WILT - 70-200 f/2.8 as a macro lens

WILT - What I learnt today
I have been playing around with my 70-200 f/2.8 with extension tubes as a macro lens and made a really cool useful discovery

I have had focusing trouble with a very narrow focusing range with the 25mm extension tube attached which has had me resort to a macro rail on my tripod instead of using the lenses focusing.

I noted early on that it will focus a lot closer at 70mm than at 200mm.

On a whim I thought I would move further away from the subject and zoom in as I was in a more comfortable position (not having to bend over as much), but when I moved the zoom ring rather than zoom, it focused! There was a small zoom affect but ended up being far more useful as a focusing ring and has made the lens much easier to use.

Anyone else noticed this phenomenon?

Correction: the extension tube is 31mm

it does work with extension tubes by zooming in and out. You would learn about this if you'd ever played with a raynox 250 macro adapter and a canon super zoom camera.

extension tubes also work well with dedicated macro lenses: canon 100mm macro for very close up shots of jewelery however you can't correct the perspective distortion unless you have a 90mm tse lens.

FlyingPete wrote in post #17065404
WILT - What I learnt today
I have been playing around with my 70-200 f/2.8 with extension tubes as a macro lens and made a really cool useful discovery

I have had focusing trouble with a very narrow focusing range with the 25mm extension tube attached which has had me resort to a macro rail on my tripod instead of using the lenses focusing.

This control is often desirable with higher magnifications and narrow depth of focus, that is why some people like to have a tripod mount on their macro lenses.

FlyingPete wrote in post #17065404
I noted early on that it will focus a lot closer at 70mm than at 200mm.

The longer focal length, the more extension you need to get the same magnification compared to a smaller FL. There are mathematical formulas for this. If you are interested, you can look them up.

FlyingPete wrote in post #17065404
On a whim I thought I would move further away from the subject and zoom in as I was in a more comfortable position (not having to bend over as much), but when I moved the zoom ring rather than zoom, it focused! There was a small zoom affect but ended up being far more useful as a focusing ring and has made the lens much easier to use.

Anyone else noticed this phenomenon?

Very much related to my previous comments!

So when you are a fixed point with the lens, you may or may not be in the small field of focus. As you change the FL (zoom) you “effectively” move the field of focus, and therefore get your subject into focus. If you happen not to be in a particular FL field of focus, using the focus ring never will get your subject into focus (you would need to move the camera unit’s position.

This unit movement is what the macro rail does for a macro prime lens; it is easier than moving the whole tripod. Similarly the moving of the zoom ring (the changing of FL and therefore focus distance) is often easier than using the focus ring (which might not work anyway due to subject’s placement/distance) Especially if your subject is moving!

Well explained, thanks!

I have also found out this, however I use stacked 12mm, 20mm, and 36mm extention tubes. Its has been very useful for photographing dragonflies and other insects.

FlyingPete wrote in post #17066456
Well explained, thanks!

You are quite welcome!