Well done Steve. I will have to get booked in to my local pool for a few evenings to try out some strobe positions when my dome arrives. I can see there being a bit of a learning curve regarding strobe positioning and I would rather do it here than at Lembeh.

All the best

Stew

Steve,

Great tests, the set up looks slick, and nice hot tub. But which duck did u order? Ive heard from pros this can make a huge difference to u/w tests. Standard ducks dont cut it and u need the ltd edition scuba duck!

Great idea with the car mitt vs anemone, all u need now is a Nemo toy...

And looks like i might be forking out for a small dome for the 7d too then.

Olly

You forgot to order the optional drink cup holder.

Hey guys

I've given my Zen 100 a good run-around here in Lembeh and then last week in Bali on the Liberty wreck (tough life eh?). Very happy with it on my Subal housing and Tokina 10-17 And it sure beats having to pack the FE2. But I am getting vignetting at around 14mm with a 20mm Subal extension. Odd. Is everyone using 20mm extension rings? (it's what Ryan suggested)

Thanks - I'm off back to the Liberty tomorrow........ :-)

Hey Tim, I'm setup with the 20mm extension on the Nauticam. Which body do you have it on? Pictures please, I'd love to see what you're able to do with it.

Chris, I was feeling decadent enough without a drink holder, that and I didn't see it in the catalog.

Steve

No, I'm using a Subal 15mm extension and getting excellent results with no vignetting. The 15mm extension was recommended by Ryan too.

There seems to be a lot of confusion and mis-information about what extension is required with the 4" Zen dome. When I first ordered mine back in early December 09 I was told by Reef Photo that no extension was required. The first time I used it without any extension it was obvious that this advice was wrong. After some too-ing and fro-ing with Ryan on what extension was needed I was given the 15mm extension advice in late February 2010, I purchased one based on this advice.

Doh. RYAN!!!

Looks like he's going to make even more cash out of me...... Thanks Steve and Gudge.

I'll flick some pics up when I get back, Steve. I've not managed to process all I brought back from my last trip yet (only got back on Friday and I'm off again....)

And in case anyone is interested..... I am leaving KBR in a couple of weeks time. I have been the dive manager here for a year and it's been great fun. But a year is enough. Besides the Tim Tams Gudge and Mary very kindly sent me for Xmas have finally run out.

I cannot recommend Lembeh Straits enough though for anyone wanting to do some amazing small critter diving. I don't know what I'm going to do next yet. Anyone want to hire a former British diplomat turned dive manager? I can tell people to go to hell and leave them looking forward to the journey.......

Should be a decent farewell party - hopefully you won't get floured like Mike was for his brithday!


Always wondered about the Canberra bit in your signature - all is explained! If you turn up in Sharm with your resume you shouldn't have too much trouble finding a job at a dive centre - good luck with the job hunt.


A friend of mine who used to work for similar masters to you used to explain it as "There's nothing I can't solve with a phone call - or 200 Royal Marines!"

On Nauticam, we recommend the 20mm extension. On Subal, the recommendation is either the 15mm or the 18mm. (and just to be clear, these recommendations are specifically for the Tokina 10-17, other lenses will be different).

While were waiting for Tim to post some real images (hint, hint) I learned a little more, playing with the dome. It's warming up nicely here in the desert, pool is up to 76F(25C) so I finally broke the ice and jumped in with the new Nauticam and the 7D. I'm still working on understanding the intricacies of the 100mm Zen dome with the 10-17. Did some comparison tests at 17mm varying f-stop. I know you pros have this down pat but thought I'd post a couple of shots for the rest of us beginners.

The first thing you notice is the optical difference between the 10mm and 17mm. Here is a comparison, both shot at f/14. The dome to subject distance was varied to fill the frame at each zoom position. It's tough to get the exact same position on multiple shots so I'm not quite squared up but hopefully you get the idea. The corners don't bend away as much at 17mm compared to the 10mm, as you'd expect.

17mm on the left 10mm on the right;



It appears that because the corners are optically closer to the focus plane you can use a wider aperture and get reasonably acceptable corners at f/11 when racked to the 17mm vrs f/14 at 10mm. f/8 would be very usable. Here is f5.6 compared to f/11. Both shot at 1/250 varying strobe power to get roughly equivalent exposures. These are 1:1 Lightroom crops of the bottom left corners. Text is 1/8 inch high on the 13" x 19" focus chart.

f5.6 on the left f/11 on the right




Thanks to Adam's fish shots, I started thinking about how the 17mm on the crop frame is getting closer to my old 28mm lens on the Nikonos that I used for fish back in the day, not at all equivalent but I started wondering about fish photos using the 17mm end of the zoom. I haven't found just the right practice rubber ducky yet so I resorted to my practice fish. He's about 6" (15cm) high. (Picture a Blue Tang) This shot was taken at 17mm f/14 1/250 ISO 160, 1/4 power on the left strobe, a notch less on the right. "fish" was roughly 12in (30cm) away from the dome. I only got one attempt at this. Turns out our female Golden Retriever is not happy about fish in her pool and she dutifully retrieved it and unceremoniously ended my practice session.




I'm liking the potential. The other thing to note is at 17mm you're farther away for the same subject size in the frame so the strobe position is less of a problem. There are lots of variables here but I can't wait to get this is some saltwater.

Cheers,
Steve

Hi Steve,

Thanks for all this-it is fascinating stuff. I think though that the blue tang image would probably work with a normal dome? If so, I think you will get round all the corner issues. You are absolutely right though, that for fish portraits, I find the 17mm end of the 10-17mm the place to be:



1/60th @ F9 ISO 200

This was with a conventional 8" dome. I think the lighting issue becomes a problem with CFWA, which this image isn't really! If you put a converter in, and then get the dome close, then where to put the strobes is a challenge.

As regards the golden retriever getting the fish-simple, hide it under your stetson!

Adam

Okay, what gives?

Following this thread I shot the 100 mm dome with the 10-17. A Subal rig with a D300 and 3rd generation mount. Using a 15 mm Subal ext. ring.

All 10 mm images showed significant vignetting. Images shot at 12 mm and longer were fine.

I looked back a the first time I shot this set up, not using an ext. ring.

Only two images were shot a 10 mm. No vignetting is noticeable. The many shot 11 mm and longer were all fine.

Why is the 15 mm ext. ring recomended with this port? It seems not to work.

From a conversation a while back with Ryan the issue may that Subal are not particularly consistent on camera focal plane position housing to housing - so your Subal D300 housing may be different to my Subal D300 housing.

If this is the case then on Subal it will be a 'suck it and see' trial.

If true this is sloppy engineering.

To be fair I guess that this placement is going to become more critical with small radius domes and WA lenses.

Paul C

If this was the case you would also have control alignment issues.

I think a more likely explanation is that bodies are set back further in the Subal housings.

Can't disagree with your logic Peter but there seems to be some unit to unit variation going on specifically with Subal.

Haven't Subal in the past have been reluctant to supply replacement backs for their housings, taking a "it needs to come back to the factory for fitting" type of position?

I had always assumed that this was just to foster a replace rather than repair type of mentality.



Paul C

Extension Ring 15 definitely doesn't vignette with the ND300 or ND30 housings (two models have actually be produced for D300), both have been tested pretty thoroughly by us and our customers. My first thought would be to measure your extension ring and make sure you have what you think you have, as both 18 and 20 vignette. They are easy to measure, just the measure the length of the knurled part you'd put your hand on when mounting.

Subal port spacings are not sloppy within a model, but they have moved the port mount to camera lens mount steadily closer to the camera on more recent models, which can make for inconsistent extension ring recommendations.

This looks like vignetting to me.
Click to view attachment


This looks like a 15 mm ext. ring.

Has the combo of the 100mm Zen dome and 15 mm Subal ext. ring been test with the 3rd generation Subal mount?
Click to view attachment

It is hard to compare due to different settings, but the edges appear sharper on the shots I took without the ext. ring.

Clearly with this dome the edges get sharper starting around F 8 or F 9.

That definitely is vignetting, and that is a 15mm extension.

We tested the combo with several Subal third generation combos, including D300 (both the ND30 and ND300 models I believe). I've sent a pm asking the housing serial number so we can look into this further.