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confused about wet mount mcro lenses


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#1 troporobo

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Posted 19 June 2011 - 01:47 AM

I want to add a wet mount macro lens to my Olympus m4/3 setup. I am confused about the lens options though.

Some (like the Olympus and Inon lenses) specify their magnification as 2X. Others (like the SubSee and Fantasea) specify +5 or +10 diopter. Can anyone tell me the rough equivalency between these?

Then I also see differences in lens design, with varying elements and varying groups. Is there a simple way to understand the advantages of these variations?

Lastly, does anyone have experience to share with any of the wet mount lenses on a m4/3 system?

TIA!

#2 bvanant

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Posted 19 June 2011 - 04:42 PM

I want to add a wet mount macro lens to my Olympus m4/3 setup. I am confused about the lens options though.

Some (like the Olympus and Inon lenses) specify their magnification as 2X. Others (like the SubSee and Fantasea) specify +5 or +10 diopter. Can anyone tell me the rough equivalency between these?

Then I also see differences in lens design, with varying elements and varying groups. Is there a simple way to understand the advantages of these variations?

Lastly, does anyone have experience to share with any of the wet mount lenses on a m4/3 system?

TIA!

It is a little more complicated than simply saying 2x. Add on lenses are diopters that have specific strengths and the effect they have will significantly depend on the focal length of the lens you are adding them to. Go to reefnet.ca (the subSee guys) and look at their calculator for magnification. FWIW, I think the Inon lens is a +6 diopter, don't know about the Olympus.
Bill

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#3 troporobo

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Posted 21 June 2011 - 05:25 AM

One thing that confuses me about the SubSee calculator is that I am not sure if it applies the same way to a m4/3 lens as a full frame SLR. For example, the Olympus lens at 42mm is equivalent to a full-frame DSLR lens at 84mm due to the crop factor. The calculator results vary from 1.3x to 1.9x depending on which value is input. I am not sure which is the right one to input, the actual lens focal length or the equivalent focal length.

#4 bvanant

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Posted 21 June 2011 - 02:55 PM

One thing that confuses me about the SubSee calculator is that I am not sure if it applies the same way to a m4/3 lens as a full frame SLR. For example, the Olympus lens at 42mm is equivalent to a full-frame DSLR lens at 84mm due to the crop factor. The calculator results vary from 1.3x to 1.9x depending on which value is input. I am not sure which is the right one to input, the actual lens focal length or the equivalent focal length.

In this case the magnification will be closer to 1.9 x.
Bill

Bill
Canon 7d, Nauticam, Lots of glass, Olympus OMD-EM5, Nauticam, 60 macro, 45 macro, 8 mm fisheye, Inon, S&S, Athena Strobes plus lots of fiddly bits.
www.blueviews.net


#5 splashdoc

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Posted 26 June 2011 - 02:03 PM

Hi,

I've been using an Inon UCL 330 (+3.03 dioptre) in front of the 20mm prime lens on my GF1 in a 10 Bar housing with excellent results.
I must admit that I've now bought an 8mm macro but I haven't used it underwater yet so I can't offer a comparison.

David

#6 Undertow

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Posted 10 February 2012 - 03:02 PM

One thing that confuses me about the SubSee calculator is that I am not sure if it applies the same way to a m4/3 lens as a full frame SLR. For example, the Olympus lens at 42mm is equivalent to a full-frame DSLR lens at 84mm due to the crop factor. The calculator results vary from 1.3x to 1.9x depending on which value is input. I am not sure which is the right one to input, the actual lens focal length or the equivalent focal length.


You use the actual focal length. The calculator expresses the magnification relative to sensor size.

This is why 1:1 will be different depending on your sensor size. 1:1 on a m4/3 sensor will be a higher magnification than 1:1 on a DX which is more than 1:1 on a full frame sensor. Hence why crop sensor cameras have an advantage over full frame for macro.

This means if you cut out a piece of paper the exact size of your sensor, then took a picture of it at 1:1 (at closest focus point for most macro lenses), it would perfectly fill the frame. 2:1 means a subject half the size of your sensor will fill the frame. Its all relative to your sensor.
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#7 troporobo

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Posted 10 February 2012 - 11:54 PM

Thanks all, that is very helpful guidance!