Crop Factor and Subsee Magnifiers

[smoore]

I have a question about using the magnification calculator at the Reefnet.ca website. For example, if I wanted to determine the magnification factor for the Subsee +5 magnifier for the M. Zuiko 60 mm macro lens would I insert a focal length of 120 mm and a magnification of 1:1? I know I have read somewhere that when considering the magnification of a 2x cropped lens I should double the specified magnification for the lens so I wondered if I should use a magnification ratio of 2:1. However, doing that for this calculator feels like I am doubling things twice.

What I am really trying to figure out is what the difference in magnification would be using the Subsee +5 with my current 14-42 II lens (which I understand has a magnification of 0.19) and the new 60 mm macro lens.

Thanks

 

[bvanant]

The 60 mm is 1:1 on 4/3 sensor so you can shoot a 17 mm subject full frame. On the 42 mm lens with the +5 you will be able to shoot something about 35 mm and get it full frame. On the reefnet calculator you can double the focal length and leave the magnification alone or you can double the magnification and leave the focal length alone and you get about 1:2 for the magnification.

Bill

 

[smoore]

The 60 mm is 1:1 on 4/3 sensor so you can shoot a 17 mm subject full frame. On the 42 mm lens with the +5 you will be able to shoot something about 35 mm and get it full frame. On the reefnet calculator you can double the focal length and leave the magnification alone or you can double the magnification and leave the focal length alone and you get about 1:2 for the magnification.

Bill

Thanks for the information. Can you confirm that for the 14-42 II kit lens with the +5 I get a magnification factor of about 1:2 (which is what you indicated) and with the 60 mm I get 1:1 and with the Subsee +5 attached that increases to a magnification factor of about 1.7:1. Interestingly, if I use the calculator for the the Reefnet site for the 60 mm I get a magnification ratio of 1.7:1 if I double the focal length and leave the magnification ratio at 1:1 and 2.2:1 if I double the magnification ratio and leave the focal length at 60 mm.

This combined with everything I have read about the lens suggests it would be a great lens to add to my epl2 and Olympus housing particularly given that I won't need to buy another port.

 

[coralcruiser]

Why don't you just send Keri at reefnet an email. He can give you the best assistance as long as he's not out somewhere diving with no wi-fi access.

 

[smoore]

Good idea.