I think you're doing fine! You've not spent much money, but bought lots of lenses and you're trying them out to see for yourself what you like and don't like.

Have fun, explore the options and eventually, as your post title suggests, you will no doubt tidy up your collection...

And then buy some more lenses.....

I think I've seen the body for £399 in a magazine advert (probably AP) but I can't remember whose advert it was.

At these sort of prices it's almost giving it away...

I did have a go with an *istD woth grip, and thought it was a pity to spoil the balance of the camera with it!

Why make a superb instrument heavy and unwieldy?

Still, many others may disagree.

Personally I find both the MX and the *istDS just right in terms of size and ergonomics. However, it is true that some photographers do find them too small. In this case adding the winder to the MX helps a lot. I'm not sure if the *istDS has a grip available, but no doubt someone can tell us!

I'm not so sure about that - how would you get redress from someone over the other side of the world? At least you can visit a UK dealer. Having said that, we weren't really talking about being ripped off, more about the inconvenience in getting replacements if something went amiss.

The main concern I would have is what would happen if the goods were damaged in transit or proved to be faulty.

I feel that a slightly higher price would make buying from someone like Jessops by far the best route - if something is wrong, you take it back and they sort it out.

That's why I didn't buy my 12-24mm lens from the USA, but have opted to wait for the new batch from Jessops as soon as it becomes available again. I understand the Vietnam factory is busy making them right now - I wonder if they've got them ready yet....

This is one reason why constant aperture zooms are quite useful.

If you take a reading with a hand held meter and your exposure indicates 1/250 sec at f8 then you can set your zoom to its widest focal length and f8 will be f8. You can set your shutter speed to 1/250 sec and then you will have achieved the settings you want.

However, as soon as you zoom you will change the true aperture value, despite the aperture ring still being set on f8 and you will then need to slow down the shutter speed to compensate and maintain the correct exposure.

That's inevitable, and there is no way we can change the laws of physics.

If you had been using a manual camera (perhaps such as a Pentax MX) then you would need to re-meter every time you zoomed, which is not very convenient.

Constant aperture zoom designs, as mentioned, have real advantages.

The whole point is that just as the maximum aperture will change, so will every aperture by a like amount. The same reason applies, but to an area of glass that is reduced by the diaphragm. Your aperture ring might well be set on f8 but the aperture is no longer f8 - in this case f13 it would seem. Some lenses have a second marker to indicate how much the aperture is changed at the other end of the scale, but these indicators are only approximate. Modern SLRs should indicate a precise value in the viewfinder.

If you look at the figures you listed originally, you will see that the same EV value is maintained throughout, so the exposure will be correct. Try it for yourself and you will see that you will get correct exposure and that there is no problem with the lens.

In shutter priority the camera will have to recognise the shift in aperture, and should do if it can understand the information it is getting from the lens. If it can't, the there would be a problem.

The clue is in the name of the lens, which has a variable maximum aperture. Every other aperture changes by a like amount as you zoom, as you have found.

This is an inevitable fact of lens design, unless (expensive) steps are taken to compensate for the effect in the design.

When you are in shutter priority and you zoom, the same thing will happen. The shutter speed may well be set, but as you zoom the aperture value will change. It has to to maintain correct exposure. How the display interfaces with the lens and shows the aperture value may or may not work correctly, perhaps this is a reason for your observation?

The usual example I give to explain the effect is as follows. Imagine a 50-100mm zoom with a front element diameter of 25mm. At 50mm the wide open aperture value is 50 divided by 25, which is 2 (that is, f2). At 100mm, it's the same piece of glass, so the aperture is now 100mm divided by 25mm, which is 4, or f4. So, as you can see, the aperture has to change as you zoom if the other things are constant.

Hope that is of assistance!

Hi George, my turn to claim "Reptition!" :