Jul 2020	3,499	amazon.com
3.		Fujifilm X100V	128 mm	75 mm	53 mm	478 g	420	Y	Feb 2020	1,399	ebay.com
4.		Fujifilm X-Pro3	141 mm	83 mm	46 mm	497 g	440	Y	Oct 2019	1,799	amazon.com
5.		Fujifilm X-Pro2	141 mm	83 mm	46 mm	495 g	350	Y	Jan 2016	1,699	ebay.com
6.		Fujifilm X-T2	133 mm	92 mm	49 mm	507 g	340	Y	Jul 2016	1,599	ebay.com
7.		Nikon D780	144 mm	116 mm	76 mm	840 g	2260	Y	Jan 2020	2,299	amazon.com
8.		Nikon Z50	127 mm	94 mm	60 mm	450 g	320	Y	Oct 2019	859	amazon.com
9.		Panasonic S1	149 mm	110 mm	97 mm	1017 g	400	Y	Feb 2019	2,499	amazon.com
10.		Panasonic S1H	151 mm	114 mm	110 mm	1052 g	400	Y	May 2019	3,999	amazon.com
11.		Panasonic FT7	117 mm	76 mm	37 mm	319 g	300	Y	May 2018	449	ebay.com
12.		Sony A7R IVA	129 mm	96 mm	78 mm	665 g	670	Y	Apr 2021	3,499	amazon.com
13.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
14.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	ebay.com
15.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
16.		Sony A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
17.		Sony A7	127 mm	94 mm	48 mm	474 g	340	Y	Oct 2013	1,699	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 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 46 percent) than the A7S III, 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. A large sensor will tend to have larger individual pixels that provide better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixel-units 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 more expensive and lead to bigger and heavier cameras and lenses.

Both cameras under consideration feature a full frame sensor, but their sensors differ slightly in size. The sensor area in the A7S 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.

With 24MP, the fp offers a higher resolution than the A7S III (12MP), but the fp has smaller individual pixels (pixel pitch of 5.98μm versus 8.40μm for the A7S III). Moreover, the A7S III is a somewhat more recent model (by 1 year) than the fp, and its sensor might have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixels. 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 resolution advantage of the Sigma fp implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the fp 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 Sony A7S III are 21.2 x 14.2 inches or 53.8 x 36 cm for good quality, 17 x 11.3 inches or 43.1 x 28.8 cm for very good quality, and 14.1 x 9.4 inches or 35.9 x 24 cm for excellent quality prints.

The A7S 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 7S III are ISO 80 to ISO 102400, with the possibility to increase the ISO range to 40-409600.

Technology-wise, both cameras are equipped with BSI-CMOS (Backside Illuminated Complementary Metal–Oxide–Semiconductor) sensors. 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 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 A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86
3.		Fujifilm X100V	APS-C	26.0	6240	4160	4K/30p	24.2	13.6	1996	84
4.		Fujifilm X-Pro3	APS-C	26.0	6240	4160	4K/30p	24.1	13.6	1968	84
5.		Fujifilm X-Pro2	APS-C	24.0	6000	4000	1080/60p	23.7	13.0	1608	80
6.		Fujifilm X-T2	APS-C	24.0	6000	4000	4K/30p	23.8	13.1	1653	81
7.		Nikon D780	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	2877	95
8.		Nikon Z50	APS-C	20.7	5568	3712	4K/30p	24.1	13.6	1963	84
9.		Panasonic S1	Full Frame	24.0	6000	4000	4K/60p	25.2	14.5	3333	95
10.		Panasonic S1H	Full Frame	24.0	6000	4000	6K/30p	25.2	14.2	2805	94
11.		Panasonic FT7	1/2.3	20.2	5184	3888	4K/30p	20.6	12.1	1028	51
12.		Sony A7R IVA	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
13.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
14.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
15.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
16.		Sony A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
17.		Sony A7	Full Frame	24.0	6000	4000	1080/60p	24.8	14.2	2248	90
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. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the A7S 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 A7S 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 A7S 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 A7S III	9440	n	3.0 / 1440	swivel	Y	1/8000s	10.0/s	n	Y
3.		Fujifilm X100V	3690	n	3.0 / 1620	tilting	Y	1/4000s	11.0/s	n	n
4.		Fujifilm X-Pro3	3690	n	3.0 / 1620	tilting	Y	1/8000s	8.0/s	n	n
5.		Fujifilm X-Pro2	2360	n	3.0 / 1620	fixed	n	1/8000s	8.0/s	n	n
6.		Fujifilm X-T2	2360	n	3.0 / 1040	full-flex	n	1/8000s	8.0/s	n	n
7.		Nikon D780	optical	Y	3.2 / 2359	tilting	Y	1/8000s	12.0/s	n	n
8.		Nikon Z50	2360	n	3.2 / 1040	tilting	Y	1/4000s	11.0/s	Y	n
9.		Panasonic S1	5760	Y	3.2 / 2100	full-flex	Y	1/8000s	9.0/s	n	Y
10.		Panasonic S1H	5760	Y	3.2 / 2330	swivel	Y	1/8000s	9.0/s	n	Y
11.		Panasonic FT7	1170	n	3.0 / 1040	fixed	n	1/1300s	10.0/s	Y	Y
12.		Sony A7R IVA	5760	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
13.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
14.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
15.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
16.		Sony A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
17.		Sony A7	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the A7S III and the fp is in-body image stabilization (IBIS). The A7S 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 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.

The fp writes its imaging data to SDXC cards, while the A7S III uses CFexpress (type A) or SDXC cards. The A7S III features dual card slots, which can be very useful in case a memory card fails. In contrast, the fp only has one slot. Moreover, both cameras support UHS-II cards (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 7S 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 A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Fujifilm X100V	Y	stereo / mono	Y	-	micro	3.1	Y	-	Y
4.		Fujifilm X-Pro3	Y	stereo / mono	Y	-	-	3.1	Y	-	Y
5.		Fujifilm X-Pro2	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
6.		Fujifilm X-T2	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
7.		Nikon D780	Y	stereo / mono	Y	Y	mini	3.1	Y	-	Y
8.		Nikon Z50	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
9.		Panasonic S1	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
10.		Panasonic S1H	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
11.		Panasonic FT7	-	stereo / mono	-	-	micro	2.0	Y	-	-
12.		Sony A7R IVA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
13.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
14.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
16.		Sony A7S II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
17.		Sony A7	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-

It is notable that the A7S 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.

Both the fp and the A7S III are recent models that are part of the current product line-up. The A7S III replaced the earlier Sony A7S II, while the fp does not have a direct predecessor. Further information on the features and operation of the fp and A7S III can be found, respectively, in the Sigma fp Manual (free pdf) or the online Sony A7S III Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Sigma fp or the Sony A7S III – has the upper hand? Is one clearly better than the other? Below is a summary of the relative strengths of each of the two contestants.

Reasons to prefer the Sigma fp:

• More detail: Offers more megapixels (24 vs 12MP) with a 41% higher linear resolution.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• 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 (2100k vs 1440k dots).
• Faster burst: Shoots at higher frequency (12 vs 10 flaps/sec) to capture the decisive moment.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More compact: Is smaller (113x70mm vs 127x97mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 277g or 40 percent) and hence easier to carry around.
• More affordable: Was introduced into a lower priced category (46 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in July 2019).

Arguments in favor of the Sony Alpha 7S 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 swivel 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.
• Longer lasting: Gets more shots (600 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.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• More modern: Was introduced somewhat (1 year) more recently.

If the number of relative strengths (bullet points above) is taken as a guide, the A7S III is the clear winner of the contest (15 : 10 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 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 Sigma fp and the Sony A7S 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 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 fp or the A7S 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 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 (USD)	Street Price
1.		Sigma fp	4/5	..	4/5	..	4/5	4.5/5	Jul 2019	1,899	amazon.com
2.		Sony A7S III	4.5/5	+ +	5/5	91/100	4.5/5	5/5	Jul 2020	3,499	amazon.com
3.		Fujifilm X100V	5/5	+ +	4.5/5	86/100	5/5	4.5/5	Feb 2020	1,399	ebay.com
4.		Fujifilm X-Pro3	4/5	+	4/5	85/100	4/5	..	Oct 2019	1,799	amazon.com
5.		Fujifilm X-Pro2	..	+	..	83/100	4.5/5	4.5/5	Jan 2016	1,699	ebay.com
6.		Fujifilm X-T2	5/5	+ +	..	86/100	4.5/5	5/5	Jul 2016	1,599	ebay.com
7.		Nikon D780	5/5	..	5/5	87/100	4.5/5	4.5/5	Jan 2020	2,299	amazon.com
8.		Nikon Z50	5/5	..	5/5	85/100	4.5/5	4.5/5	Oct 2019	859	amazon.com
9.		Panasonic S1	4.5/5	+ +	4.5/5	88/100	4.5/5	4/5	Feb 2019	2,499	amazon.com
10.		Panasonic S1H	..	..	4/5	90/100	..	..	May 2019	3,999	amazon.com
11.		Panasonic FT7	..	+	..	..	3.5/5	3.5/5	May 2018	449	ebay.com
12.		Sony A7R IVA	5/5	+	4.5/5	91/100	4.5/5	5/5	Apr 2021	3,499	amazon.com
13.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
14.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	ebay.com
15.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
16.		Sony A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
17.		Sony A7	5/5	+ +	..	80/100	5/5	5/5	Oct 2013	1,699	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. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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.

Check fp price at
amazon.com
Check A7S III price at
amazon.com

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. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting.

~

Check fp price at
amazon.com
Check A7S III price at
amazon.com

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