G9 vs. Z6 @ 2.8 in low light

Started 1 month ago | Questions thread
Anders W
Anders W Forum Pro • Posts: 22,144
Re: Less noise but also less DoF
1

James Stirling wrote:

Anders W wrote:

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!

You could be right, in my defense I tend to be dragged along to a concert my wife has chosen

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 are only interested in the brightest parts of the scene you can get away humbler gear . Not always what is desired in the image though.

I was talking about stage shooting specifically. For such shots, you obviously expose for the spotlit subject, not for the dark surroundings, which as a rule are completely uninteresting. In the shot I posted, I am grateful that the background went completely black since that makes it less distracting.

Even if you expose for the spotlit subject and have a rather fast lens on the camera, you will most likely have to deviate from base ISO, as shown by the relatively well lit image I posted. And with "humbler gear" than mine, the image would have been worse.

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.

Every stop matters in challenging lighting , especially when you need a certain shutter speed and can't take advantage of IBIS. He was also shooting at 300mm the only faster native m43 lens at that focal length is the 300mm F/4 pro. So assuming he needed that kind of focal length the best he could hope for was 1 extra stop.

Sure. I don't think you can get very good concert shots with any system if you are so far away that you need 600 mm EFL.

There are also major differences in the type of performance a classical violinist is more sedate. Than many pop performers they can do cartwheels while singing and playing a guitar , allegedly

Sure. But if you want everything sharp, a classical violinist would pose a problem with respect to shutter speed as well unless you capture him/her in the adagio phase.

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.

If you are on stage with the artists you can use a shorter focal length to compensate . Which is not a likely scenario unless you are a professional concert shooter or shooting at a low level event { school performance etc} . If however you are shooting further afield DOF issues reduce greatly

As I already pointed out, it's the magnification that matters for DoF. If you can get close, you use a shorter FL and if you are further away you go for a longer FL for the same framing. DoF will be the same at the same f-stop.

For the image I posted, I was maybe five meters away in the first row of the audience. That gave me a DoF at 75 mm and 1.8 on MFT (150 mm and 3.5 on FF) of about 20 cm. Just enough to get the face reasonably sharp. With FF at the same f-stop as MFT, DoF would have been down to about 10 cm. That's certainly too little, especially in view of the fact that the subject is constantly moving and that it's therefore very difficult to really nail focus no matter which AF system or technique you are using.

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.

Looking at the results from the mirrorlesscomparison.com sites extensive testing of BIF { a very challenging AF subject } .

I don't think the AF challenges are quite the same with BIF as with concert shooting.

There are no shortage of FF and APS cameras that are significantly better in this area. Of course I told the secret with m43 is to take hundreds of extra shots and the averages will work out. Decisive moment be damned

Well, I certainly didn't tell you that. But I am sure that concert shooters shoot liberally, no matter which system they are using. Far from every shot will be a keeper. That doesn't mean you don't try to nail the moment in each of them.

mirrorlesscomparison.com

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.

I would be very disappointed if I could not get sharp images with a 150mm EFL at 1/250th under any scenario . There are folk in this forum who claim they can get sharp tele images with multi second exposures, hand held ! I can post links

Not interested in anecdotal "evidence". It is well known that the 1/EFL rule is an overly optimistic one. Here are the results in DPR's test of the Z7 with a normal lens with stabilization turned off. As you can see, at 1/50 s, more than half of the shots are useless and only 10 percent excellent although this is a scenario where the test shooter had nothing but camera shake to worry about. Those problems won't magically disappear even if you shoot at 1/2EFL, particularly if you have a lot of things other than camera shake on your mind. Hence my conclusion that stabilization remains helpful even for the type of shooting we are talking about here.

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.

Absolutely unless you have money burning a hole in your pocket the least expensive option that does the job is the way to go. The 75mm is a lovely bit of kit both optically and aesthetically not that we car about such fripperies as how gear looks

Personally unless it was work god forbid. I would not be using FF at a a concert. m43 wins hands down for compactness. Though my wife owns the RX10 IV and it packs a lot into its size and gives decent results with good AF { after you have had a cup of tea waiting on the lens to zoom out } . Anyway we are all wasting our time , after all people talk photos at stadium concerts 90m away from the stage with a mobile

I know. But I'm not one of those people.

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