Week 4

Lens choice, lens performance, lens testing.

Lens choice is one of the first major decisions to be made when approaching any photographic subject.

Focal length comparison on canon website: http://www.usa.canon.com/app/html/EFLenses101/focal_length.html

Prime lenses are the best lenses to have. Traditionally prime mid-length lenses have been used for portraiture; 85mm, 105mm or 135mm to help fill the frame.

Interiors
-Wide angle lenses are more suited to interior photography enabling you to photograph the whole scene.
-Often a lens wider than 28mm is necessary. Prime lenses will be advantageous in this situation due to their ability to be 'faster' (interiors aren't very bright) and they have the ability to control linear distortion to keep lines straight.
-Use wide angle, but not fisheye!

Converging lines- the closer you are the worse it is. the further away you get, the less it appears.

Architecture
-Wide angled lenses are an obvious choice for architecture photography.
-Tilt shift is an even better choice.
-Prime lenses are better then zoom.

Landscape
-The choice here is pretty simple...anything goes!
-A wide angled lens to show that sweeping view.
-A long lens can be useful to show just a section of the view.
-Use a tripod.
-Stop it down and adding some foreground interesting will guarantee a great shot.

Specialised Lenses
-Apart from all the 'normal' sort of lenses, wide angel, zoom, and primes and their normal uses - don't let this restrict you either this is just a starting or reference point.
-Fisheye lenses
-F1.0 lens
-A tele-converter
-Macro lenses
-Why not try no lens?
-Soft focus
-Tilt-shift
-Plastic lens

-These lenses can be quite expensive, will you use them often enough to justify the expense?

Drill a really small hole in a lens cap and made a pinhole camera!!!

Lens choice-other bits
"Lens choice will enable you to change perspective, a lens can compress a scene and convey a feeling of space."

Lens performance- some terms
Fix in camera RAW, photoshop afterwards, lightroom.
Barrel distortion- apparent mostly in wide angle
Barrel and pincushion can be fisex in photoshop.

Transmission- Refers to the actual accuracy of the stated f-stop of the lens. this has effects on exposure
ghosting and Flare- the shiny nature of the sensor can add to the lens performance The sensor can actually bounce light around inside the body causing ghosting and flare.

Lens testing the procedure
-Place 5 targets on a flat black surface, one target in each corner and in center of the frame.
-Set the lighting as per the next diagram checking the exposure setting
-Set up your tripod making sure that it is level, place your camera on the tripod ensuring that this too is level vertically and horizontally.
-Critically focus, manually or auto, the scene.
-Using a cable release take exposures at different fstops and at different zooms.
-Critically analyse all images.
-Use tungsten
-You can also use a brick wall as a test target

You can go on here:
to look up your lens and check out the preformance, so you dont have to lens test!
http://www.photozone.de/active/survey/surveyform.jsp