105 2.8 AF-D Micro apperture limit

<p>I made a strange observation this morning. The apperture does not go lower than 5 when shooting a macro, both in manual and apperture priority mode. Meaning I cant go down to 2.8 when I am focussing anything closer than 1.5mts. It works like a f2.8 - 5. The apperture continuously varies from 2.8 to 5 as I get closer to the subject in steps. At the closest distance the max apperture I can go to is f5!! I took a shot and the apperture value in the EXIF shows f5. I was using a D200. I would have loved to try it out on my other camera but I have lent it out to a friend.<br>

The lens works normal, almost like new, shots are great, but the question is why cant I open it out to 2.8 for macro shots.....I mean close focussing. Any setting on my D200 that I might have meddled with?? I cleaned the lens contacts, I checked the apperture lug, everything looks normal. Never banged around.<br>

Appreciate your insight into this.<br>

Thank You!! What a surprise..... </p>

<p>Effective aperture drops as you focus closer; it is a lot more noticeable on a macro lens as you can focus very close. What you observed is completely normal.</p>

<p>See some old threads on this topic:<br>

<a href="http://www.photo.net/nikon-camera-forum/00Bzl1">http://www.photo.net/nikon-camera-forum/00Bzl1</a></p>

<p><a href="http://www.photo.net/nikon-camera-forum/00QU5K">http://www.photo.net/nikon-camera-forum/00QU5K</a></p>

<p>Ow! Rrrrreallly??!! Thanks Shun.....So, whats the widest lens we can get in the micro market? That was an interesting to me.</p>

<p>Most macro lenses change the effective aperture as you move closer toward 1:1 magnification ratio. The effect is similar with extension tubes or bellows.</p>

<p>Probably the Repro-Nikkor 85 mm f/1. It has an effective f/2 aperture at 1:1.</p>

<p>By the way, this lens outresolves the D3X sensor at f/1.</p>

<p>The Laws of Physics are a cruel mistress, aren't they? I remember when I first encountered this on a 60/2.8 Micro. After a bit of existential angst and testing (at which point I realized that, indeed, it's only an issue when right on top of the subject), I relaxed and thought about my light sources, instead. There's no free optical lunch, as it turns out.</p>

<p>Yea Matt....sometimes physics is indeed ruthless.....:-)<br>

So, as I understand, the apperture pysically doesnt change......but it is the light fall off that is interpreted as an apperture value, is it??<br>

So we humans have not been able to create a constant apperture macro, huh??<br>

We have achieved so much, and so much more to be achieved yet!!</p>

I'm interested what kind of shot you were trying to get shooting that close in at f/2.8, the available dof at that distance would be minuscule.

<p>It would be difficult indeed to have a greater aperture than f/1 effective at 1:1.</p>

<p>A narrow depth of field has its uses.</p>

<p>There is one constant aperture micro lens, the 70-180 micro zoom that is discontinued and very desirable and therefore ridiculously expensive.</p>

<p>EDIT: I mean to say even though it's variable aperture depending on focal length, it does NOT change aperture when you focus closer. It doesn't get all the way to 1:1 I don't think, but is quite a piece of equipment.</p>

<p>The 70-180 does not change its effective aperture, correct, but its equivalent focal length shortens. There is no free lunch.</p>

<p>Besides, it's f/5.6 at the highest magnificantion (1:1.3 at the nominal 180 mm setting).</p>

<p>What was I shooting? It was a very interesting micro spider, should I say?? hanging out in a shady corner of a tree bark. May be a 10 of pixels wide. </p>

<blockquote>

<p>The 70-180 does not change its effective aperture, correct, but its equivalent focal length shortens. There is no free lunch.</p>

</blockquote>

<p>Those well paid Nikon optics enginerrs somehow cannot overcome the laws of physics.</p>

<p>In any case, as I said before, most macros are captured at smaller apertures anyway to gain depth of file. Not having f2.8 or even f4 in the macro range is typically not an issue. Again, I said most; there is of course some occasional exceptions.</p>

<blockquote>

<p>So we humans have not been able to create a constant apperture macro, huh??<br /> We have achieved so much, and so much more to be achieved yet!!</p>

</blockquote>

<p>How about the compensating 55mm f3.5 Micro Nikkor - it compensates the iris mechanically when changing focus.</p>

<p>The compensating 55 indeed allowed a constant effective aperture. Provided it was set to f/5 or smaller :) Otherwise it couldn't open up sufficiently to compensate towards the near limit.</p>

<p>By the way, this Micro was a nightmare with a TTL aperture-coupled meter of those late 60's years. You had to re-compensate the metering and remember in which direction the adjustment should go. This because the TTL system already had registered the reduced effective aperture brought about by focusing closer. Nikon made this system before TTL metering became the norm.</p>

<p>Bjorn,<br>

I inherited a Micro-Nikkor-P Auto 1:3.5 f=55mm, serial # 665938 from my aunt, who was an accomplished nature and travel photographer. (As a high school science teacher, she did a lot of macro photography of bugs and small plants, and was recognized repeatedly at the local science museum.)</p>

<p> How does one determine if this lens is one with the compensating aperture? It was not used with TTL metering in her F.</p>

<p>Thank you.</p>

<p>David Ralph</p>

<p> </p>

<p>"How does one determine if this lens is one with the compensating aperture?"</p>

<p>Set the aperture to about f5. Remove both front and rear caps. Look at the lens from the back starting helixcoid from infinity focus position. Slowly focus the lens to 1:2. If it is a compensating aperture type lens, you will see the 6 blade hexagon slowly turn into a perfect circle (max out of effective aperture at f5). If you don't see that, the lens does not do aperture compensation. </p>

<p>Thank you.</p>

<p>It does not appear to change the shape of the iris leaves, so apparently this one is not self compensating. I am estimating this lens was manufactured around 1971 or 1972, which would have been later in the evolution of the lens. (And, an AI conversion kit appears to have been applied, likely by Nikon service facility.)</p>

<p>While the lens may not be as exotic, the non-compensating version is probably more practical today, especially on more modern bodies.</p>

<p> </p>

<p>David you are probably aware of this useful site:<br>

http://www.photosynthesis.co.nz/nikon/serialno.html#55%20micro<br>

This is Roland Vink's site where "everybody" looks up manufacturing dates of lenses and quite a bit more. Thanks Roland for this great service in case you ever read this :-)</p>

 

<p>I saw that site many years ago. It is one worth saving. Thanks.</p>

<p> </p>

<p>The reason the affective aperture changes, even though the size of the opening doesn't, as you focus more closely is that the effective focal length is increasing. Remember that the aperture is the ratio of the opening to the focal length. f/2 has an opening 1/2 the focal length, f/4 has an opening 1/4 the focal length and so on. That is why a 400mm f/2.8 has such a large diameter front element.</p>

<p>And the 70-180 macro zoom is one of my favorite lenses even though I have both the 105 VR f/2.8 macro and the 200 f/4 macro. When you are hiking around shooting wild flowers the zoom makes life much easier and the optical quality is excellent.</p>