Friday, July 06, 2018

Expose Your Triangle - ISO

Does anybody even know what ISO means? A few, maybe!

The acronym stands for International Standards Organization. It started out as an industry standard scale for measuring the sensitivity of film to light. If you're an old-time photographer who used film cameras, you'll recall that the films you purchased were rated: ISO 100 for bright outdoor light, ISO 200 for cloudy days, and even ISO 400 for evening and inside (but you likely still needed a flash).

Today, that ISO rating is applied to the sensor on your DSLR (digital single lens reflex) camera. If you've ever looked inside the body of your camera when the lens is off, you can see the sensor at the back of the body. When you push the shutter and the curtains open and pass across the sensor, it captures the light bouncing off the surfaces you are pointing at and captures the image.  You can learn more about that in your owner's manual if interested.

Basically, setting ISO tells your camera how much light you need to let in to capture the image you want. If it's a bright day, you don't need a lot so an ISO of 100 is good. If it's cloudy, maybe 200 or 400. If you are inside, you may need to bump it up to 800 or 1600. (Leave it lower if you want a dark and moody photo!)

Here are a couple of examples of mine followed by a video with an excellent explanation.

These were taken a few seconds apart at  9:01 pm on May 11, 2017. They're SOOC (Straight Out Of Camera) so no editing has been done on them. I set the f-stop to f5.3 and adjusted the ISO for each photo. You can see that the foliage just above the lamp is lighter and more detail is visible in the photo taken at ISO 1400; overall it's a bit brighter and more detailed because more light touched the sensor. You can also see how changing the ISO automatically adjusted the shutter speed from slower (1/15 sec) to faster (1/60 sec) to adjust to the amount of light being let in.

ISO 800, f5.3, 1/15 second
ISO 1400, f5.3, 1/60 second








































Here's the video for your illumination.




Monday, May 21, 2018

Expose Your Triangle - Shutter Speed

It's called the Exposure Triangle....and seems to be one of the most confusing things in photography although it shouldn't be!  I've included graphics for linear and circular thinkers...something for everyone!

So, what is it anyway? The exposure triangle is three settings that go hand-in-hand that let you create amazing photos: ISO, Shutter Speed, and Aperture.

Today, I'll cover Shutter Speed. You can think of this in terms of 'how fast can you blink' and 'how much can you see when you blink fast vs slow.'

Shutter Speed is about movement and what movement or stillness you can capture by adjusting the setting.

If you blink fast, things tend to stand still, to be stationary. If you blink slowly (keeping your view straight ahead as your camera does), things tend to pass through your vision quickly and often at a blur.

The important principle to remember when you are changing shutter speed is that a fast shutter speed will freeze action but also lets in a lower amount of light. You will need a bright setting or additional lights to capture and freeze the action.

A slow shutter speed allows for blur of a moving object but lets in a greater amount of light.

Here are a couple of examples. I was playing around with long exposures (usually considered to be longer than one second!) and took these on my street. I wanted to capture the light trails of cars driving down the road.

These are completely unedited, taken July 27, 2017 at 9:58 pm. I was just behind the red truck parked on the street and had the camera mounted on a tripod. An FYI here: if you are shooting anything that's lower than 1/60 second shutter speed, it's advisable to use a tripod.



Headlights of approaching vehicle
F22
30 seconds
ISO 100
Focal Length 18mm
(the lens goes from 18-55 mm)






Headlights of approaching vehicle
F22
7.7 seconds
ISO 100
Focal Length 18mm
(the lens goes from 18-55 mm)




You can see how much additional light was let in with the longer exposure. Had I taken a regular shot at 1/60 or faster shutter speed, the photo would have been completely blacked out due to lack of light.

You can play with this by taking your camera to a busy street or a playground with lots of kids. Take a few shots at different shutter speeds and notice how the high shutter speeds freeze action but are usually darker, and the low shutter speeds show blurry subjects (cars/kids) but are quite a bit brighter.

Here are those Exposure Triangle charts again for your convenience.













Sunday, April 15, 2018

Expose Your Triangle - Aperture

It's called the Exposure Triangle....and seems to be one of the most confusing things in photography although it shouldn't be!  I've included graphics for linear and circular thinkers...something for everyone!

So, what is it anyway? The exposure triangle is three settings that go hand-in-hand that let you create amazing photos: ISO, Shutter Speed, and Aperture.

Today, I'll cover Aperture. Ninety-nine percent of the time, I shoot in Aperture Mode on my Nikon D3200 because my general area of interest is floral closeups and landscapes - talk about being on opposite ends of the spectrum! - so I do a lot with Depth of Field.

Aperture is the size of the opening of your lens. I'll not go into what all the stops mean, but aperture is measured in f-stops.  It seems counter-intuitive, but low number = wide open lens, high number = very small opening in lens.

Depending on your lens, it can be a very low number (wide-open) f1.4 or very high number (barely open) f32.  Think of it like a cat's eye:

When the pupils of a cats eyes are wide open, they let in a lot of light that allows them to see in the dark. A wide open lens also lets in more light and takes better photos indoors or in low light.

When the cat's pupils are narrow slits, usually when the environment is very bright. Just like an f32 setting, they let in very little light because the area is bright. Too much light - over exposed photos - lose most of the detail, it's just too bright. (Conversely, an under-exposed photo is one where there was not enough light.)


Wide open pupils - Aperture small number i.e. f1.4, f2.3, f3.4, etc. - lets in a lot of light. Blurs the background (called bokeh).
Nearly closed pupils - Aperture large number i.e. f24, f32, etc. - lets in a small amount of light. Focuses the background.


(These are NOT my cat photos.)




Aperture controls that mysterious thing called Depth of Field which represents 'how far can you see clearly and in detail?" and applies to your background.

If you want a closeup of a flower in your garden and a blurry background (called 'bokeh'), or if you are shooting in a dim indoor setting, you will want an aperture number that is a small number but wide opening that lets in lots of light, say f1.8 or f2.8.

If you want your background to be in detail - as you might with a landscape shot with meadow in the foreground and mountains in the background -  you will want an aperture number that is pretty high such as f18, f22, etc. It sees clearly at a distance.

Note that not all lenses offer all apertures! When looking at a zoom lens, for example my Nikkor 55-200mm, says on the box f/4-5.6. This means that at 55mm the smallest aperture (widest opening) this lens can provide is f4, and zoomed out to 200mm the smallest aperture this lens can provide is f5.6. On the narrow side (high number, tiny opening), 55mm will go to f22, and 200mm will go to f32.

The best way to understand aperture is to play with it. I have taken my camera set up on a tripod and taken photos of the exact same subject at different f-stops, starting with wide open (low number) and going to very small opening (high number), then comparing the clarity of the backgrounds. This is best done outdoors where you have some distant details to work with, like down the street, or out in nature with hills/mountains in the background. It's a great way to learn what the different stops do, and really shows the meaning of  'depth of field.'

You can see why it's important to have an idea of what you want to shoot before you purchase a lens. Will you be shooting indoors or in low light, or outside in bright light? Do you want closeups or wide angles? A lot of detail throughout your photos, or an artistically blurry background (bokeh) with your subject in perfect clarity and detail? 

Next time, I'll cover another aspect of the exposure triangle. Meanwhile, here are a couple of diagrams to help.

















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