Since there is so little posted pictures taken with an MFO-1, I thought I would share my experience.

Here is the short story

Canon R7 with RF100mm,  1/250  f18 iso 320 on all shots.  All pictures unprocessed.

without MFO-1

with MFO similar distance

with MFO moved back to get similar size of subject compared to shot with no MFO-1

without MFO-1 100% crop

with MFO-1  100% crop

Now the long story. My main reason for buying the MFO-1 was to help focus hunting issues I was having when shooting fast moving fish like wrasses and in particular, flasher wrasse. I was very excited to find some flashers on my first dive with the MFO-1. I spent 30 minutes shooting them and did not see any noticeable improvement in focusing with the MFO-1. Many times I would preset a focus distance and when the flasher swam into focus, I would half depress the trigger and the camera would immediately go out of focus and hunt back and forth, just like it did without the MFO-1. I have had this problem ever since I got this camera a couple of years ago and even sent the camera back to Canon for repair but they did not find any issues.. The camera is awesome once it locks focus and works great on slow moving subjects. I was so disappointed I did not plan to use it again on my trip.

 

After a couple of days, I thought it would be interesting to test the enhanced image quality the MFO-1 is suppose to provide. This is where something interesting happened. I started the dive with the MFO-1 attached to my flat port. When I took it off to shoot without it, I was shocked to see lots of air bubbles escape! Was I shooting through air on my first dive with the MFO-1? I did several shots with and without the MFO-1 to test image quality (picture above) then kept it on, excited to try shooting a wrasse without any air bubbles. No flashers but when shooting other wrasse, the same focus hunting problem occurred. 

I am not sure if my camera is causing the problem.  I plan to send it back again to Canon again. So take my results with a grain of salt.  Anyone want to buy an MFO-1 that was used for only on two dives? And just to show you I do know how to use a camera, this shot below was taken from my first dive with the MFO-1, maybe through an air pocket?

Could the hunting problem just be the camera’s inability to cope with the turbidity and lack of contrast? Have you tried a focussing light to help? Perhaps with a red filter to avoid scaring your subjects?

My experience with air bubbles between the port and the wet lens is that it usually appears as tiny dark spots on the image, but otherwise doesn't really affect image quality.

I do make a habit of "burping" my lens every time I enter the water. Sometimes it's also needed when you go through another diver's bubbles.

I also believe that the MFO lens may only really improve the sharpness at the edges of the frame, by correcting for chromatic aberrations from shooting through a flat port. So crops of the corners may be helpful.

Reading the two threads on the topic, it makes me think that the improvements also depend on the lens used. Am I wrong?

35 minutes ago, shokwaav said:

My experience with air bubbles between the port and the wet lens is that it usually appears as tiny dark spots on the image, but otherwise doesn't really affect image quality.

I do make a habit of "burping" my lens every time I enter the water. Sometimes it's also needed when you go through another diver's bubbles.

I also believe that the MFO lens may only really improve the sharpness at the edges of the frame, by correcting for chromatic aberrations from shooting through a flat port. So crops of the corners may be helpful.

in air, my MFO on a 105, can only focus up to +/- 30 cm in front of my port, anything beyond it wont focus. In water, its up to +/- 100 cm (like on the nauticam port chart).

So i do believe, water has a big impact in how this lens works, although I dont know how it affects image quality.

I would not use the mfo without water between port and wetlens.

2 hours ago, Davide DB said:

Reading the two threads on the topic, it makes me think that the improvements also depend on the lens used. Am I wrong?

Probably you are right.

I can't say if the MFO-1 increase the quality with the R5 + RF100, but and that is very important for me it will limit the focus range... That so good in a wide range of situations I win a lot of time/opportunity to make nice shoots.

The MFO is designed to counteract the abberations caused by refraction of light through the flat port glass. These aberrations get progressively stronger as you go from centre of field to the corners. The camera in question here, the R7 is APS-C so much of the corners are cropped out of the frame compared to a full frame sensor camera. This means the sharpness benefits will be a little less. The aberration are worse with shorter focal length lenses like a 50-60mm lens on full frame and this is where the biggest benefits would be expected. In the past the aberrations with a 100mm range macro lens were accepted as there wasn't really an alternative and they were relatively small. I agree a 100% corner crop pasted side by side with and without the MFO would be of interest.

I think it is worth checking if the camera/lens combination also hunts on land , try shooting something in similar light levels, you could check the ambient exposure on your next dive to know the sort of light level you might need. It would also be worth asking if others have experienced hunting as bad as you describe with the RF 100mm. Also check what AF points others use, do use a single centre point or an array of some type. I would also suggest trying to find someone else with an RF100 you could try and/or an R7 body to compare how they perform compared to your gear. Also confirm you have the limit switch set for the full range. of focus.

There are now 3 threads on the MFO-1.

See my comments re Sony 90 + MFO using AFC + tracking, on the thread "MFO-1 and focus limiter".

I no longer own the MFO-1.

As for controlling aberrations on normal focal length lenses (50-60mm), these are nicely dealt with by using a dome, although depending on your dome diameter and alignment, you may lose a little working distance and hence magnification.

I do think Nauticam's promotion of the MFO-1 has caused plenty of confusion around this lens, because they have drawn attention to minor features equally to its main purpose.

I asked Nauticam to develop this product because I wanted a high quality, but weaker close up lens than the SMC. There are lots and lots of subjects that are a bit too small for a straight macro lens and too big for a SMC. The MFO was designed to plug this gap.

The optical design of all of Nauticam's close up lenses includes a correction for the image aberrations created by using a flat port in water. This is beneficial for image quality (especially away from the middle of the frame) and also by presenting the lens with a clearer image - improves focusing performance of the lens a bit.

The MFO also improves focusing because it stops the lens hunting as much because it makes it impossible to focus on very distant subjects in UW terms (as the focus range is now shifted closer) . This is particularly helpful with mirrorless cameras (PDAF) - which can struggle to know what to do when a subject is totally out of focus.

That said, I would say AF improvement is a minor benefit of the MFO. Image quality improvement is also the same as other Nauticam close up lenses (they all aim to do the same correction for the flat port). I like Mike Bartick's comment on the MFO-1 in this regard - "think of it as a make it 'betterer' switch - stick it on your macro lens and just go and use it". The MFO will allow you to fill the frame with smaller subjects, stop you shooting things that are too far away, give small improvements in image quality and AF.

The optical correction that all Nauticam's close up lenses make for the port is the reason it does not make sense to stack the MFO and SMC. As both perform a correction - you end up with a double change, in other words as far away from optimum as having no correction. So they work together, but without the image quality benefit.

The other point I want to mention is that you should not ever use the Focus Limiter Switch on your macro lens whenever you might be using UW close up lenses. You need this full range of focus to properly exploit the full range of these lenses.

I previously used the FIT +5 and the Nikon 5T for the role of the MFO. But these did not have the same image quality of the MFO, as they did not correct for the flat port aberrations (which is why I pushed Nauticam to make the MFO).

I have shot the MFO for over a year (in pre-production form last year). It does not record in the EXIF, but there are 25 pages of images on my website since I started using the MFO and most of the macro shots are taken with it:

see this page https://www.amustard.com/library/page/search/alex/26/ and forward to 1, which cover the last year (my most recent trip was sharks - so ignore the newest 90 or so images - pages 1-5!).

Edited 4 hours ago4 hr by Alex_Mustard

2 hours ago, Alex_Mustard said:

The other point I want to mention is that you should not ever use the Focus Limiter Switch on your macro lens whenever you might be using UW close up lenses. You need this full range of focus to properly exploit the full range of these lenses.

Before the MFO I build a sytem in 3D Printing who allowed me to switch under water the focus limiter, but it didn't work perfectly... now with the MFO I removed the switch system from my lens...

I put the MFO most of the time or flip away to flip the SMC-1 but since I have the MFO I can't remember that I shoot without a lens.

Sorry I forgot to say Canon R5 with RF100 in Isotta housing

Edited 5 hours ago5 hr by CaolIla

3 hours ago, Alex_Mustard said:

The optical design of all of Nauticam's close up lenses includes a correction for the image aberrations created by using a flat port in water. This is beneficial for image quality (especially away from the middle of the frame) and also by presenting the lens with a clearer image - improves focusing performance of the lens a bit.

The MFO also improves focusing because it stops the lens hunting as much because it makes it impossible to focus on very distant subjects in UW terms (as the focus range is now shifted closer) . This is particularly helpful with mirrorless cameras (PDAF) - which can struggle to know what to do when a subject is totally out of focus.

Thanks for weighing in Alex, the AF behavior described certainly sounds like a camera/lens with some sort of problem or settings issue to me. The OP mentions a fish near in focus doesn't snap to focus but instead starts hunting. I'm thinking the MFO probably shouldn't be expected to help with an issue like this.

Have any MFO users compared focus hunting with the (limiter switch on) vs (limiter switch off + MFO)? I ask, for those considering the MFO where the primary benefit they are hoping for is to improve focus hunting.