Every new lens launch comes with the same promise. Sharper, faster, better. And with Sony's FE 100mm f/2.8 Macro GM OSS, that promise is largely true. It is the first macro lens in Sony's G Master line, it reaches 1.4x magnification on its own, and it works with Sony's teleconverters. If you shoot the Sony FE 90mm f/2.8 Macro G OSS, the question is obvious. Is it time to upgrade?

I have shot the Sony 90mm for years, including the last three years on my annual month of diving in Lembeh. For the past six to seven months the 100mm has been my main macro lens, first on the Sony A7R V and more recently on the A7R VI, both in Nauticam housings. So this review comes from real time in the water, not a spec sheet.

Here is the short answer. The Sony 100mm is optically a much better lens. It is easier to use, and it is far more flexible thanks to its native 1.4x magnification and its compatibility with teleconverters. But for most underwater photographers, the upgrade will make very little difference to the images they actually take. Unless you shoot an awful lot of macro, your money is probably better spent elsewhere.

Upgrading is never just the price of the lens. The 100mm needs its own port, so you are buying two things, not one.

At Backscatter, the Sony FE 100mm f/2.8 Macro GM OSS sells for $1,499.99. The matching Nauticam N100 Macro Port 125 costs $610. That puts the upgrade at $2,109.99 before tax and shipping.

You will notice I have not added a focus gear. Nauticam makes one for the 100mm, but I don't use it. The autofocus on this lens is so good that on a modern Sony body I simply haven't needed manual focus control.

The other half of the equation is what you get back for your old kit, and right now that isn't much. The used market is flooded with Sony 90mm lenses and their ports as photographers move across to the 100mm, and prices have dropped accordingly. Realistically, expect to get somewhere between 30 and 40 percent of the new price. The 90mm sells new for $1,049.99 and the Nauticam N100 Macro Port 105 for $560, so that is roughly $480 to $640 back for the pair.

Do the math and the real cost of switching lands somewhere between $1,470 and $1,630. That is a lot of money for a lens that, as you will see, does a very similar job to the one already in your camera bag.

Yes. The 100mm is optically the better lens. Its design of 17 elements in 13 groups includes two extreme aspherical and two ED elements, and it shows in the files. Fine detail is crisper, contrast is stronger, and sharpness holds up better toward the edges of the frame.

But here is the reality. In real underwater photography, most people would not be able to see that difference in their images. The 90mm was already a very sharp lens, and underwater the lens is rarely the limiting factor. Water clarity, backscatter, strobe position, focus placement and your choice of depth of field all have far more impact on the final image than the step from a G lens to a G Master. Once an image has been edited and shared online or printed, the gap is very hard to spot.

The same goes for focal length. On paper 100mm sounds meaningfully longer than 90mm, but in practice the difference is small. If you are not a very experienced macro shooter, I doubt you would notice any difference in framing or working distance between the two. I have spent a lot of hours behind both lenses and I can feel it, but only because I know exactly where to look.

The autofocus on the 100mm is a little faster than on the 90mm. Sony drives it with four XD linear motors, and in Lembeh it locked onto small, low contrast subjects quickly and quietly. I would be lying, though, if I said it changed my photography. The improvement is small compared to what you can gain by working on your own technique. Placing your focus point carefully, using a good focus light and approaching your subject slowly will do far more for your hit rate than a faster motor ever will.

Image stabilization surprised me, and not in the way I expected. The stabilization on this lens is very good, in fact almost too good. When I was shooting slow shutter images with deliberate camera movement, the stabilization fought against the motion I was trying to create and smoothed it out. For that kind of creative work it became a real problem, so I turned stabilization off underwater altogether. If you like to play with motion blur and slow shutter effects, expect to do the same.

This is where the 100mm genuinely pulls ahead. The 90mm stops at life size, or 1x magnification. The 100mm goes to 1.4x on its own, with a minimum focus distance of 10.2 inches (26 cm). That extra reach lets you fill the frame with smaller subjects before you even think about adding a wet diopter.

The bigger change is teleconverter support. The 100mm works with Sony's 1.4x and 2x teleconverters, which the 90mm never could. With the 1.4x fitted you get an effective 140mm at f/4 and up to 2x magnification, according to B&H. Underwater, the real value of that combination is distance. It lets you sit off from skittish subjects that would vanish if you moved in closer, and still fill the frame. For the 1.4x setup I used a 25mm N100 extension ring with the port, so budget for both the teleconverter and the extension if you plan to shoot this way.

I would not recommend the 2x teleconverter underwater. The hit to image quality is simply too great, and once you add water, a port and strobes into the mix, the results are not worth it. Stick with the 1.4x.

If you shoot macro in a Nauticam housing, you probably already own some Nauticam wet optics, so compatibility matters. I have used the 100mm with the three I reach for most, the MFO-1, the EMWL and the MFO-3, and it works beautifully with all of them.

The MFO-1 is my choice for tighter compositions where I can get close to the subject. On the 100mm it does exactly what it did on the 90mm, adding a little magnification and helping the lens focus cleanly, and I have had no issues with it at all.

The EMWL has been the subject of some concern online, with photographers asking whether the 100mm focuses reliably through it. It is a fair question. Nauticam's EMWL focusing unit for Sony was designed around the 90mm, and the EMWL has a history of focus issues with certain camera and lens combinations. In my experience, though, it works great. On both the A7R V and the A7R VI, the 100mm has focused well through the EMWL and I have been very happy with the results.

The MFO-3 turns a long macro lens into something closer to a 60mm, giving you a wider view and the ability to focus right up to the glass. Nauticam's compatibility list names the Sony 90mm, but I have found the 100mm pairs with it just as well. It is a great option for blackwater and for larger critters like frogfish.

So if you are worried that upgrading will leave your wet lenses stranded, don't be. I would happily recommend the 100mm with all three.

Probably not. The 90mm and the 100mm are very similar lenses. They suit the same subjects, give a similar perspective and produce a similar look. Swap one for the other and your portfolio will look much as it did before, just a little sharper if you study it closely.

If what you really want is fresh images, a completely different style of lens will do far more for you. A Meyer Optik Trioplan 100mm, or the TTArtisan 100mm f/2.8, will give you soap bubble bokeh and an entirely different mood behind your subject, and other bokeh lenses can do much the same. You could also try the Nauticam EMWL, which lets you shoot small subjects with a wide angle view of their habitat behind them. Any of these will add real diversity to your work, and diversity is what keeps a portfolio interesting. I have written before about why experimenting makes you a better underwater photographer and how negative space can transform an image, and the same thinking applies here. Change how you shoot, not just what you shoot with.

If you shoot more than one dedicated macro trip a year and macro is where your passion lies, the upgrade is an easy decision. You get better optics, a lens that is more enjoyable to use, 1.4x magnification straight out of the box and a teleconverter option that opens up shy subjects. For someone like me, who spends a month in Lembeh every year and genuinely loves macro, it is an obvious upgrade.

If your main focus is wide angle, which is true of most underwater photographers, it makes much less sense. You would be spending around $1,500 or more after resale on a lens you might use a few times a year, for a difference you will struggle to see in your images. Keep your 90mm, keep shooting, and put that money toward a dive trip or a lens that changes how you see.

Whichever way you go, remember that the lens is rarely what holds a macro image back. Patience, technique and good light will always matter more than the badge on the barrel. For most of us, the best upgrade is simply more time underwater.