Longer zoom thoughts

About 50% I would say!......the image quality isn't effected that much,I am quite happy using the combination!.......Ken

The Sigma combo is a lot more versatile .. although obviously a lot more expensive as you already have the 300mm prime.

Nope, I don't have the DA* 300 just the 60-250 which is why I'm looking at various options....

Thanks Ken, how's the focus speed with the x1.7 converter? By the way I realise it doesn't use SDM, so presumably it's case of manual focus to close then auto focus via screw drive with the x1.7?

Oh, I presumed you did from the other post.

The only thing I will say is that once you start using the 100-300mm you will find the 60-250mm gets less and less attention .. only coming out if it looks like rain.

Sorry Mike, my mistake I didn't read Barrie's post carefully enough.

Yes regarding the 60-250 gathering dust, that sort of concerns me because as you've identified it's faster focussing, similar range and equal if not better image quality.
I guess that even though it's not sealed it could probably deal with a little light rain because of the internal focussing design.
To be honest my 60-250 has never seen rainy conditions, it's my 16-50 that always ends up taking the brunt of bad weather

Well I havent used mine much as I got it in November and the weather has been more or less against me since but here are a few pics taken when I first got it. I often go on about the colours that the DA* 60-250mm produces but I think the last one shows the 100-300mm is more than capable.

So these are all using Sigma 100-300?

Yup. Imagine it on a K-7.

One of the moon with the 2x TC attached.

Hand held.

... now you're just showing off.

Niiice shot.

Bret

Mike, do you work for Sigma by any chance:

Edit: Should have added, all very nice shots. That moon looks particularly impressive given the 2x teleconverter.

I managed to borrow the 150-500mm for a short while last Summer. Here's a couple of examples:




F8 @ 1/125 370mm.




F6.3 @ 1/500 400mm. All of these taken with a K20D.

Then I bought a S/H Sigma 100-300mm last October...



F11 @ 1/400 300mm.



F4 @ 1/800 300mm. These were taken with a K-7.

Most of the Duxford Autumn Airshow photos on my Flickr page were taken with this lens, only when the weather looked a bit grim did I then switch over to the DA*60-250mm and then noticed the fact that it was 250mm and not 300mm

I'm going to be using the Sigma a lot more this season (hopefully) and if that is the the case then the DA*60-250mm will be redundant. I also found the AF to be an acceptable speed on the K-7, it didn't seem too slow and at times faster than the SDM

All in all I am very pleased with this lens and prefer this to the 150-500mm

Hope this is of some use to you,

Rob

Rob thanks that is extremely helpful.
I think my mind is now pretty much made up. The Sigma 100-300mm seems to be a bit of a no brainer and with a matched converter that works very well I'll have the focal length flexibility I want.
Now just need to get the funds together

I have been considering the very long lens scenario myself and have tested the 150-500 recently and decided that I would rather crop my DA*60-250 shots by up to 2x.

To avoid cropping above 2x, I have recently added a (now very rare) Pro-master 1.7x Pz-AF TC that seems to give pretty good IQ and still allows SDM AF with my 60-250, although I must admit I have found it difficult to obtain reliable fast AF lock on small moving birdies, but they're darn hard to nail whatever you're using!

I suspect however that the 100-300 EX plus TC's (both 1.4x and 2x) would be my preferred choice on an IQ basis from what I've seen. But I wouldn't sell my 60-250 to fund that combo!

But I suspect there may be an updated 100-300 EX HSM AS arriving soon, together with updated SDM compatable TC's as well, seeing that the Bigma has just had HSM and AS added, but the EX classification has been dropped from the Bigma. It seems that Sigma are keeping the zoom EX designation for constant aperture lenses.

As far as Sigma offering their lens AS with HSM as standard in Pentax mounts, the 120-400 and 150-500, although with HSM, don't have in-lens AS.

It's also been mentioned that the HSM on the 70-200 EX is much faster than the HSM on the 120-400 & 150-500, maybe there will be different versions for EX & non EX versions of HSM?

Anyway, it's good to see Sigma supporting the Pentax mount with their new releases. It will be interesting to see if they bring HSM AS versions of their PK mount 300mm f2.8 and 500mm f4.5 primes.

Given the choice between my 60-250mm and 100-300mm the Sigma would be staying. I honestly dont think we will be seeing any HSM compatible TC for Pentax anytime soon and IF they did release a HSM 100-300mm (which I also can't see for the immediate future) imagine the price

You only have to look at the difference pricewise between their normal 24-70mm and the new HSM OS version to see it virtually doubled.

Pity you have to sell the 35mm Macro though Huw