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Hey to all you photography lovers! I know that life is busy and some of us dont have enough time to play with our gear as much as we want to! So i was wondering why not start a thread that will help each other out with photography and to any questions that we might have.

Now i must tell you that i am no pro in photography but i do know some things .

So lets start by people asking on what they would like to know? and then we can dedicate a week to the question chosen and ill do some research and post some techniques and stuff .

remember to take lots of

Enjoy

What a great idea... I'll be following this thread closely! Thanks Massimo!

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So you start with a question?

Why not start at the basics. F-stops is one that most people struggle with for instance?

Hi Massimo;

Great idea; I hope the idea doesn't fizzle out for lack of support, and hope there will be many followers of this thread...

Even for experienced togs; it's always refreshing to review the basics once in a while, since we all develop naughty habits

DuQues has set you off with a good topic for starters; and I'm sure I can think of some if required

Good luck...

Ok so i have been asked to get back to the basics of photography and will be starting off with the F-Stop. Il leave the topic on for a week so that people can get to read up on it and ask questions that they might have.

Were will one find a F stop on a lens?

Simple here ;


What is the meaning of F-Stops

F-stops are a bit confusing because the numbers appear as decimals. Lets take for instance the following line :

F1.4 | F2.0 | F2.8 | F4 | F5.6 | F8 | F11 | F16 | F22 and so forth...

F-1.4 lets in the most light through the lens while F-22 setting lets in the least.



Just by looking at the numbers above going from from F1.4 to a F2.0 doesn't seem that one is taking the light and halving it and What's more, F2 is a larger number than F1.4 and sounds like it should have more light, not less. Neither does f/4 to f/2.8 sound like doubling the amount of light. In fact, each of the numbers in this sequence is a halving/doubling of the amount of light from its immediate neighbours, just like the shutter speed settings are. For example:

The reason that both the halving/doubling and the smaller numbers mean more light things make sense is that the f/stop is a ratio. The ratio is between the diameter of the aperture in the lens and the focal length of the lens. The focal length is generally measured in millimeters, so we'll stick with those as our unit of measure. On a 50mm lens, f/2 is saying that the diameter of the aperture is 25mm. The ratio is: 50/25 = 2. That seems pretty straightforward.


So what makes a lens fast?


Lenses are referred to by their maximum aperture (that's the biggest hole, the smaller number).

Lets take a lens for example a "x 50mm " lenses and we will just change the F-Stop

50mm F1.4 | 50mm F2.0 | 50mm F2.8 | 50mm F3.5


All four of these lenses have a f/4all the way up to f/16. These are distinguished by the maximum amount of light they could let in. The 50mm F3.5 when set to it's maximum aperture of F3.5 lets in one third less light that the 50 F2.8 and the 50 F2.8 at its maximum aperture, lets in only half the light of the 50 F2.0 at its maximum aperture and so forth. Lenses which have wide maximum apertures and let in lots of light are called fast lenses. Lenses which let in comparatively less light at their maximum apertures are called slow lenses. The 50 F1.4 is a very fast and the 50 F3.5 would be kind of slow.

Would you always use a fast lens ?

The answer is No. The reason being is Weight and the actual cost of these fast lenses. To get those larger diameter apertures means you need larger pieces of glass which means larger lenses. These lenses are alot heavier and and therefore become harder to auto focus.

The size is also really obvious in the long lenses. The weight balloons and the cost skyrockets. Lets look at the canon 400 fixed lenses

The canon 400 F2.8 : Dimensions 6.4 x 13.7" and weight is 5.35kgs costing R+-70k
The canon 400 F5.6 : Diemesions 3.5 x 10.1" and the weight is 1.25 kgs costing R+- 11k


You also see the size in the zoom lenses. Most modern consumer zooms are handy, light and slow. They are also have a variable maximum f/stop across their zoom range. The professional level lenses tend to be fixed F- stop.

Even on shorter lenses the difference is noticeable 50 f/1.2 is much heavier than 50 f/1.8. The viewfinder is bright in the f1.2 and that last fraction of a stop can be handy sometimes, but the camera weighs a lot on the neckstrap and you start to question its value if you're shooting at f/11 anyway.

My Zoom lens says it's 24-85mm F2.8 to 4 What's that mean?

This relates to the size versus lens speed issue. Lets take a lens 24-85 f/2.8-4 zoom lens, as an example. It's not exactly small and light, but it tries. If you think about it, the size of the elements needed to get f/2.8 at 24mm is much smaller than the size needed to get f/2.8 at 85mm. To keep lens sizes and costs down, the lens manufacturer accepts that the lens wil be faster at the wide end of its focal length range and slower at the long end. As a result, you can open up to f/2.8 at the 24mm end of the range, but only to f/4 at the 85mm end. This is particularly noticeable in small lenses that do, say, 70-300mm where at the 300mm end the maximum f/stop is f/5.6 or worse. It also shows up in the compact point and shoot superzooms, which can have unspeakably slow long focal lengths. You'd better have a sunny day!


What is stopping down?

When you stop down a lens, you are going to a larger number/smaller aperture and therefore less light. Going from f/8 to f/11 is stopping down. The opposite is opening up; going from f/11 to f/8 is moving towards the smaller number/larger aperture and therefore more light.

How am I supposed to remember that f/stop sequence?

Small F - BIG LIGHT | BIG F - Small light


So basically here is a picture to sum it all up ! .



Hope this helps you guys!! IF there is something i have left out please post it so we call all read it and learn from it also!

Enjoy

You have been studying.

Hi Massimo;

An excellent start - good job

Don't want to spoil your thunder, but a suggestion if I may; perhaps you could follow-on from f/stops with an explanation as to how the choice of a wide or narrow aperture affects Depth-of-Field!

Cheers...

Thanks Massimo.

Shall I do that in the way I do it for people knowing zilch about photography, light and such?

It is rather easy really.
People, those wise ones, say that light consists of particles, and they call the photons. That is partially true.
The Photons are in fact not particles, but tiny little animals called Photons, and they create the images on your eyes, or in this case, on your sensor.

If you have your lens wide open (see above, that means f/2.8 or f/4 mostly, depending on your lens) the little Photons near your lens run in there to do their bit of painting. They very quickly fill the camera, so the shutter claps shut. The Photons from further away have no time to run all the distance in time and smack into the shutter. So they cannot help paint.
You have no depth of field.

Now when you close the lens a lot (f/16 for instance) the opening is so small that the Photons have trouble getting in, just like when a theatre goes out. This gives the Photons from far away the chance to run up and mingle. They can now paint as well: you have depth of field.

Brilliant thread Massimo Will watch it closely.

That picture sums things up very nicely

Hi Massimo There have been similar threads but still a great thread, there is always something to learn and what better way than getting tips from one another, will eargerly be following this thread.

Ciao Massimo,
I'm a Nikon user and currently using a D50, D80 and a D90. I also have Nikon and Sigma lenses and mostly use my 80-400 mm Nikon VR (Vibration Reduction) lens as my standard one.
On buying it I paid little attention to it's Vr function but had a go with it during a short trip and then decided not to use any longer. Got loads of blurred pictures and only after reading a little about it I found out that VR function should be turned OFF when using monopods, tripods or been bags.

Apparently it generates micro vibrations and was wondering if it is the same with Sigma and Canon lenses??

By the way, my last two pieces of glass were strictly NON VR ones!

It is the same yes, depending on the lens though. With for instance the Canon 100-400 it seems there are 2 versions, one which has that problem, and one with updated software for fixing exactly that problem.
It does say so in the manuals of the lenses that or if you should turn off VR/IS and all the other terms for user induced tremors.

For those that do not know what we are talking about, there is software in lenses (and sometimes in bodies, like in the Sony cameras) that tries to filter out vibrations to give you a sharper photo. And that at way slower shuttertimes than you would normally use.
It's known under several names due patenting ways, but all come down to the same thing:

When you do have the lens on a rocksolid base, like a tripod, your software is thrown off kelter, and messes up. Not bigtime, but instead of giving you sharper photos they will be less sharp.

Massimo, plenty openings here for shuttertimes and freezing the scene for instance?

Hi DQ, great to see you here!

Massimo, more info on the VR system's and when to/not to use would be useful to a lot of people here!

DQ, on the 80-400 lens manual they state that the VR functions 80% on horizontal and 20% on vertical motion. I had initially thought, erroneously!, that the VR software worked on all movement in the same way.
Basicly, if the use it and my movements are mostly vertical it provides me with 20% vibration correction against 80% on horizontal. Keep mine OFF and try not to drink and click!!

It would have been rather odd if you had not seen me here! I may learn something.... And one is never too old to learn.