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Help with camera

Dave scutt

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Hi all.

After purchasing a used 450d , I'm trying to figure out how to use it.

After watching some YouTube videos about changing the f ratio mine still says f00 and does not change is the camera broken or am I doing something wrong.





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I've not used my canon with a lens, but what lens are you using and does it support changing the aperture through the camera? 

EDIT: I posted this the same time you posted your reply!  Glad you got it sorted.

Edited by Ratlet
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What are you trying to do?

The F ratio is altered internally within the lens by closing or opening its iris. If the camera and the lens are digitally connected, the camera can be used to change the opening of the iris. If  not, the iris must be adjusted manually on the lens.

However, many astrophotographers prefer not to stop down the aperture (increase the F ratio) by using the internal iris of the lens. They prefer to reduce the aperture of the lens by using a circular mask on the front, often a step-down filter ring, or several rings threaded into each other. The advantage is that this reduces the aperture with a circular obstruction which won't create spikes or artifacts around stars. The internal iris stops down with a set of blades approximating to circle. This is fine for daytime photography but not good for stars, which are better if the stopping down is done with a circular reduction.


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  • 2 weeks later...

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