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hi people

i just got a nikkor 105 macro f2.8

i havnt used a macro lens before so excuse the newbie question

but i noticed i cant get it to shoot at f2.8 the camera doesnt see it as f28 when i turn the dial down
however when i turn the focus ring past the infinity symbol the camera automatically shifts the aperture to 2.8
but at the lens at infinity i have to stand really far away to get anything close to focus

ive noticed if i use the lens for intended closup work lens centimetres away from subject the lens focuses but it forces the aperture to something like 3.5 for f4 at this point where its in focus i cant change the aperture on camera to 2.8

so have i bought a dud or is this how this lens works?

Hey dude,

I've had the same problems instore playing with the same lens on a D300s. Not sure what up with it either, will be keen on hearing the reasons too.

ive been using it on a d200
it seems busted

Hi Wendell & photomarcs

What you describe is absolutely normal.

With a macro lens, maximum aperture is a function of focal length - as you get closer, the effective aperture changes. The camera's computer allows for this, and shows it to you.

Read this article from Ken Rockwell (I know - but he is right on this occasion!) or Google it yourself to verify. Look under the Performance heading in Rockwell's article for the appropriate info.

This article also explains it:
http://www.photozone.de/nikon--nikkor-a ... est-report

If you decide to sell, advertise here first!!!

It is very normal behaviour for macro lenses....it is basically telling you what your effective aperture is rather than your true aperture to my understanding.

o.k cool thanks so much

i bought a 24-70 f2.8 from ecs like 2 days ago and returned it today because it had a busted cpu
they wouldnt like me too much if i came back the next day and said i have another faulty lens

one question though

the f2.8 ability only works at infinity which sort of means i need to shoot a landscape subject kilometres away to get the lens to work at f2.8 which is kind of silly since you wouldnt normally shoot such far distance to make use of the f2.8 aperture
so why does nikon make this macro f2.8 when you really cant shoot closeup with 2.8?

i noticed shooting minimum distance the camera uses f4.8 and the depth of field looks shallow enough

wendellt wrote:the f2.8 ability only works at infinity which sort of means i need to shoot a landscape subject kilometres away to get the lens to work at f2.8 which is kind of silly since you wouldnt normally shoot such far distance to make use of the f2.8 aperture
so why does nikon make this macro f2.8 when you really cant shoot closeup with 2.8?

That is a tough one to answer....but I can say it doesnt take kilometers to get f/2.8, only a few metres. In terms of a macro...you shouldnt be shooting it wide open when your up close anyway hence the change in aperture is in many ways welcome for most.

Why make it a f/2.8? I dont know, because its maximum aperture is f/2.8?

the f2.8 ability only works at infinity which sort of means i need to shoot a landscape subject kilometres away to get the lens to work at f2.8

As has been said, this is normal behaviour. Other lenses demonstrate it too, but they don't focus as close, so it is not as obvious. I checked with mine. Aperture changes from f2.8 to f3 at about 2m away. That's a LOT closer than infinity. By the time you get to around 100mm it closes down to f4.5, but since even at f4.5 at that distance, DOF is something less than a hairs width, why would you want to open up that much? When using as a macro, I am usually at f22 or even slower. When I use it as a portrait lens, it works happily at f2.8, so it is the best of both worlds.

The thing that does bug me about this lens is that when in MF, turning the focus ring all the way takes it past infinity & you end up with an OOF shot. A real pest when you can't see to focus. I'm told its something to do with the way AF works. It needs to go past infinity in order to range in on distant objects.

If this is the current 105mm lens, then it does have a variable maximun apeture between F2.8 and F4. Just depends on the shot set up, includung distance to subject.

Wendell
Most macro lens users are after MORE depth of field, not less. Don't forget....the lens is designed for close up work and when the camera gets close to the subject there is almost no depth of field. The inability to get F2.8 when up close is not an issue with these lenses because macro work at F2.8 is very impractical.

Conversly to the not getting up to f 2.8 at near focus, I get down to a camera reading of f 57!!!
If you are after very limited depth you should do fine at f4 - 5 at close distances anyway.
From my experience it delivers great close up results but is not as good at distance work. This is fine for me as I bought it for close up work. As others have said it works nicely for portrait type stuff too.
Regards Colin