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Archive for May, 2008

Canon and Tamron Macro lenses extended

In my last post, I said that appearances can be deceptive.

Perhaps that’s something of a mantra in photography.

In this case, I’m talking really about the length of the lens and the focussing systems. And you can now see that the Tamron lens when fully extended is really just as long as the Canon.

This shows one of the most important points about the Canon 100 mm Macro which is that the focussing is internal.

This is important for a number of reasons.

The most important reason is that the length of the lens does not change and the front of the lens does not revolve when you change focus and this gives a number of advantages which I touched on before for my own type in photography.

One of the most important advantages is that I can use a rubber lens hood, and then press my lens against, for example, the wires or glass of a cage and I can focus the lens knowing that it will not get longer or turn round and that there will be no damage to the lens or the cage.

When it comes to the question of the actual work of macro photography, if you look further at the Canon we get to the question that Tony asked about the two settings for focus limiters.

The principle is quite simple.

If the lens has to focus from zero to infinity, the focussing system will have to travel a very long way and take a long time even with Canon’s very quick, ultrasonic motor system.

And of course by this time, the object that you are trying to get into focus may have flown away or crawled out of the frame.

So the idea of the focus limitation is to get an approximate distance that you know that you’re going to be focussing on and to set the focus to that distance.

And then hopefully, the amount of travel that the focus system needs will be much smaller.

This is, of course, a sound idea and will certainly help.

But in practice, I believe as I said before that by far and the best way of dealing with this matter is to switch off the autofocus system altogether and use manual focussing .

The Canon lens, unlike a number of autofocus lenses has got a very large rubber ring for manual focussing and its clearly designed for manual focussing .

However, manual focussing can be best organised in one of two ways.

One is that you can maintain your position and turn the focus ring around.

This of course has some of the same problems as automatic focussing because it will take time.

The other way is simply to set the approximate focus depending on the image magnification you want and then to physically move yourself and the camera backwards and forwards until you get the correct focus.

What is the correct focus? and why are autofocus system likely to fail?

The reason is quite simple.

Most autofocus cameras now have a whole range of focus spots which you can see in the viewfinder.

My Canon cameras, have several focus spots which can be set in different ways. I normally switch off all of them apart from the central one.

It is also possible in some cameras to move the focus spots around but this does take time.

And the main problem with automatic focusing is quite clearly that the lens will only focus accurately if your focus spot is absolutely over the object that you want photograph.

Let’s take a practical example.

Close up of a Fringe Tulip

Here is a photograph of a fringed tulip, a beautiful flower, which I photographed in studio conditions using a flashlight with soft box.

The focussing problems are clear.

If you focus absolutely in the centre of the image what you’ll a sharp background which might be your intention.

Still I wanted to focus mainly on the stamen.

There are obvious problems.

The stamen is not in the centre and therefore a central focus point would miss it.

I could perhaps fool around trying to get the focus point to hover over the right place but in my opinion, it’s much much easier and much better to focus manually.

manual focusing does have one or two problems.

Many modern cameras including my Canons have a mirror based reflex viewing system, rather than the traditional and brighter glass prism.

This means that you do need quite good light to focus accurately and in this case it was provided by the modelling light of my flash.

In brief, in many practical macro photography situations autofocus, even with the help of autofocus limiters. is not the best choice.

So it’s best to use manual focusing.

It’s manual for macro.

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Papyrus

Over the last few posts, I’ve put up a few images which are mostly of macro subjects.

By macro I mean, close-ups which are life size or one-to-one at the film plane.

Now there’s a reason for this.

It’s because for sometime, I’ve been meaning to come back and have another look at the Canon 100 mm macro lens, which I bought some time ago.

It’s always, in my view, important to use new equipment when you first have it to get used to its basic features and then try it for sometime in the field.

It’s only after you’ve used it in real photo situations for a while that you understand exactly, what are the good bad strong or weak points for your own photography.

Now, this was also inspired by a comment I received from a photographer in the United States. This is what he wrote to me.

“Just read your review on the Canon 100mm Macro lens 2.8. I just got one and am learning. What is the switch for limit or full on the side for? I noticed over here in the U.S. there are a lot of magazines dealing with digital photography but a majority of them all come from the United Kingdom. Is there any reason that the U.K. appears to be such a contributor to the world of photography in the U.S.?”

Now, I actually live in Bulgaria, so I don’t really follow the UK photo press very well now and I certainly don’t know how it operates in the United States so maybe some readers of this blog could give their comments on this and give us both more information.

So really, I can only respond to Tony’s comments about the performance of the macro lens. I should say right now that I immediately responded to his comments with a brief reply and I also promised that I would give a longer reply here because I think the question of using a macro lens today is a matter of some interest to a lot of photographers.

So, just in case you’re reading this Tony. Hi!

One of the points I touched on before is that the reasons for using macro lenses have changed today.

Recently I visited Egypt and like most people I bought a bunch of souvenirs and when I brought some of them home I thought I would photograph some them.

Among these were some papyrus scrolls and immediately, almost without thinking I decided straightaway to pop them into my desktop scanner.

That shows one of the changes. As I pointed out before there was a time when I would have photographed the scrolls with quite a complicated light set up and making sure that the lens I used had corner to corner sharpness and a flat field.

That is using a lens designed to reproduce a completely flat object in such a way that everything is equally in focus all over the picture.
Now today’s macro lenses are still, in most cases, more or less flat field lenses but the point I’m trying to make is that many many macro shots today perhaps most macro shots have a single point of focus or are not likely to be flat.

If you photograph an insect you want to concentrate on some particularly vital point, usually, the eyes, and everything else around it will go out of focus into a sort of blur so much more important is the way your lens deals with such things as depth of field (DOF), what sort of image is produced by the material that is out of focus.

So, when you take many macro shots, the point of focus is going to be very critical indeed.

And the main point perhaps is that whether you use a focus limiter or whether you try some other way of dealing with the focus spots that you might find in your viewfinder, in practice, the best thing to do is not to use the autofocus system at all.

This comes as quite a surprise to some people who believe that auto anything is always better.

But the fact is that almost all automatic systems are only better than humans in certain situations.

So for example, when you think of autofocus, photographers managed quite well in many cases before autofocus was invented.

This doesn’t mean that automatic systems are useless, simply that they need to be looked at carefully.

Before going further I thought it might be interesting to make a comparison with my old macro lens to see how things have changed.

When I first bought the Canon 100 mm macro lens I felt it was rather bulky, rather large, though not particularly heavy.

I thought it might be an interesting point, to compare it with my old macro lens, which is the now classic Tamron 90 mm lens.

Canon EF 100mm Macro Lens and Tamron 90mm Macro lens

It’s perhaps not directly comparable because the Tamron lens focuses only to half size without an adapter.
I’ve photographed them together but appearances can be deceptive.

So I hope in the next post, to look again at the construction of the Canon 100mm millimetre macro lens, some of its particular points that I found out more about after using it for some time.

And then too, l’ll take another look at taking macro shots today

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