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DSLR: Digital Single Lens Reflex (SLR) cameras
The Megapixel Myth:
Print quality depends on resolution as measure by pixels per inch (ppi)
Standard size prints loook very good at 200 ppi
Because they are viewed at longer distances poster sizes are very good at 150 ppi.
The professional print standard is 300ppi. This is used by professional photographers and any time a photo is printed in a magazine or other print publication.
A computer screen only shows 72-115 ppi.
Joe Holmes' limited-edition 13 x 19" prints of his American Museum of Natural History series sell at Manhattan's Jen Bekman Gallery for $650 each. They're made on a 6MP D70.
Printing at 300 ppi requires 4x (2x horiz. x 2x vert.) the pixels as 150 ppi
Aspect ratio 4:3 - point and shoot, 3:2 - SLR
Source: Megapixels for Digital Photo Printing at FlyingSamPhoto.com
DPI means dots per inch, and has to do with just how much ink your printer lays down when it prints a photograph. Printers with higher DPI settings can produce more detailed photographic prints.
DPI and PPI are used interchangeably a lot of the time, but are not the same thing. For example, you can print an image on your 300dpi printer at 72ppi, 100ppi, or 300ppi. Changing the ppi affects the size of the printed photograph.
However the number is a bit misleading since it's not always measured in the way you think it might be! Printer settings of 360dpi, 720dpi, 1440dpi and 2880dpi are often found. However the difference between then is subtle at best. Most people probably couldn't tell the difference and 360dpi usually looks great. Changing DPI does not change the size of the print.
A full frame (35 mm) sensor the same size as 35 mm film is 36x24 mm.
Desig - The type designation harks back to a set of standard sizes given to TV camera tubes in the 50's. These sizes were typically 1/2", 2/3" etc. The size designation does not define the diagonal of the sensor area but rather the outer diameter of the long glass envelope of the tube. See DPReview.com.
Factor - Ratio of vertical size to 24 mm (full frame)
* The Four Thirds system is a standard created by Olympus and Kodak for DSLRs. Lens design has been tailored to the requirements of digital sensors. The size of the sensor is slightly smaller than for most DSLRs and this implies that lenses, especially telephoto lenses, can be smaller. Olympus, Panasonic, and Leica make DSLR cameras that conform to the Four Thirds System.
ILC - interchangeable lens camera - Smaller than SLRs with no mirror.
Lenses - Focal Length / Angle of view.
*Angle - all angles of view are measured on the diagonal.|
CF - Crop Factor e.g. 36/23.7 = 1.52 where 36 is 35 mm. width and 23.7 is APS-C sensor width.
Field of View Tables, APS-C, 24x36, - PentaxForums.com
A fisheye such as Canons 15mm f/2.8 produces a 180° diagonal field of view with a full frame sensor, but results in dramatically curved images.
As of 2007, only a few current DSLRs have full-frame sensors, including the Canon EOS-1Ds Mark II, the Canon EOS 5D, and the Nikon D3
See: Canon Field of View
Because most of the digital image sensors (CCD or CMOS) are smaller than image produced by the lens they add a telephoto effect and the effective lens length is increased by about 1.5 (Nikon) - 1.6 (Canon) compared to a typical 35 mm film camera lens. e.g. a 50 mm really acts like a 75 mm on a film camera. More expensive DSLR's (e.g. Canon 5D and Nikon D3) have full frame sensors so this is not the case.
More Lens Info:
Lenses are also rated by the maximum aperture (smallest f-value = largest opening).
Lenses that are capable of very large openings like f/2.8, f/1.8 or even larger are called "fast" lenses (or fast glass) because they let in a lot of light enabling fast shutter speeds in low-light conditions. Lenses with higher minimum f-values (e.g. ≥5) are sometimes called "dark" lenses.
Wide angle 14-55mm Mid 18-85 mm Tele 55-200 Full range 18-200Because of the smaller sensor size a 18-55 mm. lens on a digital camera is the same as a 29-88 mm. lens on a film camera.
Standard or Normal lenses (50 mm on a digital camera)
Highest degree of sharpness. Natural perspective Best for flat subjects on copy stands. No barrel or pincushion distortion.Macro:
Lenses that allow close focusing.
Macro lenses allow you to focus up to 1-2 inches from the subject.
You can get a close-up filter that goes in front of a normal lens to decrease minimum focal distance.
When a zoom lens says it is macro capable it is not a true macro lens. It will not get you 1:1 life size and the macro capability usually only works at the end of the zoom range and edges will be fuzzy.
Stabilizers are a new feature sometimes included in the camera body and sometimes in the lens. This is important on telephoto shots without a tripod.
Canon and Nikon say that with an in-lens stabilizer, you can make the aperture four stops smaller without changing the shutter speed, versus about two stops on an in-camera system.
A current trend is for "thin" filters. The main reason for using the thin filters is on the wide end of things, to reduce their contribution to vigneting, which will become more obvious if you add a second filter.
Many say a polarizing filter is the most important one, however they reduce light by 1.3 stops or more. UV filters have a very small affect exposure.
* Ultraviolet (UV), skylight and haze filters:
Filter Transmission % at 400-350nm Tiffen HAZE-1 2.5% (equivalent to a 5 f-stop reduction of UV) Tiffen 812 12% - A warming (shift to red) filter Tiffen PL-C 17% - photo.net says tiffen, but the PL-C is a Canon polarizing filter Hoya 81B 18% - A warming filter Hoya UV 24% B+W KR1.5 33% 6 Others tested allow 65-90% transmissionScattered light is strongly polarized perpendicular to its direction of travel, so a polarizer will reduce haze also.
Skylight filters are pinkish to cut blue but are no more effective in the pesky UV-A band than regular UV filters.
Prices vary widely depending on the quality and number of anti-reflective coatings. For example Hoya has 4 levels of UV filters:
You can reduce haze somewhat in photoshop. Applying unsharp masking repeatedly to all channels or to the blue channel alone with very large radius and very low intensity (amount) settings can be surprisingly effective.
* Infrared (IR) (dpfwiw.com/ir.htm) Unlike ordinary films, silicon-based CCDs and CMOS sensors turn out to be quite sensitive to the near infrared (NIR) in the 700-1200 nm (0.7-1.2µ) range
* Polarizers or polarizing filters:
Scattered light is strongly polarized perpendicular to its direction of travel from the primary source, so polarizers can reduce haze from scattered light.
Basic polarizing filters are linear, but they cause problem with modern camers's light metering and autofocus systems.
Polarizers reduce your lens appeture by 1.3-1.6 f:stops. (A filter factor of 2.5 - 3 i.e. light reduced 2.5 times), more (3-4 stops) in strongly polarized ambient light.
Which brand (Notes from camera forums):
The Hoya filters are as good as any, and not just the "Pro" series. Any of their multi-coated filters are fine.
The polarization of the sky at Polarization.com (example of blue enhancement at 90° to the sun.)
* Neutral density (GND) filters
* Color Compensating/Correcting/enhancing Filters
Many filters are identified by their Wratten numbers (1A-Skylight, 2A-pale yellow, ...81A pale oranage, [warming], 82A pale blue [cooling], ...)
It seems to be the general concensus that color filters aren't really needed with digital photography. You can adjust white balance in many cameras for a Blue/Amber and/or Magenta/Green bias to get the equivalent of a color filter.
Quality - Price:
Tele Extenders or Tele Converters (TC):
See Secrets of Digital Bird Photography
AF - Auto Focus (Nikon) see EF AF D-type - Lens sends distance information back to camera to help things like fill-in flash. (Nikon) AF-S - AF with SWM motor ASPH - Aspherical Lens Element (Lica) APO - Apochromatic lens APS-C Advanced Photo System - Classic (refers to old film APS size (25.1x16.7 mm) 3:2 ratio Many digital SLR cameras use APS-C sized image sensors. which ranged in size from 20.7x13.8 mm to 28.7x19.1 mm APS-H frame size of 30.2 x 16.7 mm close to the 9x16 1.8:1 ratio of HDTV hence the H. Has a 1.3x magnification on EF lenses ASA - Sensitivity of film ((American Standards Association) same as ISO e.g. ISO 100, ISO 400 CCD Charged Coupled Device Image sensor - Traditional sensors CF - Cropping Factor see EFL and FLM CF - Compact Flash memory card CMOS Complementary Metal Oxide Semiconductor - Technology used for computer chips adapted to digital photography. Quality is close to CCD and they are cheaper and include more functionality allowing smaller camera size. DO - Diffractive Optics (Canon) DOF - Depth of field DSLR - Digital SLR ED - Extra-low Dispersion glass (Nikon) EFL - Equivalent Focal Length EF - Electronic Focus (Canon) see AF EF-S EF with Short back focus - Canon Lenses designed for camera's with APS-C size sensors. Won't work with camera's with larger sensors. EI - Exposure Index - Like ASA EV - Exposure Value Ev (ISO setting) - Sensitivity to light EVF - Electronic Viewfinder EXIF - Exchangeable Image File - Meta Data stored in the jpeg or raw image file containing information such as shutter speed, aperture, ISO, Date/Time, ... DC - (Sigma) Designed for digital APS-C cameras DG - (Sigma) Designed for digital cameras Works with Full Frame cameras DX - Nikon smaller DSLR sensors 23.7 x 15.7 mm (CF=1.5) The DX-format camera can use both types of lenses (DX and FX) FLM - Focal Length Multiplier (see CF) FX - Nikon full frame (24x36mm) sensor and lens to match HSM - (Sigma) Hyper Sonic Motor (see USM) IF - Internal Focusing (Nikon) - Front barrel fixed focus won't change if camera is tilted down IS - Image Stabilization (Canon) see VR ISO - International Organization for Standardization (see EV and ASA above) - Sensitivity to light. ISO 5800:1987-Photography - Colour negative films for still photography M/A - Manual Automatic setting (Nikon) MLU - Mirror Lock-UP NEF - Nikon Electronic Format (Raw mode) OS - (Sigma) Optical Stabilizer see IS Prime Lens - Fixed focal length as opposed to a zoom. Usually faster (lower f-number) SIC - Suer Integrated Coating (Nikon) SLR - Single-Lens Reflex SP - (Tamron) Super Performance SWM - Silent Wave Motor (Nikon) see USM TC - Tele Converter or Tele Extender TTL - Thru the Lens USM - Ultrasonic motor in Canon lenses for faster quieter focusing. see SWM & HSM VC - Vibration Compensation (Tamron) see IS VR - Vibration reduction (Nikon) see IS vignetting - a reduction of an image's brightness or saturation at the periphery compared to the image center. XLD - Extra Low Dispersion glass (Tamron) XR -Glossary at DPReview.com
Terminology - What do the lens parameter abbreviations mean? - Photography Stack Exchange
Lens Technology | Sigma
Tamron Lens Dictionary - Lens Database
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