Tamron 18-200 used on alpha-100

[Gagauza]

At what aperture is it at its sharpest results for landscapes and portraits?!

[David Kilpatrick]

Don't go to f/16 - f/8, f/9 to f/11 is best. If you use f/16 or less, you get diffraction loss of sharpness. I often use Aperture priority exposure set at f/7.1 or f/8 or f/9, f/10, f/11. These apertures yield the sharpest results with most lenses including the 18-200mm.

David

[Gagauza]

Don't go to f/16 - f/8, f/9 to f/11 is best. If you use f/16 or less, you get diffraction loss of sharpness. I often use Aperture priority exposure set at f/7.1 or f/8 or f/9, f/10, f/11. These apertures yield the sharpest results with most lenses including the 18-200mm.

David

I've tried today a few shoots in a local park and indeed f9 anf f10 are very sharp on this lens.... f10 especially in direct sun light spots...and f9 in sun/shadow.....All the pictures were made without the internal noise reduction of the alpha-100.....I've tried also f8 and f11 with not such good results but the f8 i've notice that tends to become sharper in shadow spots....

[David Kilpatrick]

Probably more to do with exposure than the physical lens aperture. Most lenses, as long as you stop down one stop from wide open and avoiding using the narrowest and next to narrowest stop as well, will be within their optimum range.

David