Photoclubalpha

I'm using Sony A700 atm, I'm looking for all-in-one travel light lens... and I think i've narrowed down to:
1 - Sony 18-250mm f3.5-6.3 DT AF Lens - £380
2 - Tamron 18-250mm f/3.5-6.3 XR Di II IF-LD - £290
3 - Sigma 18-250mm f3.5-6.3 DC OS HSM - £500

I've looked at many reviews, but there isn't one that seem to directly compare these lenses... (please note the £90 different between Tamron and Sony)
- If you pick 1 or 3, could you please explain why its worth the extra money compare to the Tamron?
- How does the autofocus differ between each lens?
- I want to avoid barrel/pincushion
- I want good bokeh
- Which are the softest, worse barrel/pincushion, sharpest, best spot for each of this lens?
- The aperture blades in Sony is circular, which in Tamron they aren't, are there that much different in bokeh?
Are there any other lenses that you can recommend which is less than £500?
Many thanks, any help is really appreciated.

I am currently testing the Sigma - in fact I am the first in the UK to have it, it goes back today, I only had three days to use it (on Canon 500D - also one of the first four to have one to test). It is much bigger and heavier than the Sony/Tamron, but well made. I do not think it offers any optical advantage and the OS behaviour/cost is not needed on Sony because the SSS does that job. You must switch off SSS manually to use the lens OS, there is no automatic linkage - Sigma just decided to make one type of lens for all bodies, regardless of internal stabilisation.

The OS element parks itself by moving upwards when the camera is held normally. When the camera/lens is turned off and locked at 18mm, this results in a 'rising front' effect equal to maybe 3mm of shift. So if you compose a shot, then turn the camera on (or press the shutter after the lens had parked itself - which happens after 40 seconds as far as I can tell) the whole image suddenly recomposes itself by about 1/4 of the height of the frame. It is very strange and disconcerting. I found it hard to compose shots at 250mm with any accuracy, as every small movement you make to get the subject perfectly framed is countered by the image moving to compensate then floating back (not a big floating effect, but even a small adjustment to composition causes an excursion for the image). It is very stable once composed, but I prefer to use a lens without OS.

Optically, I can not tell because I am using Canon with 1.6X factor and no decent raw converter to enable me to really asses the images, having to rely on their own converter and it does not render images in a way which allows fine detail to be judged easily. And 1.6X factor means I am not seeing the corners of the frame which would be present on a 1.5X camera like Sony.

Personally, I'd get the Tamron. We had one until a Sony came up at a good price mint/used. There is no gain in quality with the Sony, it is purely cosmetic, but it does focus faster.

David

David Kilpatrick wrote:There is no gain in quality with the Sony, it is purely cosmetic, but it does focus faster.

I have the Sony 18-250 can only wholeheartly recommend it. Get one (or the Tamron) - full stop. Esp. when there is enough light, I set it to F8 or F9 and keep shooting.

Concerning AF speed, while the Sony is said to be faster, it's still not a speed deamon. Today I photographed in a church and earned a really bad look. I had missed AF and the lens was going through the full range from close to far and back. Can you say ssssiiiinngggg

Hi gurluver and welcome to the forum.
May I ask why are you settling on 18-250?
Personally, I would go a bit wider and opt for either 16-80 Zeiss or 16-105 Sony. I think, while traveling a bit more of wide angle is always welcomed. As a matter of fact, 16-105 has more than 16-80 (focal and travel wise, but not quality wise).
While on a trip, I was using the 18-70 Sony lens which nearly always reminded me of the need of wider view and that's how I acquired the Sony 16-105.