A weird and useful thing I've discovered!

Cyclops · Post by **Cyclops** » Tue Dec 30, 2008 8:16 am

When I decided to reverse couple my 28mm onto the 100mm macro (as seen in my avatar pic) I was wondering what effect altering the focus on the macro lens would make. I imagined that it would increase the magnification in the way that focussing closer with the macro lens in the normal way would, but what I've found it does is actually move the focus point! This is really useful, because rather than having to move everything backwards and forwards, squinting thru a dark screen, I just turn the focus ring on the macro lens and voila! Depth control!

lauriek · Post by **lauriek** » Tue Dec 30, 2008 9:13 am

Is there a difference between changing the focus and changing magnification?

Cyclops · Post by **Cyclops** » Tue Dec 30, 2008 9:33 am

lauriek wrote:Is there a difference between changing the focus and changing magnification?

You know i don't think it is! Need further tests but I'm sure some one on here will know the answers

rjlittlefield · Post by **rjlittlefield** » Tue Dec 30, 2008 9:57 am

If I'm reading the reviews correctly, that Vivitar lens extends quite a bit as it focuses.

With a short lens on front, that variable extension will give a large change in focus for only a little change in magnification.

It's also very convenient, especially if you don't have a macro focusing slide.

--Rik

Cyclops · Post by **Cyclops** » Tue Dec 30, 2008 1:15 pm

rjlittlefield wrote:If I'm reading the reviews correctly, that Vivitar lens extends quite a bit as it focuses.

With a short lens on front, that variable extension will give a large change in focus for only a little change in magnification.

It's also very convenient, especially if you don't have a macro focusing slide.

--Rik

Just as I thought-thanks Rik. There may be some vignetting creeping in with it fully extended,need to check that. If so I can pull it in a bit and keep the same magnification