View Full Version : Extension Tubes
01-16-2010, 10:17 AM
Well I just picked up a set of extension tubes for £7.50 shipped on ebay. Obviously they don't have aperture control or AF, but they still work exactly as other tubes do, and as a way of seeing if extension tubes are right for you it seems like a pretty good option. I'd rather waste £7.50 experimenting with using them than spend £115 on some fully functional ones then discover I won't really use them.
So, I know various people here have and use extension tubes - Any hints and tips? I know the DOF will be practically nanoscopic, and that a tripod is required, and I'm fully expecting either a flash or long shutter speeds. Do you have any tips and tricks for making using them as painless as possible?
01-16-2010, 12:09 PM
What are you planning to shoot with with the extension tubes?
If it's bugs and things like that, it is often not possible to use a tripod as bugs don't stay stationairy long enough. I always use flash when shooting bugs, because it's way to dark otherwise.
I generally shoot f/11-f/13. If you get the focus right, this gives sharp results with enough depth of field and nice bokeh.
I generally use ISO400. I find that ISO200 is a bit too dark most of the time, and ISO800 is too noisy (especially if you miss the exposure, which you are bount to without any metering)
I have no metering either on the macro lens I use. Exposure is a bit tricky in this case, especially when using flash, as you need to set four variables manually. Also, the effect the flash has on the picture may differ considerably depending on the angle of the flash relative to your subject. You'll have to keep tweaking the settings while shooting. To get smooth light from the flash I generally use a omnibounce flash diffuser. It's not build for this purpose, but I find that it works quite well at a close range.
Regarding focussing, I find that it is a lot easier to focus by moving the camera forward and backward than turning the ring (which I only use when shooting from a tripod).
Hope this helps
01-16-2010, 01:46 PM
Thanks for the tips, very helpful - I have a trigger system for the flash and a little DIY softbox that could be fun to play around with in the way of lighting.
Extension tubes will lower light levels in the viewfinder won't they? How does that bode for manual focussing, either with the ring or moving back and forth? Is it dark enough to cause a serious problem?
01-16-2010, 03:39 PM
Yes, they will lower the light. I read somewhere that you lose about 2 stops for 50mm of tube (when using a 50mm lens) but that the loss of light varies with the focal length.
Losing light happens with real macro lenses too. When you focus the Nikkor 105VR f/2.8 at 1:1, it really is only as bright as an f/4.8 lens (as is shown in the viewfinder). It's a loss of about 1.5 stops. The same thing happens with Canon macro lenses, but they still show f/2.8 in the viewfinder despite the loss of light.
When shooting macros of bugs and other outdoors subjects with my macro lens, I find that I still have plenty of light. In fact, the razor thin DOF, allows you to see very clearly what you have focussed on. However, I suppose it would be harder if you are using your 55-200, which is only f/5.6 at the long end to start with.
One other thing too keep in mind is that the longer the lens you are using, the more length of extension you will need for it to have an effect. The tubes are most effective on your shorter lenses. One final thing to keep in mind, is that using your lenses at high magnifications, will magnify any focus field curvature. This mean if you try to shoot flat subjects and focussed on the center, you may see severe softening in the corners.
01-17-2010, 02:07 AM
Thanks for the all the help and advice - Sounds like it's all going to be a bit of a learning curve, but hey, that's half the fun in photography. ;)
And theoretically shouldn't you lose less light with a longer focal length, as the light is focussed onto a smaller area so less of it will hit the walls of the tubes?
01-17-2010, 03:24 AM
I would not be surprised if that were the case, but I think that advantage is off set by the fact that you need longer tubes to get as close.
01-17-2010, 03:48 AM
Shooting in ample light is helpful, I often shoot when the sun is high in the sky.
especially for bugs and things on the ground. I find using a zoom lens handy when shooting with the tubes.
With a zoom you can more easily use a tripod for support.
The zoom may change you composition a bit, but you should not have to move
the whole setup too much. I use the zoom to get close to the focus I want.
All my macro's on flickr are with tubes and the 50mm or 70-200vr
01-19-2010, 11:27 AM
Thanks to both of you for your help and input - tubes got here today, but have only been able to play with them in low light as it's night here. Won't get a chance to use them properly till the weekend, but initial tests look good - Online calculator reckons magnification is greater than 1:1 using all three tubes, and while it's a pain getting it all set up and getting the focus right with practically no light, I'm pleased with the results I've got so far. Nice sharpness and good magnification! :D
Now if you'll excuse me, I have to try taking a macro of this cake. :p
Edit: Right, test shot of (Predictably) a pound coin. First is the full shot resized, second is a 100% crop. Not at ALL bad for a very cheap telephoto zoom lens set at f/5.6 (Because I'm a moron :p) at 400mm efl with some £7.50 extension tubes. :)
01-19-2010, 06:18 PM
Looks real promising, you are in for a lot of fun.
01-20-2010, 04:13 AM
This is an interesting topic.
Back in Film days I used Extension Tubes - first I had them for my
42mm thread screw lenses - and then later again with my Olympus
OM's - I still have those and they worked quite well.
I have not tried Extension tubes with Zoom lenses though - and that is the rub,
I am still deliberating over Extension tubes VS dedicated Macro lens with my Nikon DSLR.
01-20-2010, 10:32 AM
I don't think there's any competition between a dedicated macro and extension tubes, if you have the cash - But I don't, so macro for £7.50 was my choice. :p
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