Lingo Crisis. How about some "English" definitions?

[cyracles]

Hello everyone! I hope you're all in good health. As a new kid on the "Photography block", i have been coming across some terms which I do not understand. Some are words, some are concepts.
Now, i appreciate the power of google and dictionaries and technicality does not scare me(i'm a math junkie) but i need you to tell me the meaning of the following terms in "not-a-single-sentence" format(analogies and brief storytelling will help). For some that appear naively simple, you can laugh but I'm watching you

Anyway here they are:
1. Tonality.
2. Dynamic range.
3. APO
4. What in the world am i expecting from the histogram and how does it affect the immediate shutter-pressing future.
5. Wireless trigger.
6. Flash sync.

As the thread progresses, i will drop more that cross my mind but for now, the above are a bit depressing for me not to know and the reason is not just because i want to enhance my vocabulary but because many articles and books use these terms a lot and knowing what and how they mean will catapult me to a "close to" jedi master of my Canon 1000D.

Thank you.

NB:
No one is obligated to provide all the answers per se. One of the beauties of forums like this is that differnt people can come in and share the part the find more comfortable to.
All the best!

[Polar01]

Ife
1) Tonality say take the colour orange, to that colour add some grey, see how it differs for the orginal, now add some more grey, again observe how the colour differs from the orginal and the previous one. That is tonality, same colour, different tone, if you added white than what you have is a tint, and if you were to add black than you have difference in shade.

http://www.luminous-landscape.com/co...hromatic.shtml

Cheers:

Allan

[Stagecoach]

Hi Ife, Are you aware of the excellent tutorials here at CiC ? I did a quick search "Dynamic Range meaning" and there was CiC third on the search list !!

Grahame

[Manfred M]

• Tonality is just a way of describing the contrast of an image i.e. the range of the lightest to the darkest part of the image. The histogram shows the tonality of the image. If the distribution goes from pure white to pure black, you have an image with a wide tonal range. If the range is constrained to only a small part of the histogram, the image has low tonality.

• Dynamic range is the ratio of the lightest to darkest area of an image. We will usually talk about the number of f-stops. A high dynamic range camera can produce good results from a very contrasty scene that goes from bright lights to dark shadows without blowing out the highlights or losing the shadow detail. The best modern cameras have a dynamic range of over 14 stops

• APO is an an abbreviation for an apochromatic lens; i.e. one that does a better job of correcting chromatic aberrations. Because different wavelengths travel through glass at different speeds, the normally do not focus at exactly the same point. This means you can see colour fringing when you look at an image very carefully. APO glass reduces this to the point it is negligible

• A histogram is a bar chart that shows the distribution of pixels from black to white. The horizontal axis represents the brightness; the darks are on the left side and the brights on the right. The vertical axis is a representation of the number of pixels at that colour /shade value. Generally we can get two types of histograms on our cameras. A single histogram that shows all colours together and a second one that provides a bar chart individually showing the distribution of red, green and blue pixels in the image

In my view, it is the single most important tool in your camera. It tells you if you have any blown highlights or block shadow details, It shows you if the image is tending to be dark or light and I use it to set my exposure compensation.

• Wireless trigger allows you to control your off-camera flash though the use of a radio transmitter connected to your camera and a receiver attached to your flash. I tend not to use them for my Speedlights, as I prefer to use my camera to set the lighting ratios, but I do use them with studio lights.

• Flash synch is the fastest speed that your shutter is completely open when you tale a flash picture. At any higher speed, your following shutter curtain starts travelling before the leading curtain has reach the end of the travel. If you use a “dumb” flash or studio flash, this is the faster shutter speed that you can use to take a picture. Dedicated flashes have something call High-Speed Synch, where the flash emits a series of pulses, so one can synch at any shutter speed, albeit at a reduced range.

[Glenn NK]

A histogram is a bar chart that shows the distribution of pixels from black to white. The horizontal axis represents the brightness; the darks are on the left side and the brights on the right. The vertical axis is a representation of the number of pixels at that colour /shade value. Generally we can get two types of histograms on our cameras. A single histogram that shows all colours together and a second one that provides a bar chart individually showing the distribution of red, green and blue pixels in the image

In my view, it is the single most important tool in your camera. It tells you if you have any blown highlights or block shadow details, It shows you if the image is tending to be dark or light and I use it to set my exposure compensation.

Absolutley - I use the RGB (red, green, blue) histogram extensively to check exposures.

However, I read a blurb by wildlife photographer that works in the jungle of Costa Rica, and he uses the brightness histogram.

http://www.deepgreenphotography.com/...y-image-files/

Interesting.

Glenn

[ajohnw]

Dynamic range - I think there may be some confusion with colour bit depth of the camera sensor and dynamic range. Most people are familar with sRGB. It uses 3 8 bit colour channels often referred to as 24bit colour. Cameras vary. Compacts often use 10bit colour channels, Dslr's 12 or 14 so far. I'm not aware of a 16bit or more ones. Medium format cameras often use 3 16bit colour channels usually referred to as 48bit colour. They may have gone higher. Given the cost of the sensors used in the camera they are aren't of much interest to me. There are sensors about that go even higher.

Dynamic range is different. It relates to what are often called stops. These go in ratios of 1,2,4,8,16,32 etc often with 1/2 steps in between that follow the same rule of doubling. These relate to light levels and the same rules are used on camera apertures- F numbers, ISO ratings- numbers some one came up with a long time ago and shutter speeds-fractions of second. Set up this way the 3 things relate to each other - decreasing the F number by 1 stop allows the shutter speed to be increased by one stop. That could also be done by doubling the iso setting.

Dynamic range crops up in 2 areas. In the scene being photographed and within the camera. Manufacturers get up to all sorts of things in the camera to extend it. Taking a camera where the don't do all that much in that area that I'm familiar with the original Canon 5D the dynamic range is usually reckoned to be about 7 stops which matches good quality old fashion slide film. This test report shows it as 8 stops but notice that the curves shown are not straight lines so the extra stops aren't really stops they are compressed and show a lot less actual light change than the real 1 stop changes in the middle of the graph even though the stop changes in the subject are real. The next page shows the dynamic range available in raw mode (mostly unadulterated by the camera software - it is changes though really) Here the extra stops are even more compressed.

http://www.dpreview.com/reviews/canoneos5d/22

Same thing for the latest greatest Canon 5D mkIII

http://www.dpreview.com/reviews/cano...5d-mark-iii/19

You might notice that at the bright end there is maybe 1/2 stop more and curves that compress that end more than the original 5D. Also if you put the cursor on the Nikon camera button that although the figure show more stops at the dark end they are nothing remotely like the full real stops in the centre region of the graph. Really putting it all together there is such a small real change in the actual recorded light levels for real stop changes in the subject things haven't improved that much over the original 5D. Also that Nikon are a little more perverse than Canon.

There may be some confusion in respect to display devices in the tutorial on here. It shows display devices as being capable of displaying a 12 stop dynamic range. Later it mentions that 8bit can only display 8 stops. If you think about pure grey on a PC monitor it too can only display 8 stops. so pass on that.

Hope this hasn't confused the original person that started this thread but the comment about 14 stops really needed some qualification. They aren't real stops. It's interesting to look at these dynamic range curves 9 stop range. I am currently well aware of what this does in practice against both my Canon 5D and 300D, A 9 stop range BUT

http://www.dpreview.com/reviews/olympusep3/15

It turns out that getting a decent exposure in bright contrasty situations is more difficult despite the 9 stop range. The software in the camera isn't so clever so along comes fake HDR or maybe the use of extra controls in the camera. I haven't really investigated those yet. It takes many many shots to really get to know a camera. Test reports can also be very missleading. Fortunately I knew that when I bought a Pen and in many cases scenes contain a stop range that no normal camera will record faithfully anyway.

John

[Manfred M]

Absolutley - I use the RGB (red, green, blue) histogram extensively to check exposures.

However, I read a blurb by wildlife photographer that works in the jungle of Costa Rica, and he uses the brightness histogram.

http://www.deepgreenphotography.com/...y-image-files/

Interesting.

Glenn

I hardly ever use the three-colour histogram. I might peak at it if I am getting blown highlights to figure out where the problem is, but in my work flow it is overkill. Just because I have a micrometer, that doesn't mean I use it to measure everything because a ruler is often good enough. The micrometer may be more accurate, but it takes longer to use and interpret. That's the way I look at the coloured versus the black and white histogram.

[DanK]

Hi Ife,

Most of your questions are about basic photography concepts. Please don't take this wrong, but the best thing to do with questions like that is find good sources and read. There are good tutorials here, and if you google, you will find hundreds of good sources. And, of course, you could go the old-fashioned route and get a book or two.

This forum attracts the most helpful people of any forum I read. However, asking folks here to write out answers to questions like "what is dynamic range?" is not a good use of the forum. It is just asking folks to write all over again what you can easily find yourself with a simple google search. Most of your terms would immediately get you what you need on google. For vaguer terms, like "apo", just google "apo photography". I tried it, and 3 of the first 5 hits on the first page explain what the term means.

The best use of the forum is to post questions that you CAN'T easily answer on your own. For example, if you read some web pages on dynamic range and find that they are confusing or incomplete, post a specific question, and you will almost certainly get a quick and useful reply.

Dan

[ajohnw]

I really don't know if the web is a sensible place to look for anything other than basic definitions really Dan and that in some respects is a problem because there is a lot more out there that is often miss guided / missleading / over complicated particularly at the true technical end. Dynamic range is a good example of that. People don't seem to realise what the specs actually mean. I very carefully avoided expanding on what APO actually means. That one leaves so much scope that some people who do know about these sorts of things feel it's in need of a re definition. It's being used rather loosely.

I would strongly advise people to stick to what they can glean in the tutorials on this site. I have only seen one that really needs a rather minor modification, and one that I just wouldn't agree with and probably a few that I regard as grey areas. Basically given what is out there elsewhere people are lucky to have access to this site. I was looking for a tutorial for some one else when I found it actually.

John

[Ronny]

Grumpydiver wrote: In my view, it is the single most important tool in your camera. It tells you if you have any blown highlights or block shadow details, It shows you if the image is tending to be dark or light and I use it to set my exposure compensation.

First thank you for the clear explanation, but I have also a question about your writing here above..
How do I know that the image is tending to be dark or light?

[Manfred M]

Grumpydiver wrote: In my view, it is the single most important tool in your camera. It tells you if you have any blown highlights or block shadow details, It shows you if the image is tending to be dark or light and I use it to set my exposure compensation.

First thank you for the clear explanation, but I have also a question about your writing here above..
How do I know that the image is tending to be dark or light?

On your histogram, the very left side represents pure black values and the right side represents pure white values. This means that if the bulk of the histogram sits toward the left side of the histogram, the image is tending to be dark, if the bulk of the histogram sits towards the right side, it is tending to the light side.

[oldgreygary]

Hi Ife,

Most of your questions are about basic photography concepts. Please don't take this wrong, but the best thing to do with questions like that is find good sources and read. There are good tutorials here, and if you google, you will find hundreds of good sources. And, of course, you could go the old-fashioned route and get a book or two.

Dan

Agree with Dan, a book that is a basic guide to digital photography would be a good starting place to find out this info. After that you will be in a better place to ask questions to clarify on things you don't fully understand.

Cheers for now

Gary