3. Lens doe DSLR cameras PDF

Preview

Summary

This is about lenses for the DSLR camera...

Description

3. Lens: Focal Length: - Usual length is 50mm - Focal length is the distance from the nodal point to the image point - Nodal point of the front of the lens and the image plane is where you see the photo on your camera – it’s the length of the lens Angle of view: - Different size sensors like full frame is going to have a greater angle of view then a smaller sensor like APS or point and shoot - Focal length is not the same as angle of view - 50 mm lens we see 40 degrees angle of view (full frame) - 50mm lens on crop frame camera would see a 25 degree angle of view (smaller)

Prime lenses: - Fixed focal length doesn’t move - 50 mm doesn’t move - Smaller than 50 mm is seen as a wide-angle lens and anything less than 20mm is an ultra-wide angle lens - 85 mm telephoto lens - 400 mm super telephoto lens Zoom lenses: - Range from Ultra wide angle to telephoto Angle of view: - Vertical, horizontal and diagonal angles - You want a 28mm or 18mm wide angle - 12mm is suuper wide - 100mm is a basic telephoto lens - 200 is a good telephoto lens - The bigger the number the thinner the angle but the more distance from the camera it can get

Focal length: - 16mm is a wide 98 degree for landscape or something close up and exaggerate the size of something close up - 20mm or 13mm lens APS is a good travel lens - 28mm or 19mm for APS is a good wide angle people should have at least this - 85mm is good for portraits because you’re not so much in their face Lens speed: - Maximum aperture - Aperture all use fractions - Aperture is the size of the opening through the lens that light can get through - Aperture is labeled on the lens - There is an overlapping in the term aperture on the lens o One is for the mechanics and the other is the maximum opening on the lens - 1.2 lens is really fast - 3.5 or 4.5 is pretty slow - Varies depending on focal length - Aperture is measured with a f/ (the aperture) - F-stop si the opening of the lens – how much light can get through - 50mm 1:1.4 = 50 mm f/1.4 = 50mm/1.4 =35mm Speed demons: - 21mm f/1.4 - 24mm f/1.4 \ - Etc. Fast lenses:

-

Faster shutter speed Lower ISO’s -- better quality Lower light levels Shallower depth of feel – opening lens up to a wide aperture Brighter viewfinder – brighter viewfinder with a brighter lens Focus faster – camera needs light to focus the more light on the focus centers the fast it focuses Faster focusing motors – the machine itself Better lens construction Better buttons and options to do on the camera itself with it’s construction

Aperture: - Blades inside the lens that narrows the amount of light - Different openings to different amounts of light - f/2.0 to f/2.8 is double the amount of light (full stop) - memorize major aperture settings o 1.0 o 1.4 (key number)

o

-

Controls the amount of light through the lens

-

Controls the depth of field

Depth of field: - Aperture forces the light to come in in different ways - If you change the aperture, then you can bring the object that was once blurry into focus by narrowing the depth of field and making the missing spot on the sensor smaller - Defined as the zone of acceptable sharpness - 1.4 is a shallow depth of field – the background is blurry and then 22 is a great depth of field – there is more background in focus when shooting to a close subject - The bigger the opening the less depth of field and the smaller opening the greater depth of field - Aperture the sharpest range to shoot in is in the middle of the lens

Lens quality: - Resolution – ability of the lens to resolve detail

-

Chromatic aberration – color ghosting – light rays travel through in red, green and blue making the photo blurrier if the colors don’t hit the same spot Distortion – inability for the lens to make straight lines Vignetting – darkening of the corners – fast lenses can do this Flare – some are more prone – usually zoom lenses Bokeh – quality of out of focus area Optical hierarchy: o 1. Pro prime lenses o 2. Prime lenses o 3. Pro zooms o 4. Standard zooms o 5. Superzooms o Teleconverters – take any good lens and take down the quality...