Canon EOS Rebel XTi vs Pentax K-3 Mark III Monochrome

In this comparison, we will evaluate the Canon EOS Rebel XTi and the Pentax K-3 Mark III Monochrome, highlighting the advantages of each over the other, discussing their pros and cons, shared strengths and weaknesses, and providing a rating based on their available features and specifications to assist you in choosing the one that best suits your needs.

Canon EOS Rebel XTi was introduced in October 2006 and Pentax K-3 Mark III Monochrome was introduced in April 2023. Let us first list highlights of the models.

Now that we've looked at the most essential specifications and gained a basic understanding of these cameras, we can delve into more details and see the differences between them.

This section shows those features and specifications which are the reason to choose Canon EOS Rebel XTi over Pentax K-3 Mark III Monochrome.

This section shows those features and specifications which are the reason to choose Pentax K-3 Mark III Monochrome over Canon EOS Rebel XTi.

We already listed pros and cons of each model. However, you may also find useful to look at their common strengths and weaknesses shown side-by-side.

Screen

Canon EOS Rebel XTi has a 2.5" screen with 230k dot resolution and Pentax K-3 Mark III Monochrome has a 3.2" screen with 1,620k dot resolution. Both have Fixed screens. Pentax K-3 Mark III Monochrome also features touchscreen which has advantages such as easy menu navigation, intuitive controls, quick setting adjustment and most importantly a Touch-to-Focus functionality (available only on Pentax K-3 Mark III Monochrome) allowing users to select a specific point on the screen where they want the camera to focus. This feature can be helpful for achieving precise focus in both photo and video recording.

Viewfinder

Canon EOS Rebel XTi has a built-in Optical (pentamirror) viewfinderPentax K-3 Mark III Monochrome has a built-in Optical (pentaprism) viewfinder. Canon EOS Rebel XTi has 95% coverage with 0.80x (0.50x 35mm equivalent) magnification and Pentax K-3 Mark III Monochrome has 100% coverage with 1.05x (0.70x 35mm equivalent) magnification.

Canon EOS Rebel XTi features a 10.0 megapixel APS-C CMOS sensor with dimensions of 22.2 x 14.8 mm and a total area of 328.6 mm². Its native ISO range is 100 - 1,600. Pentax K-3 Mark III Monochrome features a 25.73 megapixel APS-C CMOS sensor with dimensions of 23.3 x 15.5 mm and a total area of 240.3 mm². Its native ISO range is 200 - 1,600,000.

Here is a sensor size comparison chart where you can see how different sensors compare with each other:

Sensor size chart

	Sensor	Dimensions	Area	Aspect Ratio	Crop Factor
	Medium Format	44 x 33 mm	1452 mm2	4:3	0.79x
	Full Frame	36 x 24 mm	864 mm2	3:2	1x
	APS-H	27 x 18 mm	486 mm2	3:2	1.3x
	APS-C	23.6 x 15.6 mm	368.2 mm2	3:2	1.5x
	APS-C (Canon)	22.3 x 14.9 mm	332.3 mm2	3:2	1.6x
	Micro Four Thirds	17.4 x 13 mm	226.2 mm2	4:3	2x
	1-inch	13.2 x 8.8 mm	116.2 mm2	3:2	2.7x
	1/1.7-inch	7.44 x 5.58 mm	41.5 mm2	4:3	4.7x
	1/2.3-inch	6.17 x 4.55 mm	28.1 mm2	4:3	5.6x

Canon EOS Rebel XTi can take pictures up to 3888 x 2592 resolution. It can also take pictures with lower resolution like 2816 x 1880, 1936 x 1288 with 3:2 aspect ratios. Pentax K-3 Mark III Monochrome is equipped with PRIME V processor and can take pictures up to 6192 x 4128 resolution.

Lens Mount

Canon EOS Rebel XTi has Canon EF/EF-S lens mount and Pentax K-3 Mark III Monochrome has Pentax K_AF2 lens mount. They both have APS-C sensor but because of a small size difference their crop factors (also called lens multiplier) differ from each other. Canon EOS Rebel XTi has the crop factor of 1.6x which means that a 35mm equivalent focal length of the mounted lens will be equal to its actual focal length times 1.6. Pentax K-3 Mark III Monochrome has the crop factor of 1.5x which means that a 35mm equivalent focal length of the mounted lens will be equal to its actual focal length times 1.5.

No Low-Pass Filter on Pentax K-3 Mark III Monochrome

There is no optical low-pass filter (OLPF), also known as an anti-aliasing filter, in front of the sensor on Pentax K-3 Mark III Monochrome. This results in a slightly sharper image but may also introduce moiré patterns and aliasing artifacts when photographing subjects with fine, repetitive patterns or details.

In-Body Image Stabilization on Pentax K-3 Mark III Monochrome

Pentax K-3 Mark III Monochrome has a built-in Sensor Shift in-body image stabilization (IBIS) with 5.5 stops of compensation. This means that you are still getting vibration reduction when camera is paired with non-image stabilizied lenses. It also works with lenses with optical image stabilization and in combination can achieve even better compensation.

Built-in Wi-Fi on Pentax K-3 Mark III Monochrome

Pentax K-3 Mark III Monochrome has a built-in Wi-Fi (802.11b/g/n, 2.4 GHz) which allows to easily transfer photos and videos from the camera to other Wi-Fi-enabled devices, such as smartphones, tablets, printers, or computers. This eliminates the need for cables and allows for quick and convenient media sharing and social media integration. It gives you the ability to control your camera remotely using a smartphone or tablet. This is particularly useful for taking self-portraits, group shots, or capturing images in challenging conditions without having to touch the camera. Firmware updates can also be downloaded and installed wirelessly.
  Check out the cameras in our database that have built-in WiFi.

Bluetooth on Pentax K-3 Mark III Monochrome

Pentax K-3 Mark III Monochrome has a built-in Bluetooth which lets you to connect the camera to a smartphone or a dedicated remote control device. This allows you to remotely trigger the camera, adjust settings and controls remotely through a paired mobile app. While Wi-Fi is generally faster for transferring larger files, Bluetooth can be used for small, selective transfers, it can provide real-time information about your camera's battery status, memory card capacity, and other key settings directly on your paired smartphone or smartwatch.
  Check out the cameras in our database that have built-in Bluetooth.

USB Inputs and HDMI Outputs

Both models have USB inputs for data transfer. connector for video signal output.

Battery

Pentax K-3 Mark III Monochrome comes with D-LI90 battery pack with battery life of 800 shots.

External Storage Slots

Canon EOS Rebel XTi has a single CompactFlash (Type I/II) card slot. Pentax K-3 Mark III Monochrome has two card slots - one for SD/SDHC/SDXC (UHS-II) and one for SD/SDHC/SDXC (UHS-I).

Shutter

Canon EOS Rebel XTi has Electronically Controlled Vertical-travel Mechanical Focal-plane shutter. Pentax K-3 Mark III Monochrome has Electronic shutter. Shutter speed can go up to 1/4000 sec on Canon EOS Rebel XTi, and up to 1/16000 sec with electronic shutter and up to 1/8000 sec with mechanical shutter on Pentax K-3 Mark III Monochrome. Canon EOS Rebel XTi can shoot continuously up to 3.0 fps. Pentax K-3 Mark III Monochrome can shoot continuously up to 12.0 fps.

Focusing

Canon EOS Rebel XTi has Dual Pixel CMOS AF system with 9 focusing points and Pentax K-3 Mark III Monochrome has 101 (25 cross-type) focusing points. Pentax K-3 Mark III Monochrome has detection range from -3 to +19 EV.

Exposure

Exposure meterings of Canon EOS Rebel XTi and Pentax K-3 Mark III Monochrome range from +1 to +20 EV and -2 to +21 EV respectively and you can set the exposure compensation within the ±2 EV range on Canon EOS Rebel XTi and ±5 EV range on Pentax K-3 Mark III Monochrome. You can also do exposure lock and manual exposure adjustment on Canon EOS Rebel XTi and exposure lock, exposure bracketing and manual exposure adjustment on Pentax K-3 Mark III Monochrome.

Flash

Canon EOS Rebel XTi has a built-in flash with maximum range of 12.00 m at ISO 100 and also accepts external flash. Pentax K-3 Mark III Monochrome has no built-in flash but an external flash may be connected via Hot Shoe or PC Terminal. The fastest flash synchronization speed is 1/200 sec on both cameras.

Canon EOS Rebel XTi body has dimensions of 127 x 94 x 65 mm (5 x 3.7 x 2.56") and Pentax K-3 Mark III Monochrome body has dimensions of 135 x 104 x 74 mm (5.31 x 4.09 x 2.91"). Canon EOS Rebel XTi weighs 556 g (1.23 lb / 19.61 oz) and Pentax K-3 Mark III Monochrome weighs 820 g (1.81 lb / 28.92 oz).

Canon EOS Rebel XTi

Pentax K-3 Mark III Monochrome

127 mm

94 mm

135 mm

104 mm

94 mm

104 mm

65 mm

74 mm