Have you ever been confused by the many abbreviations whenever you look at a piece of lens? And how branding these abbreviations on the lens itself will make the price tag jump a mile? As an amateur photographer using a Nikon DSLR, I was also once lost in the ocean of alphabets. Now that I have sorted things out, I will try to explain the codes used in Nikkor and Sigma lenses. Please contribute if you find inaccuracy in my explanations.
Buying a Lens
The reason that you have chosen to buy a DSLR instead of a prosumer digital camera is no doubt the ability to change lenses to customize to your shooting interest. Since the time of 35mm (film) SLR, there are already thousands of lenses in the market to choose from. Since we are in the context of Nikon DSLR, you are probably asking whether you can use the older lenses meant for 35mm SLR, instead of the recommended ‘digital’ lenses (made specifically for DSLR only)? Which focal-length ranges will give you the maximum worth? Do single-focal-length lenses have any advantage over zoom lenses? Is a separate macro lens necessary if your zoom lens has a macro setting?
The Sensor
There are high-end professional DSLR like a Canon EOS 1DS Mk.II that has a 24x36mm CMOS image sensor (same size as a 35mm film frame), an Olympus E-series DSLR that uses a smaller Four-Thirds CCD sensor, you can safely assume that your entry/mid-range level DSLR uses a CCD or CMOS image sensor that measures about 15.6x22.3mm (same size as APS-C film cameras). This format has the same 2:3 aspect ratio and is 1.5x smaller than 35mm, thus will fit a 4x6-inch print perfectly. However, when it comes to lenses selection, the effect of the smaller sensor comes into play with the consideration of Crop Factor (1.5x or 1.6x) and Focal Length Multiplier (FLM, see below).
(CLICK ON THUMBNAILS BELOW TO ENLARGE)
Left: Image at 200mm on film SLR using a 200mm lens
Middle: Image at 300mm (35mm equivalent) on DSLR using the same 200mm lens
Right: Image at 200mm (35mm equivalent) on DSLR using a 133mm lens
The Standard Lens
Most people who buy a new DSLR get it with the standard “normal zoom” lens, such as an 18-55mm (28-70mm in 35mm equivalent). It is usually also of moderate speed, f/3.5 at the wide-angle setting and f/5.6 at the telephoto end. No doubt these are useful general-purpose lenses for getting started, but they cannot do everything. They are not wide enough to record landscape scenery or get the whole family shot in a small interior. At the telephoto end, they do not provide ideal focal lengths for portraits, sports action or wildlife subjects. They are do not have fast apertures (f/1.4 - f/2.8) that are ideal for lowlight non-flash shooting.
What about the wide-angle lenses?
To go really wide, this is a good idea if you shoot a lot of landscapes and group shots; by all means consider an 11-18mm zoom lens (17-28mm lens in 35mm). Such lenses are also usually of moderate f/4.5-5.6 aperture, so if you need something faster, opt for something with constant f/2.8 aperture, it is a commonly used by professional low-light shooters.
Focal Length Multiplier (FLM)
The diagonal dimension of the 35mm format (43.3mm) is about 1.5x or 1.6x the diagonal of your DSLR APS format (27 or 28mm).The diagonal represents the diameter of the image circle the lens must provide to give an overall sharp image. This 1.5x or 1.6x is also called the Focal Length Multiplier (FLM).
You should multiply the focal length of any given lens you use on your DSLR by 1.5 or 1.6 to calculate its “35mm equivalent focal length.”
Examples: A 50mm lens that works as a standard lens on your 35mm SLR and delivers a picture X, but when the lens is used on a DSLR, it actually works like a 75mm (50mm x 1.5) telephoto lens on a DSLR and delivers a picture x. x is thus a cropped image of the picture X. So when both x and X are developed on a same 4R print, the subject actually appears larger in X. (See graphic below for a better understanding)
Thus, when you decide to use an older wide lens (eg. 35mm SLR lens) on a DSLR, it becomes less wide (work as 52.5mm lens).
(CLICK ON THUMBNAILS BELOW TO ENLARGE)
Left: 4R Print from Image at 200mm on film SLR using a 200mm lens
Middle: 4R Print from Image at 300mm (35mm equivalent) on DSLR using the same 200mm lens
Right: 4R Print from Image at 200mm (35mm equivalent) on DSLR using a 133mm lens
So what about the ‘digital’ lenses? Do I have to take the FLM into account?
Yes, you must. Irregardless whether the lenses are made only for DSLR or not, all stated focal length are based on 35mm format. Eg. D50 kit lens (AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6G ED) is actually an 27-82.5mm lens (equivalent to 35mm). Or to put it simply, the picture from this 18-55mm lens on a DSLR, will look exactly the same as one from a 27-82.5mm lens on a film SLR.
So can I use the any old SLR lenses on my DSLR?
Yes, you can. Just note that FLM applies here. Eg. AF 70-300mm f/4.5-5.6G lens functions as 70-300mm telephoto zoom lens with a film SLR. However, with a DSLR, the lens will function as a 105-450mm (post FLM, 35mm equivalent).
So can I use 'digital' lenses on my film SLR?
Technically yes but its not recommended. 'Digital' lenses are made such that they are optimised for DSLRs. They have a smaller image circle than conventional film SLR. Hence, should you take a picture with your SLR using a 'digital' lens; your picture will most likely suffer from abberations around the edges.
What about the image quality of 35mm lenses on DSLRs?
There are three key factors, (1) the angle at which the lens’s light rays strike the sensor, (2) anti-reflection coatings, and (3) optimum format coverage.
(1) The edge light rays transmitted by many ultra-wide-angle lenses designed for 35mm SLR strike the image sensor at very oblique angles. This was perfectly acceptable when film was the capture medium, but it can cause image degradation at the edges and corners of the field when CCD and CMOS sensors are used. This effect can significant in side-by-side comparison pictures shot with 35mm and 'digital' ultra-wide-angle lenses on professional (24x36mm format) DSLRs, but it is far less significant with consumer DSLRs using APS-sized image sensors. It is also true that digitally optimized lenses made by camera makers and leading independents (e.g. Tamron Di lenses) use improved coatings designed to reduce flare, which is more likely to affect pictures taken with digital imaging systems. However, the most important lens factor affecting DSLR image quality is optimum format coverage. In general, lenses specifically designed to cover the APS-C format have an inherent image-quality advantage over lenses designed to cover the larger 35mm format because their coverage precisely matches the frame.
Which focal lengths and lens types to buy?
An 18-200mm 'digital' lens is an excellent choice, providing the equivalent of a 28-300mm in 35mm. You can leave this on as the default lens since you most likely need not switch lens, hence minimizing the possibility of dust getting on your image sensor. The only 'con' to such a long-range zoom lens is that its aperture is usually fairly small (f/6.3 at 200mm). A nice solution would be getting a 180mm f/3.5 macro lens, which would provide a long tele setting (270mm in 35mm terms) plus the ability to focus down to 1:1 (life-size). And speaking of fast macro lenses, a 90mm f/2.8 (equal to the classic 135mm tele for 35mm) is another good choice that will also get down to 1:1 and is also great for portraits. Do not worry about overlap or duplicate your normal zoom (standard kit lens). If you’re in the market for a new DSLR, buy the body only and make the 18-200mm your “universal” zoom lens!
~Nikkor and Sigma~
NIKKOR LENSES
ED
ED glass — an essential element of Nikkor telephoto lensesNikon developed ED (Extra-low Dispersion) glass to enable the production of lenses that offer superior sharpness and color correction by minimizing chromatic aberration.Put simply, chromatic aberration is a type of image and color dispersion that occurs when light rays of varying wavelengths pass through optical glass. In the past, correcting this problem for telephoto lenses required special optical elements that offer anomalous dispersion characteristics — specifically calcium fluoride crystals. However, fluorite easily cracks and is sensitive to temperature changes that can adversely affect focusing by altering the lens’ refractive index.So Nikon designers and engineers put their heads together and came up with ED glass, which offers all the benefits, yet none of the drawbacks of calcium fluorite-based glass. With this innovation, Nikon developed several types of ED glass suitable for various lenses.They deliver stunning sharpness and contrast even at their largest apertures. In this way, Nikkor’s ED-series lenses exemplify Nikon’s preeminence in lens innovation and performance.
SIC
Nikon Super Integrated Coating ensures exceptional performanceTo enhance the performance of its optical lens elements, Nikon employs an exclusive multilayer lens coating that helps reduce ghost and flare to a negligible level.Nikon Super Integrated Coating achieves a number of objectives, including minimized reflection in the wider wavelength range and superior color balance and reproduction. Nikon Super Integrated Coating is especially effective for lenses with a large number of elements, like our Zoom-Nikkors.Also, Nikon's multilayer coating process is tailored to the design of each particular lens. The number of coatings applied to each lens elementis carefully calculated to match the lens type and glass used, and also to assure the uniform color balance that characterizes Nikkor lenses. This results in lenses that meet much higher standards than the rest of the industry.
N
Nano Crystal CoatNano Crystal Coat is an antireflective coating that originated in the development of NSR-series (Nikon Step and Repeat) semiconductor manufacturing devices. It virtually eliminates internal lens element reflections across a wide range of wavelengths, and is particularly effective in reducing ghost and flare peculiar to ultra-wideangle lenses. Nano Crystal Coat employs multiple layers of Nikon’s outstanding extra-low refractive index coating, which features ultra-fine crystallized particles of nano size (one nanometer equals one millionth of a mm). Nikon now proudly marks a world first by applying this coating technology to a wide range of lenses for use in consumer optical products.
ASP
Aspherical lens elementsNikon introduced the first photographic lens with aspherical lens elements in 1968. What sets them apart? Aspherical lenses virtually eliminate the problem of coma and other types of lens aberration — even when used at the widest aperture. They are particularly useful in correcting the distortion in wideangle lenses. In addition, use of aspherical lenses contributes to a lighter and smaller lens design.Nikon employs three types of aspherical lens elements. Precision-ground aspherical lens elements are the finest expression of lens-crafting art, demanding extremely rigorous production standards. Hybrid lenses are made of a special plastic molded onto optical glass. Molded glass aspherical lenses are manufactured by molding a unique type of optical glass using a special metal die technique.
CRC
Close-Range Correction systemThe Close-Range Correction (CRC) system is one of Nikon’s most important focusing innovations, for it provides superior picture quality at close focusing distances and increases the focusing range.With CRC, the lens elements are configured in a “floating element” design wherein each lens group moves independently to achieve focusing. This ensures superior lens performance even when shooting at close distances.The CRC system is used in fisheye, wideangle, Micro, and selected medium telephoto Nikkors.
IF
Internal Focusing (IF)Imagine being able to focus a lens without it changing in size. Nikon’s IF technology enables just that. All internal optical movement is limited to the interior of the nonextending lens barrel. This allows for a more compact, lightweight construction as well as a closer focusing distance. In addition, a smaller and lighter focusing lens group is employed to ensure faster focusing. The IF system is featured in most Nikkor telephoto and selected Nikkor zoom lenses.
RF
Rear Focusing (RF)With Nikon’s Rear Focusing (RF) system, all the lens elements are divided into specific lens groups, with only the rear lens group moving for focusing. This makes autofocusing operation smoother and faster.
DC
AF DC-Nikkor lenses — unique Nikkors for unique portraitsAF DC-Nikkors feature exclusive Nikon Defocus-image Control technology. This allows photographers to control the degree of spherical aberration in the foreground or background by rotating the lens’ DC ring. This will create a rounded out-of-focus blur that is ideal for portrait photography. No other lenses in the world offer this special technique.
D Distance information
D-type and G-type Nikkors relay subject-to-camera distance information to AF Nikon camera bodies. This then makes possible advances like 3D Matrix Metering and 3D Multi-Sensor Balanced Fill-Flash.Note: D-type and G-type Nikkors provide distance information to the following cameras: Auto exposure; F6, F5, F100, F90X, F80, F75, F70, F65, F60, F55, F50, PRONEA S, PRONEA 600i, D2 series, D1 series, D100 and D70s/D70.Flash control; F6, F5, F100, F90X, F80, F75, F70, D2 series, D1 series, D100 and D70s/D70.
G-type Nikkor lens
The G-type Nikkor has no aperture ring; aparture should be selected from camera body.
SWM
Silent Wave Motor
Nikon’s AF-S technology is yet another reason professional photographers like Nikkor telephoto lenses. AF-S Nikkors feature Nikon’s SWM which converts “traveling waves” into rotational energy to focus the optics. This enables high-speed autofocusing that’s extremely accurate and super quiet.
M/AM/A mode
AF-S Nikkors feature Nikon’s exclusive M/A mode, that allows switching from autofocus to manual operation with virtually no time lag — even during AF servo operation and regardless of AF mode in use.
VR
Vibration Reduction (VR)
This innovative VR system minimizes image blur caused by camera shake, and offers the equivalent of shooting at a shutter speed three stops (eight times) faster.* It allows handheld shooting at dusk, at night, and even in poorly lit interiors. The lens’ VR system also detects automatically when the photographer pans — no special mode is required.* As determined by Nikon performance tests.
DX
DX Nikkor
Compact and lightweight DX Nikkor lenses featuring a smaller image circle are specially designed and optimized for Nikon D2-series, D1-series, D100 and D70s/D70 digital SLR cameras. These are ideal options for landscape photographers and others who need to shoot expansive scenes with Nikon DX-Format digital SLRs.Note: We do not recommend use of DX Nikkor with 35mm (135) or IX240 format cameras.
The aspherical lens complex allows freedom of design, improved performance, a reduced number of component lenses and a compact size.
This lens provides high optical performance while maintaining a compact size. For example, the 12-24 mm F4.5-5.6 EX DG ASPHERICAL lens widens the range of wide-angle lenses, and it provides distortion-free images with image reproduction performance equivalent to that of a single focal length lens. Aspherical lenses allow the production of high-quality images from compact, lightweight telephoto zoom lenses.
OS (Optical Stabilizer) Function
This function utilizes a built-in mechanism that compensates for camera shake. It dramatically expands photographic possibilities by alleviating camera movement when shooting by hand held camera.
Developed with Sigma's own technology, the OS (Optical Stabilizer) function uses two sensors inside the lens to detect both vertical and horizontal movement of the camera. This function, which works by moving an optical image stabilizing lens group, to effectively compensate for camera shake, helps to set our lenses apart from the rest. To handle all types of shooting conditions, the system has two optical stabilizer modes. Mode 1 determines camera shake in vertical and horizontal panning and compensates for image blurring. It is therefore effective for taking general photography or for shooting landscapes and other static subjects. Mode 2 detects vertical camera shake and compensates for blurring. It is effective for panning the camera to photograph moving subjects such as motor sports.
HSM (Hyper-Sonic Motor)
This lens uses a motor driven by ultrasonic waves to provide a quiet, highspeed AF.
IF (Inner Focus)
To ensure stability in focusing, this lens moves the inner lens group or groups without changing the lens' physical length.
RF (Rear Focus)
This lens is equipped with a system that moves the rear lens group for highspeed , silent focusing
Conventional focusing has normally been performed by moving either all lens groups as a fixed unit or only the first lens group. AF cameras are now widely used, even for close-up photography. Consequently, demand has arisen for a focusing system that will keep the length of the lens unchanged while showing little fluctuation of aberration. In response to this demand, SIGMA has developed a new inner focus system that moves two lens groups inside the telephoto and telephoto MACRO lenses. This system has floating elements that substantially improve the close-up capability of the lens. The super wide angle lens having a large front-lens uses a rear focusing system to move the rear-lens apparatus and enhance the floating effect, and the18-125 mm F3.5- 5.6 DC lens uses an inner focusing system to move the secondary lens apparatus. SIGMA has also succeeded in attaining a minimum shooting distance of 19.7 inches/0.5 m throughout the entire zoom range of this lens. The rear focus system ensures high-speed focusing with the APO 135-400 mm F4.5-5.6 DG and APO 170-500 mm F5-6.3 DG telephoto zoom lenses.
APO MACRO Super
Although telephoto zoom lenses can be used closer to the object than single-focal length telephotolenses, there is still a minimum shooting distance. SIGMA has made this minimum distance smaller and developed the zoom MACRO lens for taking close-up photographs of the same quality as those taken with a regular MACRO lens, while maintaining the performance specific to an APO lens. Rather than carrying around the cumbersome accessories required for close-up work, the photographer can now take photographs at amagnification of 1:2 (one half lifesize) using a telephoto lens, by quickly shifting from the normal setting to the full macro setting.
APO (APO Lens)
In order to attain the highest quality images, the APO lens has been made using special low-dispersion (SLD) glass and is designed to minimize color aberration.
SIGMA's APO zoom lenses minimize color aberration. As the refractive index of glass depends on the wavelength of light, color aberration occurs when different colors form images at different points. This problem often occurs with telephoto lenses, but the Special Low-Dispersion (SLD) glass and Extraordinary Low Dispersion (ELD) used in SIGMA's APO lenses helps to compensate for color aberration, thereby allowing them to produce of sharp images
Conv (APO Teleconverter EX)
This lens can be used with the APO Teleconverter EX. It can increase the focal length and will interface with the camera's AE (automatic exposure) function.
EX (EX Lens)
The exterior of this lens is EX-finished to denote the superior build and optical quality, and to enhance its appearance.
DG (DG Lens)
These are large-aperture lenses with wide angles and short minimum focusing distances. With an abundance of peripheral illumination, they are ideal lenses for Digital SLR Cameras whilst retaining suitability for traditional 35mm SLRs.
DC (DC Lens)
These are special lenses designed so that the image circle matches the smaller size of the image sensor of most digital SLR cameras. Their specialized design gives these lenses the ideal properties for digital cameras, the compact and lightweight construction is an added bonus ! including compact and lightweight construction.
Floating System
The floating system is used to control the focus. This system moves the different lens groups in the optical system to different positions, thereby minimizing the telescoping distance and the fluctuation of aberration at different shooting distances. This system is particularly effective for macro lenses (which encompass a wide range of shooting distances) and wide angle lenses (for Single-Lens Reflex cameras) whose lens composition is asymmetric. SIGMA uses the floating system for the MACRO 50 mm F2.8EX DG lens and the large-aperture wide-angle 28 mm F1.8 EX DG ASPHERICAL MACRO lenses.
DF (Dual Focus) System
The DF (Dual Focus) system disengages the linkage between the internal focusing mechanism and outer focusing ring when the focusing ring is moved to the AF position. This system provides easy and precise handling of the lens, since the focusing ring does not rotate during autofocusing. The wide focusing ring also enables easy and accurate manual focusing.
The 'take-home' message here is that, while you may be tech-savvy browsing through every review site about particular lenses, scourge the best deal, you should still try it out on your body itself before cashing in a lens that can worth as much as your body! Lens buying is the fun of SLR/DSLR, so no need to restrict yourself or give yourself more headaches.
Golden Rule: 'Stupid People Do Not Ask Why'
Comments