It is a well known and good source of information, but no harm in mentioning it as not everyone will be aware of it.

Thanks for posting the link.

A good start are the articles in PHOTO TECHNIQUE sometime around 1977 which provided lists and basic details of just about every lens then in existence. There were an amazing number of little known lenses that were available in K mount, some of them extremely good quality.

Finding them now in mint condition is another matter.

Carl Zeiss lenses came from either West Germany (top of the line, very expensive) or East Germany (cruder construction but good and reliable, low cost) or Japan (made under licence by Yashica and now others)

So, if the lens is good, take great pictures and enjoy the results. A Google search will no doubt bring up more details and could well find things of interest to you.

Glad you like the forum!

To be fair, EPZ is intended for uploading pictures, but forums like this one are intended mainly for conversation. The posting of pictures here is probably a secondary thing.

If it's any consolation, I don't find it easy to do either, but usually because the hosting web sites seem to block the htlinking attempt.

I have you listed on my "Favourites" page for EPZ, so I do see your latest pictures every day.

Correct. I've managed to hot-link to other sites where I have images, but it doesn't always work. Seems to depend on the site.

And with a few inaccuracies that seem to indicate that Ivor probably didn't use Pentax...

I've been very happy indeed with anything that I've bought off spbatt. His descriptions are accurate, if anything under-stated, and that means we can rely on the item being a good one. I suspect the bidders on the ME Super know this and are therefore bidding keenly.

No doubt after all these comments in this thread, Simon will be blushing....

Both should be optically superb. The decsision rests on what working distance you feel you will need for the type of pictures you take. The 100mm will give the same field of view as the 50mm but from double the distance - will this hinder or help?

For example, for photographing documents I find the 100mm needs to be a liittle too far away for convenience, and the 50mm gives a better working distance.

For butterflies and insects it might be an advantage to be further away.

It may also depend on what other lenses you already have. The 100mm makes a fantastic portrait and landscape lens, but if you already have a lens of this length then perhaps that would be a consideration.

There are two factors in particular that are relevant to designing lenses for digital SLRs.

The first is that the CCD is highly reflective and can reflect light onto the rear element of the lens. If this is not to be a problem then the rear element needs particularly good coatings. I would expect the SMC coating of pentax lenses. to be good enough to start with, but maybe even there additional layers may have been used.

The second is that CCDs like the light to fall on them at 90 degrees, and to achieve this lens makers use a telecentric design principle. This is new to digital lenses.

In both these cases film does not have the same problems, so film camera lenses were not specifically designed with these requirements in mind. Nevertheless, there are lots of film camera lenses that give superb results on digital!

The old lens has plenty of life left in it yet - it will be sharper and will have excellent freedom from distortion. Modern zooms are sharp enough (or at least the higher priced ones are) but the designers do let the distortion creep in a bit.

However, not all older lenses make the grade. This may be due to variation in individual samples, but I had a SMC Pentax-M 50mm f2 that was not as sharp as the 18-55mm until it was stopped dpwm to about f11.

So testing our own lenses for ourselves can be a good idea.