Biodives

After consultation with the store I installed the converter without the spacer and that worked fine. I have contacted Pavel to see if anything else needs to be done and if so I will post it here.

I am looking for some help with installing the UW Technics TTL converter for the Sony A7RV in a nauticam housing. I believe a few of you have this setup. The converter came with two screws and two white plastic spacers with a wide 'spacing ring' attached to a narrower tube with a hole for the screw. I was told the narrow tube part has to fit in the hole of the printed circuit board but it doesn't fit. If I turn the spacer around I can use it but the screw is too short to properly thread into the housing. It seems that it will work without the spacer but I am hesitant to leave it out as I assume it is there for a reason.

Both suggestions are correct. Chris's link is actually one of my images of an early juvenile. You need about 5 pictures to show all the intermediate forms until it becomes the adult. There is also the closely related Digramma melanacrum which overlaps geographically with D. pictum and juvenile/young individuals can be hard to tell apart. Both FishBase and iNaturalist are useful online resources to ID fish, the latter having the benefit of fellow underwater naturalists providing their input. I am working on a web portal about coastal fishes myself. At the moment is has just over 1000 species from the East Indies that you can view as 'illustrated checklists'. I will be diving about 6 months each year to cover the different regions of the East Indies and complement images with information about their identification, habitat preferences and behavior. But for now it is mostly images with identification and location. The site is now public on google cloud at biodives.com/aquanotes. An example of what the illustrated checklists look like is shown below for Dauin (Philippines). Click on the name of the species for higher resolution images and more details of the species sightings. This is also where more information about species will appear in the future.

The F/8 - F11 is what I had also read, though some suggested it depends on the camera/lens combination. Initially I had the feeling that the transition was between F4 and F5.6 for my 90mm macro lens but once you get close to F2.8 settings the difference becomes smaller to see by eye. It is rather clear though that Peaking signal in Focus Priority mode does not change as you change the aperture. I don't think they simulate that because if they did why not simulate the actual DOF? The improved live view image quality in Focus Priority also hints that the aperture is indeed open in that mode and not in the Standard setting. Perhaps the 90mm macro lens is an exception as focusing in macro photography can be more challenging?

Lacking an ability to diving until this Fall I have been studying the manual for my new Sony A7R V. I am writing up what I learn so I can efficiently experiment with options once I start diving and, hopefully, to help others make sense of the myriad of menu functions, not all of which are well explained in the manual. One example is the Focus > AF/MF > Aperture Drive in AF > Focus Priority | Standard | Silent Priority menu. The manual hints that it has to do with controlling sound volume. Other documents indicate that it affects multi-shot frames-per-second rate. The latter depending on which camera and lens combination you use. But in a series of experiments I believe it controls whether the camera keeps the aperture wide open or stops it down to the user's setting. This behavior is further coupled to whether or not you let the live view reflect your exposure settings. Since I expect others have been stumped by this I am pasting the section on this topic below. It is complex enough that there may be aspects I have missed. If so please comment. Aperture Drive in AF The Focus > AF/MF menu has a somewhat poorly defined function named Aperture Drive in AF. This can be set to Focus Priority, Standard, or Silent Priority (the latter is not available for all lenses, including my 90mm F2.8 macro lens). The manual implies that this menu function controls a trade-off between focus performance and silence. For underwater stills photography we don’t care much about silence and we do care about autofocus performance so Focus Priority appears to be the obvious choice. But what does this setting really do? Autofocus works best with the lens aperture wide open. This maximizes the amount of light to work with and it minimizes the depth of field (DOF), which helps to pinpoint the optimal focus position. On my Olympus cameras, live view is shown with the aperture wide open and you need to activate Aperture Preview, which stops down the aperture, to judge DOF under the aperture value set for the exposure. Sony does this differently. By default, they show the live view with an aperture value matching the setting chosen by the user. As a result, live view shows the actual DOF, which is nice. However, the closed aperture limits light capture which has two drawbacks: when ambient light is substantially underexposed, as is common in strobe-dominated underwater photography, the viewfinder becomes very dark. You can boost the live view brightness by setting MENU → (Shooting) → [Shooting Display] → [Live View Display Set.] → [Live View Display] → [Setting Effect OFF] but a strong boost reduces live view image quality. if the aperture is kept close this would reduce autofocus performance Impact on AF-S/DMF performance Aperture Drive in AF = Standard (live Setting Effect ON) In this mode the aperture is stopped down to the set value. You can see that by switching on Peaking in DMF mode. You see the Peaking pattern getting wider/narrower as you select higher/lower aperture values. The viewfinder simultaneously gets darker/lighter (you may need to boost ISO a bit if the view is too dark). Initiating autofocus briefly narrows the Peaking pattern (narrower DOF). Once focus is locked, the Peaking broadens again (wider DOF), indicating that the camera opens the aperture transiently to assist with autofocus. Somewhat surprisingly, the viewfinder does not briefly brighten as the aperture opens. Interestingly, this behavior is seen at F5.6 and higher but not at F4 and lower with my Sony A7R V and 90mm F2.8 macro lens. It appears that the aperture only opens when needed, with the F4 threshold dictated by either the camera body, lens, light level, or a combination thereof. (Edited: no longer sure this is the case) Aperture Drive in AF = Focus Priority (live Setting Effect ON) In this mode you see a narrow Peaking pattern that does not change as you select higher aperture values. This indicates that the aperture is kept wide open. Somewhat surprisingly, the live view brightness does respond to changes in aperture. Perhaps Sony electronically tunes the live view signal to match exposure settings, since that is what the user expects in Setting Effect On mode. This appears to be the case because if you activate AutoISO you get a much cleaner, less amplified, live view image with the Focus Priority than the Standard setting. Initiating autofocus does not alter the Peaking pattern immediately but, once focus is locked, Peaking broadens while the shutter remains half-pressed. This indicates that the camera uses a wide open shutter for best autofocus performance but once focus is acquired it stops down to allow you to judge DOF. Behavior with live Setting Effect OFF When you set Setting Effect off, the camera is no longer expected to reflect exposure settings. Checking the Peaking pattern’s response to aperture changes and focusing shows that the Aperture Drive in AF no longer has any effect and both show the Focus Priority behavior described above. My recommendation for AF-S/DMF mode Based on the observed behavior I think using Focus Priority is the best option. This gives you the same behavior independent of the Aperture Drive in AF setting, which avoids confusion. You also get a cleaner live view image when ambient light is strongly underexposed and, with Setting Effect ON the camera can autofocus instantly without first having to open the aperture. The one disadvantage is the live view does not show DOF all the time. But you can get a DOF preview simply by half-pressing the shutter. You can also assign the Aperture Preview menu function to a custom button is you wish. Finally, Sony documents indicate that Aperture Drive in AF also affects the shooting rate in multi-shot mode, but that doesn’t really affect underwater photography with strobe. Impact on AF-C/AF-C+T performance (live Setting Effect ON) In AF-C mode, optimal continuous focus requires that the aperture remains wide open and only close at the moment the image is taken. But showing exposure effects in live view requires that the aperture is stopped down to the set level. Comparing Focus Priority and Standard settings, the former could focus at F22 with shutter speeds down to 1/8000. The viewfinder was completely black but I suspect that the aperture was open. In the Standard setting, the camera showed a black screen with a shutter speed up to 1/1000 but it became bright at 1/1250 or less. Once focus is acquired it turns black again. I suspect that up to 1/1000 the camera kept the aperture stopped down to the set value while remaining able to focus. At 1/1250 or less the ambient light must have fallen below a threshold and the aperture was opened briefly to allow AF-C to continue to work. The fact that the viewfinder remains black with Focus Priority but not Standard setting suggests to me that the former electronically darkens live view to mimic the aperture setting, whereas for the latter live view gets dark as the direct result of closing the aperture. When the aperture needs to be opened when it gets too dark, it shows up in the viewfinder. As expected, when Setting Effect OFF is used the camera starts to behave as in Focus Priority mode. Again I think using Focus Priority is the best option.

I have been using a Backscatter Macro Wide 4300 as focus/video light but due to poor technique on my part (salt water dripping from fingers) the contacts have become pitted. Backscatter can repair it but I have also been thinking about what would be ideal to use with a Sony 90mm macro lens. The light would act as a focus light, night dive light, and video light. Video is not my priority but I do use it and possibly would like to use it more. The MW4300 has a focus beam with 14 degree coverage. Good for focus assist but too narrow to cover the 27 degree angle of view of the 90mm lens. The wide beam has a coverage of 90 degrees which is what I have been using. But with so many people dedicated to macro I was wondering if there are video lights with a coverage that better matches typical macro usage. I don't know what the optimal coverage would be. Wide enough that you don't need snoot-like precision in aiming the light but narrow enough to maximize light intensity for a given total lumens output. The best I have found so far is the Sola 2500 Flood, with or without focus light, which puts 2500 lumens in a 60 degree beam. Based on a back-of-the-envelope calculation, based on image circle areas, I expect that to be equivalent to a 7500 lumen light with 90 degree coverage. You can get two Solas with flood but not focus light for a similar cost as one MW4300 and the two together weigh a tiny bit less than one MW4300 with batteries. Having two, you can charge one while diving the other or mount both simultaneously to double burn time by using them sequentially, double intensity by using the simultaneously, or widen beam coverage in the horizontal plane. Redundancy is also nice in case one fails. Getting 1 or 2 is not really the point though. My main question really just is if people have been using a video light that is optimized for macro work and that doesn't cost or weigh a ton?

Just wanted to let you know that I picked up a Sony A7R V with 90mm macro lens today. I have a whole summer to get familiar with it before diving season starts again Housing and other odds and ends will be added closer to departure time. Thanks for all comments and suggestions!

That is only the case if you can actually get to the minimum focusing distance. At a distance of 1m, a 200mm lens will magnify more than a 100mm lens independent of its macro abilities. For many (super)macro subjects you can pick the subject distance freely, for many fish that is not the case. With the OMD 90mm macro I would be limited to very small subjects for the entire dive, the 70-200 on FF is more flexible, at least on paper.

As always, getting closer is your first choice underwater but when you are shooting fish you very often find that you cannot get as close as you would like. Sometimes 1m distance is the best you can do even if you have a lot of experience. That means you get a lot of water in the light path which reduces image quality and, if it is a small fish, a tiny subject in the frame. I can't do anything about the amount of water, but a longer focal length avoids having to crop heavily. With my current m43 camera, the 60mm macro lens (120mm FF eq.) does the job most of the time but I regularly wish it were longer. Maybe that is no longer the case after I get the A7R V with the 90mm macro because with 60Mpx you can crop a lot more. However, it is still better to enlarge optically than digitally. The 70-200 lens would allow me to do that without locking me into a very long focal length, as would be the case with a dedicated 150mm or longer true 1:1 macro lens. And with a working distance of only 16cm at 200mm you can get close if the subject allows it. Practical issues like the sheer size of the lens, vignetting, or imbalance when extending can make all of this a moot point. But balance may be less of an issue underwater. I am just going to wait and see what Phil's experience with the lens is.

The majority of reef fishes like damsels, gobies, blennies, wrasse, etc are longer than 3.6cm and therefore don't need 1:1 magnification. Although it wouldn't hurt to have full 1:1 macro, and yes that would be preferrable over 1:2 macro, there are currently no native long focal length macro lenses for mirrorless cameras and I don't know of any zoom lenses that give 1:1 macro. So the 70-200mm offers an interesting mix of features with a magnification that is good enough for those interested in intermediate size subjects. I think this lens would be good for shy fish like the whitecap shrimpgoby, jawfish, wormfish, sanddivers, ... It is also good for fish that you can't get close to like some pygmy and other gobies that live in the back of small caves or under overhangs that you can't physically reach. A third application would be taking video of fish behavior from a distance large enough not to interfere with what they are doing. Ultimately the proof is in the pudding. If I had that lens available for underwater use how frequently would I use it? If I had a 200mm 1:1 macro lens then it would be a specialty lens too long for most subjects. But with a 70-200mm zoom range it is pretty general purpose. In another thread we just discussed what people who take pictures for fish id books use and in two examples they used exclusively a macro lens of about 100mm focal length. That is what I probably end up with for my next trip. I bet that the great majority of images will be at less than 1:2 magnification. The question then is, how often would I have wished my lens was longer than 200mm.

Mark Erdmann just responded to my question with the following: I have the Sony A7R V and I LOVE it. Really good for gobies too given the high resolution sensor. For me, I shoot the 90mm macro and then carry the super macro convertors, which I use especially for dwarfgobies and blennies and things you can get close to without them moving. I know others that use mid-range Zoom, but I don’t see much use in it and not worth the extra weight (and cost) for something I’d hardly use I reckon. He also has a 28mm prime and uses with the Nauticam WWL but only for sharks and mantas, which are not high on my priority list. I still think the 70-200 macro is interesting but perhaps I should start out simple and shoot one trip on just the 90mm macro and then see if I feel limited in any areas before expanding my lens set.

Neat, that means the bulk, and most interesting part, of the focal range is accessible in the 'tele configuration'. At 70mm the minimum focus distance is 16cm less than at 200mm. So if you put the lens behind a dome to get access to the full zoom range you get the wider field of view benefit but at the wide end of the range there will be almost no working distance left.

That is exactly the style of images I am taking and two new species added to the forthcoming second edition of Reef Fishes of the East Indies are based on my images. Since I am in regular contact with Drs. Allen and Erdmann I should ask them about their preferred camera setup. If you think in terms of 'framing' then m43 and APS-C have more reach. But if you think in terms of croppability, much more relevant to me, then that is not the case. For instance, if I compare a 20Mpx m43 image to a 20Mpx crop of a A7R V FF sensor then the m43 only has 10% more reach. Another way to think about it is that I can crop up to 1.8x on a A7R FF sensor and get the same or better resolution than a 20Mpx m43 would give me. So the 90mm macro becomes a 90-160mm 'cropping zoom' compared to m43. Of course the cropping is optional so a 28-75mm zoom on FF becomes a 28 - 135mm 'm43-equivalent zoom'. At the same nominal focal length, you can get much close with a FF sensor than a m43 sensor to get the same FOV. So the Sony 90mm FF macro is a more general purpose solution, comparable to a 45mm m43 macro, then the OMD 90mm macro which will be mostly limited to very small subjects. Where things change is if you get to 1:1 macro where subject distance is not limited by framing but by the minimum focus distance limit. Here a longer lens on FF will lead to longer working distance but, unless you are in really murky water, even the FF macro distance is close enough to not make that much of an issue with the greater working distance often being an advantage. Extending zoom lenses can result in vignetting and at the wide end of the range there is a large air gap between the lens and port which means you don't get the optimal working distance and I guess it also affects close-up adapters. The Olympus 12-50mm lens uses internal zoom which was great but all FF internal zoom lenses I looked at have a too long minimal focus distance. So the 70-200mm F4 macro is rather special and if it works well under water, even if with some restrictions, it would be worth the significant cost. It would be a nice topside lens as well.

I just looked up the port chart on the Marelux site and see the two focal range configurations you mention. I assumed the numbers on the ports and extension rings referred to their length. In that case, the 70-100mm configuration has 70 + 104 = 174mm length and the 100-200mm configuration has 100 + 71 = 171mm length. I assumed that the 70-100 focal range configuration would be significantly shorter to avoid vignetting and have more working distance. Am I missing something?

I replied in the new thread you created for this lens (https://waterpixels.net/forums/topic/1069-sony-fe-70-200mm-f4-macro-lens/#elShareItem_1953065761_menu) What port did you use for the Tamron 28-75mm while you had it and did it give vignetting issues. It only extends 18mm so hopefully it is not a problem.

Hi Phil, two questions: - Does the 100-200mm setup start vignetting right at 100mm? - How much working distance do you get at 200mm? Looking forward to your experiences with this setup. PS: That is quite a 'he-manly' rig 🙂

Thanks Phil! I appreciate the value of the 20-70mm F4 for most underwater photographers and this discussion need not be limited to my less common usage pattern. But, as indicated in my opening post, I rarely use focal lengths wider than 35mm because my main targets are small motile fish that you can never approach closely enough to need such a wide angle. Occasionally I get a large grouper or sleeping wobbegong where a wide angle would have been nice but that is a limitation I can live with. Your second suggestion is more up my alley and I actually spent quite a bit of time yesterday reading about the 70-200mm F4 macro. It is a very interesting focal range for me and its ability to provide 1:2 macro throughout its focal range is amazing. The minimum focus distance is 26cm at 70mm and even at 200mm it is an impressive 42cm. I used Backscatter's ordering page to see if this lens is supported but it is not listed for the Nauticam or Isotta housings. Fully zoomed in to 200mm this lens extends to 205mm length. To house it I would need a 7cm exension port plus the macro port for the sigma 105mm macro which I think is the longest port they have. This sounds a bit extreme but not impossible. The lens extends by about 5.5cm when zooming to 200mm so vignetting and loss of working distance at the wide end of the zoom range are drawbacks, but if the 70-200mm F4 macro can be housed I would consider it. While on Backscatter I checked out supported lenses and noticed that Nauticam makes a zoom gear for the Tamron 28-75mm F2.8 RXD lens. This lens has a minimum focus distance that ranges from 19 to 39cm giving 0.31 to 0.25x max magnification. This lens has now been replaced by the 28-75mm F2.8 VDX G2 model with MFD 18 to 38cm and max magnification at the wide end boosted to 0.37x. The new model also has better optics, focus motor, and the cost has stayed pretty much the same (US$799 at B&H). Another attraction of this lens is that it only extends by 1.8cm when zoomed in and fully extended it is exactly the same length as the Sigma 105mm macro so I assume it will work behind that port. I have inquired if this lens is, or will be, supported.

I had seen that video and the one they made for m43 lenses (where they don't even mention my favorite 12-50mm kit lens). The most interesting bit in the Sony video was that the 100mm EF and 60mm EF-S Canon macro lenses can both apparently work with autofocus, apperture control and distance communication with the metabones adapter. To my surprise the EF-S lens supposedly even covers the FF sensor (but perhaps only when focusing very close?). If so, the adapter is worth it just to use the 60mm Macro. They don't comment on performance of the 100mm macro on a Sony body but there is a 4 year old youtube video comparing the Sony 90mm vs Canon 100mm macro with a metabones adapter Apart from video autofocus, the canon lens is working very well. From the Metabones website, with newer Sony bodies and the 5th generation adapter video AF-C should now also work. However, Wolfgang ("architheutis") posted on DPreview about his experience with exactly this configuration (100mm macro, A7R V, and metabones mark V) and he ended up getting the Sony 90mm macro. Others suggest the Sigma MC-11 adapter works better. More to test but, since this will be a workhorse lens, going native is probably best. The UW Sony lens video mostly focuses on WA and macro and doesn't really go into the intermediate or longer range as it is of less interest to most divers. For me it does because I want to image fish of different size without having to back off too far. For zooms, they do mention the Sony 20-70mm F4 but not the 24-105mm F4 which for me is a more interesting focal length range. For primes, they mention the Sigma 150mm F2.8 macro which I looked at in my Canon 20D DSLR days but never bought. There is an even more extreme 180mm F3.5 'L' macro lens from Canon. I fear these are too specialized to warrant their cost but with DSLR users switching to mirrorless they should become more widely available as second hand options. Just checking the internet, the 150mm macro seems to go for only 300-400 Cnd$. Maybe that would be a fun experiment some day in the future. Or perhaps by then Sony has come out with a native longer focal length macro lens.

I visited my local camera store yesterday to finally get my hands and eyes on some cameras. Reading about handling isn't the same as actually handling the cameras. For instance, I had read many times that FF lenses are much larger but I wasn't prepared for how much larger they were. Similarly, I was surprised how little difference there is in body size. When comparing viewfinders the Sony A7C R was noticeably poorer than the other two so that camera is no longer a candidate. One concern with Sony cameras for me is whether I can determine the length of fish from an image. To check that out I took a series of images of a ruler. I just did some stats on the EXIF information and it turns out that the reported focus distance correlates very well with the observed image width based on the ruler. It is actually easier than on my current Olympus camera because it is a linear relationship, as shown below. I also tried it on the 24-105mm zoom lens at a few different focal lengths and it seems to work there as well. Hopefully that means all modern Sony lenses have an accurate distance decoder. So, for now both the OM-1 and A7R V remain in the running to be my next camera with the latter becoming more interesting.

I dive about 5 months in the October - April period each year (just in the airport at the end of my first such trip). So I have time to consider all options before locking into new gear for the next 5-10 years. I am excited to see what, if anything, else becomes available, especially lenses and lens support by housing makers. I would expect (distant) birds in the sky to be easy to track, like fish against a blue ocean background. And even between trees, birds may work better than fish because the AI chip is trained on birds and locks onto the eye. But I have read people being impressed by the Sony camera's ability to recognize and stick to the eye of fish, even if the fish is partly turned away from the camera. So I think there is hope that these new AI-assisted AF systems are noticeably better then what I have now. The Oly 12-100mm F4 is interesting with its combination of long focal length and close focusing but the vignetting issue Phil pointed out must be more of a problem when dealing with such a large zoom range. Once I get back home I can visit my camera store to check out some of these lenses in the flesh.

I haven't used C-AF + Tracking recently as in the past I found it to be not that useful. For fusiliers or other plankton feeding fish that swim some distance from the reef it may be great because it is clear what the camera should focus on. But most of my fish are on, in, under or around coral and then the camera often ends up focusing on the coral. It seems you did get the magnification argument. To get a fish to cover the same %age of the frame the projected image will be twice as large on the FF sensor compared to m43. When pixel sizes are similar you will get many more pixels to cover the subject and thus can record higher resolution features. Achieving this shouldn't be hard, just use a double focal length lens on FF and shoot from the same distance as you would do on m43. In cases where framing is a challenge, and perhaps make it easier to keep the subject in the center of the frame when using C-AF + TR, you can opt to not use a longer focal length lens and optimize for wider field of view instead of magnification. Either way is a win for me. If you are mostly interested in the entire scene then you may not notice the extra resolution unless you start pixel peeping. But for my use cropping, or zooming, to look at details is important. Important enough to switch systems and give up some nice features from Olympus I don't know yet. In the past cost and to a lesser extend size would dominate my decision. Now that I am retired and can make 5-month dive trips to study coastal fish biodiversity it makes sense to get what is best for that purpose.

Thanks Phil, this will be critical to test. If I loose the 24-35mm part of the zoom range that is not a deal breaker. If I loose everything below 50mm then it isn't worth it and it may even push me to stay with m43 as 24-70mm isn't long enough on FF. The Oly 12-50mm doesn't have this problem because it uses internal zoom and focusing. But I can also use the much shorter Oly 25mm F1.8 in the 60mm macro port without vignetting so I hope a large part of the 24-105mm zoom range will remain available in a flat port.

Thanks for all the feedback. It is good to see that Marelux supports the 24-105mm F4. All recommended configurations use dome ports but as long as the flat ports have a wide enough diameter it should fit, ideally behind the 90mm macro port with extention tube (the 24-105mm F4 has a 5mm greater diameter than the 90mm macro). If there is distortion or vignetting at the wide end that is acceptable for me. The Oly EM1 mk2 AF is not good enough for me to track wrasse, damselfish and all the other erratically moving small reef fishes that interest me. In many/most cases, when you get the camera to focus on the fish in C-AF mode it will jump back to the coral in the background when the fish makes a few sharp turns and you can't keep it under the focus point. If the new AI-assisted focus systems are sticky enough to track fish with a much higher hit rate, that would be a major benefit for me. My alternate focusing method is to focus on a solid object at the distance I hope/expect to be able to take my shot and then wait till the fish shows up at the right distance and pose, using the viewfinder to judge focus. So viewfinder quality is also something I care about. I do have a 45 degree magnifying viewfinder but mostly use it for stationary subjects as I haven't mastered the spatial awareness needed to hover very close to the reef with my eye on that type of viewfinder. Discussions about sensor size typically involve depth of field (DOF), resolution, equivalent focal length and aperture, etc. I prefer to see these as properties of the image projected by the lens and not of the sensor. In other words, at the same distance a lens with a given actual focal length and aperture setting has the same magnification, DOF and resolution, whether attached to a crop or FF camera. With this perspective you can look at different outcomes: with the same focal length, aperture and distance, the benefit of FF is that you can image a scene that is twice as large with the same resolution and DOF. Which is the same as saying that m43 represents an enforced 2-fold crop of the FF image. This is important to me. With m43 you can half the focal length or increase subject distance to match the scene captured by FF but now the latter corresponds to a 2-fold higher magnification (the physical size of the image projected on the sensor). If the two sensors have the same pixel size a FF pixel will correspond to a feature that is half the size in the scene. So you get up to twice the resolution. This is important to me. If the two sensors have the same number of pixels then the FF sensor will have a 4 times larger area per pixel, giving greater dynamic range and lower noise. This is not important to me hence less interest in the A7 IV. With higher magnification comes shallower DOF. This is desired by some for artistic reasons but is not important, or mostly disadvantageous to me. Less DOF is not a disadvantage of FF because it is just the price you pay to get higher resolution. To get the same resolution on m43 you simultaneously reduce DOF back to the same level as FF. You can restore DOF on FF by stopping down the aperture. That will make the strobe work harder compared to m43 but not an issue if your strobe has enough power. Moreover, if you use double the focal length on FF you can increase the aperture by two stops without having more diffraction effects than m43 (in both cases the physical diameter of the aperture will be the same). Diffraction sensitivity does depend on pixel size. The larger the pixel, the more resolution loss due to diffraction you can tolerate before it becomes noticeable. This is not an advantage because it just means you can't record the full resolution the lens can deliver. But the 61Mpx FF sensor pixels are similar to the 20Mpx m43 sensor so not too much difference. I am sure there is more to say about in the FF vs crop discussion and different ways to look at it. But this is the way that works for my interests.

After almost 7 years with my Olympus EM1 mk2 in a Nauticam housing it is time to upgrade. Moving on to the OM1 mk2 would be the logical progression but because I will be diving for about 5 months every year from now on I can work with a much larger budget than in the past and size/weight is a bit less important. That means I am also looking at full frame and in particular the A7R V. That said, my underwaterphotography focus is on fish portraits with a more scientific than artistic interest and the image quality of my current camera is already plenty enough. The same applies to other well known (dis)advantages of cost, size/weight, video specs, readout speed/rolling shutter, ..., none of those are critical to me. Another factor to consider is that I haven't used lenses wider than 24mm (FF) in the past 2 decades and rarely go lower than 35mm (I do have a WA wet lens for occasional images of fish habitats). I thought it might be fun to consider pros & cons in this context where my priority is to maximize the chance of getting a good image rather than maximizing my ability to capture the perfect image. Below I list a few no-brainer reasons to prefer the A7R V, some that look good on paper but may not be that important in practice, and some where the OM1 has unique advantages. Ideally some of you have used both systems or have tips relevant to these issues. No-brainer advantages for the A7R V (and other high resolution FF cameras) For fast and erratically moving fish you can't make them fill the frame without too high risk of cutting off some parts. With a 61Mpixel FF sensor I can frame the fish to cover the central part, crop as needed, and still end up with an image of a size similar to the 20Mpixel m43 sensor. So 'croppability' is a big plus of FF sensors for me. With a m43 sensor I can rarely shoot a fish at 1:1 magnification because few fish are small enough to fit the 17mm width of the sensor. The FF sensor size is a better match to the typical size of small gobies etc. For skittish fish you often can't maximize magnification by getting closer. So, at the closest distance you can achieve, you maximize magnification by using a longer focal length (or a teleconverter). This is easier on FF where you typically work with longer lenses already and you can get that magnification without making the field of view so narrow that it becomes impractical. The higher Mpixel count gives greater resolving power (if you don't close the aperture too much). A7R V advantages of unknown practical benefit The latest generation of Sony cameras (and Canon?) are supposed to have superior continuous AF, subject detection and focus tracking. But the OM1 also has AI subject detection and AF improvements over previous models. Has anyone used both systems? If so, how much better is the sony AF compared to the OM1 mk2? The A7R V has a large high resolution viewfinder (0.9x, 9.4MPx) but the OM1 mk2's 0.82 (FF equiv.) 5.7Mpx viewfinder is quite impressive and much better than my current 0.74 (FF equiv.) 2.4Mpx finder. OM system benefits Olympus cameras are the only ones I know of that allow me to very accurately measure objects in images (about 1% accuracy, blog to be posted soon). That is important for my scientific use of the images. The Oly 12-50mm powerzoom kit lens is a very practical underwater lens. You can zoom it without need for a zoom gear (it seems other camera brands don't offer that feature for their powerzoom lenses). It's 24-100mm range, FF equiv., and focus distance is very practical, it does not extend when zoomed or focused, and it can be used in the same port as the 60mm macro lens. It also has a special 'macro mode' that focuses down to 20cm and creates a 0.36x image with a fixed 43mm focal length. But I don't use that. OM systems recently came out with an autofocus 90mm F3.5 macro lens that can do 2:1 magnification. Cool, but the magnification is not really that useful for fish. For lenses, the Sony 90mm F2.8 macro will be a good and likely superior replacement for the Oly 60mm F2.8 macro lens. The Sony 24-105mm F4 would be a logical, and optically superior, lens to the Oly 12-50mm. However, Nauticam's port chart does not include a zoom gear for it and there is no discussion about it's use underwater on this forum. There has been discussion on waterpixel about using the Canon RF 24-105mm F4, for which Nauticam does make a zoom gear. The Sony lens actually focuses closer (38cm vs 45 for Canon) and reaches higher magnification (0.31x vs 0.24 for Canon). Both lenses extend when zooming, so why is the Sony lens not considered for underwater use? It would be a nice top-side lens as well.

Hi Keith, I should just go to stores and check it out myself but if you use the viewfinder underwater, how does the one of the A7cR compare to the EM5Mk3? I am more concerned about that than the sync speed. Bart