m4/3 Lenses "only" f1.8?

[AlterEgo]

My E-m1 is base ISO 200.

that is a nominal ISO, based on the brightness obtained during raw conversion to OOC JPG... same Panasonic sensor in GH4 implementation has SSat ISO = 88 @ nominal ISO100 and SSat ISO 122 @ nominal ISO200 in Olympus implementation in E-M1 - that's what counts for a raw shooter.

[Bob Rockefeller]

that is a nominal ISO, based on the brightness obtained during raw conversion to OOC JPG... same Panasonic sensor in GH4 implementation has SSat ISO = 88 @ nominal ISO100 and SSat ISO 122 @ nominal ISO200 in Olympus implementation in E-M1 - that's what counts for a raw shooter.

That agrees with DxOMark's measurements. Rated ISO 200 = Measured ISO 122.

For whatever that's worth.

Their measurements get progressively farther "off": Rated ISO 6400 = Measured ISO 3870. It makes the indicated ISO more of a reference than an absolute.

[Telecaster]

It seems as if it's a rare lens indeed in the m4/3 lineup that is faster than f1.8. None of the M.Zuiko line is. Is there something that just makes it real hard to get to f1.4?

IMO f/1.8 (or 1.7) represents a sweet spot where you get speed and resolving capability while keeping lens size relatively compact. Faster lenses like the Voigtländers aren't really that much faster in terms of light-gathering ability (or, maybe more accurately, in terms of the sensor's ability to make use of the extra light gathered). Based on my own use of the Voigts you gain ~1 t-stop of effective speed between f/1.7 and f/0.95. You also get softer, hazier images along with that extra speed…which I like as an effect while realizing most folks don't. Panasonic's 42.5/1.2 is a good performer wide open but it comes with a significant weight/bulk increase over the tiny Oly 45/1.8.

-Dave-

[tom b]

Voiglander f0.95.

Cheer,

[tnargs]

It seems as if it's a rare lens indeed in the m4/3 lineup that is faster than f1.8. None of the M.Zuiko line is. Is there something that just makes it real hard to get to f1.4?

No reason at all. Why, do you want one?

Lumix 25/1.4
Leica DG 42.5/1.2
Voigtlander 10.5/0.95
Voigtlander 17.5/0.95
Voigtlander 25/0.95
Voigtlander 42.5/0.95

I don't see many Fuji's faster than f/1.2. Do you think there is something makes it real hard?

[Bob Rockefeller]

No reason at all. Why, do you want one?

Lumix 25/1.4
Leica DG 42.5/1.2
Voigtlander 10.5/0.95
Voigtlander 17.5/0.95
Voigtlander 25/0.95
Voigtlander 42.5/0.95

I don't see many Fuji's faster than f/1.2. Do you think there is something makes it real hard?

Snark aside, these are, of course, viable choices. But only the first two ate auto-focus, correct?

[tnargs]

My point being made, though. There is clearly nothing stopping m43 lenses at f/1.8, because they don't stop at f/1.8. The question was ill-informed from the outset.

But it certainly is answered.

[Guillermo Luijk]

I'm not personally sure of what the E-M1 does to get to 100 ISO. It appears that they might get somewhat better dynamic range at 100 vs. 200.

But I do know that all cameras lose dynamic range as you increase ISO.

There are some nice charts on DxOMark that show the effect:

http://www.dxomark.com/Cameras/Olympus/OM-D-E-M1---Measurements

Olympus camera's ISO100 is one of the strangest things in the digital camera industry. Unlike other camera manufacturers (Canon, Nikon), which implement ISO50 using the same ISO100 gain with an extra clandestine software exposure correction by -1EV (this doesn't prevent from blowing highlights since metering for ISO50 and capturing at ISO100 means 1 stop of overexposure), Olympus' ISO100 works at a different gain than ISO200, in fact it works at a nonsense ISO250 gain (1/3EV over the expected ISO200 gain), blowing even more highlights than the Canon and Nikon cameras in their low ISO modes.

If DxOMark would plot correctly Olympus' ISO100, it would fall as follows:



This means that if you shoot at ISO100 on an Olympus camera according to the camera meter, you can loose up to 1+1/3EV in the highlights vs metering and shooting at ISO200. A real example here:





RAW histograms of the previous shots (the ISO200 RAW file holds 1,33EV more information in the highlights):




I have studied this in deep and can assure it's like that:

http://www.guillermoluijk.com/article/lowiso/index.htm

Regards