Kenko m4/3 extension tubes

[snaarman]

[Ross the fiddler]

Re: Kenko m4/3 extension tubes

Thanks Pete. The extension tubes are designed to allow closer focussing & with some lenses it becomes impractical to use, such as the EX25 with the ZD14-54 for the 4/3's cameras. With the EX25 on the DSLR's there is a compatibilty chart (from Olympus) but to use these Kenko tubes on micro 4/3's bodies & lenses, then it is going to be a 'suck & see' with each lens, unless someone can make up a complete compatibilty chart. So thanks for starting it.

[timg]

Re: Kenko m4/3 extension tubes

Certainly be interested to hear your findings Pete, I bought the EX25 on a bit of a whim (mainly used with the 40-150) but I'd certainly miss it if it were gone...

[Guest]

Re: Kenko m4/3 extension tubes

One can make a rough prediction of what an extension tube will do to a lens by comparing focal length to extension length. The general rule of thumb is that an extension of half the focal length will give a field of view about double the sensor size. With a four thirds sensor this means a field of view about 26mm x 34mm, aka .50x, or 1:2. Using the kit 4/3rds 40-150 as an example, a 25mm extension has a big effect in the 50 to 70 range, and much less effect at 150mm.
This "rule" is a rough one, but applies equally (more or less) to all cameras, lenses and sensors. Variations to the rule come from a lens' focusing ranges, or built in close focusing (which is usually a built-in extension on its own).
Olympus' EX-25 table shows the effect of a 25mm extension across various focal lengths. Olympus also likes to add in parentheses the corresponding effect for 24x36mm sensors, but I find it best to ignore that data. It points out the advantages of smaller sensors (i.e., 1:2 with 4/3rds gives an FOV 34mm across, 1:2 with a 24x36mm sensor is merely 72mm across). Olympus' data should be at the bottom of this page:

http://www.olympus.co.jp/en/support/imsg/digicamera/compati/di004042e.cfm#chk2

Sorry for the clunky syntax here, was written on my phone and my finger is about to fall off.

[snaarman]

Re: Kenko m4/3 extension tubes

OK, here are some tests with the 45mm f1.8 portrait lens, made macro by these extension tubes:

10mm tube and f1.8 Hmmm.



10mm tube and f5.6 Phew, that's better



16mm tube and f1.8



16mm tube and f5.6 I start to see a pattern. This isn't designed as a macro lens, but it will do if stopped down enough.



26mm tube and f1.8



26mm tube and f5.6




In each case the working distance was between 100 and 50 mm..

But here's a surprise:
The 40-150mm 4/3 kit lens at 150mm and wide open f5.6 on 26mm of tube. The working distance was about 250mm.





First, the colour cast: These were taken under a blue sky, so don't worry about that..

The tubes themselves are quite well made.





Sometimes the EVF went black with a -- where there should be aperture after I had done some lens or tube swapping, but pressing the camera lens release button woke it all up again.
The EXIF reports what it should. In general I think they work correctly.

Conclusion? Well the 45 isn't terribly happy as a macro, but if I stop it down enough the 16mm tube will do fine for scanning my remaining slides.
The AF is still nice and fast (if the target is within its restricted focus range).

The old 40-150 turns out to make quite a good tele macro really.

I tried the Panasonic 14-45 but it wasn't at all happy. At the wide end the focus point is inside the lens. At the long end (f5.6) it's less sharp than the 45mm Oly at 5.6, so I won't be using that with tubes...

Pete

[Guest]

Re: Kenko m4/3 extension tubes

That's a good test, Pete, and a good lens, looks plenty sharp stopped down a bit. I guess it would be unusual to be sharp wide open, without costing a king's ransom. I like those close up numbers, too, very good magnification with all extension lengths. The Kenko tubes look like a good product.
Just now with my 40-150 and the EX-25 (on the 620) I got about a 42mm horizontal FOV, a close up ratio of 1:2.5, or .40x, which matches what you've found and what Olympus lists in their table. The 40-150 is versatile in so many ways.

[snaarman]

Re: Kenko m4/3 extension tubes

Just now with my 40-150 and the EX-25 (on the 620) I got about a 42mm horizontal FOV, a close up ratio of 1:2.5, or .40x, which matches what you've found and what Olympus lists in their table. The 40-150 is versatile in so many ways.

[Ross the fiddler]

Re: Kenko m4/3 extension tubes

BTW, for a laugh, I parked my Vivitar 200mm on these tubes. So that is E-M5, 10mm tube, 16mm tube, MMF-1 adapter, 4/3 to M42 adapter and finally, lens... Amazingly, it makes a pretty good long distance "macro" arrangement and is quite sharp. Almost impossible to hold though.

Pete

I'd like to see a photo of that. (& with it)

[Guest]

Re: Kenko m4/3 extension tubes

Yes, a photo would be nice, and maybe Pete could find an EX-25 to stick in there as well!

[snaarman]

Re: Kenko m4/3 extension tubes

Here you go: This is the pile of optics



And here are two I took with the above 200mm macro. The working distance was about 1.5m, and the field of view about 50mm.
The Vivitar was stopped down to f8 to avoid longitudinal CA.






(Hand held of course!)

Finally, here's an old slide I "scanned" with the 45mm and the 16mm tube.
This combination is ideal for imaging a 24x36mm target and has a working distance of about 75mm.



Pete

[Guest]

Re: Kenko m4/3 extension tubes

Very nice! 50mm and 1.5m puts it in the company of the 70-300. Why is piling up a lot of precision-made tubes and glass so much fun? Manfrotto makes a nice long lens support, the 293, that might mate to the Vivitar stack quite well, if one were so inclined.

[timg]

Re: Kenko m4/3 extension tubes

Digging up an old thread...

Pete, I just wondered if you'd ever tried the extension tubes along with the 12-50mm in macro mode? (assuming you have that lens!)

[snaarman]

Re: Kenko m4/3 extension tubes

Digging up an old thread...

Pete, I just wondered if you'd ever tried the extension tubes along with the 12-50mm in macro mode? (assuming you have that lens!)

No, sorry I don't have that lens (but if someone was to post me one I would gladly test it )

Generally zoom lenses don't mix well with extension tubes, however the 12-50 does have a macro mode so maybe it will be OK.

I tried them on the 14-54 and the 14-45 but the results were not great. Quite often the focus distance is actually inside the lens... they are OK on the 45mm if you stop it down enough, surprisingly good on the 40-150 tele zoom and they're also fine on a purpose designed macro lenses like the Tamron SP90mm.

They get my thumbs up provided you use them with the right lens.

Pete

[Zuiko]

Re: Kenko m4/3 extension tubes

Wonder what they would be like with the 70-300mm?

Zooms normally work better with a supplimentary close-up lens.

[Ross the fiddler]

Re: Kenko m4/3 extension tubes

Wonder what they would be like with the 70-300mm?

Zooms normally work better with a supplimentary close-up lens.

The EX25 works well with it, so the Kenko set should work even better (with more extension) & the M75-300 might be good too.