Tele converter v extension tube with macro lens

[Red Squirrel]

Can anyone tell me please which of these would be best to use with my 70mm Sigma macro lens to take my macro photography to the next level ie beyond 1:1 ?
I'm a bit confused about the difference.

[Tobyh]

Hi there,

If you were to choose one at this point I would go with a teleconverter.

In basic terms (and how I understand it) is that a TC increases the magnification of the lense in front of it, so a 70mm becomes 98mm with a 1.4TC or 140mm with a 2x. If used on a Digital body then you probably have another 1.5x or thereabouts crop factor caused by the digital sensor.

An extension tube allows a lense to focus more closely than it normally would be able to. You can stack them too to get even closer should you wish. One thing to bear in mind with tubes - you lose the ability to focus on infinity. An example would be you have tubes fitted to shoot a tiny subject when a dragonfly lands close - you may find you'll have to move closer to it to get your subject in focus whereas without the tube you could just focus immediately.

Remember both options mean a loss of light dependant on how many you use (with tubes) or the size of the TC.

Just to confuse matters you can also use both at the same time - higher magnification with closer focusing.

One to thing to bear in mind is that if your subject is really small then you can end up in a situation where the lens hood is casting shadows on your subject (an issue I had when i first reached the hurdle you are at) - this is where off camera flash / ring flashes play a part.

Hope I didn't confuse you

TobyH

[Red Squirrel]

Yes I understand that Tobyh, thank you.
I've read that because a tube has no glass there's no distortion. Obviously a TC has got glass so which, in your opinion, gives the best results.

[Tobyh]

Quite correct, a TC will mean a very slightly softer image but I find that often it's barely perceptible. I use a TC alot more often than the extension tubes come out thats for sure and, although I'm very picky about my pictures, I can't say I've rejected images purely on the slight difference a TC will make.

They are hard to compare directly because they do different jobs.

My opinion is still that a TC is the place to start, it gives you your required better than 1:1 and gives you a large working distance when required.

TobyH

[Geoff F]

What exactly do you wish to photograph?

A 70mm lens is quite small for macro wildlife work. OK for flowers etc where you can get really close but rather limiting for insects. A 1.4x converter would take you up a bit but there are limitations on the results, as has already been mentioned.

A 2x converter probably won't auto focus well and the distortion will be worse.

Tubes can be useful for getting you closer to the subject but are most effective at turning a reasonable sized zoom into a macro type lens. They can give a closer focusing distance of, say for example, around 1 ft closer with a 300 mm lens using a 25mm tube. The downside is a loss of light although this can be overcome by increasing your ISO.

But when we consider cost to results I wonder if you would be better to put that money towards a bigger macro lens. A 25mm tube will cost around £100 while a 1.4x converter will be at least twice this (I'm out of touch on current prices) and they both have drawbacks.

A 100mm lens will be fine for flowers etc and larger insects; the 150mm size is popular as a general purpose macro lens which will do a lot better for insect work.

I use a 180mm but this is a more expensive and heavier lens altogether.

[Red Squirrel]

Thanks Toby and Geoff. The 70mm macro takes some very nice flower and insect pictures but I want to go beyond 1:1 ie a bigger magnification mainly for insect pictures.
Trouble is I'm finding macro photography addictive and what I was satisfied with a little while ago, I'm now wanting a higher magnification. Hence any help appreciated.

[Words]

I've used both tubes and a TC with my Sigma 105mm lens. Generally I've used the tubes when I want to get really close on subjects such as frog spawn. I use the TC when I more distance without loss of size (as such). I tend to use flash with both . A ring flash is very nearly essential for very close working with tubes. An external flash is generally fine with the TC.

[Red Squirrel]

Thank you Words and thanks for your frog spawn link, it's great. Saving it to show my grandaughters when they come up next week.

[WhiskyBottle]

Lenses are corrected to work within a certain range.

Using extention tubes changes the light path through the lens beyond what it was designed for. For example my 500mm is quite exceptable, but when used with extention tubes it produces noticable chromatic abberations.

My vote would be a good teleconvertor. Concensus is that they don't degrade the image like they can with long lenses. They will always magnify any defects in the lens though.

Another option if you want to get real close is to get a 50mm standard lens from an old manual focus SLR (e.g. Olympus 50mm f/1.4 or 1.8), a lens reversing ring, and extention tube. You'll be shooting way beyond 1:1 with this setup, but you'll need flash and a tripod.

[Red Squirrel]

Thanks WhiskyBottle. It seems a teleconverter would perhaps suit me the best. Next problem is I've got a Canon camera and a Sigma macro lens so do I go for a Canon or a Sigma TC?
Problems, problems.