07-28-2012, 10:04 AM
(This post was last modified: 07-28-2012, 10:05 AM by Ballonseide.)
Thanks for your answers.
[quote name='photonius' timestamp='1343329019' post='19611']What body? edit, I see it must be a pentax? So, it's an APS-C?[/quote]
Yup, K-5.
That could at least explain the underexposure at f/1.4 and f/1.6. I understand this needn't happen with any fast lens but depends on the optical construction, too?
I don't even get cat's eyes in the corners, so unlikely. Also I don't think it's physically possible to get any kind of vignetting in the image center with the aperture wide open.
[quote name='karlmera' timestamp='1343407087' post='19620']That is not normal. You can choose in between clickstops between 1,4 and 1,8.[/quote]
Do you have the lens? Mine has half-EV clickstops between all apertures, except for the step from f/2 to f/1.4 which is a full stop. According to [url="http://www.lenstip.com/265.3-Lens_review-Voigtlander_Nokton_58_mm_f_1.4_SL_II_Build_quality.html"]LensTip[/url], the older version didn't even have half-EV clickstops.
[quote name='photonius' timestamp='1343329019' post='19611']What body? edit, I see it must be a pentax? So, it's an APS-C?[/quote]
Yup, K-5.
Quote:I have seen reports where people say that it's hard to take advantage of very fast lenses, since basically with very fast lenses, a lot of the peripheral rays are cut off by the microlenses of the sensor.
That could at least explain the underexposure at f/1.4 and f/1.6. I understand this needn't happen with any fast lens but depends on the optical construction, too?
Quote:Another alternative is perhaps that the out of focus highlights get vignetted. You get cat's eyes at the borders due to vignetting. Is it possible that you get round vignetting with very large aperture lenses in the center? (lens hood?)
I don't even get cat's eyes in the corners, so unlikely. Also I don't think it's physically possible to get any kind of vignetting in the image center with the aperture wide open.
[quote name='karlmera' timestamp='1343407087' post='19620']That is not normal. You can choose in between clickstops between 1,4 and 1,8.[/quote]
Do you have the lens? Mine has half-EV clickstops between all apertures, except for the step from f/2 to f/1.4 which is a full stop. According to [url="http://www.lenstip.com/265.3-Lens_review-Voigtlander_Nokton_58_mm_f_1.4_SL_II_Build_quality.html"]LensTip[/url], the older version didn't even have half-EV clickstops.