28-105 macro on DX sensor

[ptkeam]

<p>Hi.<br>

I use a Nikon 28-105mm "macro" zoom lens on my D70. (GREAT results -- I LOVE this lens). Anyhow, I'm wondering what effective magnification I am getting on a DX sensor. The lens focuses to 1:2 reproduction ratio on 35mm film @the 105mm setting but I'm wondering if I'm actually getting 50% "closer" in effect on the DX sensor because of the crop factor. <br>

Optics geeks please advise.<br>

Thanks</p>

 

[Michael R Freeman]

<p>The magnification at the image plane does not change. It is still a 1:2 reproduction ratio. Stick a piece of paper measuring 24×16mm (the size of the D70 DX sensor) with some text or other fine detail on a wall, focus on it at the minimum focus distance at the 105mm focal length, and you will find that it fills 50% of the frame area in the final image (which is not the same as the image shown in the viewfinder).</p>

[Michael R Freeman]

<p>Alternatively, if you have a ruler or measuring tape graduated in mm, take a photo of that at minimum focus and 105mm. You should see 48mm of graduations in the horizontal orientation.</p>

[Michael R Freeman]

<p>Sample below. DX format D200 with AiS Micro-Nikkor 105/2.8 focused at approximately 1:2 ...</p><div></div>

[rossb]

<p>I also use that lens and really like it. It makes a nice companion with the 12-24. </p>

[vince-p]

<p>I just bought this lens and am awaiting its arrival -- to replace the 28-70 f/3.5-4.5 macro. Question: can extension tubes (and manual focusing, obviously) be used on these lenses? K-rings? I also have some lovely Nikon magnification lenses. What do the knowledgeable advise? Thanks. </p>

[Michael R Freeman]

<p>Yes, both autofocus and manual extension tubes can be used on the AF-D 28~105mm. If they are manual tubes (no CPU) then you will lose metering on bodies that require a CPU lens for metering function. Some of the K rings can be used. Check the "Incompatible Accessories and Non-CPU Lenses" section of your camera instruction manual; the K2 Ring is usually listed as incompatible.</p>

[radfordneal]

<p>The responses above are all correct, but not necessarily helpful. The helpful answer is "Yes, you do effectively get a bigger magnification ratio from using a DX sensor camera". A lens giving you a 1:2 magnification ratio when used on a DX camera gets you the same ability to fill the frame with a small object as you get when using a lens giving a 1:1.33 magnification ratio on a "full-frame" camera.</p>

 

[vince-p]

<p>@Michael F. Thank you. I have the D300, the F100, and an F 2. The D300 and F100 will be able to meter but, now that I think of it, my only extension tube is non-Ai. My K rings, I'm not sure. So even if these go on those cameras there'll be no way for the camera to know what aperture is selected. I can meter on my own pretty well so I'm not worried. Anyway, macro is fun but I do much more street photography and small scale nature photography (local woods and trees sort of thing) than I do macro. Thanks for the info.</p>

[ptkeam]

<p>Radford,<br>

Thanks so much for you response. This is what I suspected -- logic seemed to dictate that the effective magnification would be greater -- but I wasn't sure. </p>