G9, Ike Housing, W-20 WA lense and Vignetting

[paradicio]

Hey all,

So…I’m very excited! I just got the flat port for my G9 in the mail which means I’ll be able to use my Ikelite W-20 wide angle lens on my next dive trip (hopefully this weekend).

Looking at the owner’s pamphlet I noticed a little section on possible vignetting when using the W-20 and the flat port. They recommend zooming a bit to correct it.

My question is… Has anyone here had much experience using the G9 with the Ike housing, flat port, and W-20 wide angle lens? If so, have you seen the vignetting? Do you have to zoom out very far to fix it?

 

[Chris Walrod]

I just got back from my first dive trip with this very setup. Yes, some vignetting occurs at full wide lens position. Just by tapping the zoom (actually turning a knob on the housing) a few clicks removes it from the exposure.

One thing I am trying to figure out is that even zoomed in a little, I get an out of focus ring around the exposure from the WA lens. Anyone care to share why this is?

Here is an example:

 

[paradicio]

Hi Chris, thanks for the answer.

I noticed the out of focus ring today when I tried the lens on the surface. Just curious, did you put your lens on at the surface or did you put it on underwater? I'm wondering if that may be the issue?

 

[NTSilver]

paradico
I have also recently taken this setup into the water for the first time. I learned that there is a fine line between zooming too far and not far enough. Several times I zoomed too far and got the "lens error" and had to restart the camera. I too got the focus ring but on other shots did not. (examples in my gallery - mantas no ring, eel and cortez chub have a ring) I chalked it up to luck that I had somehow zoomed the exact length.

I always put my lens on above water. We did no air in BC roll off the skiff entries. On a few occasions I had to remove and totally unscrew the lens UW to remove a few air bubbles but that was two times out of thirty dives.

The other issue I had was how to restart the camera once it had gone to sleep. On my old A80 I used to be able to hit the shutter button and it would wake the camera up and then I could take a picture. On the G9 when I hit the shutter button to wake the camera up it would always take a picture. No big deal as I could delete it, but I am guessing there is a way to wake up the camera without taking a picture and I just haven't figured it out yet.

 

[Nemrod]

I studied photography long ago, the mechanical aspects of lenses. The out of focus ring IMO with nothing more to go on is that your focused very close in the moray shot. I bet the lens is open wide and in conjunction with the close focus the depth of field is very small and that the wet lens/G9 combination does not have a optimal "flat" focus plane resulting form a minor problem with optical compatibility between the lenses. My bet is that if you use the wide angle lens to photograph objects that will allow the camera to focus at a further distance and or smaller lens opening the out of focus ring may go away. I probably have not explained this phenomena well but I tried.

N

 

[paradicio]

That actually makes a lot of sense Nemrod, thanks for the reply!

The only reason I mentioned putting the lens on underwater is because the owners pamphlet states that there will be focus issues if you put the lens on at the surface.

 

[stu_in_fl]

"The only reason I mentioned putting the lens on underwater is because the owners pamphlet states that there will be focus issues if you put the lens on at the surface."
- usually that just means there is an air bubble trapped between the port and the wet lens if you attach it at the surface - so you need to get rid of it when you get u/w.

actually the moray shot looks quite good with the in focus eel with out of focus background...but could be a little problematic if the subjuect isn't in the in focus area !

 

[Nemrod]

"The only reason I mentioned putting the lens on underwater is because the owners pamphlet states that there will be focus issues if you put the lens on at the surface."
- usually that just means there is an air bubble trapped between the port and the wet lens if you attach it at the surface - so you need to get rid of it when you get u/w.

actually the moray shot looks quite good with the in focus eel with out of focus background...but could be a little problematic if the subjuect isn't in the in focus area !

The Inon lens I have specifically states that it will operate correctly only underwater because the water between the lenses acts as something like another lens element so you could be right, perhaps the lens/camera connection needs to be "burped" but at least mine seems to fill with water on it's on but perhaps this one is different.

Does the G9 have a manual focus overide? You might toy with that.

N

 

[Chris Walrod]

I studied photography long ago, the mechanical aspects of lenses. The out of focus ring IMO with nothing more to go on is that your focused very close in the moray shot. I bet the lens is open wide and in conjunction with the close focus the depth of field is very small and that the wet lens/G9 combination does not have a optimal "flat" focus plane resulting form a minor problem with optical compatibility between the lenses. My bet is that if you use the wide angle lens to photograph objects that will allow the camera to focus at a further distance and or smaller lens opening the out of focus ring may go away. I probably have not explained this phenomena well but I tried.

N

Thanks for the help! This may be what I was experiencing.

I understand the Ikelite WA lens to be a 'wet' lens where it requires it to be removed once underwater to rid itself of any bubbles trapped between the port and the lens. After dropping down each dive, I removed the lens and 'waved' away the trapped bubbles. There were indeed bubbles each time.

The only trouble was [due to its fine threads] getting the lens started onto the housing without cross-threading it. Also, the time we dropped down at Baracuda Reef in Cozumel, I was fumbling with screwing the lens back on when a large sized spotted eagle ray cruised on by. Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh! Missed it!!!