Seacam Nikonos RS 13mm on Sony A1 with Monster Adaptor LA-FE2 issues

[Gerald Rambert]

Hi Everyone, 

 

I can see that there are a few posts on the RS 13 mm lens on the forum and I thought I might share my recent experience with it and the issue I encountered. Maybe some of you can also help me find a solution to my problems.

 

So, I recently purchased a Nikonos Rs 13 mm and had Seacam convert it for me. The conversion was super well done and the finish of the product is stunning. 

 

I have adapted the lens on my Sony A1 using a Monster Adaptor LA-FE2 and used it for about 3 weeks on multiple dives. 

 

First, I noticed that the lens was underexposing. When I would normally shoot at an aperture of F4 with a speed of 1/125, with the RS, I would have to bring down my speed to 1/30, 1/50 to have the same exposure compared to a normal Sony lens or Canon 5-15 mm. 

 

2 of my dive buddies also bought the lens and on the last dive, comparing our shots underwater I realized that they were shooting at a much higher speed than me. So we took a side-by-side comparison underwater.. with the same settings... my lens was underexposing about 4 stops. 

 

Once on land, we exchanged lenses and tried all the different monster adaptors and my lens was again underexposing on different cameras. 

 

How could the same product give different results in regards to exposition? is the real Aperture different? when the camera reads 2.8 is it actually 4.5?  Any idea why this could happen? 

 

In regards to the Autofocus, forget AF-C... it is useless and jams the camera. As for AF-S, the camera will freeze at least once per dive. You will need to turn it off, wait a few seconds, and let your flash fire... then you can turn it on again and carry on with your dive. I think the monster adaptor is the issue there...  

 

 

[Chris Ross]

Welcome on board Gerald, hope you find the forums useful.

 

On your question about the Nikonos lens perhaps you could ask the question in this post where it might get more visiblity?

 

 

[Gerald Rambert]

Hi Chris, 

 

Thanks a lot for the welcome and the reply,

 

Ok i will try to put my post on this existing one, 

 

thanks a lot