They don't.

Some could, and quite happily too.

The manual says that for exposure using the aperture ring, either with a pre-A lens or an A lens set other than to A, centre weighted metering is automatically set. Regardless of what we set the meter to.

Why not try the experiment using a grey card, controlled lighting and the stop down round the shutter release. And a tripod of course.

Eliminate any variables you can think of and the experiment will be more valid.

Did you format the card in the camera before you started to use it?

And the more glass you have the more internal reflections. Even with 0.2% reflection thanks to SMC coating, that adds up with every surface in a 17 element lens...

Without coating, reflections can be 5% per surface, so the development of modern lenses needed superb coating technology.

This is one reason why the aforementioned 50mm lenses often amaze digital ohotographers - with only 6 or 7 elements there is much less relection, therefore higher contrast.

We were, but one thing leads to another and certainly the concept of f numbers is relevant to understanding.

One of the great things about photographic theory is that it all inter-connects, so when all the pieces fall into place it's quite fascinating. Certainly there's plenty to keep us amused for a very long time.

As has been pointed out, lenses need more than one element to work effectively as photographic lenses. The most versatile lens is probably our own, everyone has one in each eye, and there's a simple one element lens that is capable of remarkable things.

For a simple one element lens the f number is obtained by dividing the focal length (say 50mm) by the diameter of the lens (say 25mm) which in this case would give us f2.

If the focal length had been 100mm then if the glass diameter stayed the same the f number would be f4.

With a complex lens of many elements the front element may have to be much much larger and what we need to calculate the f number is the effective diameter of the optics.

It's also easy to measure the focal length of a single element lens, but in a complex lens we measure from the nodal point which lies within the lens.

When we talk about many of these things it's helpful to restrict it to the simple lens as it makes a general understanding of the principles a little easier.

Welcome, Martyn!

It's very important not to discourage people by thoughtless or smart comments, but equally well it's important not to deceive them into thinking that they are good photographers when they actually have a long way to go and need to develop their skills.

A case in point is our youngest ADAPS member, 8 yeears old, who recently started putting his pictures in competitions. One or two people said "You should have told the judge so he could have given him more marks".

I totally disagree. Without any special consideration he competed against everyone else and got two good results, not at the top but very respectable indeed. And because of his own skills. This I think has more value, because we are telling him the truth.

I am also a judge and i believe in telling the truth as well, but always in a constructive manner and not putting down anyone's work. When people enter or post a picture they have made something that they want to share and have an emotional connection with it. As such, it deserves our proper attention and consideration.

This isn't, by the way, a comment on the pictures posted or the comments given, just a few thoughts on the nature of the situation.

You're right of course, digital is the way to go, but I just think slides might still have a place to remind us of the quality we are chasing. After all, we've forgotten what is possible with traditional black and white printing, as I proved when I dug out the ADAPS archive prints and showed them to the club. It gave us a new incentive to make our digital prints better. It didn't make us long to use large format SLR cameras with plate backs.

Whe it comes to honing our skills with composition and exposure, slides are also useful there. What you take is what you get, no errors accepted. It's an excellent discipline that can only improve our digital photography. I still say if you can do good slides, digital is, relatively speaking, a doddle...