Av and M....I just don't get it...help please

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cherokee1111

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Another newbie question, sorry but I'm keen to learn...

I've read and re-read Bryan Petersons 'Understanding exposure' plus read the usual photo mags etc etc, Bryan advocates Av and M most of the time and with 'M' states frequently he sets the camera exposure setting by turning the dial till the meter shows a 'correct exposure', when I do that its usually a black picture or shutter speed is so slow its majorly blurred:(

When in Av and I want a faster shutter speed it still doesnt get fast enough without having to use a flash which defeats the point of controlling the speed IMO plus I dont get to use the f stop I initially chose as that increases with the shutter speed............:bang:


These (and my other posts) questions might be very simple to the experienced here but help me understand and start enjoying photography and stop me constantly being dissapointed in the quality of the pics..

Thanks
:help:
 
If using Av the camera sets a shutter speed based upon the aperture you set.

If using Tv the camera sets the aperture based on the shutter speed you set.

If using M you set the shutter speed and the aperture.

It sounds to me like you are using too high an f stop (aperture size) too allow sufficient light onto the sensor.

The other factor to consider is your ISO setting. The higher the setting the more sensitive the sensor is to light. The trade off is more noise.
 
It sounds like you are trying to shoot in low light and it is insufficient for the combination of ISO, aperture and fast enough shutter speed to avoid camera shake.

As a rule of thumb, a 'safe' handheld shutter speed relates to the length of the lens and as a guide 1/60th should be safe enough with a 50mm lens. If the light is low and the aperture is wide open (say f2.8 depending on your lens) and the meter is showing underexposure at 1/60th you have 2 alternatives.

1. Increase the ISO but this may limit quality (increased noise) depending on the camera's high ISO limitations.
2. Put the camera on a tripod and decrease your shutter speed. This will also be limited if your subject is not static.

Why some shots come out black if the meter really is showing correct exposure is a bit more confusing. As Graham said, first thing to check is that you do not have minus exposure compensation dialled in, for a black picture you would need to be 3 stops or more under.

If you are shooting night scenes but have a bright light or two in the image, these could fool the meter into underexposure.

Chris.
 
When in AV mode and you wish to keep the aperture you initially selected but increase the shutter speed you will have to increase the ISO setting on the camera.
 
cherokee1111 said:
I've read and re-read Bryan Petersons 'Understanding exposure' plus read the usual photo mags etc etc, Bryan advocates Av and M most of the time and with 'M' states frequently he sets the camera exposure setting by turning the dial till the meter shows a 'correct exposure', when I do that its usually a black picture or shutter speed is so slow its majorly blurred
Click to expand...

You should not get a black picture if the exposure is correct in M.

In M when you look through the view finder you should something like this.

'-2 -1 0 1 2' and a marker or series of lines off to one side or the other. The camera thinks the optimum exposure is when the marker is in line with the '0'. Although with practice you may find it is slightly under or over this mark.

So you set the f-stop, what ever this is set to is down to practice and experience. To test, set it to the lowest number you can, this will certainly not be the optimum f-stop for the lens, but don't worry about that for now.

Set the shutter using the thumb wheel until the marker is over the '0'.

Now check the shutter speed, if it is too low, say 1/2 second you will more than likely get a blurred image. Have a read here about shutter speed / focal length

http://digital-photography-school.com/shutter-speed

You can also increase the ISO, the trade off here is the higher the ISO, the more noise or grain you are likely to see in the picture. This all varies from camera to camera.
 
Hi Cherokee

I recently attended a "know your DSLR" course at my local adult education centre. The course was 10 weeks long and covered all the modes on the camera with a field trip on the Bluebell Railway at the end. I have to say it was my Eureka moment as I understand all that these guys are saying in the posts to you now.
I also have the Bryan Peterson Understanding Exposure book and am getting used to using just the "M" setting.
I would imagine that you are about the same stage as me from your post.

There is so much to learn about this hobby and would suggeat that you maybe look toward a similar course in Adult Education as you can also feed off everyone else that is in the same position.

I am also joining my local Camera Club who welcome newbies.

I wish you all the best and hope that you get your Eureka moment soon!!:)
 
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