help! Metering

[Cutter]

Hi everyone, I would like to know a little more about metering. I do not have a light meter except whats on the camera. If someone can explain, when you talk about metering the subject and then having the backgound 3 stops below to produce a black background, where on the camera (canon50d ) do you look to see the figures required? I assume you have it set to spot metering ! but what do you look for? snd how do you set it?

Flake if you answer be kind to me

[flake]

Wow am I that bad?

Firstly I think what you are talking about is exposure, and most people nowadays don't bother with a light meter as the cameras meter is pretty accurate.

What I think you are describing is low key photography? Where the subject is correctly exposed, but the background is black?

To do this you ideally need a flash gun and a snoot, where you can control the specific area you want to illuminate, control the exposure of the background using aperture.

In post processing open the levels box in photoshop and while holding down the 'alt' key move the left hand slider until you have the black you want, this will remove any areas of low level detail you don't want, and it gives you a margin of error to work within.

You may need to consider an off camera flash trigger to do this and I'm afraid that you're going to have to do the whole thing in manual settings - no bad thing as you'll learn loads from it, just practice on a non living subject !

[Cutter]

Thanks flake I knew you would come up trumps! and no, not that bad just a bit scary with all that knowledge you have
Ok heres the scenario: a black backround 4ft away an object on a black cloth, lit up by a strong torch or a flash across the side so not lighting the background, but this lights up the cloth base, how to you stop the base from showing and if I wanted to light up the front how do you stop the flash from lighting the background ? I hope this makes sense.
Also what I dont understand is how you get the correct exposure to allow for the flash? (is it just trial and error?)

[flake]

When you're using flash, as a rule of thumb (and this is not exhaustive before someone picks me up on it!) set the camera to the fastest flash sync it can manage, most times this will be 1/250 sec control the exposure with the aperture and the flash power. The flash power & the zoom you dial in will vary according to how far away the flash head is and the size of the object you want to illuminate. Start off at f/8 and 1/8 flash power , and so long as the depth of field is what you want then just turn the flash up or down if it's a long way out, or fine tune with the aperture. Check the exposure with the histogram on the back of the display to make sure it's as far over to the right as possible without clipping.

If the light has spread more than you want then use the zoom to refine it, but remember to drop the power accordingly. If it still spreads too much you will need a snoot, and there's a little tutorial somewhere on here on how to make one from a pringles tube.

The photoshop technique I told you about will take away areas which are undesireable (within reason).

Hopefully that makes some sort of sense! I think you're going to need to watch the snoot video to get the results your describing.

[matt wilson]

Cutter .If you treat yourself to either the 480 or 580 Canon flashes it will really open up a lot of scope .My current and last comp entries both used black card as the background .

As Flake says it's a case of shooting in manual on the camera and flashgun.It may sound daunting but as it's often a still subject set the 1/250th sync speed .Select desired aperture and then just alter the flash power up or down.

One advantage of Canon's guns is you can control the flash via the camera.You can even dial in flash exposure bracketing so it becomes semi automatic .

I would like an off camera trigger but a cheaper solution that will work to a degree is a cheap off camera flash cord .My jessops one works and allows me to move the flash around a fair bit.

On my elephant pic I also got around the fact the background was not the perfect black everywhere by dodging with a soft brush set at 10% for shadows only .(this is ok as long as you don't have shadows in the pic you want to retain against the background.

[Forseti]

and without flash...........

Place something like an angle poise lamp above the subject and illuminate to taste. Spot meter for the subject and then set the camera to manual with these settings so they don't change. Pre focus before turning off AF. Set the camera to 10 second timer which gives you enough time to hold a piece of black card behind the exposed bulb blocking out rear illumination of the background but experiment with this last part a bit first. Fire away. Oh, you either need a tripod or very long arms.

If you're really into this in a big way (isolating subjects) then you might want to consider doing a bit of a Google search typing in 'chroma key' - a technique often used in the film/television industry. Here a green or blue background (preferably green) is used and in this technique it is the background that must be carefully and evenly lit so that later the subject can easily be cut out from the background. Next time you watch the weather report and see the presenter pointing at a map of the world behind them think chroma key - they are pointing at something that really isn't there at all most of the time. I often wonder whether I'm really here or not or am I just an illusion.

As the other posters in this thread have essentially implied - whilst flash can be used it entails a fair amount of trial and error. Also implicit in this is a thorough understanding of using flash and a complete understanding of what is meant by terms such as first and second curtain exposures, sync speeds and above all, taking control of the flash/camera manually. In normal auto mode the flash will expose correctly for the subject allowing ambient light to illuminate the background. Although in everyday and normal use this is often what you want, in your case it's the exact opposite because you don't want/need background illumination - whether flash or ambient.

[flake]

One advantage of Canon's guns is you can control the flash via the camera.You can even dial in flash exposure bracketing so it becomes semi automatic .
Just one caveat here, you can only do this with the flash on camera ( and why you'd want to I can't imagine!), once you take the flash off camera you have to do it all manually. This has been a bug bear of Canon users for years, and on the 7D they have built it in to the camera. If you really want this feature you need Canons STE-2 transmitter, one of Canons most over priced accessories.

If you use the flash off camera with the snoot, you will not need a black background, a small enough aperture will not allow sufficient light so long as it's not hugely bright. You can try this out with out a flash, just shoot a few frames in your living room set 1/250 sec and f/8 see how dark the image is, play around with a few different apertures and you will find the one where the black pleases you most. Remember that it's always adjustable in Photoshop later.

Forsetis method has certain advantages, (and disadvantages). Using constant light you are able to position it/ them and you can see the shadows cast, they can be arranged to best advantage. I don't think Forseti has done this, but setting the white balance to daylight when using tungsten lighting gives a lovely warm glow to stone (if you want it!)

The disadvantage is that the light is not controllable either in output or in its spread. You need a background card, and most important of all, a power source, which is easy if you're in the house!

Forseti is right that off camera flash is going to involve a lot of trial & error, but this is how you will learn, and with experience you will be able to make a pretty close guess to what settings you need. The Strobist web site contains a lot of tutorials for flash, it's a whole field in itself, and can produce some very satisfying images in situations you might think were impossible.

[Cutter]

Thanks everyone for your input, I will have to try out all the methods you sujest and see if the results are what I am after. The problem is , that when your a begginer like me you tend to think : oh piece of black card and snap away ! it's not till you try to do things like this, that you realise the skill and understaning needed to get the result you want.
Thanks again

[Forseti]

Originally Posted by flake

I don't think Forseti has done this, but setting the white balance to daylight when using tungsten lighting gives a lovely warm glow to stone (if you want it!)

Yes I did actually, and you are correct it does warm stone up a bit. In this case however I chose to leave it in the 'As Shot' setting (LR) because it more accurately represented what I saw and I've never been a great believer/follower of manipulating images to what I would 'liked to have seen'.

Originally Posted by flake

The disadvantage is that the light is not controllable either in output or in its spread. You need a background card, and most important of all, a power source, which is easy if you're in the house!

Agreed - in the house almost everything is possible LOL - you can even go so far as making a snoot for the angle poise lamp should the fancy take. I think it's like most things - if projects like Cutter is undertaking are to be repeated on a regular and repetitive basis then there's nothing like obtaining the right equipment for the job. For one-offs then a bit of DIY won't go amiss. Talking about DIY, here's an excellent site: http://www.diyphotography.net/seven-...ography-studio

Originally Posted by flake

The Strobist web site contains a lot of tutorials for flash, it's a whole field in itself, and can produce some very satisfying images in situations you might think were impossible.

Yes, always good to remind people of the Strobist site - vast quantities of information to be found there.

Originally Posted by flake

on the 7D they have built it in to the camera.

Nice isn't it? That said, someone near and dear to me has promised me a couple of Pocket Wizards - even better.

[Cutter]

I have taken these two photographs with natural light and spot metering , I am happy with the results , thankyou. I think it might be more complicated when i try to light the subject up.