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In article < >, nikki
<> writes
>
> F/16 is the smallest aperture available, partially because
>(probably) you'd encounter image-degrading diffraction at smaller
>apertures, and also because of the light losses you get at higher
>magnifications. These light losses are laws of optics, and not a
>problem with the way Canon designed this lens. At the full 5x
>magnification, you've lost about 5 stops of light, so f/16 is
>equivalent to approximately f/90 in terms of light transmission to the
>film.
>
It is also f/90 when looking at degradation due to diffraction - a point
often overlooked.
--
David Littlewood

In article < >, nikki
<> writes
>
>David Littlewood wrote:
>>The kind of magnifications you are looking for are extremely
>challenging
>>for use in the field. The very tiniest breath of wind will ruin
>>pictures, and lighting will be a real challenge. If you can, you
>would
>>be much better off taking the subjects indoors and using a bellows
>macro
>>set-up. There are numerous good books on this subject, ask again if
>you
>>are interested - tell us what camera body you plan to use.
>
>I am primarily interested in imaging snow and ice crystals(that is why
>I want 10X), mostly natural formations, so exclusive studio work is
>not an option. I like the idea of a very compact and tough lens, like
>the MP-E65mm.
>I use a Canon DSLR with multiple flash (550's) off camera.
>I will probably just buy the extender and try it anyway(good excuse to
>buy one for my other lenses). They are not expensive, as compared to
>the lens. I don't think there are any physical restrictions to using
>the extender, other than the camera vibrations as noted. Still, no
>one seems to know.
>nikki

Do be careful also of the possibility of physical interference between
macro lens and extender.
--
David Littlewood

Here's another anecdote:

http://www.vividlight.com/articles/2914.htm

In article < >,
says...
> Has anyone had any good experiences with the MP-E65mm f/2.8 1-5x
> Macro.
> The Canon Tech department doesn't seem to know much about it. It looks
> very convenient for field use.
> I would also like to know if there is a way to increase the
> magnification to 10-15X. The Canon Techs could not say if the
> extenders(1.4x and 2x) would be compatible with this lens.
> Nikki
>
I have this lens but use it sparingly. It works just fine with my Canon
1.4X TC with moderate magnifications and should work OK with the 2X
Canon TC. However, with the 2X converter and lens set to 5X
magnification @ f8 (the equivalent of f12, I suspect would be VERY
hard to see the image well enough to focus unless you have the ring
light or dual macro light's modeling lights on, even then it would still
a very dim viewfinder. The factory specs state that to use this lens
with TTL ambient light metering you need to have an EOS 3, 1n or 1v. In
any case, the TTL meter works fine on my 10D both for ambient light and
flash. You can read my comments on this lens at

http://www.sphoto.com/techinfo/phototech.html#65mm

Cheers, Steve

--
Steve Hoffmann
http://www.sphoto.com
Photo Gallery & Digital Imaging Information
Remove NO if replying via email

[defalkner]

Originally Posted by Brian C. Baird

In article <>,
says...
> With a digital and 1.5 magnification factor, X5 becomes X7.5.
> You will then be cms away from the object.

Not quite correct. Magnification stays the same, but the field of view
changes. It's a 1.6 crop factor, not magnification.

Well your not correct either...

You have a crop factor which wide angle 'EF' lenses on a Canon APS-C type body (non full frame like 20D, 30D, 40D, XT, XTi, XSi), will cause vignetting. But there is ALSO a magnification factor. Don't believe me? Read about it here - it's very simple to understand.

http://www.lonestardigital.com/multipler.htm

You have a crop and a multiplier factor. Which a magnifier would be the same thing. A 300mm EF telephoto lens will act as a 480mm on an APS-C based camera. That's a fact. Period. The lens sits further away and the increased distance causes increased telephoto end on a camera. This is NOT true for EF-S lenses!!! EF-S lenses are specifically made to correct this issue and work in their true "mm" range.

Now this works against you if you are using EF lenses lower than 55mm. You will experience vignetting around the frame, the wider you shoot (eg 18mm).

So hopefully this answers that. I work with Canon directly and am also a photographer.

Just remember all EF lenses on Prosumer cameras (APS-C type sensor) that I listed above all have a 1.6x crop and magnification factor.