Firstly, it may not be a perfect seal against very bright light.

Secondly, the meter cells were traditionally placed either side of the eyepiece and hence relied on the face of the user shielding them.

I'm not sure where the meter cell(s) are in the DSLRs currently, but it's clear from the instruction manual that the metering is potentially vulnerable to stray light.

The first clue is that the Viewfinder cap M is supplied with the K10D.

The second clue is the memo on page 83 of the manual.

The short answer is yes.

Welcome to the forum! Hope someone comes up with an answer for you, you've left me with this bizarre image of lots of Pentax users lined up, wiggling their cameras....

The second hand value of camera lenses is more to do with simple supply and demand than any writing down. Maybe a lens will have no book value to a company, but it could still be sold on eBay or elsewhere, perhaps for quite a bit of money.

These days there is a high demand for good A series lenses, and the prices reflect this.

The future can only be guessed at!

Resale value tends to really tell later on. Just look at the price of A series Pentax lenses on eBay and compare it independent ones...

The price levels of the more exotic lenses hold up even better, and in future years the 12-24mm might well be one of more sought after lenses.

Not a comparison, but I can tell you that the Pentax 12-24mm is a cracking good lens with outstanding optical properties. It also has very, very low distortion making it suitable for architecture. £489 will get you one compared to £429 for the Sigma.

Is the £60 difference worth it for Pentax coatings, construction quality, ergonomic compatibility, low distortion, high resolution and constant aperture? Not to mention an enhanced second hand value if you change your mind later on.

Very good, Chris, nice and crisp.

Was this the dental version or the standard version of the lens?

It's the same lens with extra magnification markings on the barrel. Also in the kit are close up lenses, colour coded to the barrel markings.

You know whenever I pop into the AP Forum I get this terrible sense of deja vu....

Thanks for the tip on the lens I'll have a look.

It depends on the condition and the version. I have bought SMC Pentax-M 100mm f4 Macro lenses in mint condition for under £100, but these days prices are going up rapidly.

I would pay a good price for one of these lenses in Mint or Near Mint condition.

Someone showed me a superb example of the SMC Pentax-A 100mm f4 Dental Macro Lens today. Beautiful. I'd pay £150 for that one, but it wasn't for sale...