Nex 5R and Nauticam Focus Issues

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

Anthony A.

Contributor
Messages
570
Reaction score
163
Location
Toronto, CAN & Hollywood, FL
Ive been using my Nex 5R for quite some time with nauticam housing and 4.33" dome port. Ive used so many lenses with this port and usually stick with the sigma 19 as it provides excellent sharpness and auto focus. On a recent trip, I tried using a sigma 30 lens (same size as the 19) but the entire dive day I was unable to take shots in focus. Topside on the boat, everything worked perfect. As soon as I get underwater, the autofocus would just refuse to lock on and get focus. This was on 3 seperate dives that day. So my question is: has this ever happened to anyone before? Could it be a defective lens? What could have caused this?
 
It's possible you require a dioptre to focus with the dome underwater, Nauticam should know.
 
It's possible you require a dioptre to focus with the dome underwater, Nauticam should know.

Would this be because of the lens' focal length or could it be lens specific? Ie. If i use a different lens like the sony 35mm willit have the same behaviour?
 
The problem is likely that the Minimum focus distance for the 19mm is around seven inches and for the 30mm it is close to one foot. Because of the port size the virtual image is not within the focus range of the lens. As BigJeff has said you will likely need a +2 to +4 closeup lens (also call diopters by many) to make this lens work in that port.

With a flat port the lens should focus without a problem. I suggest you Google dome port theory and acquaint yourself with the virtual image concept.
 
Ok great. I read up on diopters, virtual image and dome ports and now understand what is going on. So based on this info, I am looking into b+w diopters from +2 to +4 but is there a formulw to figure out which one is best or is it just trial and error?

Also, what would happen if I put a +4 diopter on the 19mm? Will it act as a 30mm lens since it magnifies it?
 
Ok great. I read up on diopters, virtual image and dome ports and now understand what is going on. So based on this info, I am looking into b+w diopters from +2 to +4 but is there a formulw to figure out which one is best or is it just trial and error?

Also, what would happen if I put a +4 diopter on the 19mm? Will it act as a 30mm lens since it magnifies it?

There are formulas for a perfect spherical dome however real ones are not, including the Nauticam

Moreover you don't know where is the focal point of the various lens so you have some idea of where to start but not necessarily this will warranty your lens will work

For a 4.33" dome which is rather small you are looking at +4 diopters, for 9" domes you are in the region of +2

So you may buy a +4 and still it does not work, this is the reason to follow the nauticam port chart so you avoid those sort of issues and lack of testing yourself
 
First of all the Sigma lenses are not listed in the Nauticam port charts and second none of the Nauticam ports require a closeup lens for the matched lenses. The Sigma 30mm has no real upside for your NEX system other than the fact that is is inexpensive to buy. I have both the Sigma 19mm and 30mm for M43 and they work well above water but are of little value underwater. I would be happy to sell both for $200.00 in like new condition. Adding any magnification (+2 to +4) only degrades the lenses even more. If you want to use a 30mm lens with NEX the Sony 30mm macro is a much better choice and it will focus inside your dome port so should work well with the flat port or the 4.33 dome port.
 
I wonder if the distance between your lens and the glass of your dome port will affect.
I have been using 10bar 5r housing and I have different port, usually flat port for 30 macro
 
Sorry for my bad english. About the use of the more lenses that apperar on the market with domes, I am very disappointed with Naticam for the lack of tecnical informations about their ports, and also is for Zen ports. I have a Nex6 housing that is a marvelous done housing and I wont change it with other ones: it is perfectly done and robust and practical in every command, and also the housing for the Nex5N is perfect. But the Nauticam port chart for Sony is old, do not consider some new lenses and lacks of some accessories that would be very interesting.
You know that using a dome is very important that the center of the curvature is in the entrance pupil of the lens. To judge if a lens can work with that port, you mus know the radius of the port: only if you know this number you can judge if the lens is in the right place AND if the minimum focus distance of the lens is ok for focusing the virtual image.
In the Nauticam chart is written that, for the 16 mm pancake lens ( know, not the best lens, but useful and cheap) you can use a flat port (horrific thing, for a 84° wideangle) and the 4,33 dome. I asked to Nauticam the radius of the dome but haven't any answer. I tried practically the 16 with the dome, that the chart sees usable, but discovered that the minimum focus is about 1,5 metres (5 ft), due to the short distance of the virtual image of the dome and the longer minimum focusing distance of the lens. That means the lens can NOT be fully usable with the dome. Also using a +4 diopter, as Rudin sees, is not a solution, but not only because the image degrades, but also because the autofocus became very slow and imprecise. Really, it would be quite useful if you can do a manual focusing, but Nauticam do not procuce a focus gear for 16 mm pancake. Therefore, the 16 mm is not usable by itself. Also, i had the chance to test with the 16 mm with the 36131 Nauticam 3,5" dome for Panasonic, and it works better because , also if the diameter is less, the radius of the dome is longer, and the lens focusing better. But the 36131 is not in the Sony Nauticam Chart.
You would use a Sigma, or other lenses? In the Nauticam chart they are not present. But this not means you cannot use, only means Nauticam do not care. As i read in the before posts, the Sigma 19 works, and the 30 mm do not. A photographer that is skilled about underwater optics can judge if a lens can work if he knows the radius of the dome, but Nauticam do not tells this number, or infos. Just buy before, and throw in the bin later if doesn't works.
Also, for more easy focousing, you can think to buy a bigger port, because the virtual image is more far away ad easy to focus. An example: the 36133 6" dome (for Panasonic) or the 36129 7" dome that the chart points out only for the Sony 10-18 zoom. But you take for sure it works only with 10-18, because is the only lens in the chart. Asking for radius? No answer. Asking via the Italian representative,? No answer also. You mus buy before, then test and if it is not working, throw o resell.
The same for the beautiful Zen domes: I would buy a DP-170 dome, not cheap but marvelous. I emailed many times to know the tecnical caracteristic of the item, but they not answer. You must before buy a 1000$ or so dome, and then test, because you cannot have any thechnical infos.:depressed:
The optics of dome ports are very known from many decades, they are not a secret, or patented. But you can have them. So, I am very disappointed and cannot improve my uw photo gears without "before buy, then test".
It is a pity, because Nauticam and Zen are the best crafters of underwater housing and domes. :depressed:
 
im getting a set of +1, +2 and +4 diopters to test on the 19mm and 30mm lens im using for a trip coming up next week. since the 30mm focuses perfectly inside the dome topside but does not when under water, how can i test out which diopter will work at depth? how deep do i need to go to test if the 30mm lens will focus with said diopter? i guess i will have to try it in a pool before the trip.
 
https://www.shearwater.com/products/teric/

Back
Top Bottom