Thanks I will do.

What I meant was they shouldn't be so difficult for IIF shots if you have them on a piece of cotton

My wife tells me they used to do that with crickets and cicadas too (both fly of course - which was the fun of it for children that couldn't afford anything except home-made toys).

So you didn't get any IIF shots then ? Should be easy enough if they are flying around in circles

I will look out for these next Summer.

If you want macro on the cheap then use extension tubes or a Raynox (I prefer the 250 over the 150) to turn virtually any lenses into a macro lense. Both methods can give you excellent macro shots - with practice & patience !

Please note that when manufacturers talk about min focus distances (MFD) then they mean from the sensor to the subject and NOT from the end of the lense to the subject .... depending on the circumstance then this can mean taking up to 3" (7.6 cms ) or so off of the MFD.

Generally a 90 or 100/105 is considered the most useful length for a good macro lense. Anything less than that (50 or 70) tends to mean much lower MFDs and so not so useful for live subjects. Anything more than that 150 / 170 / 180 are very expensive !

That's what plastic bags and rubber bands are for

Today I went and compared the Tamron to the 16-50 on my K7 at my favourite Pentax stockist (the Sigma wasn't in stock - should be there within the week). I was shocked - the sharpness from the Tamron blew the Pentax away at 2.8 although at F8 there was nothing in it. I also found the Tamron very fast to focus - I'd expected Pentax to edge it but there was nothing in it. I can't say that build quality looked an issue on the Tamron either - by look & feel there was nothing in it.

US$900 and a one year guarantee vs. US$360 and a three year guarantee ..... it's down to the Tamron or the Sigma (quoted US$550) I'm afraid, though I will be sorry to give up the WR if the Tamron/Sigma takes a drenching I can buy another one (and get another new 3 year guarantee) !

A link to an excellent test between the 3 lenses (in Slovenian but you can understand the comparisons) :
link

This is what I got (although this could just be sample variation too) :

Sharpest at 16/17/18mm @ F2.8 : 1. Sigma 2. Tamron 3. Pentax
Warmest Colours at 16/17/18mm : 1. Pentax 2. Sigma 3. Tamron

Sharpest at 16/17/18mm @ F8 : 1. Sigma 2. Tamron 3. Pentax (noticeably darker too).
Warmest Colours at 16/17/18mm : 1. Sigma 2. Pentax 3. Tamron

Sharpest at 30mm @ F2.8 : 1. Sigma 2. Pentax 3. Tamron
Warmest Colours at 30mm : 1. Sigma 2. Tamron 3. Pentax

Sharpest at 30mm @ F8 : 1. Sigma 2. Tamron 3. Pentax
Warmest Colours at 30mm : 1. Pentax 2. Sigma 3. Tamron

By 50mm Pentax & Tamron seem to have taken over as #1 in the sharpness and colour warmth.

In PF Tamron is a clear winner, followed by Sigma and then Pentax.

Ghosting & flare : 1. Sigma 2. Tamron 3. Pentax

Bokeh : the Sigma seems smoother and isolates better (@2. with nothing much between the Pentax & Tamron.

Of course this is just one test I we can't vouch for the conditions / accuracy but it's interesting to see real life side-by-side comparisons nevertheless. One thing is clear, these lenses are so closely matched in IQ that I couldn't go wrong with any of them.

If anyone can comment on the test or disagrees with my observations - please come forward and say why, I'd love to hear other people's opinions.

I want to thank you all for the superb response to my quandary on this site. I posted this on a number of forums and this one has by far the most response so far !

Just to point out that money isn't the issue here but I don't see the point in putting down hundreds more if a) the lense is going to be unreliable and b) I can get something just as good (and that is the point) for half the price.

I have to say I am really confused by the number of technical reports I am seeing that say both the Tamron, & especially the Sigma (exceedingly sharp), are better than the Pentax. And a number of people above are testifying that the Tamron is a great lense too.

I have put this question out on a number of forums and I'm getting some great feedback - however it does seem that the SDM problems are not a thing of the past, a number of people are reporting lenses bought recently (within the last year) that have problems - and I only get a one year guarantee over here. I was almost ready to pull the trigger on the 16-50 but this issue - and the technical reports - have me spooked.

Thanks again for the response and keep 'em coming !

OK I have made a decision on my next two lenses, the 60-250 (for a very specific purpose next year) and something missing from my range ...... one of these three before Xmas !

I have seen the 16-50 thread here and absolutely loved it ..... however I'm becoming very worried about the SDM issue. Pros though are great build quality and WR.

Then I go over to the reviews here and to Photozone, SLRgear and DPR and check all the ratings / reports / comments and the numerous threads and see that both the Tamron and Sigma seem to be technically higher rated (especially on DXOmark, Pentax tested on a K20d, Tamron & Sigma tested on a 50D as the nearest equivilant). Which confuses me considering how people rave about the 16-50 (and with good reason it seems from the 16-50 thread) especially with CA and distortion better in the 3rd party brands.

Then there is the price issue, over here (Shanghai) it's US$900 for the Pentax, US$330 (non VC) and US$400-450 (VC) for the Tamron and US$500 for the Sigma. That's quite a range for three supposedly very similar lenses.

It must be a constant 2.8 so I've decided the reduced range (so no 17-70 suggestions please ) will give me higher quality, so which one should I go for ? Is the Pentax really worth the extra money or is it just brand premium ?

Note : I should mention I have the Sigma 10-20 and the 43 Ltd so this is to fill the gap.

This is driving me nuts ! My post missing again and I know why

I must have written a 100 posts and then hit Return to Forum instead of the tiny Add Comment ! Make it bigger PLEASE !!