Quick Question Regarding Nikkor 105mm Micro f/2.8

[droidz]

Hey everyone,

So i just got the nikon 105mm micro. Wonderful lens i must say! just one quick question: why does the max aperture of 2.8 stop down to 4 as i focus closer up? and if it has something to do with the lens' IF construction then im okay with it, but even when i just focus at a bit less than inifinity the lens goes down to f3 or f3.5.

thanks!


and I just realized that the focus assist lamp on my d7000 is pretty useless cuz this lens blocks it out. I havent managed to find the setting to turn it off. someone wanna give me the quick tip here?

 

[joealcantar]

Is it in Program mode?
-
Shoot well, Joe

 

[droidz]

aperture priority

 

[Overread]

This is perfectly normal for the lens, and indeed pretty much all current generation macro lenses on Nikon camera bodies.
Simply put macro lenses perform some changes to their properties as they focus down into the close focusing distances, the result of which is that their effective aperture reduces and their focal length shortens. With Nikon camera bodies the effective aperture change is reported to the user; whilst on Canon and some other brands this chance is not reported to the user (even though the very same process is occurring).

This generally means that Nikon shooters can use about one stop more in reported aperture over canon users with regard to the minimum usable aperture before diffraction softens the photo too much. So whilst f13/16 is about the limit on canon its about one stop further down for nikon shooters - the apertures (depth of field, blurring etc..) are the same, its just a difference in how the user is being informed

 

[droidz]

This is perfectly normal for the lens, and indeed pretty much all current generation macro lenses on Nikon camera bodies.
Simply put macro lenses perform some changes to their properties as they focus down into the close focusing distances, the result of which is that their effective aperture reduces and their focal length shortens. With Nikon camera bodies the effective aperture change is reported to the user; whilst on Canon and some other brands this chance is not reported to the user (even though the very same process is occurring).

This generally means that Nikon shooters can use about one stop more in reported aperture over canon users with regard to the minimum usable aperture before diffraction softens the photo too much. So whilst f13/16 is about the limit on canon its about one stop further down for nikon shooters - the apertures (depth of field, blurring etc..) are the same, its just a difference in how the user is being informed

thank you!

 

[BlairWright]

All macro lenses do this. I have the 105 too and that freaked me out the first time I saw it too so I called Nikon... Yup, it's by design

Personally, I don't think they shouldn't be calling it a 2.8 if it does that but they do for some reason.