Camera operation? am I missing something?

[blakejd]

I'm shooting a Canon XS and it always seems that when on manual mode I can't get my aperature to go as low as I want. For instance when shooting manual the lowest I can often go is 5.0 but if I switch to the macro setting it will automatically drop to 4.0. Just a moment ago I was fooling with it trying to take one pic and the aperature on manual went down to 3.5 so I thought huh thats the apt I want for another pic so I took the tripod over (and didn't touch the settings) to the other object and took the shot. At some point the camera adjusted back to 5.0. Is there something I'm missing or some way to over ride this? Thanks ahead of time. I'm sure there's a simple explaination I'm missing.


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[Bitter Jeweler]

What lens?!

 

[blakejd]

It happens both on the stock 18-55 lens and my 35-80 canon which doesn't show min aperature but has a little macro flower showing .4m or 1.3ft.

 

[Samanax]

Those are variable aperture lenses...you'll only get the bigger aperture (smaller f/stop value) on the short end of the lens. On the long end of the lens you'll be stuck using f/5.6. There are constant aperture zooms, but they tend to cost a lot more than variable aperture lenses.

 

[blakejd]

So I understand Short end vs. long end. If I get the camera closer and have the camera at its min "zoom" say 18. I'll be able to get a lower aperature?

 

[Samanax]

So I understand Short end vs. long end. If I get the camera closer and have the camera at its min "zoom" say 18. I'll be able to get a lower aperature?

Yes, but depth of field (DOF) will change. Wide lenses have a deeper depth of field. Long lenses have a more shallow depth of field.

Understanding Depth Of Field In Photography

 

[blakejd]

Thanks. Just played with both lenses and voila theres the answer. Thanks for the DOF link too.