<p>Depends on the size of the sensor and the magnification of the lens. You raise the possibility of other lenses, and I do not think you indicated what kinds of camera body you were thinking of using. That leaves us to speculate on what you have and flop around rather than just to provide a dedicated response. Nikon or somebody else's?</p>
<p>For crop sensor Nikons, the new 40mm autofocus Dx macro lens is new and unique IF you are using a Dx camera -- any Dx camera body will do, although the modern ones with higher pixel density would likely do better for resolution. The 40mm will autofocus on the slide just fine, are the reports.<br>
<br /><br />For Fx, full sensor sizes, some of us have used the old manual focus 55mm Nikkor micros, 3.5 or 2.8. They are sharp and are known to have a flat field of focus on the sensor -- often regarded as superior to many lenses for copying flat subjects because everything will be in sharp focus. For this lens on Fx, one needs extension tubes as it does not natively go 1-1. [Google the lens if you want the history of the extension tube developed to go with the lens for macro work -- but not necessarily an Ai or better interface for use with a digital body.] Take a look at the Nikonians blog which I linked to above. I use my 55mm f3.5 Nikkor Micro, which I have had for a very long time, the ES-1 and Kenko extension tubes.<br>
<br />If you do much macro work a set of extension tubes can be very handy. The Kenko tubes maintain autofocus and metering info for many Nikon cameras; Nikon's tubes do not. Some of the older Nikon extension tubes should not be used on a modern Nikon digital body. My old 55mm was converted to AI which made it safe to use. The old lenses tend to be pretty cheap on the used market, but pay attention to whether the lens is AI or you will need to spend a little to get it converted by the folks out there who do that pretty reasonably.</p>
<p>The most simple solution if you have a Dx body is to get the new 40mm Dx macro lens from Nikon. Less than $300 at B&H, and about $30 less than B&H but refurbished from Nikonusa.com.</p>
<p>Oh, and for any of these easy Nikon solutions you need the ES-1 slide copy attachment which just screws into the filter threads on a 52mm lens front. I suppose you could use step down rings for other lenses. And, extensions tubes would enable larger magnification of a portion of a slide, where the simple rigs are basically a set up to copy the entire slide. Since the ES-1 is attached to the camera, you do not even need a tripod because it is one rigid unit. http://www.bhphotovideo.com/c/product/37453-REG/Nikon_3213_ES_1_Slide_Copying_Adapter.html</p>
<p>Either way works. Pick your poison. Or, you could spend a lot more $$ on rails, bellows, mounting other lenses, reversing lens rings, etc. That could be a lot of fun though, especially for other macro work.</p>