Well, I should fess up, I guess, and admit to losing much of my earlier enthusiasm for this project - until today I hadn't done any scanning since 15/11 last year, after discovering that there were about 10k frames in total, rather than the 4k I originally thought.

However, I'm pleased to report that I'm going again. The scanner is working as well as ever (touch wood). If I find anything nice I may post it on my other thread, and of course people are welcome to comment as brutally on it as they like.

I hope people won't be offended if I repeat my earlier shameless plug - as I've said, it would be nice to recoup some of the outlay on the scanner, so if anyone has a few rolls of negative film that they would like to scan at high resolution, but have been stunned at the huge prices charged on the high street, do please feel free to drop me a PM.

I assumed you only posted that to wind me up, mate

There are four normal causes of blur that I can think of:

- inaccurate focus
- insufficient depth of field
- camera movement
- subject movement

If it's none of these, then there is something wrong with the camera and/or lens.

I take it you've tested carefully using tripod and delayed release to eliminate shake, and achieved careful focus on a focus chart so that you know for certain that you're focusing on what you think you're focusing on?

And that you have focus confirmation for every shot that appears unexpectedly unsharp?

Sorry if this is teaching granny to suck eggs, but it's always worth verifying these things.

Do you get any sharp pictures at all at 1/125?

You'd be surprised how many people that have been taking photographs for quite some time have no idea how a focal plane shutter works.

Or, consequently, how shutter speeds faster than the sync speed are actually achieved.

If you think about it, most of the time, you have no need to know.

Well, it's nothing to do with focus.

It's all about when, during the exposure, the flash happens, specifically in terms of any movement taking place during the exposure.

Consider the example of a person carrying a candle across a room, in the dark.

The important things to note are:

- the candle provides its own light, so will be visible whether illuminated by a flash or not.
- the person doesn't, and so won't be visible, except in the instant when the flash goes off.

Consider now a very slow exposure, long enough for the person to walk across the frame. The flash will go off during the exposure, and is effectively of zero duration compared with the exposure.

If the flash happens at the beginning of the exposure, you'll get the person lit by the flash, and then the candle trail continuing in front of him.

If the flash happens at the end of the exposure, you'll get the candle trail first, and then the person lit by the flash at the end of his travel. The light trail from the candle will appear to trail behind him.

If you think about whether the flash happens at the end or the beginning, and what else in the frame is providing non-flash-lit illumination, all becomes clear.

'Trailing curtain' is when the flash happens at the end of the exposure, ie just before the trailing curtain (of the shutter) passes across the film/sensor plane.

The explanation in the manual doesn't help all that much, either - it's far from clear.

You could probably work it out from the illustrations, I guess, which are at least the right way round. I've come across explanations in the past where they weren't!

Be careful what you wish for.

Ironically, when I had one of mine published in the mag last year, they *only* published my user name, not my real name at all.

I was a bit narked about that, I have to say. The only time in the last 20 years I've had a picture published, and they couldn't even take the trouble to credit me properly for it.

I have both of these too, and I'd agree with this. Especially wide open, where the Sigma suffers from a lot of CA.

I've had both of these. The Tamron 70-300's main shortcoming is its horrendous purple fringing. The Pentax isn't anywhere near as bad in this respect.

ISTR that the Tamron can focus a bit closer, and is quite a bit cheaper than the Pentax. That said, I sold my Tamron and kept the Pentax.

Just noticed this comment.

The Pentax DA 50-300 is often described as having very slow focusing. If you need it to go from one end of its throw to the other in the blink of an eye, forget it. However, if it's already reasonably close, it's fine (I use it at airshows). And 'reasonably close' means anywhere from a few metres to infinity - about half the focus throw is the first 3m.

Quick shift, which the Tamron doesn't have, is very useful in this respect.