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It is common for macro shooters aficionados to mount their lenses in reverse, that is, to thread a camera-mount specific adapter onto the lens' filter thread. Lenses from about 50mm to 100mm are commonly mounted this way.

But while a lens' main body makes one solid and strong block with its "normal" (camera body) mount side, going toward the threaded end of the lens is a mechanically less strong focusing mechanism, either mechanically or electrically controlled. Also the thread depth is often shallow as its primary design is to accommodate a very light filter.

How strong is this threaded side of the lens, and how big a lens can be mounted in reverse? And as a corollary, can mounting a lens in reverse damage the focusing mechanism?

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3 Answers 3

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Lens weight when reverse mounting is rarely an issue.

  • The technique gives the best result with normal or slightly wide angle prime lens. These are not heavy. Mounting a telephoto lens in fact gives you an inferior result (low magnification). Mounting a zoom in reverse is bad optics.
  • You can not control the aperture from camera; it is therefore easier to use an old manual lens (where the aperture is set manually). These are light, abundant and cheap.
  • You do not use the focusing mechanism in the lens; you focus by moving your camera forward / backward (a sturdy tripod and a focusing rail are not essential, but help greatly). In fact some of the best results can be had using reverse mounted enlarger lens, which have no focusing at all.

So my recommendation if you want to start with reverse mounting is not to start with your main lens, but get an old manual Tessar type lens. They can be had very cheaply on the well known auction site.

A side note: lens coatings are optimized for light coming from the front, which is the wrong way around when reverse mounting. You really do want a hood. You can improvise one by putting an extension ring on the "camera" side of the reverse mounted lens.

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  • \$\begingroup\$ or you could buy a lens cap and remove the lid encrypted-tbn0.gstatic.com/… \$\endgroup\$
    – Noldor130884
    Commented Jun 20, 2017 at 10:53
  • \$\begingroup\$ @Noldor130884 - can you explain how that works? I'm not doubting you, I'm just curious. \$\endgroup\$
    – FreeMan
    Commented Jun 20, 2017 at 12:36
  • \$\begingroup\$ @FreeMan it is a technique I found described on extreme-macro.co.uk/reverse-lens-hood - I prefer the cheap extension tube approach, but hacked lens cap seems to have a decent reputation too... \$\endgroup\$
    – Jindra Lacko
    Commented Jun 20, 2017 at 13:18
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    \$\begingroup\$ Very interesting, thank you! (and you, too @Noldor130884). \$\endgroup\$
    – FreeMan
    Commented Jun 20, 2017 at 13:32
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    \$\begingroup\$ The first point is by far the most significant one. Retro focus and telephoto lenses don't reverse well as macro lenses from an optical formula standpoint. Those are typically much heavier than the simple designs of normal lenses. \$\endgroup\$
    – Michael C
    Commented Jun 20, 2017 at 17:01
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I have never trusted a reverse mount for macro photography.
Partly because of your noted concerns regarding the stress on the screw-thread [& possibly worse on the zoom, should you try to use one], but also because you're pretty much turning it into a manual lens.

Also consider price-point.
One Lens reverser - one per lens thread size, or a bunch of ever-weakening adaptors - $£€ 15 or so.

On the other hand...
One set of extension tubes with full electrical connections - $£€ 30 or so - & you get to keep everything working except probably auto-focus.
Fits all your lenses, has three segments so you can choose how far to extend & all your electronics still function.

IMO, no contest.

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    \$\begingroup\$ Extension tubes are a sensible choice. But they will get you only so far - about 1:1 magnification. A reversed lens on an extension tube will let you go beyond that. \$\endgroup\$
    – Jindra Lacko
    Commented Jun 20, 2017 at 10:06
  • \$\begingroup\$ @JindraLacko - tbh, I'm not certain how you measure it. I've found that I can get best magnification at around 50mm, too much wider & I'm focussing inside the lens. This is about the smallest I've captured so far using tubes - i.sstatic.net/ro3iP.jpg - bud is about 2mm long. \$\endgroup\$
    – Tetsujin
    Commented Jun 20, 2017 at 10:46
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    \$\begingroup\$ There a 3th option: A Len reversed in front of a another lens(28 or 50mm in front of 100+mm), you get full metering. \$\endgroup\$
    – Rodrigo Menezes
    Commented Jun 20, 2017 at 12:03
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    \$\begingroup\$ @Tetsujin That all depends on the specific lens mount and how the aperture is controlled as well as if the lens has an aperture ring or not. Most reversed Nikon lenses will be at narrowest aperture when not mounted to a camera which compresses the spring. Electronically controlled apertures have some interesting capabilities for free lensing and reversing. \$\endgroup\$
    – Michael C
    Commented Jun 20, 2017 at 16:37
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    \$\begingroup\$ You can get adapters that fit on the camera end of the lens when it is out in front of the camera to compress the aperture spring. If you have an "D" series lens with an aperture ring you can then set the aperture using the ring on the lens. Just keep in mind that the f/numbers won't be accurate since you've changed the magnification of the lens as the camera sees it. \$\endgroup\$
    – Michael C
    Commented Jun 20, 2017 at 16:54
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Consider why the prime is revise mounted? Most camera lenses are designed to image a curved world (objects at differing distances from the camera. Then the lens projects this image on a flat target like film or digital sensor. Copy work is mainly flat work so what is needed is a “process” lens. This is a lens optimized to image flat subjects and project the image on a flat surface (flat to flat). By reversing the lens, you utilize that part of the lens that is optimized to project on a flat plane and use it to image. Thus, sometimes a superior image results when doing flat copy. Also, by reversing the lens, the optical center of the lens is now likely further from film or digital senor. This adds addition spacing that increases somewhat the resulting magnification. Consider a tube or bellows or a macro lens instead.

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