Stops in Photography

Lots of beginners to photography hear the word "stop" or f-stop" and become quite confused. So, I thought I would try and explain the theory behind the mysterious "stop".

In photography, "stop" is the word used to mean double the previous amount of a value applied to a camera setting - if the value is increasing - or half the amount if the value is decreasing. It applies to ISO, shutter speed and aperture settings.

The term f-stop refers specifically to an aperture setting - because on old film cameras the ring around the lens that was used to change the aperture values had a notch it in when the next "stop" for the aperture setting was reached.

But, for shutter speed and ISO changes, the term "stop" is also used (without the "f") to signify a change in the value. 

With ISO (which start from 50) a one stop increase is 50 to 100 or 100 to 200 or 400 to 800. Two stops is 100 to 400 or 400 to 1600. So, from 100 to 200 ISO you are making the sensor twice as sensitive to light, and if you go from 200 to 100 ISO, you are making the sensor half as sensitive to light. 

With shutter speeds, a one stop change is 1/30th second to 1/15th second, or 1 second to 2 seconds, for example. Two stops is 2 seconds to 8 seconds (all examples - there are others). A one stop shutter speed change lets in half as much light if the shutter speed is doubled (slower speed) or twice as much light if the shutter speed is halved (faster shutter speed). With most cameras,  shutter speeds start at 30 seconds and go to 1/4000th or 1/8000th second.

For ISO and shutter speed settings, the values are arithmetical - so you can easily work out the change needed for any number of stops - just double or half the previous amount. If you want to increase an ISO by 3 stops and you are starting at ISO 100, you go to ISO 800 (100 x 2 x 2 x2). If you want to increase the shutter speed by 4 stops and you're starting at 2 seconds, you go to 1/8th of a second (2 seconds halved, and halved again, and halved again and halved again).

Just be aware that there are a couple of changes in the shutter speeds that are not exactly arithmetical.Shutter speeds change from 1/8th second to 1/5th second (not 1/16th) and 1/60th second to 1/125th (not 1/120th), for example.

With Apertures:

Depending on where you start, 3 clicks of the dial (on most cameras) is one full stop up or down. If you start at f4 it goes: F4, f/4.5  f/5, f/5.6 (f5.6 is one stop smaller than f4). At f5.6 the aperture is now half as big as it was at f4 and only half the amount of light that was coming through the lens when set at f4 will reach the sensor.

One stop from 5.6 is f8 (f5.6, f6.3, f7.1, f8). Now half the light that was coming in at f5.6 is coming in at f8 (the aperture is only half as big again).

You can also see that there are now 2 stops between f4 and f8 (6 clicks). 4 times less light is coming in at f8 than there was at f4.  If the exposure was correct at f4, it's now 2 stop UNDER-exposed (4 times less light).

The list of f-stops below starts at f4 (and ends at f32) with the full stops in bold.
f4, f/4.5 , f/5, f/5.6, f/6.3, f/7.1, f/8, f/9, f/10, f/11, f/13, f/14, f/16, f/18, f/20, f/22, f/25, f/29, f32

Each stop is letting in half as much light as the previous one (or twice as much more - if you work backwards and open the aperture up).

The smallest aperture numbers signify a wide aperture. The larger aperture numbers signify smaller apertures. The wider apertures give the effect of what is called "shallow depth of field" (lots of blurring in the foreground and background of the photograph) and smaller apertures give the effect of "wide depth of field" (lots of sharpness throughout the entire photograph).

See the two photos above for examples of a wide and small aperture used on the same scene. 

Unauthorized Use of Photography and Copyright Abuse

In the last 3 days alone, I have found - either through looking or by sheer accident - around 20 examples of my photographs being used without my knowledge or permission. These uses include commercial websites, forum posts, email newsletters and the cover of a specialist, internationally published magazine.

In every case, I was not asked if my photographs could be used, I was not told about their use, my name was not used with the photographs and I was certainly not paid for the useage.

I managed to contact some of those who had taken my images, via: email, Facebook messaging and telephone. The responses that I got back have, so far, varied from: no reply; abuse ("we don't want your **** pix anyway"); outrage ("how dare you suggest that I have stolen your images - I will be calling my solicitor"), surprise ("I had no idea that they were not free - I found them on Google images"), apology ("I am genuinely sorry to have caused you upset") and practical reparation ("how's this for a solution?").

One person has taken the webpage with my image on it down, another person has issued a correction giving a link to my website and the magazine has offered free advertising space in the next edition. Some webmasters have not replied as yet, and many of the photographs are still (illegally) on show. Interestingly, although I told everyone that there was a fee involved for using my images, no one has offered to pay hard cash for them.

Before I give some practical tips on how to find and persue the misuse of photographic imagery, I just want to let those people who trawl the web looking for free top-class photography into a secret:

Someone took that photograph you found. And because they own the copyright to it, taking it without permission is likely to be an offence in law. But more importantly, if you go onto a professional photographer's website and take thier images - you are also taking their opportunity to make a living. Professional photographers (like me) only make our money (you know, the stuff we use to get food and keep a roof over our heads) from taking photographs and selling them. Not by letting you use them for free, without asking and without even having the decency to say who took the photograph that you now use to adorn your own website or magazine cover or office wall.

I have spent nearly 30 years honing my craft so that my photography is good enough to be used in books, magazines, websites and brochures. And, (this is really important) it is now good enough to be paid for. Unless I have expressly given my work to you for your own use (only) - often with my thanks for help you have given me - I will expect you to pay for it.

How to Find Your Photography on the Internet

1. Use a reverse search engine such as "Tineye" or "src-img". (click the names to go to the websites for these utilities). They are very easy to use, and basically all you have to do is highlight the photograph that you want to find. The reverse search engine will then show you any uses of the image on the internet. It may only find where you have put the image yourself (say on your own website - or where you have sold the image to others for legitimate use). But it may also find the photograph where you least expected it.

2. Use Google Analytics to narrow down your searches. If you have a large number of photographs on your own website, you may not know which ones to search for first. I use Google Analytics to show me what searches have lead to my own website. If I see a recent visit which has come from a search for "red door" or "coffee cup with hearts" or whatever, and I know that I have an image like that on my website, I go to it and do a src-img or Tineye search on the photograph. I did just that recently and came up with 8 illegal uses in less than 15 minutes.

How to Protect Your Images on the Internet

1.  Put a watermark on every image that you have online. This is easy to do in software such as Photoshop and Lightroom and you can Google tutorials on how to go about it.

2. Make the watermark BIG and OBVIOUS. It doesn't matter what you put - it can be your own name or the traditional copyright symbol or "keep off it's mine" (or whatever - see my example above) just make sure it's right in the middle of the photograph. If you tuck it away neatly in the corner, it will be easily removed as if it never existed. You can make the opacity lower so that it doesn't completely obscure the image (again easily done in Photoshop) but make sure it covers most of the main parts of the photograph to deter others from trying to take it off.

3. If you sell (or give away) your photographs for website use: Ask the webmaster to copyright the image or use a copyright statement which may (hopefully) deter third-parties from lifting the images. This gives less protection than the previous method, but at least you are giving out the message that your work is not there for the taking by all and sundry.

4. Put a clear notice on your website stating that you images are not free and that all usage will involve payment. Put it on every page that you have images. Again, it may ignored, but at least no one can then say "oh, I thought this was free photography!"

What to Do When You Find Unathorised Image Use

This is a very complex area and there doesn't seem to be one clear solution, yet. But there are some very basic things to do in the first instance.

1. Take a screenshot of the unathorized use. With the website open so that you can clearly see the website URL and your image on it, press "prtscn" (print screen) on your keyboard, then open "Paint" in "all programs" on a Windows machine (or similar program on a Mac) and then open a new document and click "paste". This saves the screenshot of the webpage - and you have your evidence that the image was used against your wishes - even if they take it down later.

2. Bookmark the URL of the offending web page. So that you can find it again easily. I have now built up a sizable folder of "illegal usage" bookmarks in my documents directory.

3. Let whoever used your photograph KNOW that you KNOW. There will usually be some form of contact on the offending website. If not, you can go to whois.net and search for the owner of the website. Doing that, I have found not only contact emails but even phone numbers and full addresses of the website owners. How you let them know may vary - email is often the obvious way, but I have also used social network site messaging and even phone calls. Basically you need to tell them that you have seen your photographs used without payment or permission and tell them to take it down immediately.  You could also contact forum / website webmasters or social networking sites head offices and report the unathorized usage. This usually (but not always) results in the image being removed or the page being taken down.

Then of course, there is the thorny issue of  getting paid for the illegal usage. I know of some photographers who have done this very successfully - and recouped thousands in a short space of time - and others who have come up against a brick wall and got nothing. I will return to how this can be dealt with in another post.

I must be a good photographer - I have a Good Camera!

I had a brief stint as a wedding photographer, in the mid 1980's, and I was recently reminded of something that happened at that time...

I was photographing the bride and groom in a church garden, in Liverpool, with low afternoon sunlight behind the couple, using a fairly inexpensive TLR (twin lens reflex) with a reasonably good lens. There was basically nothing else to the camera, and so I was using a hand held meter to take a reading close from the bride.

When I got back to the tripod, a guest (a cousin of the bride) was snapping away at the happy couple with a 35mm camera, and so I thought I'd be helpful and said "by the way, have you compensated for that backlight?"


He turned to me with a conptemptuous look on his face and, in a thick "Scouse" (Liverpool) accent said "compensated for the backlight mate? You're joking aren't ya - it's a f***ing Nikon!"

The moral of the story is that when I took the album to the bride and asked about the photographs that the cousin had taken, the reply I got was - "they all came out black!"


Lots of so-called photographers out there today have managed to rake enough cash together to buy a high-end camera, set up a website and hand out a few hundred business cards. But what business do they really have selling themselves as professional photographers, with training or experience.

Have a look at this blog that spells out the dire consequences of hiring a "photographer" with no experience or training, to do a professional job (a wedding). Scroll down to the photos - they speak for themselves - and be warned. You get what you pay for!

Rejection? What Rejection?

Rejection is something that we photographers come cross on a regular basis - some would say far too regulary. And in all sorts of different guises. 

You may come across rejection when contributing to a stock agency that fails your submission due to technical errors or another that declines your submission simply because they have too many images of the Eiffel Tower, or just because they don't think it's a good enough photograph. 

Or, perhaps you're a student on a photography course getting grades that are lower than you would like or expect?

Or maybe, like me on this occasion, you were submitting proposals to book publishers in the hope of getting a contract for a new book. 

Well, whatever the reason that you may be feeling rejected the correct response is to keep at it. Take on board the feedback you may get (if any) and use it to further your dream. Looking for sympathy doesn't usually help, nor does attacking a doll fashioned in the image of the rejecter with a long pin. The only thing that really helps is that you get back in the proverbial saddle and try again - IF you think that the project is still worth trying for, and adjust your approach to suit the buyer, if you think it needs it. 

I recently spent 3 months changing the proposal for a book project, which was constantly being reviewed and changed by the potential publisher. The proposal began life as 1600 words and ended up as 8000 words (none of which will actually be in the book itself) and it was reviewed by 5 different people on a panel that the publisher set up. I got the contract last week, and the publisher expects that the book will be one of their better sellers, when it is published next year.

As a final bit of positivism; here is an email that I received, today, from a publisher in London. It refers to a book proposal I sent them in April 2011. The positive bit is in my reply, below it.

Dear Stephen Power,

Thank you for sending your proposal for Traditional Notes, which was read with interest.

Unfortunately, after some consideration, our editors have decided that it is not suitable for our current list.

You will appreciate that we cannot publish every interesting proposal we receive. We would like to thank you for considering ******** when sending your proposal, and we hope that this disappointing response will not deter you from seeking publication elsewhere.

I apologise for the length delay in responding to your proposal. 

My Reply

Hi *******

Thank you very much for your interesting email. My book "Traditional Notes: A Celebration of Irish Music and Musicians" was published by the Liffey Press (Dublin) in November 2011. It was launched at the Irish World Academy of Music and Dance in the University of Limerick on 16th November. 

Sales are quite buoyant, at the moment, and it has received several very good reviews in the national and international Press - as recently as yesterday, with an excellent review in the Irish Post newspaper (published in London).

I am sorry that ********** was not able to publish it, but I have to say that some things work out for the best, as I am very happy with the publisher that I did find, quite soon after submitting my proposal to you. Please see the link below my signature for full details of the book.

I am currently working on new proposals, and I would be interested to know if you might like to see them.

Best wishes,

Stephen Power

Self Published Books

I finally got around to self-publishing a book via Blurb.com It took me several months to finally make up my mind about the photographs that I wanted to include; and even now I feel that I would like a second attempt to stream-line the theme a bit more.

I have so many photographs on my hard drive (many thousands) that it was difficult to chose a topic for the book initially. I eventually decided to use images taken over 2 years in County Kerry, Ireland. I'm now planning a series of books on a very specific theme, which could be taken all over Ireland (and elsewhere).

Ironically, since finishing the Blurb book, I now have a publisher interested in an idea I have for another one.

You can see the preview of "A Small Window on Kerry" below, and the book is available for purchase via Blurb (just click the "buy" icon or the hypertext link below the preview window to g to the purchase page on Blurb).

A Small Window on Kerry by Stephen Power | Make Your Own Book