Dome: plexi or glass?

Hi everybody,

Any comments on the choice between plexi or glass front ports and domes? I am currently using a Subal housing with glass front ports and domes, considering to go digital with Hugyphot but they use plexi. Is there a noticable difference in image quality?

Best regards,

--Rob

There have been a couple of threads on this topic. I suggest you do a quick search for them.

Here's one:

http://wetpixel.com/forums/index.php?showtopic=10260&hl=

I currently have acrylic dome ports by Aquatica, Nexus and Sea & Sea. I have a glass dome port by Subal.

It is my experience (and the particular position of the camera in the housing relative to the port might have some bearing) that the acrylic Sea & Sea port gives the best corner to corner sharpness. I cannot tell you about the Sea & Sea glass dome yet because I simply have not used it enough.

So? Get the housing you want and buy the dome port that the manufacturer supplies!

You don't have to buy the acrylic Hugyfot domeports since they provide adapters that enable you to attach subal ports to a Hugy housing.

The main advantages of acrylic ports is that you can remove scratches and they're a lot cheaper. On the other hand acrylic ports are also more sensitive to scratches than glass ports

cheers, udo

You don't have to buy the acrylic Hugyfot domeports since they provide adapters that enable you to attach subal ports to a Hugy housing.

The main advantages of acrylic ports is that you can remove scratches and they're a lot cheaper. On the other hand acrylic ports are also more sensitive to scratches than glass ports

 

cheers, udo

I heard (don't remember who) that acrylic should give sharper images? I have never seen that though. Udo is right of course, acrylic is more sensitive to scratches.

I have used acrylic from Sea & Sea and glass domes from Subal and Seacam. For me the main disadvantage of acrylic is that these ports attract more dust in the inside (static energy).

I agree with the dust issue. I have a terrible time keeping my Aquatica port clean. I have been wondering if it would be possible to apply some sort of static dissiapitive coating to it without screwing it up. I have been afraid to try, but if possible, it would be a great improvement.

I know you can get flat sheets of static treated polycarbonate, which is commonly used in cleanrooms, but I don't know of a spray that could be aplied. For example check out

http://www.esdproducts.biz/CleanroomProduc...ycarbonate.html

http://www.boedeker.com/pc-300_p.htm

Someone tells me that because acylic has the same refractive index as water, it optically disappears (leaving only the dust on the inside behind by the sound of it). I guess that if the point of focus of the virtual image and the depth-of-field is such that you can get both that and the dust in focus, you have a problem. I have not experienced that but then I have given inside of my Subal glass port a good rinse with seawater a couple of times, followed by some clean resh water as soon as possible afterwards! I have always used a backcap when any port (glass or acrylic)is off the housing. I found I always needed to make a pinbhole or it gets locked on during trips in low pressure aircraft holds.

Index matching is why scratches on the outside aren't too noticable. One of the problems with dome ports is that since you focus on the virtual image you are actually focusing close to the surface, and hence the dust. The polycarbonate attracts dust because it gets static charged easily, hence the idea of the static dissiapitive coating.

Another advantage of glass is its weight, it is heavier than acrylic and the housing remains more stable underwater. I had a big problem with my Sea&Sea when I used the acrylic dome on it, the light dome would constantly pull the front of the housing upwards and I had to hold it strongly to aim it forward. My wrists would get very tired after long dives, and that doesn't happen with the Subal glass port.

I agree with the dust issue. I have a terrible time keeping my Aquatica port clean. I have been wondering if it would be possible to apply some sort of static dissiapitive coating to it without screwing it up. I have been afraid to try, but if possible, it would be a great improvement.

 

I know you can get flat sheets of static treated polycarbonate, which is commonly used in cleanrooms, but I don't know of a spray that could be aplied. For example check out

 

http://www.esdproducts.biz/CleanroomProduc...ycarbonate.html

http://www.boedeker.com/pc-300_p.htm

I used distilled water to clean the inside of the port. I blew it dry with air (dive tank).

But I have never done that with my Seacam class dome ports. I don't want to mess the optical coating of the super dome.

Another advantage of glass is its weight, it is heavier than acrylic and the housing remains more stable underwater. I had a big problem with my Sea&Sea when I used the acrylic dome on it, the light dome would constantly pull the front of the housing upwards and I had to hold it strongly to aim it forward. My wrists would get very tired after long dives, and that doesn't happen with the Subal glass port.

Wow. I have the opposite problem. My Aquatica, with its "light" acrylic dome, is very topheavy. My wrists get tired holding it up. I am going to make some floats to attach to my strobe arms to help improve the system's trim.

Steve, that's probably because the aquatica dome has that heavy dome shade, right? The Sea&Sea doesn't have a heavy dome shade...

I do have the dome shade. I didn't think it was that heavy, but I guess it does have a pretty big moment arm. The system is also top heavy with the macro port, but less so. It may also be my choice of Inon strobes. They pack a lot of punch in a small package, but they are pretty negative.