OM-D EM-5 Nauticam with 9-18 zuiko?

[nudibranco 26]

Great results Storker! I bought the diopters as well a few months ago but never went into the water to try them. As soon as I can I will try with the 4.33" and 3.5" domes as well. The results look good. There has been an ongoing complaint for more than a year about softness on the edges with the 9-18mm lens open and the diopters do seem to solve the issue then.

 

+2 diopters does not even change FOV that much either it seems so it may be the optimal value. I saw the +4 was not bad either and that may be a choice if you want a closer focus. The 18mm focal setting may even allow getting some decent close ups (I never liked the fact that the 9-18mm does not have close focusing capability).

 

THANKS!

[Storker 13]

So your conclusion is to always use the +2, right?

 

Yep, at least for the time being and until I gather additional data on the subject.

 

 

 

Part from the added distorsion, what are the drawbacks of the diopters?

 

I think I saw some added CA, but it was quite manageable in Lightroom and could be almost completely removed. On a normal underwater subject, I doubt if it's very noticeable. And, of course, an extra layer of glass will decrease optimal sharpness and increase the risk of flare. However, with the much better corner sharpness, I'm willing to accept that tradeoff.

 

 

 

What is the actual subject distance by the way?

 

Somewhere around half a meter, maybe a little less. Just enough to fill the frame with an A3 size sheet at 9mm FL.

 

 

 

How does the distortion look change with the diopters, more barrel-like?

 

Pincushion. Very noticeable if the subject has straight lines close to the edges of the frame. For that kind of subjects, you need some correction, but as I said in one of the previous posts, LR (or PS/ACR or PSE) can handle it easily.

 

 

I bought the diopters as well a few months ago but never went into the water to try them. As soon as I can I will try with the 4.33" and 3.5" domes as well.

Please do. I'll be looking forward to the results!

[nudibranco 26]

BTW I also noticed in my limited experience that correcting in SW for typical underwater pincushion distortion on the rectilinear lenses will improve the softness on the edges dramatically...

[chris_l 6]

This is the nauticam 4" dome correct?

 

I wonder if this translates to the the Zen WA-100 dome for the olympus PEN housings:

http://www.zenunderwater.com/products.php?prodID=5

[coroander 16]

The soft corners are because the curved virtual image that we are photographing has the corners much closer to the sensor than the centre. We rely on depth of field for the corners to be in focus (but it's often just not enough). I think that the diopters work by causing the image to appear further away to the camera (the camera focus changes from say 0.4m to 0.8m). This, of course, also allows you to get much closer to your subject because the minimum focus distance is now much closer than where the camera thinks it's focusing. By making the virtual image appear further away, the focus distance is also at a place where depth of field is greater and the corners can now be sharper. That's my take on it, i've never read why this works, but this seems reasonable.

Edited February 19, 2014 by coroander

[oskar 6]

Yes, + 1 on that it would be very interesting to see how the works with the 4.33" (+ some extensions)

 

Another useful piece of information would be to get the optical dimensions of the 4" port, as compared to the others.

 

I suppose length from port mount to dome top would be useful for comparison. And dome radius. However I've heard that the 4.33",3.5" and 4" ports all have the same dome radius but I don't know if that is correct.

 

Great results Storker! I bought the diopters as well a few months ago but never went into the water to try them. As soon as I can I will try with the 4.33" and 3.5" domes as well.

[nudibranco 26]

The 4" semi-dome certainly looks like a larger radius...

[breathless 1]

Long time lurker, first time poster. Inspired by the excellent work of Storker I tried the same trick with my setup - EM-5 in the Oly housing with Zen dome and adapter. Shots run through LR, tone adjusted with auto (sun kept moving behind clouds) and a quick distortion correction for the +2 and +4 diopters. I also shot freehand with the chart stuck to a pool wall so the same caveats around accuracy apply, however I think you'll agree the differences aren't subtle at the 9 mm end (corner crops):

The +4 diopter didn't gain much on stopping down, the +2 caught up with +4/ f5.6 at around f10. The CA cleans up in LR nicely even on the +4, the diopters were cheap close up lenses I brought about 10 years ago so it may be nicer with more expensive glass (or maybe not). The corners were much nicer at the 18 mm end for all settings.

[Storker 13]

Good work, breathless!

 

I had my first real-life test of the +2 diopter inside the 4" Nauticam dome port yesterday, and those results pretty much confirm what my rather dull pool shots of a res chart told us (click image for larger version):

 

 

 

9mm @ f/5.6, 1/60 sec, ISO400, 4m depth:

 

 

 

18mm @ f/5.6, 1/20 sec, ISO400, 3.5m depth:

Edited February 24, 2014 by Storker

[nudibranco 26]

I quickly tried the 3.5" and 4.33" domes with a 30mm extension on the EM-5 and the 9-18mm and a good +4 topside diopter.

I did not upload the pictures but the findings:

- the 3.5" dome just sits too close (maybe a mm) from the lens and diopter. The result is just unacceptable unless you close to F11 or so.

- the 4.33" dome is acceptable once you correct for distortions (both chromatic and focal). Good results at f8.

However the 4" semidome still behaves better and for some reason it can focus much closer (like 20% or 25% better magnification). Good even wide open!

 

Maybe with 2 20mm extensions make the 4.33 worthwhile but at this point I do not see a reason to use the 3.5" or 4.33" domes with the 9-18mm.

The trials have shown that at least a +2 diopter will make the 9-18mm lens work well in the 4" semidome. I wished I had known before as I have used this lens underwater very seldom....!

 

This port can now be used with good results for the 9-18mm, 60mm macro, and 12-50mm lenses. A DIY macro adapter or the expensive flip holder would make it even more versatile. I am thinking the 12-50mm in this port with the new SMC nauticam macro lens would probably be better than the same lens in the super expensive flat port offered by Nauticam to use the lens macro function. I never liked much the 12mm focal length behind a flat port and with an equivalent expensive 4" port and SMC macrolens you could get real macro and reasonable wide angle with this port.

Has anybody tried the 12-50 with the powerful SMC lens?

[Alex_Tattersall 90]

Yes, my friend Doug did well with the SMC on the 12-50mm in uncropped splendour

 

 

[oskar 6]

Ok thanks, as you seem to have found out the nodal points of the domes must be corrected with extensions to coincide with the lens' nodal point otherwise the results will always be bad.

 

So there could be hope for the 4.33" maybe? Anyone that have a couple of 20mm extensions lying around to test?

 

Edit: could i ask you to measure the 4" port length from base to, say inside top of dome?

 

I quickly tried the 3.5" and 4.33" domes with a 30mm extension on the EM-5 and the 9-18mm and a good +4 topside diopter.

I did not upload the pictures but the findings:

- the 3.5" dome just sits too close (maybe a mm) from the lens and diopter. The result is just unacceptable unless you close to F11 or so.

- the 4.33" dome is acceptable once you correct for distortions (both chromatic and focal). Good results at f8.

However the 4" semidome still behaves better and for some reason it can focus much closer (like 20% or 25% better magnification). Good even wide open!

 

Maybe with 2 20mm extensions make the 4.33 worthwhile but at this point I do not see a reason to use the 3.5" or 4.33" domes with the 9-18mm.

The trials have shown that at least a +2 diopter will make the 9-18mm lens work well in the 4" semidome. I wished I had known before as I have used this lens underwater very seldom....!

Edited March 6, 2014 by oskar

[coroander 16]

Thanks nudibranco for trying out the 9-18mm in the 3.5 and 4.33" domes. These have much tighter optical radiuses and so results will never be near as good as with the 4" semi-dome.

 

Keep meaning to ask, nudibranco, if you could post results with the 8mm FE inside the 3.5" and 4.33" domes, particularly with regard to corner sharpness. I find that below f/8 with the 8mm FE in the 4.33" dome, that the corners get soft quite quickly. I'm wondering how the corner sharpness holds up with the 3.5" compared to the 4.33"??? Easiest to use the corner of the pool and use the tiles or place targets on two walls since the 8mm FE is so wide.

[Storker 13]

I find that below f/8 with the 8mm FE in the 4.33" dome, that the corners get soft quite quickly.

I know this is a bit OT, but would you mind expanding a bit on this? I'm considering the transition from rectilinear to FE, and I'm wondering if I should go for the 4.33" or the 3.5" dome

 

 

--

Sent from my Android phone

Typos are a feature, not a bug

[coroander 16]

Panasonic 8mm FE behind Nauticam 4.33" dome centre 100% crop at f/3.5:

 

And the corners (100% crop, click image for full-size); note that the corner target was about equal distance from the camera as the centre (focus) target:

Edited March 7, 2014 by coroander

[oskar 6]

Is this typical performance with this combination? I thought that i got quite decent corners already at 3.5, but need to check closer!

 

Cheers

/O

 

Panasonic 8mm FE behind Nauticam 4.33" dome centre 100% crop at f/3.5:

 

 

And the corners (100% crop, click image for full-size); note that the corner target was about equal distance from the camera as the centre (focus) target:

 

[coroander 16]

The 8mm test is representative of my real world images underwater in the 4.33" dome. I was somewhat surprised by the test results, but when i went back and checked my real images, they were very similar.

[emapola 0]

wow, nice job!. Just buy b+w 52mm +2

 

many thanks

[oskar 6]

Agree, this is where forums like this shines. Have you and more people tried the diopter in the wild yet and possibly have some moore feedback and examples?

[Storker 13]

I've been shooting with the +2 diopter permanently attached since I did my test. I'm pretty sure I'm getting better technical quality on my pictures now, although I haven' done any systematic comparison. There's just too many variables to do a reliable comparison in the wild.

 

--

Sent from my Android phone

Typos are a feature, not a bug

[oskar 6]

I sure understand! If you have been photographing any subjects with subjects filling both the middle of the frame an some parts of the peripheri, that could reveal some difference, right?

 

/O

 

 

I've been shooting with the +2 diopter permanently attached since I did my test. I'm pretty sure I'm getting better technical quality on my pictures now, although I haven' done any systematic comparison. There's just too many variables to do a reliable comparison in the wild.

--
Sent from my Android phone
Typos are a feature, not a bug

[Storker 13]

If you have been photographing any subjects with subjects filling both the middle of the frame an some parts of the peripheri, that could reveal some difference, right?

Yes, I've shot a few subjects covering the whole frame. And according to my unscientific opinion, I see a clear difference. However, since I haven't done any systematic comparison, I can't say for sure.

 

 

--

Sent from my Android phone

Typos are a feature, not a bug