I have in my possession:

A Tokina 10-17

A Metabones V

A Sony 2.0TC

Zen DP100 Tokina version, and

30mm extension.

I knew from previous experiments that the Tokina covers the Sony FF sensor from ~15mm and tighter. So I had to try the TC under the theory that will expand the image circle.

IT WORKS! The camera shows 19-34mm in Advance mode and the sensor is covered through the zoom range. Looks roughly 150 degrees or so on the wide end. Focuses on the glass if you're patient.

I have no fancy charts to check IQ, it's likely poor but so is our visibility.

AF on my A7Riii is not great but not dramatically worse than the bare lens. Hunts like crazy in AF-C but that's the same as no TC.

Would I purposely buy this combo? Definitely not, it's temporary while I decide on a FF zoom fisheye.

Does it seem perfectly functional? Absolutely!

I other news the Canon 60 EF-S also covers FF with the TC.

Edited October 25Oct 25 by Grantmac

3 hours ago, Grantmac said:

I have in my possession:

A Tokina 10-17

A Metabones V

A Sony 2.0TC

Zen DP100 Tokina version, and

30mm extension.

I knew from previous experiments that the Tokina covers the Sony FF sensor from ~15mm and tighter. So I had to try the TC under the theory that will expand the image circle.

IT WORKS! The camera shows 19-34mm in Advance mode and the sensor is covered through the zoom range. Looks roughly 150 degrees or so on the wide end. Focuses on the glass if you're patient.

I have no fancy charts to check IQ, it's likely poor but so is our visibility.

AF on my A7Riii is not great but not dramatically worse than the bare lens. Hunts like crazy in AF-C but that's the same as no TC.

Would I purposely buy this combo? Definitely not, it's temporary while I decide on a FF zoom fisheye.

Does it seem perfectly functional? Absolutely!

I other news the Canon 60 EF-S also covers FF with the TC.

You got me thinking with this brain-teaser! 😜

Is it a better idea to spend 10-thousand scuba bucks to get a high end beast of the FCP dome, matching lens, and end up with barely measurable but incrementally better quality? Or better to spend Zero scuba-bucks to put together a grab-bag-hobo-hodge-podge of leftover parts and end up with barely measurable but incrementally worse quality? Or do you just slap your forehead in the realization that the problem was with the strobes and lighting all along??!!

Or the guys behind the camera? 😝

7 hours ago, Grantmac said:

I have in my possession:

A Tokina 10-17

A Metabones V

A Sony 2.0TC

Zen DP100 Tokina version, and

30mm extension.

I knew from previous experiments that the Tokina covers the Sony FF sensor from ~15mm and tighter. So I had to try the TC under the theory that will expand the image circle.

IT WORKS! The camera shows 19-34mm in Advance mode and the sensor is covered through the zoom range. Looks roughly 150 degrees or so on the wide end. Focuses on the glass if you're patient.

I have no fancy charts to check IQ, it's likely poor but so is our visibility.

AF on my A7Riii is not great but not dramatically worse than the bare lens. Hunts like crazy in AF-C but that's the same as no TC.

Would I purposely buy this combo? Definitely not, it's temporary while I decide on a FF zoom fisheye.

Does it seem perfectly functional? Absolutely!

I other news the Canon 60 EF-S also covers FF with the TC.

Way too much for a Sunday...

16 hours ago, Dave_Hicks said:

You got me thinking with this brain-teaser! 😜

Is it a better idea to spend 10-thousand scuba bucks to get a high end beast of the FCP dome, matching lens, and end up with barely measurable but incrementally better quality? Or better to spend Zero scuba-bucks to put together a grab-bag-hobo-hodge-podge of leftover parts and end up with barely measurable but incrementally worse quality? Or do you just slap your forehead in the realization that the problem was with the strobes and lighting all along??!!

It's always the loose nut behind the camera.

I confirmed today that in lower light it really struggle to focus.

Ultimately I'll end up with a 140mm dome and 8-15 of some sort.

Confirmed that IQ is irrelevant if you can't get a lens to focus. Cropping the bare lens on the same sensor worked better.

Next step is waiting on a 8-15 and figuring out which extensions I need to make it work in the DP100T, I believe 20mm should do it.

The 8-15 arrived.

50mm of total extension shows just a slight vignette at 15mm with the 2.0tc, more on one side than the other so I think I have a slight alignment issue.

Probably a 17mm extension would be ideal but other than 3d printing I don't think they are made.

This is really an intern solution until I decide on which 140mm dome to buy so I'm not too invested into making an ideal solution.

There is always the Dremel Tool!

Let me know if you need a custom extension.

Definitely not afraid of modifying things!

There's a lot of things to consider. First of all, if you are using a 2x TC I would definetly go for a much more flat dome port, you'll be surprised with this combo. Or for that zen dome I would use a 1.4x TC

But if you want to keep using that dome, what you need ir order to not lose wide angle degrees is to put the lens as far away as possible to the front of the dome with no vigneting. No vigneting with a 10-17 is around 15-16 mm. Remember, what you are focusing is the virtual image inside the dome. But with a FF and such a tiny dome what you will notice is a lack of focus at the corners. I thing you need a bigger ring. And if you don't want that lack of focus a bigger dome, I have found 140 mm diameter is the best one for that.

Or, you can buy an unexpensive 24-50 lens, put behind a flat port with M67, and attach a Nauticam WWC-L lens, so you can do high quality wide angle and quite small fishes during the same dive.

I own all the options above, including the Tokina 10-17, the Canon 8-15, the 4" dome port, the 140mm dome port, the 2x TC and the 1.4 TC less. The last option I have bought ii but still haven't arrived.

I had an WWL-1 and just didn't enjoy using it. Heavy, not wide enough, couldn't snorkel with it.

The 8-15 along with 2.0tc seems like it will fit a lot of my uses. It's interesting to hear that it might perform better behind a flatter port. I was assuming that the 140mm would be the ideal.

I have dived a lot with the 8-15 plus 2x TC, with a flatter dome port you can be really close to subjects about 5 cm and you'll get kinda endoscopic pictures, wit due allowance for differences. The hard part for this is to find that flatter dome port. In fact I manufactured mine one. But I have seen some of them manufactured by Subal.

Do you have a picture or dimensions? Because I've been assuming that you need a hemispherical dome to use these lenses.

2 hours ago, Grantmac said:

Do you have a picture or dimensions? Because I've been assuming that you need a hemispherical dome to use these lenses.

Not "need" as such, more that the optical performance will be better with a hemisphere as you can place the entrance pupil closer to the centre of curvature of the dome. However many fisheye lenses seem to be less sensitive to this and perform quite well when the entrance pupil is not optimised. A flatter dome port requires the entrance pupil to be placed forward of the dome centre of curvature so it doesn't vignette, it also increases barrel distortion.

Think of it more as a CFWA optimisation, the flatter dome or the smaller dome allows you to get closer to your subject with CFWA work and this increases the size of the subject in frame. This ability to get closer is set off against poorer corner performance. If you look at this thread you can see the dome height of the 170mm Zen dome vs the 140mm Nauticam dome, scroll down to the post with dome pics by Dave Hicks:

You can get about 1.5cm closer with the Zen 170mm dome. You can readily test what this means for subject size in frame on land. The larger diameter of the 170mm dome may get in the way when trying to get in close though. A prime example of this is the Ikelite compact 8"dome, it's really flat, it's definitely not optimised for entrance pupil position, but seems to take decent images with the Canon 8-15.

Very interesting.

Perhaps I should look for a Zen170 to complement the DP100.

I find the strobes and overall size of the camera the biggest limitation for CFWA although the longer extension should make that a little easier.

22 minutes ago, Grantmac said:

Very interesting.

Perhaps I should look for a Zen170 to complement the DP100.

I find the strobes and overall size of the camera the biggest limitation for CFWA although the longer extension should make that a little easier.

What's the challenge with the strobe position? I just move them out or up or back & pointing inwards if you can't get them close.

Just now, Dave_Hicks said:

What's the challenge with the strobe position? I just move them out or up or back & pointing inwards if you can't get them close.

I started CFWA with a combo that was a small housing, N85 65mm port then the WWL-1 in top. So it was very long and pretty narrow without a huge FOV. I could basically put the strobes right next to the port.

I'm finding that now I need to move them back and start angling in as you say. Just a shift of mindset.

It appears the DP100t with just the 30mm extension and 35.5mm N100-N120 gives acceptable IQ with the 8-15 had 2.0tc, at least for shots where the corners aren't a big deal. It'll do in the meantime while I look at my next move for domes. Probably the Howshot 140mm.