Diopter with macro lens???

[Liang]

Hi Everyone,

I heard that the cheapest way to further extend the lens is to use a + diopter.

I am thinking of using a + diopter on iwth 105mm lens. What will be the effective magnification if I were to use a +3 or +4 diopter on the 105mm lens.

Will it fit on my Sea&Sea NX90 housing???

Is it worth trying?? Any comments?? I tried taking the pygmy seahorse using 105mm and it is not good enough. Most pygmy seahorses are about 5mm to 10mm, that is 1/7 to 1/5 of 35mm if taking 1:1 ratio.

Cheers
Liang

 

[Rooster]

Originally posted by Liang
Hi Everyone,

I heard that the cheapest way to further extend the lens is to use a + diopter.

I am thinking of using a + diopter on iwth 105mm lens. What will be the effective magnification if I were to use a +3 or +4 diopter on the 105mm lens.

Will it fit on my Sea&Sea NX90 housing???

Is it worth trying?? Any comments?? I tried taking the pygmy seahorse using 105mm and it is not good enough. Most pygmy seahorses are about 5mm to 10mm, that is 1/7 to 1/5 of 35mm if taking 1:1 ratio.

Cheers
Liang

Though I have used Diopters, I have had much better luck using teleconverters. A diopter is basically a magnifying lens that allows you to focus closer, thus increasing the magnification ratio of the lens. A teleconverter increases the focal length of the lens without increasing the minimum focus distance. So with a 2x teleconverter a 105 mm macro lens now becomes a 210mm lens, and still focuses at the minimum focus distance of 12?. This gives a ratio of 2:1 instead of the original 1:1. Another thing about diopters is you lose focus at infinity; you don?t lose that with a teleconverter. If you must use diopters, I recommend to more expensive multi element ones, they produce less softening of the edges. I use Kenko Pro 2X and the new 3X teleconverters. You could use one of Woody?s Diopters. It is an external lens that fits on the end of your port and can be installed and removed UW. I have not used these, but I think he has one to fit your set up. Check out http://www.nexusamerica.com/ for info on the Woody's diopter. Hope this helps.

 

[Liang]

Thanks rooster, greatly appreciated

 

[vicky]

Using a teleconverter has some cons to consider:
Less light (2 stop reduction) comes into the AF sensor, which may cause focusing problems with some AF cameras.
Depth of field is also reduced by a 1/2 factor, causing focusing problems with slight camera / subject movements.
Reduction of light also means you may need a stronger ($$$) strobe. Supose your lens bigest aperture was f/4.5 with the tele it becomes an f/9 so you can figure out what strobe GN you need.