G9 vs. Z6 @ 2.8 in low light

Started 3 months ago | Questions thread
Anders W
Anders W Forum Pro • Posts: 22,144
Re: Less noise but also less DoF

James Stirling wrote:

Anders W wrote:

Sundre wrote:

It's not the sensor, but the lens. Since FF using double the focal length for the same framing as mFT, at the same f-number, the aperture diameter will be doubled, which will result in 4x as much light being projected on the sensor, which will result in a photo half as noisy (all else equal).

This is the part I don't understand at all. And when I google it, or search the forum, everyone seems to disagree... I really don't want to spend time trying to understand the technicalities, I'm not a tech guy. I guess I can rent a Z6 with a lens and see what it's like in real world use...

The f/4S zooms (equivalent to f/2 zooms on mFT) and f/1.8S primes (equivalent to f/0.9 on mFT) are not that big, though. Bigger than mFT, but not hugely so. They're also "reasonably" priced. The longest f/1.8S prime is 85mm (42.5mm mFT equivalent), so I don't know if that's long enough for you.

I would rather use zooms, if they are good enough... Hard to compose well when you're in a crowd.

Wow -- that's pretty dark (and/or you're using a really short exposure time to mitigate motion blur).

Very dark. And to avoid motion blur, I had to stay at 1/50s or faster, which most of the time resulted in ISO values in excess of 8,000. Most of my shots came out blurry, even at ISO 12,800.

Well, mFT can give you the same shutter speeds as FF, it's just that it's twice as noisy for the same exposure. Whether twice as noisy is "too noisy", only you can say.

I find myself surprisingly happy with DxO-cleaned high-ISO shots from my G9; but I'm not sure that even ISO 12,800 is enough to avoid motion blur at some events...

Be aware that at the same ISO, the same f-stop, the same shutter speed, and the same field of view, the Z6 will give you a two-stop improvement when it comes to signal-noise ratio (which is of course desirable) but also two stops less depth of field (which is less desirable, at least based on my taste and experiences). So what you gain in one regard, you lose in another.

When I shoot concerts, I typically try to do it primarily with the Olympus 75/1.8 (which corresponds to a 150 mm lens on FF wrt angle of view). Shooting that lens wide open, I usually manage to get enough DoF for decent shots (see example below) but I’d rather have more than less of it. This is particularly so since musicians tend to move when they play making it harder to nail focus.

One thing I don’t understand is why you need as high an ISO for concert shots as 8000 and still can’t use a shutter speed higher than 1/50 s at f/2.8. What type of concerts are these?

I usually try to keep shutter speed at 1/250 s or so since many musicians move quite a bit as they play/sing. At f/1.8, that typically means ISO 400 to 800 with standard stage lighting (or ISO 800 to ISO 1600 at f/2.8). See example below illustrating my point about DoF as well as the ISOs/exposure values I typically use.

That is a very well lit concert to be able to shoot 1/250th at ISO 400 . Most concerts I have been at do not have such generous lighting

You should go to better concerts!

Unless you just expose for the brightest part of the scene and let the rest fade to black.

As I did for the shot I posted. Usually a very good idea for concerts in my experience.

If you look at the OP's gallery the couple of concert shots are in far more challenging lighting .

As the OP has already told us, he was shooting at f/5.6 whereas my shot was at f/1.8. This makes the difference in lighting only half as large as it seems to be be if you look at the ISO settings and shutter speeds alone.

As for DOF that really depends on many variables such as distance from subject etc .

Where did I say anything to the contrary? But many concert shots are at a magnification where DoF tends to get in short supply.

Unless you are actually on stage with the artist with your camera in their face.

DoF depends on subject distance (or more generally magnification) regardless of where you are.

The typical shooting distances involved will offer no challenges for DOF with FF .

If you want to get a magnification large enough for a half-figure portrait, as in my sample image, it does. In addition, you have the problem of nailing focus on a moving subject when DoF is in short supply.

As you rightly mention most artists are moving to one degree or another so IBIS etc offers little help .

Right. Although IBIS remains helpful. At 150 mm EFL, you can't be sure to get images free from blur due to camera shake at 1/250 s without the help of a stabilization system, especially since you are busy nailing other things (focus, framing, the right moment) and can't really concentrate on minimizing shake.

In saying that you can indeed get very good results with m43 , and as the OP already owns m43 gear. The lovely 75mm would be a cheaper option if that works for him.

Glad we agree about that.

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