To bring far away subjects closer into the frame photographers have a choice to either use a telephoto zoom lens or to move closer to take the shot at a closer focal length. The latter is not always possible, and many photographers rely on a variety of zoom lens options for bringing a variety of subjects closer.
DSLR and Compact Zoom Options
A DSLR (digital single-lens reflex) camera system consists primarily of a camera body and one / variety of removable lenses, covering various focal lengths, for different photography genres. One lens category is zoom (standard / telephoto) lenses to capture distant subjects such as certain landscapes, wildlife and / or sporting activities.
Canon standard zoom versus telephoto zoom lenses
DSLR zoom lenses cover different focal lengths ie 18-55mm and telephoto zoom lenses are zoom lenses with longer focal lengths ie. 55-250mm (see table below).
Typical focal zoom lengths of standard / telephoto zoom lenses as categorized by some of Canon's EF-S (standard / telephoto) / EF lens (telephoto) ranges:
- Canon EF-S 18-55mm f/3.5-5.6 IS STM (standard)
- Canon EF-S 18-135mm f/3.5-6 IS STM (standard)
- Canon EF-S 18-200mm f/3.5-5.6 IS (standard)
- Canon EF-S 55-250mm f/4- 5.6 IS STM (telephoto)
- Canon EF 70-200mm f/4 L IS USM (telephoto)
- Canon EF 70-300mm f/4-5.6 IS USM (telephoto)
- Canon EF 100-400mm f4.5-5.6L IS USM (telephoto)
A compact zoom camera facilitates a fix lens capable of wide-angle to very far reaching focal lengths ranging from 18mm to a whopping 1200mm+ optical (and digital) super zoom (ie. 50x zoom on the Canon PowerShot SX50 HS). For many enthusiast photographers this is a very cost-effective and all round solution with good all-round image quality.
This beckons the question: why do photographers require DSLR-type telephoto zoom lenses between 100-400mm (ie. the Canon EF 100-400mm f4.5-5.6L IS USM lens) if a compact camera offers more optical zoom?
A DSLR camera system is by [optical] design superior / more versatile ito:
- Compatibility with purpose-designed (Macro / Ultra-Wide / Prime / Zoom) lenses.
- Superior optical lens design and quality multiple lens elements.
- Faster Auto-Focusing (AF) / Optical Image Stabilization (IS) systems.
- Larger image sensors capable of much higher image quality (in various lighting conditions) than advanced / super-zoom compact cameras.
Difference between Optical and Digital zoom (demo)
Optical Zoom
Optical zoom uses the actual lens optics to transmit and magnify light via various lens elements to the camera's image sensor. It works similar to a binoculars and use various ratios of magnification to zoom in or out to subjects of what the photographer will see in the camera's viewfinder and / or LCD screen. This is also refereed to as true zoom.
Example: Images 1-3 with the Canon PowerShot SX40 HS (35x optical zoom covering a focal length range of 24-840mm)
Digital Zoom
Digital zoom is generally added 'at the end' of the optical zoom range (on most compact cameras) and will enlarge the optical framed image at the maximum optical range similar to cropping in software post-processing. It retains the aspect ratio, but with the lack of optical resolution may see an increase in digital noise (as cropping is applied),
Example: Images 4 / 5 with the Canon PowerShot SX40 HS (140x zoom - including 35x optical zoom). Both images are at 840mm with extended digital zoom applied to 1700mm and 3497mm.
Cape Town Shooting Location
From Arnhem, Milnerton Cape town (over Table Bay)
(Click to Enlarge)
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| Image 1: Optical Zoom +- 24mm (35mm eqv) f/8 ISO 100 |
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| Image 2: Optical Zoom +- 133mm (35mm eqv) f/8 ISO 100 |
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| Image 3: Optical Zoom +- 840mm (35mm eqv) f/8 ISO 100 |
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| Image 4: Digital Zoom +- 1700mm (35mm eqv) f/8 ISO 100 |
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| Image 5: Digital Zoom +- 3497mm (35mm eqv) f/8 ISO 100 Canon EOS 6D / EF 70-300mm f/4-5.6L IS USM Lens - Zoom Test Canon EOS 6D / EF 70-300mm f/4--5.6L IS USM Lens - Zoom Test Zoom Test: Canon EOS 7D Mark II / EF 100-400mm f/4.5-5,6L IS II USM Lens Zoom Test: Canon EOS 7D Mark II / EF 100-400mm f/4.5-5,6L IS II USM Lens |