Extension Tubes + what lens?

[Hazio123]

Hi all,

Disappeared from here for a few years but I'm back again with a couple more questions.

I've recently just upgraded loads of kit, and after digging through a few bags I found my Kenko extension tubes which I bought a few years ago. Now, I never really had very many good experiences with them...but I don't think I tried too hard either and with a sudden passion to give a bit of macro photography a go, I find myself in a similar situation.

I have a Sigma 17-70 OS Macro, but I want to go closer than that can do (or more magnification I should say). So, my question is this...

What lens would you recommend with my extension tubes?

As I understand, they basically put distance between the lens and the sensor meaning a closer focus point can be achieved and thus resulting in a smaller area filling the frame. With this in mind, considering my Sigma 17-70 focuses ridiculously close already, there's no point in pairing them up... no advantage. So I had another dig around and found a really old Sigma 70-210 UC zoom lens (the ones that you pull to zoom)... only to find out it needs re-chipping to work at smaller apertures with my 60D. The results (magnification) were good, but the DOF is rubbish due to it being wide open...

So (I know this is all a big backwards - buying a lens to work with extension tubes...just buy a dedicated macro lens I hear you say), ...with extension tubes, is it best to buy a lens that has a far focus point? ...and how would I go about achieving max magnification? At the wide end?

Somebody help...

...pleaaaaase!

 

[petersmart]

I would say the kit lens I assume you got with your camera or the "Nifty Fifty" - with tubes both can give very good results:

http://www.flickr.com/photos/20926615@N05/sets/72157625975281497/

In fact someone on here mentioned this set of tubes at £60.00 for 3 which means you could get quite a good macro set-up for about £140.00 inc the "Nifty Fifty" lens:

http://www.amazon.co.uk/Polaroid-Fo...BAT2/ref=sr_1_6?ie=UTF8&qid=1323278417&sr=8-6

And extension tubes can be used with almost any lenses.

I myself have been using them this summer with my Canon 70-300mm L IS USM lens with excellent results:

http://www.talkphotography.co.uk/forums/showthread.php?t=353822

.

 

[Hazio123]

I would say the kit lens I assume you got with your camera or the "Nifty Fifty" - with tubes both can give very good results

Bah...I bought it Body Only...well, I actually bought it with a Canon 10-22mm but again there's no point in going there.

You've got some really nice shots there with your 70-200, my next lens purchase. Maybe I should invest in a cheapo 50mm...

Could anybody explain to me the method of magnification with different focal lengths and extension tubes?

 

[vaizki]

It's quite easy. Magnification will be increased by x/fl where x = extension tube length and fl = focal length of the lens. The normal magnification of the lens you can find in the lens specs or in reviews.

So, nifty fifty fl = 50mm, magnification = 0.15x but if you add a 30mm tube you are looking at:

magnification = 0.15 + 30/50 = 0.15 + 0.6 = 0.75x

which is already solidly in macro territory. Many third party (Sigma, Tamron, Tokina etc) lenses that have Macro in the name are just close focusing lenses and the native magnification is modest but with tubes you can bump them up. I would however recommend getting a fixed focal length lens..

For cheap macro, I would probably suggest looking for an old manual focus macro lens and an adapter. I picked up a Canon FD 50/3.5 Macro (0.5x native magnification) from eBay for about £25 or so a few years back and use an adapter to mount it on m4/3 and EOS. Looking at eBay now it seems like they are up to £100 or so which sounds insane There must be better deals around than that.

Just note that with many old lenses mounted on Canon EOS, you can't focus to infinity because of the difference in flange focal distance - but for macro work they are ok and there's no reason to stay with Canon as you can get any brand you want with an adapter. Good idea to make sure it has a manual aperture ring of course..

 

[vaizki]

I just checked up on your Sigma 17-70.. it has a minimum focusing distance of 22cm (from the sensor) which at 70mm gives max magnification of 1:2.7 or 0.37x which is not really Macro but not bad either.

Adding the 36mm kenko tube on it gives +0.51x more (36/70) for a good 0.88x magnification, comparable to a dedicated 1.0x macro lens. Add more tubes (and a stable tripod) for more magnification.

Whether you're happy with this combo is then up to the lens optical quality as you're basically magnifying also all the compromises introduced by zoom lens design.

 

[Hazio123]

Vaizki, thanks for the fantastic replies... that makes a lot more sense now.

I've had a good play around with all my options here and it's not really doing it for me. As in your post, with my sigma @ 70mm I'm starting to get the kind of magnification I'm after...but I'm practically touching my subject.

I'm trying to figure out what magnification my really old sigma 70-210 UC gets, but can't find specs anywhere. That gives me suitable magnification but not being able to shoot with the smaller aperture doesn't work for me.

Thanks again for the posts, definitely well on my way to understanding what I'm after now.

 

[modchild]

I use my set of tubes on my nifty fifty and even on my 100mm f2.8 L macro, which is 1:1 already, so it's output is more than 1:1. I'm getting a MP-E65 lens for christmas that goes to 5:1 so I think the tubes will be pretty much redundant after that. The tubes will go on basically any lens you want, you just have to learn to focus all over again lol.

 

[vaizki]

As Hazio has found out, tubes don't increase magnification at a certain distance (unlike teleconverters) so you're basically getting a closer focus distance with them which results in a bigger image on the sensor.

The result is that by adding enough tubes, the focus distance will be so short it's actually behind the front element of the lens ie. your subject can't be there. You're running into the so called "working distance" when you're having to basically touch the subject with the lens.. this is where something like a 100/2.8 Macro will shine as it'll give you 1:1 at a reasonable 15cm from the front element