Beyond 5x

arun0116 · Post by **arun0116** » Wed Nov 20, 2013 2:01 pm

Hi. Is there any possibility of pushing the magnification beyong 5x on a canon mpe-65mm lens, I mean with with the help the help of any sort of adapters .

rjlittlefield · Post by **rjlittlefield** » Wed Nov 20, 2013 3:10 pm

Simplest and most effective is to stick a teleconverter behind it. A 1.4X TC changes the range of the MP-E 65 to be 1.4-7X; a 2X TC gives 2-10X.

You can also make modest changes by adding extension. When the MP-E 65 is cranked out to full length its effective focal length shortens to around 40 mm, so then every 40 mm added behind it adds another 1 to the magnification.

But keep in mind that pushing the MP-E above 5X will also take it farther into diffraction territory. Wide open at 5X, it's already running at effective f/16.8, which is diffraction limited on APS-C. Push it to 10X and it'll be beyond f/32 and obviously blurred when you look at pixels.

--Rik

arun0116 · Post by **arun0116** » Wed Nov 20, 2013 4:33 pm

Thanks Rik.

Yousef Alhabshi · Post by **Yousef Alhabshi** » Wed Nov 20, 2013 9:24 pm

I sometimes use the Raynox250 with the MP-E65. I think you'll reach up to 6.4X

rjlittlefield · Post by **rjlittlefield** » Wed Nov 20, 2013 10:39 pm

Good point. And in that case with the extra glass, the extra magnification comes without added diffraction.

--Rik

lauriek · Post by **lauriek** » Wed Nov 20, 2013 11:52 pm

rjlittlefield wrote:And in that case with the extra glass, the extra magnification comes without added diffraction.

I thought for a moment that was impossible, then I realised it could happen if the Raynox increases the aperture of the lens (decreases the F-stop), but then I thought how does it do that, when it's in behind the aperture from the sensor's point of view?

I can see how it can affect the focal length of the lens but the aperture? I'm confused!

rjlittlefield · Post by **rjlittlefield** » Thu Nov 21, 2013 12:11 am

I can suggest two ways to think about it.

1. The Raynox goes in front of the physical aperture and does not restrict the light path, so inserting it does not change the effective aperture on the camera side. Same effective aperture means same diffraction. I really like this argument -- dead simple, no calculations involved.

2. Adding the Raynox reduces the overall effective focal length, but it doesn't change the physical aperture size. So yes, adding the Raynox does decrease the F-stop.

--Rik

arun0116 · Post by **arun0116** » Thu Nov 21, 2013 4:09 am

Thanks guys. Your answers were very informative.

lauriek · Post by **lauriek** » Sat Nov 23, 2013 8:07 pm

Thanks for that Rik, that does make sense!