What is the mirror lock-up on my camera and what does it do? (John Charles from London)

I used flash fill-in while taking some photos of a child playing in a reasonably well lit (daylight) room but – not helped by the fact that he was crawling all over the place – found it hard to get the exposure right. Any advice for future sessions would be appreciated. (Frank Brennan from London)

I like to take impromptu/un-posed shots of people but find that I regularly miss the moment because I’m busy trying to get the metering right or I over/underexpose the image. Any tips on metering in these situations would be appreciated. (Frank Brennan from London)

I have a lot of dust and dirt on my sensor. What is the best way to get rid of it? (Katherine Nelson, from Bristol)

I went on a tour down a silver mine and had difficulty trying to get the camera to focus on the various different settings I was using, including with flash. Do you have any suggestions on how to get focus in situations like this? (Katy Pittaway from Auckland)

I have been told that I should get a model release if I take any pictures of people. Is this true? (Chris Allen from Manchester)

Should you pay local people for posing for photographs?(Paul Jeffries, from London)

Help! I have just accidently reformatted a memory card. Are all of my pictures lost?(Michael Roberts, from Wolverhampton)

What is the mirror lock-up on my camera and what does it do? (John Charles from London)

If you are using an SLR or a DSLR camera, then there is a mirror in the camera that reflcts the light up to the viewfinder. When you take a picture, the mirror is moved out of the way, before the shutter opens to expose the picture. This act of moving the mirror can cause camera shake on slow shutter speeds. If your camera has a mirror lock up facility, then the mirror can be moved out of the way first - minimising the chance of shake during the exposure, You won’t be able to see through the viewfinder, but if you are using a long shutter speed then you will be using a tripod anyway, and so can compose the picture before locking up the mirror.

I used flash fill-in while taking some photos of a child playing in a reasonably well lit (daylight) room but – not helped by the fact that he was crawling all over the place – found it hard to get the exposure right. Any advice for future sessions would be appreciated. (Frank Brennan from London)

When using flash it is virtually always worth shooting with at least the flash on automatic. There are a few things that you can do to make the exposure more accurate.Firstly, set the flash to TTL Auto, which means that the flash exposure is measured though the camera leans. Next make sure that the camera meter is set to a multi-zone evaluative meter, such as the Nikon matrix meter. This will give much more accurate results.

You can moderate the flash output by setting exposure compensation on the flash only. Try a value of -0.5 or -2/3 stop. This will make the flash under expose slightly, reducing glare and the chance of over-exposure.If you use a separate flash, then you can soften the light by fitting a diffuser, or by bouncing from a nearby white ceiling or wall.

I like to take impromptu/un-posed shots of people but find that I regularly miss the moment because I’m busy trying to get the metering right or I over/underexpose the image. Any tips on metering in these situations would be appreciated. (Frank Brennan from London)

The last thing that you want to be doing when apporaching someone for taking a portrait is messing around with the settings on your camera. One way to avoid this is to switch your camera to automatic. and just hope that the lighting is such that the exposures will be accurate.

A more polished way is to work out a manual exposure before you approach someone. Exposure is affected by the light falling on a subject, so if you calculate the exposure in advance, by pointing your camera at an object in similar light to your subject, then you can confidently use the same exposure. It is even worth firing off a test shot and checking the histogram in advance to make sure that everything is set correctly. I also previsualise the photograph I am going to take, and then select the appropriate focus sensor point in advance too.

When I come to take the picture, then everything is set up ready and all I have to do is think about the composition and taking the picture.

I have a lot of dust and dirt on my sensor. What is the best way to get rid of it? (Katherine Nelson, from Bristol)

It is possible to have a sensor professionally cleaned but this can take some time, and is relatively expensive. It is also not practical when you are on the road! On the simplest level then you can clean the camera using a manual bower brush. Trip the shutter on a long or bulb exposure without the lens on the camera. This will expose the sensor. Give it a couple of good strong blows and a lot of the dust will be removed. Be very careful not to touch thesensor and never, ever use a can of compressed air, as this will leave deposits behind.It is possible to buy a sensor brush called an Arctic Butterfly from a company called Visible Dust (see weblinks). This is electrostatically charged and if you wipe in gentely across the sensor it will lift dust particles off. You should make sure that you have the canmera set to the bulb setting and preferably use a locking cable release, as if the shutter closes on the brush you will likely ruin the camera.

One thing to think about (or possibly bear in mind for your next camera) is that some cameras have a built in sensor-cleaning mode, which will literally vibrate the dust from the sensor. You should check if yours has this function, as it makes cleaning simple!To minimise the chance of getting dust on the sensor, try to avoid changing lenses, especially in dusty conditions. If you use a wide range superzoom, such as an 18-200mm lens then you might never need to change lenses again.

I went on a tour down a silver mine and had difficulty trying to get the camera to focus on the various different settings I was using, including with flash. Do you have any suggestions on how to get focus in situations like this? (Katy Pittaway from Auckland)

Your camera needs light and contrast in order to be able to focus. In low levels it sometimes can’t do this. Many cameras will have some level of focus illumination, which can help, but it might be switched off on your camera. People often switch it off as it can be intrusive in certain situations, such as a theatre performance.If you have a seperate flashgun, these often have infrared focus illumination, which tends to be less intrusive and better at focussing.Another thing that can have an effect is the focussing mode. If your camera is on a continuos focussing mode then it will allow you to take a picture even if the camera isn’t focussed. If you select the Single focus mode then the camera won’t fire until it thinks the picture is in focus. This won’t help the focus, but will prevent you taking an out of focus picture!

I have been told that I should get a model release if I take any pictures of people. Is this true? (Chris Allen from Manchester)

A model release is basically a legal document where someone states that they have given you permission to take their picture, and for you to then commercially exploit that picture.Model releases only affect you if you are planning on publishing a picture, and even so people generally only expect a model release for commercial applications such as advertising. Editorial uses (such as uses in magazines) are usually fine without model releases, although there are privacy laws in certain countries (notably France and Spain) which can cause problems.

If you are planning on publishing pictures, then there is more information on Model releases and their pros and cons on the Further Information section of the website, including some links to sample model releases.

Should you pay local people for posing for photographs?(Paul Jeffries, from London)

I am more than ready to pay for pictures if I think that it is appropriate. Many people in poorer parts of the world are leading pretty difficult lives and if a small amount of cash from me can make that easier then I am more than happy to give something back. I only pay people who have made some sort of effort though, and never children. Generally the people who make an effort are older people (who are usually already pretty corrupted) and they are often wearing traditional dress. Offering them a small gift after taking a couple of pictures can help redress the age balance in many traditional societies where older people are less respected as younger people make money from tourists as guides or touts. This can overturn generations of respect for the elderly members of society. I also find that rewarding those who maintain their traditions, can help to preserve them. Often these traditions were not respected by Europeans, such as colonial officers and missionaries!

Obviously there are a lot of cases where people would be insulted if they were offered a gift following a picture. Sometimes this is a class thing - people we think are not doing well are actually quite well off in their own society – or a cultural thing. As a rule of thumb, if there is a great financial disparity between you and them and you haven’t been introduced to them, or got to know them another way, then you should consider whether you should give them something. It is a difficult one to guess, but with a bit of practice you can get it right! If you are at a religious building then leaving a donation or buying something at a stall can get around the difficulties of actually handing money to people. 

Whilst some people who don't pay for pictures don't do it for moral reasons, a lot are too arrogant and mean to pay, and just think that they have a right to steal shots of people. I also think that you have to be careful of just stealing pictures, not interacting and then buying someone off with a bit of cash. I still talk to, interact with and generally respect people - even if I am going to pay them as well.

Help! I have just accidently reformatted a memory card. Are all of my pictures lost?(Michael Roberts, from Wolverhampton)

No, not necesarily, but you should stop using the card straight away! Do not take any more pictures as these will overwrite pictures on the card.What happens when you format a card (or any type of computer disc) is that you simply erase the directory. All of the files are still present on the disc until a new image is written over them.What you will need to do though is run some sort of file recovery program as soon as possible. If you buy a Lexar or SanDisk card it might come bundled with a file recovery program (remember to copy it to a computer BEFORE you format and use the disc). If not, then you will have to buy a third party program. I use Data Rescue by Prosoft, which comes in both Mac OSX and Windows versions. www.prosofteng.comThis is another reason why it is worth having a few spare cards with you. If you delete a file, or erase a card, then you can put it to one side until you can recover it, but still be able to take pictures on another card.