Camera Labs

If I focus, then change the aperture, will the focus change and do I need to re focus?

_________________
Canon EOS 500D
Lenses: EFS 18-55mm IS, EF 50mm F/1.8 II

The focus point will remain the same distance from the lens, if thats what you're asking. The rest goes without saying - depth of field, accuracy, yadda yadda yadda...

_________________
----------------
Trevor Harris

Nikon D200
SB-600
YN-560 II
YN RF 603 x 4
Tamron 17-50mm f/2.8
Nikon 50mm f/1.8

Yes, changing the aperture without having to re focus.

_________________
Canon EOS 500D
Lenses: EFS 18-55mm IS, EF 50mm F/1.8 II

Refocusing moves the plane of focus, changing aperture changes the depth of the plane of focus, but it doesn't move it.

So, changing aperture without refocusing (assuming no camera movement) will not change your focus.

_________________
Canon EOS 5D MkII | Canon EOS 7D | Canon Digital Rebel XSi | EF 35mm f/1.4L | EF 50mm f/1.8 II | EF 85mm f/1.8 | EF 100mm f/2.8 Macro USM | EF 135mm f/2L | EF-S 18-55mm f/3.5-5.6 IS | 580EX II | LumoPro LP-120

My Flickr

Potentially VERY wrong, guys!

dubaiphil,
Can you explain why you think it is wrong?

_________________
Canon EOS 500D
Lenses: EFS 18-55mm IS, EF 50mm F/1.8 II

Some fast lenses in particular are known for something called Focus Shift.

A couple of classics that come to mind - Carl Zeiss 1,4/85 and 1,4/50, but more 'modern' optical designs can also exhibit this.

So stopping down from f1.8 to f.4 might not change your focus, but you might be equally out of focus! End result = blurry image anyway.

I wasn't sure on this one, hence why I asked.

I am finding the primes and zooms work differently. Sometimes I get unwanted bokeh on the primes (numerically lower F stops), where's the zooms aren't as servere.

_________________
Canon EOS 500D
Lenses: EFS 18-55mm IS, EF 50mm F/1.8 II