Odd issue with Nikon 105mm on D5000

[DrRusty]

Late Friday I was quickly using my works 105mm macro lens on my now trusty work D5000.

After taking the necesssary pictures I wanted to see how the lens really perfomed at maximum aperture F2.8 . However, even after switching to manual I couldn't get the camera to fully open the aperture F2.8. I check the exif files and it was definately not fully open.

I didn'y have enough time to fullly investigate the cause and will probably take my D90 in to work next week to see if it is a lens problem or camera issue.

I ensured I switched off all auto settings and tried the camera in Aperture priority and manual but to no avil??

Just seems odd and wondered if anyone else had experienced similar ?

 

[redddraggon]

The 105 macro isn't ever f/2.8 at close focusing distances.

e.g. at 1:1 it's f/5 and doesn't become F/2.8 until about 10ft (roughly).

 

[DrRusty]

The 105 macro isn't ever f/2.8 at close focusing distances.

e.g. at 1:1 it's f/5 and doesn't become F/2.8 until about 10ft (roughly).

Well I have just learnt something new, feel a but silly now. I can't say I ever thought a lens could control maximum aperture against focus distance. Although it makes sense as zooms control aperture against focal length.

Thanks

 

[hyeongsoong]

all micro lens do that. it just Nikon report it, while rest of lens marker report it as F2.8