This table is to try and help figure out the calculations for the different Value Factor fractions against different shutter speeds to help you figure out the maths.
Shutter Speed Value Factor Final Shutter Speed
1/10 5 0.5 sec (1/2 a second)
1/100 5 0.05 sec (1/20 second)
1/1000 5 0.005 sec (1/200 second)
1/10000 5 0.0005 sec (1/2000 sec)
1/100K (1/100,000) 5 0.00005 sec (1/20000 sec)
1/10 5 0.5 sec (1/2 a second)
1/10 50 5 seconds
1/10 500 50 seconds
Tuesday 15 January 2013
CHDK Shutter speed... a reminder that I hate maths!
So I have frazzled my brain a lot and with thanks to 89rafa from YouTube for explaining the basics of the maths to me on my original video, I now believe I have an understanding of the way in which you can calculate the shutter speed in CHDK when you are multiplying the shutter speed by fractions. For a loser in maths like me this is a real headache but I hope I can simplify it the best I can to make it clear for others too.
So the easy part of overriding shutter speed with CHDK is taking the value factor (number you multiply the shutter speed by) as a single number and working out how many seconds you want your shutter speed. This would be something like:
Shutter speed: 60
Value Factor: 1
1 x 60 = 60 leaving a 60 second shutter speed.
Not too tough right?
This is the way the shutter speed is calculated in "EV step (Exposure Value step) shutter speed enum type" in CHDK. However when we use the "Factor shutter speed enum type" it gets harder to calculate.
We change the bottom number to a fraction and it gets more complicated.
Here is a simple version...
Shutter speed: 5 (seconds)
Value Factor: 1/10 (One tenth of a second)
Here we are multiplying 5 seconds by one tenth of a second. The easy way to do this is to divide 5 by ten which leaves us with 0.5 of a second, or.. half a second.
As another example...
Shutter speed: 50
Value Factor: 1/10
We are still dividing the top number by the fraction so if we divide 50 by 10, we get 5. So the shutter speed is 5 seconds.
And so on and so forth. So in those examples we were changing the shutter speed and always dividing the number by ten.
However, we can also change the fraction and this is where things switch around and the shutter speed can be lower than the number dividing it.
As an example...
Shutter speed: 5 (seconds_)
Value Factor: 1/100 (One hundredth of a second)
Here we are dividing 5 seconds by one, one hundredth. The way to figure this one out is to calculate how many 5's there are in one hundred, in this case the answer is 20. This number then goes into a fraction as we are dividing 5 by 100 and the answer is 1/20th of a second.
It's a lot to take in but once you get used to it you can figure the maths out. Here are some ways to remember how to calculate it...
If the shutter speed number is smaller than the bottom fraction number e.g SS 5 VF 1/10 then you are calculating a faster shutter.
If the shutter speed number is larger than the bottom fraction number e.g SS 50 VF 1/10 then you are calculating a slower shutter.
If you are keeping your value factor at a certain fraction, then all you have to do is move the decimal point. For example here I am always using the fraction of 1/10 so I am always dividing by ten:
1/10 x 5 = 0.5 of a second
1/10 x 50 = 5.0 seconds
1/10 x 500 = 50.0 seconds
So if I were using a Value factor of 1/100 I would move the decimal point two points over instead of one.
So the easy part of overriding shutter speed with CHDK is taking the value factor (number you multiply the shutter speed by) as a single number and working out how many seconds you want your shutter speed. This would be something like:
Shutter speed: 60
Value Factor: 1
1 x 60 = 60 leaving a 60 second shutter speed.
Not too tough right?
This is the way the shutter speed is calculated in "EV step (Exposure Value step) shutter speed enum type" in CHDK. However when we use the "Factor shutter speed enum type" it gets harder to calculate.
We change the bottom number to a fraction and it gets more complicated.
Here is a simple version...
Shutter speed: 5 (seconds)
Value Factor: 1/10 (One tenth of a second)
Here we are multiplying 5 seconds by one tenth of a second. The easy way to do this is to divide 5 by ten which leaves us with 0.5 of a second, or.. half a second.
As another example...
Shutter speed: 50
Value Factor: 1/10
We are still dividing the top number by the fraction so if we divide 50 by 10, we get 5. So the shutter speed is 5 seconds.
And so on and so forth. So in those examples we were changing the shutter speed and always dividing the number by ten.
However, we can also change the fraction and this is where things switch around and the shutter speed can be lower than the number dividing it.
As an example...
Shutter speed: 5 (seconds_)
Value Factor: 1/100 (One hundredth of a second)
Here we are dividing 5 seconds by one, one hundredth. The way to figure this one out is to calculate how many 5's there are in one hundred, in this case the answer is 20. This number then goes into a fraction as we are dividing 5 by 100 and the answer is 1/20th of a second.
It's a lot to take in but once you get used to it you can figure the maths out. Here are some ways to remember how to calculate it...
If the shutter speed number is smaller than the bottom fraction number e.g SS 5 VF 1/10 then you are calculating a faster shutter.
If the shutter speed number is larger than the bottom fraction number e.g SS 50 VF 1/10 then you are calculating a slower shutter.
If you are keeping your value factor at a certain fraction, then all you have to do is move the decimal point. For example here I am always using the fraction of 1/10 so I am always dividing by ten:
1/10 x 5 = 0.5 of a second
1/10 x 50 = 5.0 seconds
1/10 x 500 = 50.0 seconds
So if I were using a Value factor of 1/100 I would move the decimal point two points over instead of one.
Tuesday 8 January 2013
Using Photoshop to blur out image details/logos
Sometimes we take a really great picture, and then we realise we have someone's car registration or personal information or perhaps a child walking through the image that we don't really want to expose to everyone just incase it could upset the child's parents or upset the car owner etc.....it's nice to respect other peoples information.
So with a little help from the Filter Gallery in Photoshop we can still keep that picture we took and share it with whoever we like by covering up those individuals details.
I took this shot of a car going through a puddle on Christmas day and decided to share it having covered up the registration number first. This gave me the idea that it would be worth doing a quick tutorial on some techniques for covering up parts of pictures.
So with a little help from the Filter Gallery in Photoshop we can still keep that picture we took and share it with whoever we like by covering up those individuals details.
I took this shot of a car going through a puddle on Christmas day and decided to share it having covered up the registration number first. This gave me the idea that it would be worth doing a quick tutorial on some techniques for covering up parts of pictures.
By selecting the area of your image you would like to blur out you can cntrl/apple + C to copy that part of the image and cntrl/apple+ V to past the copied part of the image into a new layer. When we use the filter gallery it will affect the whole layer that we are on so we only want those small parts to be affected, hence why we copy and paste to a new layer.
On the top bar select filter and then filter gallery and there is a whole menu of different effects to choose from so it's worthwhile taking your time to look through them.
Check out the new tutorial to see some suggestions:
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