finding the sharpest appture on kit lens?

[topcat07]

Read for the sharpest appture use go two stops up from the minimum appture of the lens.

But I'm not sure where to work this out from as with focal length the smallest appture would change? At 55mm mine is f5.6 and at 18mm around f3.5

Do I work it from the very widest appture possible on the lens with shortest focal length? Or would you work it individually from each focal length?

If I took it from the shortest focal length my 'sweet' spot would be 4.5?

If someone could clear my confusin up I would be greatful please

 

[vetonbike]

You could do a few shots at say 18mm 25mm 35mm and 55mm. through the apature range of the lens at 1 stop intervals for each. Then judge the results for yourself.

 

[topcat07]

You could do a few shots at say 18mm 25mm 35mm and 55mm. through the apature range of the lens at 1 stop intervals for each. Then judge the results for yourself.

I will have to do this tomorrow really got to stop reading so much theory and go do a little more

 

[Dave *]

Have a look at photozone.de, they have detailed resolution tests at various apertures and focal lengths.

 

[petersmart]

I think if you set it to f8 you would find it was fine - it's very easy to start worrying about every little thing and missing the overall picture - which is to take pictures!

.

 

[Dave *]

Here is a link to the VR version, looks like f8 is the optimum.

http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/632-nikkor18553556vr?start=1

 

[HoppyUK]

Read for the sharpest appture use go two stops up from the minimum appture of the lens.

But I'm not sure where to work this out from as with focal length the smallest appture would change? At 55mm mine is f5.6 and at 18mm around f3.5

Do I work it from the very widest appture possible on the lens with shortest focal length? Or would you work it individually from each focal length?

If I took it from the shortest focal length my 'sweet' spot would be 4.5?

If someone could clear my confusin up I would be greatful please

That's far from an absolute truth, though as a very rough rule of thumb it's generally not far off.

With a typical kit zoom, it will probably be sharpest around f/5.6 in the centre, but the edges and especially the corners will always lag and might continue to improve up to f/11. Between f/5.6 and f/8 is probably about right.

Edit: you mean maximum aperture, ie lowest f/number. It sounds a bit backwards, but something like f/22 would be referred to as the minimum aperture (smallest hole).

 

[Nod]

Melvyn's already said it - take a series of shots through the whole aperture range and judge for yourself which gives the best results at the usual end product stage. At a guess, the best results will come at around f/8 but only you can judge which you like best!

Don't forget that ultimate sharpness isn't the only factor to judge - Chromatic Aberrations may vary through the range, as will the bokeh.

Personally, I would do the test shots at 1/2 stop rather than full stop intervals. Don't forget to make a note of the preferred stop somewhere - maybe on the lens cap?