Recently many DSLR user have been moving to Mirrorless, while some are still waiting. The entire world of photography has practically abandoned DSLR but underwater photography is traditionally lagging and this is due to a combination of factors one of the most important being availability of appropriate lenses to fit specific use cases.

Unfortunately underwater use cases do not form part of the design criteria of lens manufacturers due to the tiny size of the market, so you need to hope something comes up that can fit that shooting situation you are trying to master. To date there is no native OEM fisheye lens for mirrorless for full frame. There are of course plenty of lenses for micro four thirds but this is only mirrorless so it does not form part of this evaluation because if you are on that format you have moved on already.

Full disclosure I am a Sony Mirrorless shooter but have owned and used Panasonic, Nikon, Canon and Fuji and I keep myself up to date with the latest innovations. This piece is based on data as you can see it not on opinions which I have little interest in.

Brand Loyalty?

One thing that is very important when making this step is to ignore entirely brand loyalty. This is somewhat difficult for the user that is accustomed to a certain menu system and look and feel or even color rendition of the camera but it is an imporant factor.

Let’s have a look at few examples considering the two main DSLR brands Canon and Nikon starting from the latter.

Nikon

Probably the market leader in underwater DSLR shooter has been delaying the transition to mirrorless and only recently catching up.

Nikon D850 vs Z8 vs Z7II

The D850 and Z7II have the same sensor and therefore identical performance, the Z8 has a new stacked sensor however according to a variety of sources the additional speed that is no doubt very useful to topside bird or sports shooters comes at price.

This is corroborated by DxOMark results

The Z8 has indeed less dynamic range and therefore scores less. Obviously this is only taking into account purely image quality however other factors are important namely the autofocus, ergonomics and the availbility of lenses.

The Z series has a limited amount of native lenses compared to the armory of FX lenses however you could say you can get by.

The autofocus has really improved in the latest Z8 while it is fair to say it was not as exciting in the Z7II.

In conclusion looking at Nikon full frame the transition from DSLR to Mirrorless looking purely at underwater use cases will not move your image quality forward and probably be on par on autofocus.

Nikon D500 vs Z50

When we look at Nikon DX format considering a transition from D500 to say Z50 the image quality is identical but here the lens assortment is even less therefore many users go full frame instead of staying on crop.

In conclusion I would say Nikon FX/DX to Z is not a really strong case and is penalised by Nikon being a total laggard in the transition to Mirrorless. Perhaps Nikon users should consider changing brand if they are keen to move forward due to topside use cases, or wait a bit longer.

Canon

Canon has been more decisive in moving to Mirrorless and it shows.

The RF series has an excellent display of macro and rectilinear lenses while it lacks a native fisheye overall the comparison is fair while certain niche lenses like the Nikkor 60 macro

Looking at sensor performance the situation is also more favourable.

Here the improvement is across the field. When we look at the cropped format the EOS90D and R7 there is a smaller improvement, however a no regret situation.

Taking as thermomether the Nauticam port chart for RF system we can see that the selection is pretty decent for full frame, the same cannot be said for APSC where the number of supported lens is small but so is the topside selection.

In summary a Canon user wanting to be loyal to the current brand will find an improvement in full frame but not in APSC having to resort to older DSLR lenses for a small improvement in image quality.

Sony

Sony is the leader in mirrorless camera having been the first brand to embrace it for full frame. At present Sony Semiconductors Corporation provides image sensors to Nikon and Panasonic amongst other and only offers the most advanced solution to Sony Consumer Cameras unless the customer pays for a custom project.

Looking at full frame sensor performance of the fast models those preferred by topside wildlife shooters we can see that the A1 and Z8 are indeed very similar with the A1 having more megapixels and offering an edge on dynamic range and high ISO performance and the Z8 edging on color depth.

Those cameras make sense if you have a variety of topside use cases and also like to do some video or if you are really needing the last bit of strength from the superior autofocus.

When you compare the Z8 to the A7R V which is a ‘slower’ camera you see that the latter has an edge this is also true if you look at the A1 of course. An underwater shooter that does not need the speed of the A1 or Z8 should stick to a model like the A7R V and benefit from additional megapixels and sensor performance with a loss of speed that underwater does not mean much. This camera has a very slow burst rate and topside will be easily affected by rolling shutter and it is not a favourite for topside wildlife shooter but more a camera for landscape, architecture and portraits.

The selection of lenses for E-Mount is vastly larger than Z mount at present and there are adapters for both Canon EF and Nikon FX formats.

Sony full frame cameras tend to be smaller and the housing cheaper so you can see why some previous Nikon DSLR users have moved to Sony Mirrorless.

Canon users instead are not migrating to Sony because of lens selection and backwards compatibility and more importantly are also gaining on image quality and features moving to Canon mirrorless.

Micro Four Thirds

Some users have done differently and gone to a smaller mirrorless format. Micro Four Thirds is where mirrorless started long time ago and offers plenty of lens choices. Contrary to what people think Micro Four Thirds cameras can closely match the performance of APSC cameras the gap is more or less half stop and operating at equivalent depth of field can match both ASPC and Full Frame cameras.

While the increased depth of field has been a strenght of this format underwater the autofocus has been historically the biggest let down.

As of today there is not a single MFT camera that can match the simple tracking without subject detection that old Canon and Nikon DSLR and current Sony Mirrorless can do. Brands have been focussed on shooting people or birds and animals but this did not include fish and so far the simplest use case which is to shoot a fish portrait with a macro lens has been where this format has lagged.

Unless you are interested in the video features or you only shoot wide angle and don’t care about the autofocus issues Micro Four Thirds is typically not a path of choice for an existing DSLR user.

Panasonic

With a strong tradition in video, Panasonic has recently mastered autofocus and released the S5II with PDAF that is a very interesting camera at reasonable price point. L-Mount has started to offer a good selection and using the sigma adapter you have access to Canon EF lenses. The Nauticam lens chart for L-Mount shows a good selection.

While cost effective the S5II has only 24 megapixels and more importantly does not offer a solid tracking autofocus as Nikon, Canon and Sony do and therefore is a risky path to take unless you are also moving to the S5II for other reasons.

Conclusion

When I write pieces like this there is always someone that comes but at the end we took amazing pictures with film camera or with Camera X that had 8 megapixels. Well that is fine but at that time this is all you had.Or even better let’s look at some open water images to have a view, which of course can’t be done as conditions can never be replicated.

Today there are many options and choices and while having options is a good thing it does make decision making more complicated. While there are many factors that make the image at the end the photo needs to be in focus and have the appropriate quality.

This short write up covers both this factors and hopefully you will find it useful. If you are regularly on underwater photography trips you will also be able to compare this article with real life scenarios. While few years ago it was rare to see a full frame sony user on a trip today the numbers have largely increased as consequence of the migration of users to mirrorless cameras.