Viewfinders are obviously fundamental for SLR photographers, they are the frame within which we create our images. But trying to review the different options available is a challenge. Viewfinder choice is very personal. Housings and strobes are straightforward to review because there are clearly rights and wrongs in designs. Finder preference is much more subjective.
You could argue that the only objective feature is that the viewfinder must allow us to see the entire frame (plus the settings information) without us having to move our head from side to side! Not being able to see the whole frame means lots of unwanted objects in the corners of your fisheye shots and compositions squashed in the centre of the frame.
Sadly this is something that is not a guarantee when looking through all housings when wearing a facemask. There are a number of housings, whose standard viewfinders do not provide this fundamental requirement. A cynic might suggest that this is in a housing manufacturer’s interests to encourage you buy a more expensive viewfinder option!
A solution, that used to be popular, is the reducing viewfinder, which actually makes the image a bit smaller, but at least it reveals the whole frame when viewed through your goggles. This solution plunged in popularity when Velvia SLRs (some of which had very nice optional action finders) gave way to digital SLRs (the majority of which have had cropped sensors). As sensor size reduced, the viewfinder image shrank accordingly and nobody wanted to make it even smaller with a reducing viewfinder. As a result, during the last 5-8 years we’ve seen magnifying viewfinders go from being a niche product to the SLR mainstream. These external viewfinders are usually quite expensive, but show the whole viewfinder in enlarged beauty. Once sampled they usually prove completely addictive. On the trips I run, I now see magnifying viewfinders on the majority of housings.
The downsides of magnifying viewfinders start with the price ($500-1000+). They are big investments, but at least they can be transferred to newer housings when you upgrade. They can also be a packing nightmare, when sticking out from the back of the housing. At least some are intended to be removable.
Magnifying viewfinders have a narrower eye point angle, meaning you have to get your eye exactly lined up and the right distance away to see clearly through them. But once you have adapted they provide a splendid view for focus and composition. Many people say they find such a view inspiring for their photography. Also by sticking out from the back of your housing they also provide space for your regulator.
Magnifying viewfinders fall into two categories: straight and angled (usually 45 degrees). Each has advantages. Straight magnified viewfinders are much easier to adapt to. This is an important point, as 45 degree viewfinders can be very disorientating, especially for macro shooting. A 45 is best avoided if you are an infrequent underwater photographer. You will be re-learning it on each trip.
I advise people who have just bought one to do an intensive week of diving (on not-too-exciting wide angle dive sites) to get through the acclimatisation period. Everyone hates a 45 degree viewfinder for the first five dives, this mellows to dislike for the next 10. After this period, the advantages of the 45 begin to blossom.
A 45 degree viewfinder is generally more comfortable when diving horizontally, as the camera is held slightly lower and in front, where you hands fall naturally. This certainly makes intensive shoots less tiring. They are even more comfortable for vertical shooting as 45 degree viewfinders can be rotated to make these angles very convenient. These advantages are even more important if you are constricted (particularly shoulder and neck movement) by lots of thermal layers when diving in cold water.
When photographing subjects on the seabed, such as muck diving, a 45 degree viewfinder makes it easier to compose with the camera at the lowest angle possible to the subject. This improves your images by making the background more distant from the subject increasing subject separation, making the picture pop.
On the contrary, I find 45 degree finders a pain for shooting vertically up and particularly for shooting vertically down. I also don’t particularly like them for split level photography, although they are much improved when the rubber eye cup is removed to stop it collecting water and obscuring much of the scene.
A final disadvantage of a large magnifying viewfinder (straight or angled) is for video. Most viewfinders are carefully designed not to block the all-important LCD when viewed directly from behind. However, when shooting video it is much more comfortable (and therefore steady) to hold the camera lower, rather than straight in front of your face, and here a magnified viewfinder completely blocks the view of the video stream. If you plan to shoot lots of video make sure you keep your housings original small viewfinder.
Anyway, this article was supposed to be a review of Nauticam’s new 45 degree viewfinder, but like I said there is so much personal preference I felt it was more use to write more generally about viewfinders to inform your preference. Briefly, Nauti’s 45, like their straight viewfinder, can be adapted for a number of housing brands and offers a dioptre adjustment underwater. In the past I have stated that I am not a fan of this adjustment (which is too easily knocked during handling by the crew etc), but all my friends who wear glasses tell me it is great. So I stand corrected.
The Nauticam viewfinder offers a larger viewpoint than the Inon 45, but is more expensive, although cheaper than the Nauticam straight viewfinder (Nauti 45 $950, Nauti straight $1150, Inon 45 $698- source Reef Photo Video, all prices USD). I definitely prefer it to the INON on the Nikon D7000, where I have shot both. The Nauticam offers a bigger and sharper view than my Inon. One issue with Nauticam’s dioptre adjustment knob is that when rotated 45 degrees (for shooting verticals) it has the potential to partly obscure the LCD. However, Nauticam have moved the knob from the right to the left (compared with their straight viewfinder). Not only does this make it easier to adjust with your left hand (while holding the housing with your right), but more importantly this side means that the knob points away from the LCD when shooting verticals with your hand at the top of the housing. Generally it makes sense to shoot verticals this way around because when on the sand you want the housing as low as possible and having your hand in the way rather defeats the object of having a 45 degree viewfinder in the first place.
So in summary, the Nauti 45 is an excellent viewfinder. Whether it (or any angled viewfinder) is the right viewfinder for you, I cannot say. But it is happily installed on my housing now. It outperforms the Inon 45, but is about 20% more expensive. Whether it is worth the premium, again, depends on your taste.