Chris, you may be right, but I was hoping for something more definitive.

I don't know why, but today's sunshine seems to have brought out a crop of people who specialise in non-answers, like the one at the top here. Quite how he thought he was being helpful, I have no idea. Perhaps he has no idea himself, but just thought he should say something out of politeness.

G

Bear in mind that the same technology is also used by other manufacturers. I have found Panasonic Evoltas to very good, and 7 Day Shop sell them at very reasonable prices.

G

Cuz that's where the money is!

(To quote Willie Sutton.)

G

I have no idea how many tubes you would need with your 135mm lens. Picking upon David's point, it all depends how close the lens will focus to start with.

If you don't already have one, you should buy a set of tubes. They come in an assortment of lengths so that you can choose a combination that suits your requirements at the time.

Here is an example: Tubes

There are three tubes in the set, of differing widths, so you can experiment to see what works best.

Good luck.

G

No. Now I have confused things!

David was talking about lenses of the same focal length, so that is what I was commenting on.

The only purpose of tubes is to enable you to focus closer to the subject. Macro lenses are simply sharp lenses, generally with a fairly flat plane of focus, which have more travel in the focusing mechanism (than ordinary lenses), so can focus closer.

The angle of view remains the same, and a longer focal length will enable you to photograph things that are further away.

G

After some deliberation, I think I prefer the first. For the tranquility.

G

Some people have wives.

G

I assumed you had.

G

I think you are in danger of confusing things. It is irrelevant what the normal closest focussing distance is - you use tubes to reduce that distance. A lens that doesn't focus quite so close simply needs another tube.

A longer focal length will give you more space between lens and subject - useful if the latter is venomous.

G

It was a serious question. How do they help? How do you use the system correctly?

On cameras I have owned, I have found multiple AF points to be waste of time. But perhaps I wasn't using them correctly.

G