Hard Light vs. Soft Light

Hard light can be defined as “high contrast” lighting that brings defined shadows, and noticeable and sometimes overblown highlights. Soft light on the otherhand is less contrasting light that reduces hard shadows and is almost always more pleasing to the eye.

So you might ask where do these sources come from? Well, its quite simple. Hard light is from “small” light sources and soft light is from “larger” light sources such as soft-boxes, umbrellas, etc…Technically, standing next to the sun would be the softest light, but since its so far away the effective size of the source is small when viewed from earth, and thus direct sun light is harsh. To better visualize between hard and soft light, see the image below.

The Rule of Thirds

The Rule of Thirds is a principle of composition used for centuries by artists and photographers. The underlying principle is really very easy to understand and use.

In photography, using this The Rule of Thirds keeps the main subject off center, away from the middle of the frame. As a result, a photo looks more dynamic and interesting.

The Rule of Thirds envisions two horizontal and two vertical lines trisecting an image with four intersecting points. You place your main subject where the lines intersect rather than centered in the frame. For example, placing the horizon on an upper or lower line helps create a well-composed landscape photo. For portraits, placing person where lines intersect vertically produces a more compelling photo.

A Rule of Thirds grid is built into some digital cameras. It can be turned on and viewed on the LCD. Use it as as a guide when taking a photos. If you don’t achieve this layout just right with a camera, apply the principle when cropping an image.

What is Hyperfocal Distance and Why Should I ...

Whenever you focus your lens there will be an area that is in focus and areas that are out of focus. The in focus area is referred to as the focal plane.

The import thing here is that 1/3rd of the focal plane is ahead of the thing you’re focused on and 2/3rds of the focal plane falls behind what you’re focused on. Focus your lens at infinity and the leading edge of the area that is in focus is the hyperfocal point for that lens. Focus on that point instead of infinity and you’ll have the greatest range of focus from infinity back toward your location.

Read More.

What is flash trigger voltage and why should ...

The flash trigger voltage is the internal voltage used inside the strobe/flash to trigger it’s circuit. To activate a flash the circuit needs to be closed (turned on) and the flash trigger voltage needs to flow thru the switch. Simple right? Yes, but what is usually the trigger? Well your camera is. Hot shoe or pc sync are built in switches of the camera that close the circuit when the shutter button is pressed.

So what? Well, most newer digital SLR cameras have a limit to how much voltage it can switch. Hence, there is usually a “safe” pc-sync or flash sync voltage that the camera must not exceed. Some flashes with a trigger voltage of say 250V is not intended to work with your Digital SLR with a sync voltage designated at 6V. This is important to know since most early model flash units had high trigger voltages.

I highly recommend you check out the “Photo Strobe Trigger Voltages” Website to see if your flash and camera are compatible before starting a fire Maybe not so bad, but you get the point.

PS. If you have a newer SLR and are thinking about the Vivitar flashes get the 285HV. This has a low triggering voltage and will work with most modern SLRs. The original Vivitar 285 will do some damage!

Where can I find the trigger voltage of my st...

Here is the site you need to go to: http://www.botzilla.com/photo/strobeVolts.html

How do I calculate the Depth of Field?

Use a DOF calculator: http://www.dofmaster.com/

In most cases your lens will come with a DOF chart that you can refer to.

What is the crop / maganification factor?

Here is everything you need to learn about it:
Write-up at Luminous Landscape

Ivan

How do I perform a lens focus test?

Focus Test Links:

http://md.co.za/d70/chart.html

http://www.photo.net/learn/focustest/

Ivan

What are some useful equations for Macro?

1. Effect on magnification

m’ = m + (L/f)

where m’ is the magnfication with the extension tube in place, m is the magnfication with no extension tube, L is the length of the extension tube in mm, and f is the focal length in mm.

Note that this will work for any (consistent) position of the focusing ring, but is usually of interest at the "closest focus" setting (which pertains to the greatest magnfications).

2. Effect on working distance

W’ = W - f((m’-m)/(m’m))

where W is the working distance with the extension tube in place, W is the working distance with no extension tube, and m’ and m’ are the magnifications with the extension tube in place and without.

As before, this will work for any (consistent) position of the focusing ring, but is usually of interest at the "closest focus" setting.

Do note that the "focus distance" often quoited for lenses is not the same as the working distance; the working distance is measured either from the front (’vertex") of the front element of the lens, or from the front of the entire lens. (The difference is pertinent only to lenses with an "inset" front element - "integral hood" lenses.) Thus one must be careful when dealing with the specifcations of "inset front element" lenses.

Equation (2) will work for either definition of working distance.

Doug

What is the Sunny 16 Rule?

The Sunny 16 Rule says that on a sunny day the exposure is the reciprocal of the film speed at f16. That’s 1/ISO @ f16.? So say I was using 160 ISO film and the nearest shutter speed was 1/125 so I
added 1/3 stop to line up with the available shutter speeds. This give me 1/125 @ f16.? Simple as that.
Ivan

Is there a Sunny 16 chart / cheat sheet?

Most certainly:

What is Depth of Field?

When a lens focuses on a subject at a distance, all subjects at that distance are sharply focused. Subjects that are not at the same distance are out of focus and theoretically are not sharp. However, since human eyes cannot distinguish very small degree of unsharpness, some subjects that are in front of and behind the sharply focused subjects can still appear sharp. The zone of acceptable sharpness is referred to as the depth of field. Thus, increasing the depth of field increases the sharpness of an image. We can use smaller apertures for increasing the depth of field.Ray

Explain gray card (white card)?

Camera exposure systems are calibrated on the assumption that the overall brightness of the scene will average out to the “18%” or mid-gray found on a gray card. In other words, if you looked at the entire scene in black and white, all the white highlights, midtones, shadows and blacks when mixed together would average out to the same tone as on a gray card. This is what the camera assumes it is seeing when you half-press and get a shutter speed/aperture combination.

Of course, the brightness of most real life scenes doesn’t conveniently average out to mid gray, so it’s usually necessary to dial in some exposure compensation to correct for the difference between the camera’s expectations and the actual scene. This is most obvious in the case of beach or snow scenes (which need +1 or 2 stops compensation, otherwise the camera would render them as mid-gray) or predominantly black or dark objects which would otherwise end up being over-exposed.

The second use, as mentioned above, is to set “white balance”. This essentially sets the correct “mix” of red, green and blue, rather than overall brightness. This is because all sources of “white” illumination have a slightly different colour cast. If we assume sunlight as being our reference for “true” white, then shots taken on a cloudy day will take on a bluish cast and those taken under tungsten lighting indoors will look reddish. So a gray (or white) card, photographed under the same lighting conditions as other shots to be taken, gives us a convenient reference for white balance as well as for correct exposure.Tomas