Be safe and have a great time!

Yes, the moderators are reading this. Opinions are allowed and only when things go too far are they pulled.

Not many threads disappear as we tend to be quite a civilised bunch.

DonaldM, not a problem, I would summarise the Pentax 18-250mm as follows. But just to clarify, what I'm saying about Pentax lenses is not loyalty but rather a conclusion arrived at after wasting probably a small fortune on alternative makes. If there's one useful thing I could possibly tell anyone it would be that we might as well save up and buy the best option because in the long run it won't need to be replaced and will prove to be the cheapest option.

The lens is bulky and heavy and does not focus as close as I would like. Its AF is probably slower than some more modest lenses.

The resolution and sharpness are excellent. The colour balance is in keeping with the other DA lenses and is warm neutral.

The distortion is slight barrel at the wider end, but not excessive and certainly fine for general subjects. It would not be OK for critical architectural photography.

Vignetting is not significant for general purpose use.

Contruction quality is excellent and it should serve well for many years.

Hope that helps!

All things are relative. I've personally never been impressed by Sigma lenses, but others will disagree and that's fine.

I think it's well established that I only buy Pentax lenses these days, and to be honest that has been saving me time, trouble and money for a few years now. I try others from time to time, but they have never offered anything that would make me change the basic philosophy.

I would also buy Nikon lenses, but they are not available in Pentax fit!

It's worth noting that high quality purchasers for book and magazine publications who use fotoLibra are now insisting on best quality JPEG images and no longer accept TIFF.

They also accept in-camera sharpening but not Photoshop sharpening, so clearly things are changing. It looks as though the quality of JPEG capture has improved and its universal nature is rather appreciated by all parties.

Testing lenses is a very complex affair, as is interpreting the test results. There's a good deal more to a lens than resolution alone, or indeed than figures for distortion and vignetting. You will never get a perfect lens and one that appeared to be nearly perfect when photographing test charts might not be so good "in the field" for a variety of reasons. Apart from anything else, the distance the tests were carried out at will also be relevant factors and you can be sure only the manufacturer will have gone to the required lengths with this.

You don't come across badly in any way, so don't worry about that. Technical conversations get technical, there's no avoiding it.

I have not done bench tests on the 18-250mm Pentax lens that Sue uses, but I do know that she takes brilliantly sharp images with it and I have been very impressed. Its resistance to flare is excellent - the other night at Plover Scar I noticed you can see right through the lens and the individual elements are quite invisible, a good sign of high efficiency coating. Her images in normal use do not show vignetting. Sharpness and resolution are fine.

In summary I would say if you had gone with your "gut feeling" and ignored the tests you would have been very happy with the lens. What more is needed?

We're not using the Canon version....you can't compare unlike things.

In normal use there is no excessive vignetting and in any event this would be a good thing in some respects. Slight vignetting at wide angles, like slight barrel distortion, is actually very acceptable. Unless we are shooting architectural subjects of course.

In the darkroom "darkening the corners" of a print was normal practice as it helped to darken the sky and concentrate the viewer to the centre of interest of the image. Ultra wide angle lenses often accomplish this for us, such as the SMC Pentax 15mm f3.5 which darkens skies nicely on film without the need for a polariser. It's technically a defect, but pictorially very useful.

Don't worry too much about these internet tests - they test using test targets and rulers and so on, but those are not the subjects we usually photograph. In the real world all the Pentax lenses can be used with confidence.

I'd question the "nearly as good" - I've used these lenses and the quality control is dreadful, the construction stinks of machine oil and they are basically pretty rough.

Russian cameras are about as dismal - my Kiev 60 shutter lasted about 10 exposures before totally unravelling. The prism didn't fit properly either...

My Zenit B had a viewfinder that was a miserable 24mm across, showing only part if the frame, and had barrel distortion worthy of a fisheye lens...

My Kiev 4 self timer failed to work after one use. It also had a viewfinder that scratched my glasses and was impossible to compose with, although to be fair that was only a copy of the Contax design...

They are all solid though!

The Pentax 18-250mm is a very respectable general purpose lens.

As I understand it when you open your RAW file into Photoshop it is displayed as a bitmap image. This could happily be printed at any stage by your computer.

The problem arises when you save it to a CD (or whatever portable device) to take your image to the shop. Their machines would not recognise your RAW data so you would save your image to the CD as a JPEG or TIFF file. Sometimes it has to be a JPEG, so for this purpose that's probably the safest option to use.

Their machine will be able to handle the JPEG file to make a print.