Taking up one of George's points, I understand the theory regarding optimising a lens for digital capture - that is, the CCD prefers light arriving perpendicular to the surface rather than at an angle. But as we are using only the central part of the frame, surely that is less of a problem anyway?

It will also mean that we are using the part of the field of view with the highest resolution and best control of abberations (which fall off towards the edges) so the APS sized CCD should give conventional lenses more than an equal break :

No, the digital sensor is smaller than the 35mm frame, so effectively you only use the central part of any lens' field of view. If you multiply the actual focal length by 1.5x then you will get an idea of the "equivalent" focal length.

The most recent DA lenses only cover the CCD and if you use them on film cameras you will get some vignetting. I haven't explored this yet, but it is possible that there may be some creative mileage in this effect.

Each drive on a computer has a letter to define it - when we load the software for a new piece of kit it will allocate a new letter, or when the kit is attached it will deliver a "New hardware Found" message and go through the process from there. During this process, I think you can allocate any unused letter you want. On this PC, for example, I have drives labelled from C through D, E, F, G, H etc.

I hope that answers your question.

"Very Useful" for two reasons. Firstly, it is a fast standard suitable for low light use and secondly on a DSLR it makes a fantastic 75mm - equivalent portrait lens, perfect for studio use. The fact it is a "A" series lens means that all the exposure modes will work fully on all bodies.

"Only" because the f2 lens was a low cost option in the range, but it is still a creditable performer.

There are several questions on the listing, and one answer says "Not a Macro lens" and another indicates an aperture range of 2 - 22.

Even if this is "only" a SMC Pentax-A 50mm f2, it's still a good lens, very useful for the digital bodies and well worth the price you bid.

To make the deal even better, why not put the converter back on eBay and get a fiver or more back?

As regards set-ups for close up work, it will also depend on what end product you have in mind.

As an example, I take pictures of items to put on eBay, some quite small, so a very simple set up is used. Two Jessops print mounting boards 20" x 16" are set up as the background, one flat, one upright and slightly tilted. Lighting comes from one large window. Digital cameras focus very close, so a bridge SLR-style is used to take 3MP pictures. There is no need for bellows or extension tubes for this sort of photography with this sort of camera.

Digital is so good at taking close-up pictures that I have actually stopped using film cameras for this. Film is now used for portrait (sometimes), architecture and landscape work.

Sorry if that strays from the point a little, but I hope the thoughts are useful anyway.

Slower shutter speeds will let more light in, thus compensating for the light loss.

The aperture should be kept as small as practicable because there is very little depth of field close up.

The further you move the lens elements awy from the film/CCD plane, the closer you focus, so a bellows unit or extension tubes take this further by adding more extension between the lens and the camera body.

Tubes are provided as sets of various size, and a bellows unit uses a bellows on a rack that allows adjustment continuously over a wide range.

As you extend further, exposeure needs to be increased to compensate for the fall off in light reaching the film/CCD.

Two SG13 silver oxide cells, also known as SR44 I think. They are not expensive, and should be readily available.

On the subject of exceptions, these lenses probably stand out as particularly good independent optics:

Kiron 28mm f2
Elicar 90mm f2.5 Macro
Tamron 90mm f2.5 Macro