Tale of two 300mm f/4 lenses.


Mu-43 All-Pro
Jan 14, 2018
I dug out my old Nikon D800E and attached the Nikon 300mm f/4 PF lens to it to shoot the hummingbrids. Just as a comparison to the E-M1X and the Olympus 300mm f/4 Pro lens.

Surprised to find out the two setups were so different in weight. The E-M1X weighed in at 2,953 grams, and the Nikon was at 2,089 grams. Big difference! Not only that, but the two side-by-side showed the E-M1X to be much larger too. I'm guessing with the new Nikon Z7 it may be less, but maybe not since I'd need their FTZ adapter added.

Both had the RRS L-plates, and the Godox XT1 flash triggers mounted since I generally use flash. The RRS L-plate for the E-M1X is a lot beefier than the Nikon one too. The Olympus lens had the tripod collar too which the Nikon 300mm does not have, maybe it being plastic and the Olympus being metal.

The Nikon may be less sharp than the Olympus lens too. Still fighting with that one and the bird's feather detail. I did find with the Reikan FoCal focus tuning software the AF fine-tuning differs from a +4 at 21 feet, and goes to a -2 at 7 feet where I had to move in to the hummers, and was about the equivalency field of view at around the 14 feet I normally shoot them with the E-M1X and Olympus 300mm combo. Sort of odd, but I know with the Sigma 35mm ART for the Nikon that it can be user tuned with the docking station over maybe 5-6 distance settings where the Nikon is factory set.


Mu-43 Hall of Famer
Aug 13, 2014
Honolulu, HI
Real Name
Surely a more relevant comparison should be between an Olympus 300mm f4.0 PRO and a 600mm Nikon lens ?
I don’t see the point in comparing the weight of two lenses with 100% difference in FOV
Am I missing something ?
You're right. Equivalent Field of View. The eFOV of a Nikon 300 FF lens is the same as a 150 mm MFT lens.

These combos would have the eFOV of 600 mm on a 35 mm frame camera and the equivalent light gathering aperture.

Nikon 800E w/600 f4 and EM1.3 w/300 f4 Pro. I chose the 1.3 because, like the 800E, it lacks the vertical grip extension like the EM1X.

Nikon combo is 4,810 g, Olympus is 1,850 g.

One could pick any combo and make a point.
Last edited:
Sep 26, 2011
Brookfield, IL
For what it's worth, I didn't read Mack's post and get the impression he was claiming the two setups were equivalent.

I'm sure if someone sends him a Nikkor 600mm he'd probably be happy to make the proper comparison. Or i'll volunteer, but I need the D800 too. :biggrin:


Mu-43 Legend
Jan 3, 2014
Not really sure what the original post is about.

- Two completely different cameras. Would be more appropriate to either slap the grip on to the D800 and compare weights or swap it for a D5 or swap the EM1X for an EM1mk3

- Once the camera is worked out then the lenses should either be the Olympus 300/4 vs Nikon 600/4 or Nikon 300/4 vs Olympus 150/2 (since it is the only 150mm prime in the Olympus ecosystem).


Mu-43 All-Pro
Feb 29, 2012
A 300/4 is a 300/4, regardless of 35mm or m43. I understood the comparison. You can’t make a 300/4 any smaller even if it’s for m43... medium format would be a different story, I have a 300/5.6 in a Pentacon mount (6x6 coverage) that weighs as much as my 300/2.8.

The Nikon is a PF lens which is much lighter due to its design (similar to Canon’s DO lenses). You should put it on a Nikon 1 body with a one inch sensor and see how that performs. It would be a great birding setup.
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