A Few Quick Questions

mattchewone

mattchewone

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Name
Matt
Edit My Images
Yes
When people mention stopping down, what way do they mean as this always confusing me? Is it the meant increase the f/number? For example 50mm f/2.8 stopping it down would be to set it to f/4 for example? or have i got it muddled up?

Also is there a chart of the full f/stops as i get a little confused.

Also is there a recommended setting/settings for jpeg in camera setup? As i know you can adjust the sharpness, contrast and brightness i was wondering if there are any settings people can recommend. I am using a 400D

Matt
 
I hear it alot when regarding sharpness as well. Stop it down to make it a little sharper, i always get confused by it. My poor little brain cant cope with all the different confusing things i need to remember lol.
 
Trev Rich said:
yes choosing a higher F-no to under expose.
It's easier to bring back information from an image thats underexposed than it is to do with an overexposed image.
Click to expand...

No it higher Fstop for greater DOF you will change the shutter speed the same amount to keep exposure the same, You should not underexpose on digital keep your histogram to the right.
Underexposed is the HARDEST to recover from but saying that do not overexpose it just keep it as high as possible as the top 1/5 of the histogram has 50% of the total detail in the whole image
So missing the top1/5 you have lost 50% detail in the image.
 
Stop down does mean increase the f/ number. It will increase DoF which will lead to a greater depth of sharpeness but most lenses are at their sharpest when stopped down a couple of stops as it' uses the central region of the glass, not the softer edges.
 
Right histograms are a something i have never looked in to. I have seen them but never understood them. Do you mind explaining how to understand them.

I have gotten mine up on my 400D and its a rectangle with 5 divisions.
 
pxl8 said:
Stop down does mean increase the f/ number. It will increase DoF which will lead to a greater depth of sharpeness but most lenses are at their sharpest when stopped down a couple of stops as it' uses the central region of the glass, not the softer edges.
Click to expand...

Do you mean stopped down a couple of stops from the lenses smallest f/stop?

ie 18-55mm kit lens is f/5.6, so stopping it down would be setting it to f/8 or f/11?
 
Yes and no.

Smallest f/stop is the highest number. I know, it's confusing but f/ represents the size of a hole so f/4 on a 50mm lens means a hole that's 12.5mm wide. f/8 on a 50mm means a hole that's 6.25mm wide. So the larger the f/ value the smaller the hole, that's also why terms like open up, wide open, etc. are used for lower f/ values.
 
mattchewone said:
Right histograms are a something i have never looked in to. I have seen them but never understood them. Do you mind explaining how to understand them.

I have gotten mine up on my 400D and its a rectangle with 5 divisions.
Click to expand...
Hard to go into in any depth here
I have some note I use when talking at camera clubs I can e-mail them to you
 
Woah thats confusing lol. I am still a little lost. I understand the smaller the number the larger the whole.

So when some mentions stopping down one or two what should i do.

Use the nifty fifty as an example lens 50mm f/1.8
 
mattchewone said:
Woah thats confusing lol. I am still a little lost. I understand the smaller the number the larger the whole.

So when some mentions stopping down one or two what should i do.

Use the nifty fifty as an example lens 50mm f/1.8
Click to expand...

Stopping down one stop means going from say f/2.8 to f/4.

These are the main stops

f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22 f/32
 
Thanks pxl8 thats great!
 
mattchewone said:
When people mention stopping down, what way do they mean as this always confusing me? Is it the meant increase the f/number? For example 50mm f/2.8 stopping it down would be to set it to f/4 for example? or have i got it muddled up?

Also is there a chart of the full f/stops as i get a little confused.

Also is there a recommended setting/settings for jpeg in camera setup? As i know you can adjust the sharpness, contrast and brightness i was wondering if there are any settings people can recommend. I am using a 400D

Matt
Click to expand...

OK Full f stops

1 1.4 2 2.8 4 5.6 11 16 22 32 etc.

If you think of it as 2 series it may be easier to remember:

1 2 4 8 16 32 plus
1.4 2.8 5.6 11 22


Each doubling of an f stop number gives you 1/4 the light.
So f8 gives 1/4 the light of f4, or f4 gives 4 times the light of f8.
Going from, say, f4 to f5.6 is stopping down 1 stop and gives you 1/2 the light, going from f5.6 to f4 gives you twice the light.

As has been said many times before on the forum the f stop number is based on the focal length of the lens divided by the diameter of the aperture. The light admitted is proportional to the area of the aperture, hence the "funny" numbers.

Have a look here http://dryreading.com/camera/index.html
 
There are plenty of things out there about histograms (google is your friend!! ;) ) - in fact, do a thread search on here, and somebody will have gone into detail. As a general rule, unless your going for a high key or other effect, your histogram should show values spread across the full graph as much as possible (a bit like a normal distribution curve if you ever did stats) - if it's all bunched to one side or the other, you are either underexposing or overexposing, and will be losing detail within the image, which you may struggle to recover using your processing software.

On my 450D (and on my old 400D), I use the histogram, and the clipping tool (shows where the highlights are blown on screen) when I'm taking most of my shots now. It allows me to adjust manually to get as close to a well exposed shot as possible.
 
Let me try to explain how it works in easy terms.
In your lens is an adjustable hole (for want of a better description)called an aperture. This controls the amount of light that passes through the lens. You can adjust this in what we call steps or stops. Each step (or stop) is roughly a double or half of the previous or next one.Some lenses can be adjusted in half stops.

Lenses are often described as fast or slow. Typically a fast lens may have a maximum of f2.8(or less) where as a slower lens may be f5.6.Lenses have these settings to help with exposure, so in darker scenes to help achieve a higher shutterspeed we may need to allow more light through the lens (often refered to as opening up).For this we would adjust the setting in the camera to a smaller f number which would increase the hole (aperture) to allow more light to pass through the lens. In brighter scenes we may have to reduce the size of the aperture (called stopping down) by selecting a larger f number. On various auto settings your camera will do this for you.

There is however an effect on the image caused by adjusting this setting called depth of field (DOF). This affects the area in front and behind of your subject that remains in focus. This area of depth of field varies according to the setting. So if selecting a lower f number (say f2.8) the DOF would be vary shallow, and if selecting a larger F number (say f16) would grately increase the DOF. By using the f numbers creatively you can greatly affect your image.

As a general rule landscape photographers will want to gain the maximum amount of focus in their shots so would be looking to set a small aperture (say f16) where as a portrait photographer may want a more blurred background so may set f5.6 to make the background out of focus.We do this with portraits to "seperate" the subject from the background.

Sorry if this is too basic but hopefully understandable for anyone who has been confused by it.
 
It gets confusing, so I hope this doesn't make things worse, but just to add to the above:

The term 'stop' dates back to the very early days when the lens aperture was a piece of metal with a hole in it, which stopped a certain amount of light. This term has now come to refer to any halving or doubling of the exposure, including shutter speeds and ISO.

The halving/doubling routine is essential to an understsnading of how exposure control works. Once you've twiggged that f/4 is twice the light-passing area as f/5.6 for example, it is easy to see how 1/125sec at f/5.6 is the same exposure as 1/250sec at f/4.

There is a lot of confusing terminology used. For example:

f/2 is low (f/number), wide (diameter), fast (allows shorter shutter speed), big (diameter).

f/16 is high (f/number), narrow (diameter), slow (needs longer shutter speeds) small (diameter).
 
If you think of light as water going through a hose pipe
You need to fill a bucket
The bigger the pipe the quicker it will fill
So Big hole let in more water so shorter time to fill (double the size you half the time)
Small hose slower to fill so longer time (half the hole you double the time)
Hose size is your F-stop.
Time it takes, is your shutter speed
Water is your light.
Oh and the bucket is your sensor.
Hope this help
 
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