Lens or User problem?

[koren]

I've recently bought the Pentax SMC-M 50mm F1.7 lens from a forumer. But the photos were not quite sharp at F1.7. It turns out better at F4 or smaller. I dont know if its the lens issue or my settings. can anyone advise?
F4

IMGP0335 by Li Shixian, on Flickr
F1.7

IMGP0334 by Li Shixian, on Flickr

 

[koren]

F4

IMGP0353 by Li Shixian, on Flickr

F1.7

IMGP0352 by Li Shixian, on Flickr

 

[rhino123]

Most, if not all, lenses are not at their optimal sharpness wide open... plus as the aperture is wider, the DOF is shallower, so onlycertain portion of the over image is in focus, others are off focus.

So it also depend on where you are focusing on.

 

[ZerocoolAstra]

I've recently bought the Pentax SMC-M 50mm F1.7 lens from a forumer. But the photos were not quite sharp at F1.7. It turns out better at F4 or smaller. I dont know if its the lens issue or my settings. can anyone advise?
F4

IMGP0335 by Li Shixian, on Flickr
F1.7

IMGP0334 by Li Shixian, on Flickr

The 'P' in Pentax looks sharp enough. I presume that's where you were focusing, coz that's roughly in the middle of the photo.
But the bokeh.... much to be desired...

 

[pinholecam]

Most lenses are not as sharp wide open and will have less contrast too.
The area around 'PEN' looks sharp enough, remember that you are dealing which very shallow DOF too, so not all the letters can be as sharp.
Use a hood to get minimize loss of contrast (Note : this is not a cure-all, just to maximize what is possible)

 

[xtunbox]

Photos look under exposed to me and the environment maybe too dark for you to properly manual focus. Maybe you can try repeating the whole "experiment" again with sufficient light and with a stable tripod.

 

[Daoyin]

F4

IMGP0353 by Li Shixian, on Flickr

F1.7

IMGP0352 by Li Shixian, on Flickr

Looks like the second shot was hand held.

 

[yrh0413]

doesn't look like handshake to me, the fonts are sharp... this looks more like ghosting/ lack of contrast at wide aperture which is pretty normal for most large aperture lenses.

 

[stunna88]

The first sample is normal, at f1.7 DOF is super shallow anyway, at least the part u're focusing on is still sharp.

The second sample at f1.7 is a too hazy...looks like ghosting but there is no direct light source. Not sure why.

 

[koren]

Hey.. thanks everyone for the help... after playing around with the lens today, i found that F1.7 would focus on a really small point. F2.8 onwards would have a shallower DOF. Having fun with the lens now..


IMGP0443 by Li Shixian, on Flickr


IMGP0429 by Li Shixian, on Flickr


IMGP0430 by Li Shixian, on Flickr

 

[ZerocoolAstra]

Hey.. thanks everyone for the help... after playing around with the lens today, i found that F1.7 would focus on a really small point. F2.8 onwards would have a shallower DOF. Having fun with the lens now..

You mean deeper DOF?
Your outdoor photos look pretty sharp.

 

[Daoyin]

doesn't look like handshake to me, the fonts are sharp... this looks more like ghosting/ lack of contrast at wide aperture which is pretty normal for most large aperture lenses.

The fonts do look sharp enough. I stand corrected.