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adamhanlon

What are the advantages of small domes?

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Hi all,

I am really interested in finding out people's views about small dome ports.

For the purpose of our discussion, let's define these as 4"-5" (100 to 125mm)?

Do you use them?

If so, with what camera/lens combinations?

What are the advantages of the small dome over a larger one? 

Thank you!

Adam

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Hey Adam

I use a 100mm dome with the Tokina 10-17 on a D500.

Advantages: Small size, portability, ease of use on reef, lightweight for travelling, price (!), perfect for CFWA

Disadvantages: Impossible for over/unders unless flat calm. Can't think of any others!

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For me the biggest one and the reason I am trying to find ways to completely eliminate my 7" dome from my setup is travel size/weight. I live in Germany so there is not that much high quality local diving. The other benefit is close focus wide angle and also the lower price.

Downsides: For MFT there are no real high quality alternatives other than 180° fisheyes and the Olympus 12mm prime that go into small domes. Laowa just released a tiny 10mm prime. Maybe that will work.

Splits are also harder, but to be honest I've not had any luck in a larger dome...

The only other option to get a smaller FoV in a small dome for MFT is adapting the fisheye zooms, which is incredibly expensive.

 

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These are both with 4" dome on 8-15mm on D850. I use it when I don't have my Nikonos 13mm with me, and value a very close focus view over ultimate image quality. The Nassau grouper is from Cuba and the frogfish is from Philippines.

CUB20_am-17481.jpg

PH19_am-18271.jpg

Alex

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I've been doing some more reading since our chat the other day Adam and you're absolutely right, there's costs and benefits to every setup. I'm still convinced a small dome is ideal for me but keen to hear other contribution here.

I've been shooting with the Panasonic 8mm Fisheye behind a 4 inch Precision dome for a few years now. The minimum focus distance is 10cm and with this dome I can get in really really close - almost touching the dome. It's perfect for me as I'm shooting the UK which means lower vis and smaller subjects. Also, the port doesn't protrude vertically from the housing either, which means I can get the full setup really low on the seabed and shoot up if needed - this has made a huge difference. I'm not convinced I could have gotten this catshark shot with a bigger dome. 

I've managed to shoot decent splits with it - not easy but I get there eventually. This jelly shot was taken with the 4 inch dome too. 

P1200448.jpg

P5190074-Edit.jpg

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Are all the wideangle shots from your scotland gallery shot with the 8mm fisheye?

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1 hour ago, mark kirkland said:

I've been doing some more reading since our chat the other day Adam and you're absolutely right, there's costs and benefits to every setup. I'm still convinced a small dome is ideal for me but keen to hear other contribution here.

I've been shooting with the Panasonic 8mm Fisheye behind a 4 inch Precision dome for a few years now. The minimum focus distance is 10cm and with this dome I can get in really really close - almost touching the dome. It's perfect for me as I'm shooting the UK which means lower vis and smaller subjects. Also, the port doesn't protrude vertically from the housing either, which means I can get the full setup really low on the seabed and shoot up if needed - this has made a huge difference. I'm not convinced I could have gotten this catshark shot with a bigger dome. 

I've managed to shoot decent splits with it - not easy but I get there eventually. This jelly shot was taken with the 4 inch dome too. 

P1200448.jpg

P5190074-Edit.jpg

Nice pics, Mark

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First from Adam's original post I would expand the small dome range to include the 140mm optical glass dome offered by Nauticam and used by many with Fisheye lenses.

Second I think price point is what drives many investments in photo equipment. I reviewed the Canon SL3 a 24MP DSLR with an Ikelite housing recently. The Ikelite housing with the "kit" 6" dome port, gear, camera body and 18-55 kit lens package sells for less than my Nauticam 230mm fisheye dome port II. 

With fisheye lenses I like smallish ports for close focus and large ports for splits and larger scenics if you are carrying both. Full frame cameras with greater MPs like D850 and A7r IV seem to benefit from larger ports. I moved from 100mm to 140mm in 2016 when I started shooting Canon 8-15 fisheye zoom with Sony full frame.

My photos, #1 Frogfish Canon 8-15 with Zen 100mm port on full frame, #2 Olympus 8mm F/1.8 with Nauticam 140mm, fingers in focus touching the port, #3 Canon SL3 with Ikelite kit port and Tokina 10-17 at 11mm, photo of me by Roman, #4 Canon EOS R with 8-15 fisheye and Ikelite compact 8 inch port which is around 6 inches and #5 Nikon Z 6 with Nikon 8-15 fisheye at 8mm also Ikelite compact dome.

I am sure you could also fill a thread on circular fisheye love it or hate it.

  

 

 

 

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23 hours ago, hyp said:

Are all the wideangle shots from your scotland gallery shot with the 8mm fisheye?

Yeah, that's all the 8mm and 4 inch, apart from the basking shark shot which is a bigbigbig dome. 

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Mini-dome is my favourite dome. It’s all about getting close, then even closer, for eye-popping CFWA. IMHO. 

0ACC016F-B339-4379-BEB1-F191E2BBA1D7.jpeg

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Thank you for your responses.

I get that lots of people like them. My question is why? 

With the possible exception of Alex's grouper shot, all the above images could have been shot with larger domes. Of course it is impossible to be absolute without knowing all the variables, but some of the optical problems in the images may have been alleviated by using a bigger dome?

I think the key advantage is lighting with a small dome, rather than the physical distance  of the subject in front of it. Intermediate sized domes like 140mm or 6" do not offer this advantage, so I really wanted to limit this discussion to 100-125mm sized domes only.

I also understand the cost, weight and travel advantages of small domes. However, the weight difference is not relevant in the water, and the cost/travel advantages are "relatively" small compared to the overall costs of equipment and travel.  This is, of course, subjective!

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42 minutes ago, adamhanlon said:

 

I also understand the cost, weight and travel advantages of small domes. However, the weight distance is not relevant in the water, and the cost/travel advantages are "relatively" small compared to the overall costs of equipment and travel.  This is, of course, subjective!

Hi Adam

I agree, the travel advantages are "relatively" small. But the problem is, with the amount of gear that many of us travel with, every ounce and inch counts. Travelling with a 100mm dome will fit in my Pelican roller case - or in my pocket if necessary. An 8" dome - or, God forbid a 9" dome just won't. And is the advantage that having the bigger dome worth the extra travel hassle? I really wonder. 

Lucky me now based in St Martin, I may well use a larger dome as travel is not an issue. But as you point out, and something I'd forgotten on my list, the smaller dome is much better for strobe placement. So it's going to get  plenty of use.

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I use the 4" Zen mini dome with my EM-1 mkII plus Panasonic 8mm fisheye combo.  It's quite sharp except for the very extreme corners. 

Searching around on the net it's actually quite hard to find comparison shots between the same lens in a 100mm vs a 230mm dome, the closest I found was this page, which is only on a APS-C: 

https://reefphoto.com/blogs/photography/canon-8-15-4l-fisheye-and-thoughts-on-domes-1

Fisheyes are not as sensitive to dome size of course, but I've never really seen anything published on exactly what is happening with the optics with a fisheye specifically behind a dome.  A rectilinear lens has a depth of field issue as the corner of the curved  virtual image is physically closer, but this is not what's happening with a fisheye which is designed to take in a semi circular image and render it to a flat sensor.   Taking in a 180° view of a straight line parallel to the image plane is not really possible geometrically. 

I suspect the issue is corner aberrations in the lens itself interacting with the extreme light rays coming in through the dome, it responds to stopping down but I don't think it's depth of field improving - more that those aberrations are suppressed by stopping the lens down

Image below is from a reef in Halmahera.   Looks pretty good until you get right into the corners.  below that is a 100% 1000 px crop the centre and then the lower RH corner for comparison.  It's a direct straight onto the reef view from about 1m back rather CFWA.  Taken with the 8mm f3.5 fisheye, so for m43 at least the little dome does a pretty decent job.

Advantage of small dome?  - I have it and it works well enough for me + all the previously discussed advantages for travel and getting in close, lighting etc.  And I can carry it, housing macro port and also the 170mm dome for the 12-40 and strobes plus all those lenses in a carry on size backpack.  I wouldn't want to take more bags along on a trip like the one I did to Halmahera.

Plus of course I don't own a larger dome that I can use with the FE - it only gets pulled out on tropical trips and the occasional outing around Sydney.  The Zen DP-170 type II I have can't be used with the FE so the DP-100 is my only option.

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Adam, possibly yes, but likely not. The potato cod above would be difficult to light with a larger dome at that proximity, which I reckon was just a couple of centimetres from the dome. Plus with a small dome you can manoeuvre your rig into a smaller space, nearer the subject, at angles otherwise unavailable to a large dome... :pardon:

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Q for Alex: How much better for CFWA is the Nikonos 13mm over the 8-15mm in a mini dome?

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59 minutes ago, Matt Sea said:

 Plus with a small dome you can manoeuvre your rig into a smaller space, nearer the subject, at angles otherwise unavailable to a large dome... :pardon:

Totally agree :good:

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I have 4", 6" and 9" domes to choose from, but I almost always go with the 4" (unless I'm shooting splits). A significant percentage of my wide angle shots would not be possible with a large dome. I'm often shooting subjects that are nearly touching the 4" dome or maneuvering the camera into tight spaces/low angles, things that wouldn't be possible with a large dome.

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So, There is no issue with shooting subjects on the dome with an 9" dome!

AH_UPY_21-1.jpg

While I understand that small domes can fit into smaller spaces, you still need to get the lighting in too!

150105_ahanlon_6864.jpg

Intended as somewhat of a joke, but it was also shot with a 9"dome...

Mini domes offer more magnification so can make smaller subjects seem larger in the frame, which can of course be a creative advantage. However, unless all you are shooting is this type of image, I am unconvinced that the optical disadvantages outweigh the creative advantages!



 

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5 minutes ago, adamhanlon said:

150105_ahanlon_6864.jpg

A great "in your face" shot!

Wouldn't a large dome get a higher chance of scratch vs a smaller dome in this type of situation?

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I'm not sure, but it is nice to have a big dome to hide behind!

It is a glass dome and did not scratch. More pertinently, the tiger was not biting the dome (look at the position of its teeth), but just mouthing it to try and figure out what it is...

It was a challenging shot to light as you can see

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58 minutes ago, adamhanlon said:

So, There is no issue with shooting subjects on the dome with an 9" dome!

AH_UPY_21-1.jpg

While I understand that small domes can fit into smaller spaces, you still need to get the lighting in too!

150105_ahanlon_6864.jpg

Intended as somewhat of a joke, but it was also shot with a 9"dome...

Mini domes offer more magnification so can make smaller subjects seem larger in the frame, which can of course be a creative advantage. However, unless all you are shooting is this type of image, I am unconvinced that the optical disadvantages outweigh the creative advantages!



 

Nice images, Adam. However, obviously it all depends upon one's situation and subject matter. Not everyone shoots large subjects in open water with artificial lighting. I'm normally shooting small subjects in shallow freshwater streams with natural lighting. And yes, many of my wide angle shots could not be gotten with a large dome. Here are a few examples with subjects less than an inch from a 4" dome (closer than a large dome could get) and/or with the housing pressed against the stream bottom (lower than a large dome could get):

Neosho%20Smallmouth%20Bass.jpg

Striped%20Shiners%202.jpg

American%20Toad%20Tadpoles.jpg

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3 hours ago, adamhanlon said:

So, There is no issue with shooting subjects on the dome with an 9" dome!

AH_UPY_21-1.jpg

While I understand that small domes can fit into smaller spaces, you still need to get the lighting in too!

150105_ahanlon_6864.jpg

Intended as somewhat of a joke, but it was also shot with a 9"dome...

Mini domes offer more magnification so can make smaller subjects seem larger in the frame, which can of course be a creative advantage. However, unless all you are shooting is this type of image, I am unconvinced that the optical disadvantages outweigh the creative advantages!



 

I heard Mimmo Roscigno using the same terminology mini dome offer more magnification. That does not sound correct. Assuming the minidome is actually a full semicircle and it is correctly positioned a mini dome only offers a shorter working distance things at infinity and field of view would be unchanged.

If you are on a cropped format this shorter distance may not be material example smaller dome 4.5 cm radius normal 5.5. cm 1 cm matters little

Full frame large dome 12.5 cm radius smaller dome 5 cm radius difference is significant and does give that 'magnification' effect

However other than a full frame crowd there are zoom fisheye lenses on relatively small domes so nobody really cares about those distinctions that are mostly for a full frame user having issues of bulk/space/proximity

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Posted (edited)

One of the main reasons for me to use small dome ports is because the water is too shallow to use a large one. I have used the Seacam fisheye macro port FMP and wide port WP for this with the Nikkor 10.5, 16, and 8-15mm and Canon 8-15mm fisheye lenses. The WP is not made for fisheyes but when the fisheye lens used with it is focused very close, it will not vignette. The WP is also the least expensive Seacam dome and given that the ports are often scratched by rocks being tossed at them by my photo subjects need to be considered expendable.

First attached shot shows a Sockeye Salmon pair preparing to spawn. The other pix show Sockeye Salmon gathered at the mouth of a creek located about 2 km away from where I am sitting. They are gathering here prior to final maturation to beach spawn in the lake around the mouth of the creek. I planned on staying here several hours to do the shoot..... The creek as you can see is very shallow - Pink Salmon spawn here. Even the FMP is too big to fully submerge at some some spawning locations in the creek. I have used this creek to do a number of tests over the years (because it is so close and fairly clear).

Another type of small dome port about the same diameter as the port mount so looks like cylinder with a dome on the end made by Seacam was simply called dome port DP. They came in various lengths for different lenses. Alex Mustard mentioned a similar Subal port here a number of years ago. I have used my DP with macro focusing wide angles (the now long-discontinued 20-28mm f/1.8 Sigmas and the more recent Tamron 28/1.8 lens) and the Nikkor 60mm macro lens. The 20 in Nikon mount was used quite a bit with the D2X (i.e. APS-C or DX). I also have this in Canon mount but have only used it with the superdome (and 1D series full frame cameras). There is a curved field so smaller apertures should be used. In my experience the 60 macro with a DP is much better than using a flat port other than for night photography. I shot quite a few pix with this dome and the 60 near Kauai in 2019.

example.jpg

eyak1.jpg

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Edited by Tom_Kline
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Responding to this thread, @Alex_Mustard and @adamhanlon chat through small dome ports' pros and cons. These offer some unique creative possibilities, reduced cost, and portability advantages, and have limitations that should also be considered.

 

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