To optimize the portability of a serious travel camera (recommended here), get 1-inch Type sensor size or as large as APS-C sensor. Above this range, full-frame sensors overly increase camera weight for most travelers. Below “1-inch” size, sensors can suffer from poor image quality (especially in dim light) when making large prints. The archaic inch-sizing of sensors is clarified in the illustration and the table further below with relative sizes and millimeters.
For a given year of technological advance, a camera with physically bigger sensor area tends to capture better image quality by gathering more light, but at the cost of larger-diameter, bulkier lenses. Recent digital sensor advances have shrunk cameras and increased optical zoom ranges while preserving image quality. If you avoid using their poor digital zoom, even good smartphones such as Google Pixel, Samsung S6/S7, Apple iPhone 6s, and later can potentially make good 18-inch prints; plus smartphones can instantly share images. A powerful image can be created with any decent camera in the hands of a skilled or lucky photographer. But for superior optical zoom, better performance in dim light and sharper prints, get a bigger camera.
Below, compare sensor sizes for digital cameras:
In the above illustration, compare digital camera sensor sizes: full frame 35mm, APS-C, Micro Four Thirds, 1-inch, 1/1.7″ and 1/2.5” Type. For new digital cameras, a bigger sensor area captures better quality, but requires larger diameter, bulkier lenses. To optimize the size of a serious travel camera, consider 1-inch-Type sensor or up to APS-C sensor size. “Full-frame 35mm” sensor / film size (36 x 24 mm) is a standard for comparison, with a diagonal field-of-view crop factor = 1.0. In comparison, a pocket camera’s 1/2.5” Type sensor crops the light gathering by 6.0x smaller diagonally (with a surface area 35 times smaller than full frame).
1″-Type sensor size is now optimal for travel camera portability:
I upgrade my digital camera every 2-4 years because the latest devices keep beating older models. As of 2016, a 1″-Type sensor size is perfect for a portable, lightweight travel camera, as in the following which capture excellent dynamic range (bright to dark) with exceptionally fast autofocus:
Or the following top APS-C-sensor camera lets you interchange lenses (though I prefer the above all-in-one solutions for travel convenience):
The next step up to full-frame-sensor cameras costs extra, adds bulk, and is only needed if you regularly shoot in dim light higher than ISO 6400, or often print images larger than 2 or 3 feet in size to be viewed closer than their longest dimension by critically sharp eyes.
But huge effective billboards can be printed from compact 3-megapixel cameras (read my article).
How to compare cameras
- My CAMERAS article updates Light Travel camera recommendations several times per year.
- If possible, compare cameras shot side-by-side under a variety of actual field conditions (which I do just before selling a former camera to confirm the quality of the new replacement camera). I like to “pixel-peep” a side-by-side comparison of two different cameras capturing the same subject under same lighting conditions. Be sure to mentally or digitally normalize any two given shots to compare their fine detail as if printed with equal overall image size.
- I judge image quality and resolution not by megapixel (mp) count but instead by comparing standardized studio test views at 100% pixel enlargement and checking resolvable lines per picture height (LPH), at the authoritative dpreview.com (owned by Amazon since 2007) and handy Comparometer at imaging-resource.com. Check other review sites analyzing a camera’s telephoto in addition to standard lens.
For me, yearly advances as of 2014-16 put the sweet spot for a serious travel camera between 1”-Type and APS-C size sensors. Most cheaper compact cameras have smaller but noisier sensors such as 1/2.3″ Type (6.17 x 4.56 mm) — tiny enough to miniaturize a superzoom lens (above 15x zoom range), but poor for capturing dim light or for enlarging prints much beyond 12-18 inches.
Smartphones can have even tinier sensors, such as 1/3.0″ Type (4.8 mm x 3.6 mm) in iPhone 5S. Top smartphone cameras have improved miniature sensors to the point where citizen journalists can capture newsworthy photos with image quality good enough for fast sharing and quick international publication. My Samsung Note 5 smartphone (same camera as S6/S7 with 1/2.6″ sensor) captures sunny 16 MP images sufficient to make a sharp 18-inch print, virtually indistinguishable from that taken by a larger camera. Tip: avoid the digital zoom on smartphones, and instead move closer before shooting or crop at editing time, if needed to isolate subjects.
Read this pointed perspective on how far image quality has progressed from early DSLR to 2014 smartphone cameras. Historically, evocative images can clearly be captured regardless of camera size or modernity. But for a given year of technological advance, tiny-sensor cameras can have severe limitations compared to physically larger cameras in terms of print enlargement, autofocus speed, blurred performance in dim or indoor light, and so forth. The “best” travel camera is the one that you are willing to carry.
The non-standardized fractional-inch sensor sizing labels such as 1/2.5-inch Type and 1/1.7″ Type confusingly refer to antiquated 1950s-1980s vacuum tubes. When you see those archaic “inch” size labels, instead look up the actual length and width in millimeters reported in the specifications for each camera:
Table of camera sensor size, area, and diagonal crop factor relative to 35mm full-frame
||Sensor Area (in square millimeters)
||Full frame sensor area is x times bigger
||Diagonal crop factor* versus full frame
|1/3.2″ (Apple iPhone 5 smartphone 2012)
|1/3.0″ (Apple iPhone 5S smartphone 2013)
|1/2.6″ Type (Samsung Galaxy S6 & Note 5 in 2015)
|1/2.3″ Type (Canon PowerShot SX280HS, Olympus Tough TG-2)
|1/1.7″ (Canon PowerShot S95, S100, S110, S120)
|1/1.7″ (Pentax Q7)
|2/3″ (Nokia Lumia 1020 smartphone with 41 MP camera; Fujifilm X-S1, X20, XF1)
|Standard 16mm Film Frame
|1” Type (Sony RX100 & RX10, Nikon CX, Panasonic FZ1000)
|Micro Four Thirds, 4/3
|APS-C: Canon EF-S
|APS-C: Nikon DX, Sony NEX/Alpha DT, Pentax K
||28.2 – 28.4
||23.6 – 23.7
||368 – 370
||1.52 – 1.54
|35mm full-frame (Nikon FX, Sony Alpha/Alpha FE, Canon EF)
||43.2 – 43.3
||23.9 – 24.3
||860 – 864
|Kodak KAF 39000 CCD Medium Format
|Hasselblad H5D-60 Medium Format
|Phase One P 65+, IQ160, IQ180
|IMAX Film Frame
* Crop Factor: Note that a “full frame 35mm” sensor/film size (about 36 x 24 mm) is a common standard for comparison, having a diagonal field of view crop factor of 1.0. The debatable term crop factor comes from an attempt by 35mm-film users to understand how much the angle of view of their existing full-frame lenses would narrow (increase in telephoto power) when mounted on digital SLR (DSLR) cameras which had sensor sizes (such as APS-C) which are smaller than 35mm.
With early DSLR cameras, many photographers were concerned about the loss of image quality or resolution by using a digital sensor with a light-gathering area smaller than 35mm film. However, for my publishing needs, APS-C-size sensor improvements easily surpassed my scanning of 35mm film by 2009.
An interesting number for comparing cameras is “Full frame sensor area is x times bigger” in the above table.
- In comparison to full a frame sensor, a pocket camera’s 1/2.5-inch Type sensor crops the light gathering surface 6.0 times smaller diagonally, or 35 times smaller in area.
- An APS-C size sensor gathers about 15 times more light (area) than a 1/2.5” Type sensor and 2.4 times less than full frame.
- APS-C sensors in Nikon DX, Pentax, and Sony E have 1.5x diagonal field of view crop factor.
- APS-C sensors in Canon EF-S DSLRs have 1.6x diagonal field of view crop factor.
- 1 stop is a doubling or halving of the amount of gathered light. Doubling a sensor’s area theoretically gathers one stop more light.
Lens quality & diameter also affect image quality
For improving image quality, the quality and diameter of the lens can rival the importance of having a physically larger sensor area. Prime (non-zoom) lenses usually are sharpest for larger prints, but zoom lenses are more versatile and recommended for travelers.
Small sensor can beat larger with newer design (BSI) plus faster optics:
In my side-by-side field tests, the sharp, bright 25x zoom of Sony RX10 III resoundingly beats the resolution of 11x SEL18200 lens on flagship APS-C Sony A6300 at 90+ mm equivalent telephoto, even as high as ISO 6400. (Wider angle zoom settings show little quality difference.) Apparently RX10’s faster f/2.4-4 lens plus backside illumination (BSI) technology magically compensate for the sensor size difference, 1″-Type versus APS-C. Like most APS-C-sensor cameras in 2016, A6300 lacks BSI. Surprisingly little noise affects RX10’s image quality at high ISO 6400 in dim light. Its larger lens diameter gathering more light also helps in this comparison (72mm filter size of RX10 III versus 67mm SEL18200 on A6300).
Larger lens diameter can help dim light photography:
In my field tests, the linear sharpness of Sony’s high-quality SEL1670Z 3x zoom f/4 lens on flagship A6300 is only about 5% better than Sony RX10 III f/2.4-4 in bright light in the wider half of its 24-105mm equivalent range, but no better in dim light. I expect that RX10’s catch-up in quality under dim light is due to superior light sensitivity of BSI sensor plus larger lens diameter gathering more light, 72mm versus 55mm.
Using sweet spot of full-frame lenses on APS-C may not improve quality:
In principle, you might expect a slightly sharper image on an APS-C sensor when using the sweet spot of a lens designed for a full frame (which has a larger imaging circle), but results actually vary, especially when using older film-optimized lenses. In fact, a lens which is designed and optimized specially “for digital, for APS-C” can equal or exceed the quality of an equivalent full-frame lens on the same sensor, while also reducing bulk and weight (as in the Sony E-mount example further below).
Theoretically, new full-frame lenses “designed for digital” (using image-space telecentric design) may perform better on a digital sensor than would older lenses designed for film:
- Unlike film, digital sensors receive light best when struck squarely rather than at a grazing angle.
- Digital cameras perform best with lenses optimized specially “for digital”, using image-space telecentric designs, in which all the rays land squarely on the sensor (as opposed to having incoming rays emerge at the same angle as they entered, as in a pinhole camera). The light buckets (sensels) on digital sensors require light rays to be more parallel than with film (to enter at close to a 90 degree angle to the sensor).
- Film can record light at more grazing angles than a digital sensor. Because older film-optimized lenses bend light to hit the sensor at more of a glancing angle, they reduce light-gathering efficiency and cause more vignetting around the edges (which is somewhat mitigated by the image circle being cropped by the APS-C sensor, which uses just the center part of the full-frame lens).
Side-by-side testing works better than theory to distinguish lenses:
Compare the following two Sony E-mount zoom lenses, full-frame versus APS-C:
- 2015 full-frame “Sony E-mount FE 24-240mm f/3.5-6.3 OSS” lens (27.5 oz, 36-360mm equivalent).
- 2010 APS-C “Sony E-mount 18-200mm f/3.5-6.3 OSS (silver SEL-18200)” lens (18.5 oz, 27-300mm equiv).
Both lenses are optimized for digital, yet the APS-C lens is much lighter weight and performs equal to or better than the full-frame lens. Side-by-side comparisons and also DxOMark tests on a Sony A6000 camera show that while they are about equally sharp, the Sony 24-240 has more distortion, vignetting and chromatic aberration than the 18-200mm.
Raw format and advantages of large sensors over small
For a given angle of view, cameras with larger sensors can achieve a shallower depth of field than smaller sensors, a feature which movie makers and portrait photographers like to use for blurring the background (at brightest aperture setting, smallest F number value) to draw more attention to the focused subject. Conversely, smaller-sensor cameras like the Sony RX10 III and RX100 III tend to be much better at capturing close-focus (macro) shots with great depth of field(especially at wide angle), at ISO up to 800. But the macro advantages of small-sensor cameras can diminish in dim light or when shooting at ISO higher than 800.
Landscape photographers often prefer to capture a deep depth of field, which can be achieved with both small and large sensor cameras. Optimal edge-to-edge sharpness usually occurs when stopping down the aperture once or twice from brightest opening, such as between f/4 to f/5.6 on 1-inch Type sensor, or between f/5.6 to f/8 on APS-C (which also helps diminish chromatic aberrations). Stopping down further with f/numbers larger than this increases depth of field, but worsens diffraction through the smaller pupil opening (such as at f/11-f/16 on 1″ sensor or f/22 on APS-C), noticeably softening detail.
To maximize raw dynamic range of brightness values from bright to dark, use base ISO (around ISO 100 or 200 in most digital still cameras), rather than higher ISO settings which amplify noise (blotchiness at the pixel level, most-visibly in shadows). However, using the latest full-frame sensors at high ISO values 6400+ can capture unprecedentedly low noise and open new possibilities for dim-light action photography at hand-held shutter speeds, indoors or at night.
Without the help of a flash, night and dim indoor photography is best with a full-frame sensor to gather more light with less noise. Low-noise night photography is usually best shot on a tripod at slow shutter speeds in raw format between ISO 100 and 800 (or as high as 1600-3200 on the latest large sensors).
For a given year of technological advance, cameras with larger sensors typically capture a wider dynamic range of brightness values from bright to dark per image than smaller sensors, with less noise. In 2016, Sony’s 1″-Type backside illumination (BSI) sensors capture sufficient dynamic range for my needs.
Camera raw format allows editing recovery of several stops of highlight and shadow detail which would be lost (truncated) in JPEG file format (if overexposed or underexposed). Alternatively, PC software or camera firmware using HDR (High Dynamic Range) imaging lets any size of sensor greatly increase an image’s dynamic range by combining multiple exposures. But for me, the great dynamic range of a single raw file (from 1″-Type BSI or APS-C sensor) usually makes shooting extra images for HDR unnecessary.
Despite advanced circuitry, cameras are not smart enough to know which subjects are supposed to be white, black, or midtone in brightness. By default, all cameras underexpose scenes where white tones (such as snow) predominate, and overexpose highlights in scenes where black tones predominate. IMPORTANT TIP: To correctly expose for all tones, you need to lock exposure upon an actual midtone (such as a gray card; or on a line halfway between light and shadow) in the same light as your framed subject.
For greatest editing flexibility, rather than shooting JPEG format, serious photographers should record and edit images in raw format, which is supported in advanced cameras (but often not in small-sensor devices). Editing raw format fully recovers badly-exposed images − allowing you to “point and shoot” more freely than with JPEG. Even so, I carefully shoot to expose each histogram to the far right while avoiding truncation of highlights, in order to capture the highest signal-to-noise ratio in each scene. Try to stay close to base ISO 100 or 200. I typically first shoot a test shot on automatic Aperture-preferred priority, inspect the histogram, check any blinking highlight warnings, then compensate subsequent shots using Manual Exposure (or temporary Exposure Lock grabbed from the scene). Tonal editing of JPEGs can quickly truncate color channels or accumulate round-off errors, often making the image appear pasty, pixelated, or posterized. White Balance (Color Balance) is easily adjustable after shooting raw files, but tonal editing often skews colors oddly in JPEG. 12-bit Raw format has 16 times the tonal editing headroom and color accuracy compared to JPEG (which has only 8 bits per pixel per red, green, or blue color channel). In their favor, automatic point-and-shoot JPEG camera exposure modes get smarter every year, making advanced larger cameras less necessary for many people.
Detailed full-frame comparison of low-light Sony A7S 12 MP versus A7R 36 MP
How can we distinguish the image quality captured by different cameras? Images are best compared at a normalized pixel level (with fine detail examined on a monitor as if printed with equal overall image size) after shooting side-by-side in the field with comparable lens and shutter speed settings. Consider two sibling full-frame-sensor cameras:
- Sony Alpha A7S (12 MP of large-bucket photosites optimized for high ISO, low light, and videography plus stills, new in 2015) versus
- Sony Alpha A7R (36 megapixels of smaller-bucket photosites optimized for high resolution, new in 2014)
Despite its tinier but denser photosite buckets (also called sensels or pixel wells for catching light photons), the 36 MP Sony Alpha A7R beats the dynamic range of 12 MP Sony Alpha A7S in a normalized comparison of raw files (see dpreview article). While both cameras spread their photosites across the same surface area of a full-frame sensor, the 36 MP A7R trumps the 12 MP A7S for exposure latitude flexibility in raw post-processing at ISO 100 through 6400. Overall image quality of the 12 MP A7S doesn’t beat the A7R until ISO 12,800 and higher (but only in the shadows through midtones under low-light conditions). Sony A7S is better for low-light videographers, whereas A7R is better for low-light landscape photographers who value high resolution and dynamic range.
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