Limitations of m43 in bright light. OMD and Leica 25mm f1.4

Started Apr 14, 2013 | Discussions thread
Anders W
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Re: Limitations of m43 in bright light. OMD and Leica 25mm f1.4
In reply to Mark Chan, Apr 15, 2013

Mark Chan wrote:

Anders W wrote:

Sergey Borachev wrote:

:-OMark Chan wrote:

Went to Hong Kong Disneyland yesterday.

Facing the sun around 2:45pm insisted on using larger aperture (against gut feeling)to try and get some background blurring, so used anywhere between f2.0 - 2.8 whilst attempting to keep shutter speed within 1/4000.

Result was lots of CA making pics generally unsharp...I really appreciate the FF in this situ. Need to use zoom and distance with m43 to make up for this somewhat.

As a bonus can confirm that my copy of the Leica definitely has af issues. Af somehow extends away from the af box with ONLY this lens. I don't experience this with any of my other 6/7 lens.

That is a known issue with the E-M5 when using very fast lenses - lowest ISO being 200 and highest shutter speed 1/4000 sec.

Exactly what is a known issue here? That you can't shoot the E-M5 with a fast prime wide open or thereabout in bright sunlight without over-exposing unless you use an ND filter? Sure.

That you will get some longitudinal CA even in the in-focus area if you shoot a fast prime wide open or thereabout no matter which camera or camera system we are talking about? Again sure, but as a rule no more and sometimes less with MFT lenses (which tend to be pretty well corrected for in-focus LoCA, at least in the center) than with others. At any rate, this is hardly an E-M5 issue.

And I talked about this weakness a whole year ago while researching this camera.  Me bad, bad mouthing something I did not own and had not even touched at that time.  (How dare you?!)  

Anders,

to be fair, this IS a limitation to the current mft - at least to my understanding.  I have yet to purchase a quality ND filter to test whether the bright conditions can be successfully ameliorated to maintain sharpness and background blurring, but I am guessing an ND filter will not help fix the possible 'reflections / refractions' that may result from the large aperture and hence CA (the LoCA you mentioned before?).

I think it is important to keep the ISO issue and the need for an ND filter apart from the LoCA issue. The first is indeed an issue, not so much because the base ISO on MFT cameras is really so high in comparison with other cameras (remember that the DxO "measured ISO", which is what matters if you are a RAW shooter, is actually about 100 rather than 200 for the E-M5) but because MFT users might want to use really low ISOs more often than those shooting larger sensors (since MFT has more DoF at any given f-stop). I would personally much like to have arbitrarily low ISOs (not only to obviate the need for an ND filter in cases like the one you describe but also because it could potentially yield higher SNR) and I am hopeful that we will have them in a not too distant future. See here

http://www.dpreview.com/news/2013/02/27/rambus-shows-binaryt-pixel-sensor-technology-for-expanded-dynamic-range

and here

http://www.pixim.com/products-and-technology/technology

for example. In the meantime, here is an interesting alternative to an ordinary ND filter:

http://www.dpreview.com/forums/thread/3451295

When it comes to LoCA, using very large apertures increases the likelihood of LoCA in the in-focus area and MFT users might have stronger incentives (again for DoF reasons) to use such apertures under conditions such that the LoCA becomes rather visible. On the other hand, as I already said, in-focus LoCA is pretty well controlled on most fast MFT primes so I don't see this as a major issue.

I have to stated that the f2.8 setting still gave for a 1/4000 setting, so I was not working out of the limits of the situation.

The FF cameras perform better in built unless you purchase those with 1/2000 (the RX-1) as stopped down to f4, they still give you SOME background blurring, and is critical for portraiture.

I could walk the distance and get a 75-300mm and make do with zooming...

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
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