Meikon Dome Port

[Hizkia Christie]

Hi guys, I've a meikon dome port with the original sony rx100 housing. is there anyone wearing it too? Since I use them, I've a problem with soft blur and less focus on all of my footage. Is it normal, or is it a fail of the product? Thx

 

[Barmaglot]

I have used it with my A6300/16-50mm until I moved to a new housing with interchangeable ports and dry domes, seemed to work fine.

 

[Chris Ross]

How big is the dome? Dome ports need your lens to focus on the virtual image which is 3 dome radii from the dome for a subject at infinity. In a small dome this is very close and your lens needs to be able to focus close enough to focus on that virtual image. It is even closer for nearby subjects.

It also needs to be positioned correctly with respect to the lens bit there is some tolerance in this measurement.

 

[Hizkia Christie]

How big is the dome? Dome ports need your lens to focus on the virtual image which is 3 dome radii from the dome for a subject at infinity. In a small dome this is very close and your lens needs to be able to focus close enough to focus on that virtual image. It is even closer for nearby subjects.

The size of the dome is like this. What do you think, is it too small? And what am I supposed to do, I've a plan to buy a flip adapter, which is will add more space between the lens and the dome port, is it will help or make it worse?

It also needs to be positioned correctly with respect to the lens bit there is some tolerance in this measurement.

 

[Hizkia Christie]

 

[Chris Ross]

It is hard to tell just looking at a picture - do a test, estimate the radius of the dome, multiply by 3 see if you camera will focus on something that close to the dome. If it does - there is a different problem. A quick google reveals the RX100 mk1 focuses to 5cm at its widest setting, but this rapidly becomes longer as you zoom in. Are you shooting wide angle or macro?

When you say the footage is soft - is it soft all over or in the corners? You need to stop down to get enough depth of field to focus on all of the virtual image. The virtual image is curved at 3 dome radii and the corners are physically closer to the camera than the centre. If you are stopped down to f5.6 or so it should be fine I would guess. Maybe post a sample of soft images.

I'm not sure what you mean when you talk about a flip adapter. Normally a flip adapter is used with a closeup lens on a flat port not a dome port and is used to allow you to switch between shooting wide and macro.

Also checking on the dome, if I'm not mistaken this is meant to be a wet lens put on underwater - Is it this one:
Wide Angle Wet Correctional Dome Port Lens Version II (67mm Round Adapter) with 67mm to 67mm Flip adapter & CamDive Red Diving Filter

Is the dome free of air bubbles when you put it on?

 

[stuartv]

Is the dome free of air bubbles when you put it on?

This is the most important question of the moment.

When you get in the water, do you remove the dome and let all the bubbles out from between the housing port and the dome, then put the dome back on before you start taking pictures?

I have shot a fair bit with the Meikon dome (using an Olympus OM-D E-M10 camera and the cheap, "kit" 14-42 lens). I upgraded last year to a Nauticam WWL-1 dome and the image quality is better, but the IQ with the Meikon was not bad. It just was not as good as with the WWL.

"soft blur" and "less focus" is hard to quantify, so without seeing what images you are getting, it's hard to say if your rig is performing as it should or not.

These are a couple of photos I took using the Meikon dome, to give you some idea of what the dome is capable of. Not great photos for composition or artistry. But, to give you an idea of the sharpness that is achievable.

 

[stuartv]

Also, I would not bother with the flip adapter. I have one that I tried for one dive. I found the whole thing to be too awkward and unwieldy. There is no catch to hold the lens in place, so it can "flip" any time you orient the rig the wrong way. And even when flipped, it's still kind of in the way.

I got a magnetic bayonet style mount that I used. That makes it a lot easier to pop the dome off to let the bubbles out. And it still keeps the dome at a usable distance from the camera lens (for my rig, anyway). If you also go with the magentic mount, just make sure you put a leash on the dome. Mine stays on pretty reliably, but one of my first dives with it, the dome still somehow came off as I was climbing back onto the boat. If the mate had not seen my dome floating in the water at the stern and grabbed it, I would have lost it.