OH NO, EQUIVILENCY TALK?!?! I fear it has begun...

Seriously though, a tc would be great, and would make the 75 a much more practical, versatile lens.

I would very much like this.

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Olympus E-PL5
M. Zuiko 17mm ƒ1.8 | M. Zuiko 17mm ƒ2.8 | M. Zuiko 14-42 II | M. Zuiko 14-150 ED | M. Zuiko 45mm ƒ1.8 ED | M. Zuiko 75mm ƒ1.8 ED | M. Zuiko 75-300 ED II | Leica DG Summilux 25mm ƒ1.4 ASPH | Lumix G Vario 45-200 |

If Panasonic comes out with a 2x TC, I will buy one and a 35-100/2.8 to replace my 45-200. Otherwise, the loss of long end is just too much.

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Comments and criticism welcome! It's how we get better!

White G3:P20/1.7:P45-200:PL45/2.8:P8FE:P12-35/2.8

Pictures here: http://troyandmollyalloverthemap.shutterfly.com/

http://500px.com/TroyGorrell

I imagine with the advent of Pany's 150/2.8, there will be increased demand for just such a device.

A 1.4 with the 75 sounds interesting as well.

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OM-D | E-PM1 | P14 | O15 | PL25 | O75

I don't need teleconverter ;) for amateur purposes I am satisfied with adapted old manual telephoto lens. In other words my Sonnar 135/3.5 is giving me impressive 270mm. I know f/7.0 after conversion is not very good, but sharpness remains unchanged, and it is producing pleasant pictures on good light conditions

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G3, GF2, Samy7.5/3.5, P14/2.5, PL25/1.4, PL45/2.8, mZD60/2.8, P14-45/3.5-5.6, PZ45-175/4.0-5.6, adapted: Helios 44M 58/2, Sonnar MC 135/3.5
FL-36R with DIY diffuser, Tripods Velbon REXi L + 494RC2, Monopod Manfrotto 294A4 and UltraPod II

Your Sonnar is still an f/3.5 in terms of exposure. Only in DOF is it equivalent to a 270mm f/7 (or a 135 f/3.5).

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I'm not lazy. I'm energy efficient.

I too have been wanting a tc for m4/3 and the new 75mm would be a perfect match for it. The 150mm when it comes would be even better. The sad thing is both the 75 and the 150 are(will be) pricey.

If you used a 1.4tc on the 100-300mm f4-5.6 it would become a 140-420mm f5.6-8. This would be very usable for bright sunny conditions. It would be the equvilant of a 280-840mm in FF!

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Olympus E-PL1, E-PL2
VF2 two of them!
Oly 14-42mm, Oly 40-150mm, Oly 14-150mm, Pan 14mm, Pan 20mm, Oly 45mm, Sigma 30mm - more coming soon!
Many legacy lenses, mostly Nikkor.

I'd be more worries about sharpness in that case. A middling lens with a teleconverter often looks worse than simply cropping and upsampling an image taken using the lens without the teleconverter.

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E-M5 | E-PM2 | mZD 12-50 | ZD 12-60 | P 14-42 X | mZD 40-150 R | PL 25 | mZD 45

Any increase in the focal length of a lens will cause a reduction in DOF. This includes TC's.

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"There is hardly anything in this world that someone cannot make a little worse and sell a little cheaper, and people who consider price alone are that person's lawful prey." Eile mit Weile

I had a word with a lens design expert at the optical company I used to work for and teleconverters for micro 4/3 are very difficult to design, due to the short back element distances to the sensor, and the need for particular diameters of the elements, which would get in the path of the electrical contacts.

The constraint is the electrical connections required for the native lens, they impinge on the diameter of the glass elements in a converter.

It can be got around, with the connectors feeding a wiring harness to get by the glass and connect to the lens, but this would be expensive to do and might push the converter from general use cost to a specialist price level item.

I think it more likely a maker like Panasonic or Olympus would offer a matching teleconverter for a particular lens, than for general purpose ones to appear.

Converters can be used with legacy lens of course, as there is no other connection than the mount to worry about, no bank of electrical connections to make.

Converters do reduce definition by the extension factor, but may still leave the apparent DOF seemingly untouched, most better lens can have the definition reduced without the shot looking at all bad.

Stephen.