Extension Tube Info + Question

[NikonUser]

Hi there,

I picked up a set of Kenko Auto Extension tubes today and thought I'd put them on my macro lens quickly to have a go...

I took some quick shots of a ruler to see what sort of magnification I can get..

180mm macro ~ 23mm across the frame
180mm macro + 1.4x tc ~ 16.6mm across the frame
180mm macro + 68mm extension ~ 12.5mm across the frame
180mm macro + tubes + tc ~ 9mm across the frame

EDIT: And it also makes my 500 f4 focus down to around 2.5 metres (with all 3 tubes). This is why I actually got the tubes in the first place. I didn't think they would have quite that much of an effect (...the lens focuses to 5m with no tubes). WOW.

Now for my question:

According to what I have read extension tubes don't lower image quality because they don't have any optics... does this mean that if I can get the focus correct (OUCH!!!!) I can expect the same sort of image quality with the 180mm+tc+tubes combo as with just the 180mm+tubes combo? Or am I dreaming?

Thanks for the info.

Paul

[pippin88]

Sounds good.

Be aware that you will lose light though (and maybe even have to dial exposure compensation (though you should have to)).

[NikonUser]

After some test shots I've determined that:

1) Using the lens + extension tubes results in fantastic quality. Very hard to tell any difference between the lens with and without tubes...

2) Using all three extension tubes gives greater magnification than the TC by quite a significant amount (by my results it's 1.4:1 vs 1.8:1)

3) Using the tubes and TC together doesn't work. Results are very soft and... crap.

4) Using the tubes reduces your MAX focusing distance by a HUGE amount.

I'll have to wait until some daylight until I can test the tubes with the 500.

Paul

P.S. If no one is interested in this info let me know and I'll stop posting

[DionM]

Yes you are right - tubes don't affect image quality due to no glass.

b