I can help with some of your questions.

The Pentax 18-250mm was made by Tamron so they are optically identical. The only differences are in the badging and the type of coating used. I have never seen a review that says that the Tamron coating is in any way inferior to the Pentax one.

I don't believe there would be a significant difference in a good copy of this lens regardless of the badging. Any difference between the lenses would in sample variation, not because of whose name is on it.

I have the Pentax version (which usually sells for a little more than the Tamron one despite everything I said above!) and think it's just about the best travel lens you can get. Others would disagree (especially people who haven't used one), but if you want to cover a long range with excellent image quality you can't go wrong with one of these for travel.

Bottom line is that they are no longer made and still sought after so if you don't get on with it, you won't lose any money when you re-sell, unless you buy at a silly price as they were on Ebay around Christmas time.

I paid £210 delivered for mine, which is about right. If you dig around on my threads there is one with a number of pictures from a trip to Asia last year, all taken with the 18-250mm.

I've tried the cheap £8 ones and they aren't very good quality. Never had one stuck, though, though I guess it's always possible due to poor manufacturing.

Basically a tube is a tube, to an extent. No glass to worry about so, in essence, a cheap one should work as well as a more expensive one.

If you are just after a basic set with aperture linkage for use in manual mode then you really don't have to pay much more for quality.

I bought a set of Vivitar AT-22 tubes recently for around £25 delivered and they are often available on Ebay, though £30 delivered is more usual. They are fantastic quality and will last for ever. They feel good to use as well!

Not sure which your camera is, but they might need a little of the anodised black paint removed on the rear to connect properly with a K-x/K-r. It's a simple enough job.

Pentax make a 'K' set, but they don't come up too often and can be quite expensive. They do the same job as the Vivitars, though.

There are a few other clones of the Vivitars around as well for much the same price. All are all metal, with stainless steel connector plates and decent catches.

Thanks goodness for that......I was feeling a little out-voted

Just assumed I had no eye for a photo at all.........

Landscape isn't something I often do, so this is purely a personal opinion with no technical basis.

I think they are all very good. If I had taken them I'd probably be most pleased with number 3, but prefer number 2 from an artistic point of view.

That may simply be because I prefer a landscape shot in landscape format. I suspect I'd go for number 3 if it was the same format as number 2!

Chris

I have the Redsnapper 284 - it's excellent.

Thanks Lily

I wasn't at all happy with my image, but wanted to enter. I couldn't get Corel PSP X2 to produce a traditional vignette in any shape or form - the online tutorials just produced a cut-out with a contrasting coloured background. Even feathering at maximum still left a pretty hard edge.

Having failed with that I went for something different, but that didnt work either! I knew exactly what I wanted to do, but my (lack of) technical expertise with processing let me down.

Never mind, that's what these competitions are for. This time I learned that I can't do vignettes!

Congrats to the winner and looking forward to the next challenge, but no vignettes, please!

I didn't know that. Very helpful, thanks.

The other thing I forgot to mention it's worth having a play with 'catch in focus' if you have it (not sure which camera you have). It's not always appropriate, but will certainly help with moving objects. I sometimes use it for macro as well.

Thanks Mike

I'd pretty much come to that conclusion having read the reviews.

Accounting software is supposed to make life easier, but I'm rapidly coming to the conclusion that for a sole trader with no employees and not VAT registered who usually gets paid at the end of a job without any problems then I'd be better off doing it the old fashioned way.

Sage doesn't seem to get much better reviews either, at least the entry level packages.

Just need to dust off my old accounting books!

I rarely have a problem focusing M lenses, but don't have any Helios lenses.

Bear in mind that the beep and red square isn't the focus confirmation, at least with my K-r. The green hexagon is the focus confirmation. They are always pretty close, but it might be enough if you are relying on the beep.

Check the diopter for the viewfinder is properly adjusted. If it's clear in the viewfinder, but not in the picture, then that might be the problem.

You could double check using liveview. I often find myself using that, particularly for macro and find it pretty accurate.

Lastly, perhaps use a smaller aperture to give greater depth of field.

All the above is based on my experience with the K-r. It should be pretty general advice, but you might not have liveview, for example, depending on your camera model.