AUTO ISO: Issue to set lowest ISO setting (Z8)

[Nimi]

I indeed do not comprehend what the size of the sensor has to do with it because I only use the DX/APS-C part of it. Which is in theory and practice only the middle section of the FF sensor.
On the other hand... Looking at the dynamic range of the D500 and Z8 in DX mode shows that the D500 has more dynamic range...???
But why does the Z8 in FX mode has more dynamic range than in DX mode? Is the dynamic range calculated over all photosites? If so than I only should compare the dynamic range of the Z8 in DX mode with the D500. Otherwise it would be logical to shoot in FX mode and crop to DX mode in postprocessing while in my perspective the end results would be the same. You crop off the photosites out of the APS-C frame in camera or in PP.
I clearly miss some basic understanding here.

Bingo. Dynamic range is calculated over the entire sensor. Bigger sensor - more dynamic range regardless of site size (except specialized cine sensors). A site only sees or doesn't see a photon; dynamic range is the statistical distribution of clusters of sites exposed to varying degrees of light.

In modern sensors, with some difference among them depending of whether they are stacked, back-lit, etc, noise at the sensor level is very very low and generally generated by amplification above the native ISO.

So an FF sensor will have a lower dynamic range in DX mode than its FF mode.

 

[PhotoLover]

I indeed do not comprehend what the size of the sensor has to do with it because I only use the DX/APS-C part of it. Which is in theory and practice only the middle section of the FF sensor.
On the other hand... Looking at the dynamic range of the D500 and Z8 in DX mode shows that the D500 has more dynamic range...???
But why does the Z8 in FX mode has more dynamic range than in DX mode? Is the dynamic range calculated over all photosites? If so than I only should compare the dynamic range of the Z8 in DX mode with the D500. Otherwise it would be logical to shoot in FX mode and crop to DX mode in postprocessing while in my perspective the end results would be the same. You crop off the photosites out of the APS-C frame in camera or in PP.
I clearly miss some basic understanding here.

This is a slight tangent, but if I had a Z8, I would usually shoot in FX mode and crop in post, since that gives me more flexibility on exactly what I want the crop to be. I.e. don't crop until you have to.

However, in some threads on the DX function in the Z8 and Z9, posters have asserted that the AF might sometimes get a lock on a smaller subject in DX mode better than if it was in FX mode. (Not having a Z8/Z9 I have no opinion on this).

For the record, I would also have assumed that shooting a Z8 in DX mode with a 500pf would result in an image with about the same quality (noise, etc) as shooting a D500 with a 500 pf.

 

[bleirer]

I use the same lens on both D500 and Z8 in DX mode. This delivers a picture with the same view, same DOF, same amount of pixels (approx)!

In that case you can't say the z8 is noisier than the d500. You could say that the cropped z8 is noisier. But as the link below shows it is very little, maybe 1/3 stop in the lower iso range.

Photographic Dynamic Range versus ISO Setting

 

[John Navitsky]

In that case you can't say the z8 is noisier than the d500. You could say that the cropped z8 is noisier. But as the link shows it is very little.

this

 

[DRwyoming]

I indeed do not comprehend what the size of the sensor has to do with it because I only use the DX/APS-C part of it. Which is in theory and practice only the middle section of the FF sensor.
On the other hand... Looking at the dynamic range of the D500 and Z8 in DX mode shows that the D500 has more dynamic range...???
But why does the Z8 in FX mode has more dynamic range than in DX mode? Is the dynamic range calculated over all photosites? If so than I only should compare the dynamic range of the Z8 in DX mode with the D500. Otherwise it would be logical to shoot in FX mode and crop to DX mode in postprocessing while in my perspective the end results would be the same. You crop off the photosites out of the APS-C frame in camera or in PP.
I clearly miss some basic understanding here.

The key to understanding why the full frame D850 has higher DR than the same camera in crop mode or a crop camera of similar sensor technology is image size normalization.

Basically for at least a hundred years the accepted way to compare images from different media sizes(e.g. 8x10 vs 4x5 vs 35mm) for various things like: DoF, resolvable detail, observable grain/noise, etc. is to compare the same scene captured from the same distance with the output image resized as necessary to the same output size. If you dig around you can still find old papers by the likes of Zeiss and Leica on these topics.

For the best apple to apple comparisons this still applies with digital photography. If you just think of a DX cropped D850 image as a smaller center cutout of the full frame image then of course noise and from it DR (as DR is measured between fully saturated white and a defined noise level in the shadow areas) doesn’t change. But when you resize one or both images to the same output file size you either upsize(interpolate) the crop image or downsize the full frame image. Upsizing makes noise more apparent and downsizing averages noise and makes it less apparent.

It’s in that output size normalization step that the noise of the cropped image becomes worse relative to the full frame image. And as posted above size normalization is how this is typically approached. For instance when crop body shooters talk about increasing their effective ‘reach’ they’re not talking about sharing or printing images that are 2/3 the size of full frame images, they’re generally talking about sharing or printing the same size images as what they’d normally share/print from their full frame cameras.

BTW, @Steve has a good video on this and why cropping leads to higher visible noise in images.

 

[John Navitsky]

ok, that’s why we’re all confused. that’s a bit of an unusual approach

What is so unusual?
I first had a D500 and shot birds with the 500PF and now I do exactly the same with the Z8.
In FX I get a wider view due to the FF sensor so I would crop more to get the same end result. If I shoot in DX the pictures are directly comparable.
And that is what I do. I compare the pictures with the same view, same lens, same ISO etc. and than I think the Z8 has more noise at ISO 400 and I thought the chart from potonstophotos (see post before) does verify this.

in general when people compare _cameras_, they are comparing a similarly framed subject across the _entire_ frame

i went back and re-read your original post and i don't see mention that you were actually considering only the dx portion of the sensor

so everyone was answering a different question from what you were asking

 

[bleirer]

Looking again at the photonstophotos chart though, I would agree with the op there would be a slight benefit from shooting at 200 or 500, skipping the in between. I do that with my Canon if I think of it, jumping from 200 to 400. Mostly I'm busy with other distractions though.

 

[John Woodworth]

In my mind, this thread raises the question: "Why doesn't Steve use a medium format camera for his backcountry bird photography?"

Afterall, the bodies aren't that much bigger than 35mm these days.

 

[CameraLex]

This is a slight tangent, but if I had a Z8, I would usually shoot in FX mode and crop in post, since that gives me more flexibility on exactly what I want the crop to be. I.e. don't crop until you have to.

However, in some threads on the DX function in the Z8 and Z9, posters have asserted that the AF might sometimes get a lock on a smaller subject in DX mode better than if it was in FX mode. (Not having a Z8/Z9 I have no opinion on this).

For the record, I would also have assumed that shooting a Z8 in DX mode with a 500pf would result in an image with about the same quality (noise, etc) as shooting a D500 with a 500 pf.

another benefit is that you see the object itself enlarged when shooting in DX and you will not fill up your buffer and memory card as fast as in FX.
But cropping later on gives you more flexibility that's for sure.

 

[CameraLex]

in general when people compare _cameras_, they are comparing a similarly framed subject across the _entire_ frame

i went back and re-read your original post and i don't see mention that you were actually considering only the dx portion of the sensor

so everyone was answering a different question from what you were asking

My original question, that Steve answered, was if there was a possibility to set the base iso in auto iso to 500 because I noticed something...
You all assumed and discussed it in your own way while in many replies I tried to explain that I crop untill smaller than APS-C/DX size on both camera's.

 

[Nimi]

In my mind, this thread raises the question: "Why doesn't Steve use a medium format camera for his backcountry bird photography?"

Afterall, the bodies aren't that much bigger than 35mm these days.

None has the AF and framerate, let alone the lenses for what he does.

 

[CameraLex]

The key to understanding why the full frame D850 has higher DR than the same camera in crop mode or a crop camera of similar sensor technology is image size normalization.

Basically for at least a hundred years the accepted way to compare images from different media sizes(e.g. 8x10 vs 4x5 vs 35mm) for various things like: DoF, resolvable detail, observable grain/noise, etc. is to compare the same scene captured from the same distance with the output image resized as necessary to the same output size. If you dig around you can still find old papers by the likes of Zeiss and Leica on these topics.

For the best apple to apple comparisons this still applies with digital photography. If you just think of a DX cropped D850 image as a smaller center cutout of the full frame image then of course noise and from it DR (as DR is measured between fully saturated white and a defined noise level in the shadow areas) doesn’t change. But when you resize one or both images to the same output file size you either upsize(interpolate) the crop image or downsize the full frame image. Upsizing makes noise more apparent and downsizing averages noise and makes it less apparent.

It’s in that output size normalization step that the noise of the cropped image becomes worse relative to the full frame image. And as posted above size normalization is how this is typically approached. For instance when crop body shooters talk about increasing their effective ‘reach’ they’re not talking about sharing or printing images that are 2/3 the size of full frame images, they’re generally talking about sharing or printing the same size images as what they’d normally share/print from their full frame cameras.

BTW, @Steve has a good video on this and why cropping leads to higher visible noise in images.

But this is so not relevant to my comparison about the Z8 and D500.
Yes I crop heavily and yes that shows all the noise available, I know. And I also know that if I fill the frame entirely with the subject the noise will be less due to downsampling. And ofcourse if I can fill the full frame sensor of the Z8 I get even less noise than a filled APS-C sensor (if and when the photosites are comparable!).... but that is not applicable.
I am not in the circumstances that I can get my frame filled with my subject. I rely heavily on cropping even on APS-C. That's why I compare FF DX (or FX and cropping to same view in PP) with APS-C. And because the photosites of both camera's are almost the same size I would have expected the Z8 to perform better because it is a newer sensor. But I guess that due to the fast read out and other adjustments in the sensor the sensitivity (don't have a better word for it) is a bit lower.

 

[Steve]

In my mind, this thread raises the question: "Why doesn't Steve use a medium format camera for his backcountry bird photography?"

Afterall, the bodies aren't that much bigger than 35mm these days.

As @Nimi says, frame rate, AF for starters, but also lenses. As far as I know, there aren't any 500mm / 600mm equivalents out there for medium format. I think I saw Fuji was making a 400mm or 500mm, but on medium format that's still a little short (and I don't think it was very fast). Still, I'd be lying if I said I didn't think about it from time to time

 

[CameraLex]

None has the AF and framerate, let alone the lenses for what he does.

But in my case I use the same FF lens on my D500 as on my Z8. And in my opinion it doesn't matter if I crop my image in camera (DX mode) or later on in post processing.
If I could mount this lens on a medium format body and shoot from the same spot the same bird I only have to crop more to get the same image.

 

[DRwyoming]

In my mind, this thread raises the question: "Why doesn't Steve use a medium format camera for his backcountry bird photography?"

Afterall, the bodies aren't that much bigger than 35mm these days.

Not sure if you’re serious or just having fun, but remember the concept of crop factor works both ways. If you can get a frame filling subject of a wildlife subject with a 600mm lens on a full frame (36x24mm) sensor camera you’ll need a substantially longer focal length lens on a medium format sensor camera.

For instance on a camera like a Fuji GFX the effective 35mm crop factor allowing for differing aspect ratio is approximately 0.8. So where you might use a 600mm or 800mm lens on a Full Frame camera you’d need roughly a 750mm or 1000mm lens for the same subject size in frame.

A 750mm f/4 or 1000mm f/5.6 lens would be huge and very expensive compared to a 600mm f/4 or 800mm f/5.6 which are already pretty huge and expensive.

That said, medium format for shorter lens work like landscapes, architecture and portraits can be pretty awesome and is done all the time.

 

[Nimi]

As @Nimi says, frame rate, AF for starters, but also lenses. As far as I know, there aren't any 500mm / 600mm equivalents out there for medium format. I think I saw Fuji was making a 400mm or 500mm, but on medium format that's still a little short (and I don't think it was very fast). Still, I'd be lying if I said I didn't think about it from time to time

Watch Red... It won't be a MF, but it'll be a 16 stop dynamic range, extremely high frame rate, global shutter, probably an FF sensor and an RF mount. They've already been teasing with some very good extracted frames from the Komodo chasis.

 

[Nimi]

But in my case I use the same FF lens on my D500 as on my Z8. And in my opinion it doesn't matter if I crop my image in camera (DX mode) or later on in post processing.
If I could mount this lens on a medium format body and shoot from the same spot the same bird I only have to crop more to get the same image.

I was replying to a different question.

 

[CameraLex]

As @Nimi says, frame rate, AF for starters, but also lenses. As far as I know, there aren't any 500mm / 600mm equivalents out there for medium format. I think I saw Fuji was making a 400mm or 500mm, but on medium format that's still a little short (and I don't think it was very fast). Still, I'd be lying if I said I didn't think about it from time to time

You are ofcourse right but I think the question that was asked was more in the meaning of:
If you crop your image using a 600mm on a FX body, would you gain any benefit when you mount a medium format body on the same setup shooting the same object from the same distance (asuming the photosites on both sensors are equal in size)?
In my opnion you only get bigger files and you have to crop more giving you no benfits at all.

 

[DRwyoming]

But this is so not relevant to my comparison about the Z8 and D500.
Yes I crop heavily and yes that shows all the noise available, I know. And I also know that if I fill the frame entirely with the subject the noise will be less due to downsampling. And ofcourse if I can fill the full frame sensor of the Z8 I get even less noise than a filled APS-C sensor (if and when the photosites are comparable!).... but that is not applicable.
I am not in the circumstances that I can get my frame filled with my subject. I rely heavily on cropping even on APS-C. That's why I compare FF DX (or FX and cropping to same view in PP) with APS-C. And because the photosites of both camera's are almost the same size I would have expected the Z8 to perform better because it is a newer sensor. But I guess that due to the fast read out and other adjustments in the sensor the sensitivity (don't have a better word for it) is a bit lower.

I was responding to your specific question of why a Z8 in Fx mode has more DR than a Z8 in DX mode.

As to the other question in that post of why a D500 has slightly more DR than a D850 in DX crop mode, it’s because the D500 has slightly higher pixel density so basically a bit larger dimensions (roughly 21 mega pixels instead of roughly 19) so again it comes down to comparing the output size normalized images.

You posted those two questions and asked what basics you were missing. The answer to both lies in output image size normalization and what that does to apparent noise and from it DR.

The DR charts on photonstophotos compare output size normalized images the sensor read noise charts do not.

 

[Nimi]

You are ofcourse right but I think the question that was asked was more in the meaning of:
If you crop your image using a 600mm on a FX body, would you gain any benefit when you mount a medium format body on the same setup shooting the same object from the same distance (asuming the photosites on both sensors are equal in size)?
In my opnion you only get bigger files and you have to crop more giving you no benfits at all.

The only relevant MF sensor is the one on the GFX 100, which is significantly more dense than the one on the Z8. So you get much higher resolution and can enlarge it more. It also has a full stop of extra DR range AND shoots at 16 (vs 14) bit RAW. For things that don't require continuous shooting, that are going to be printed above 30x40 and/or cropped deeply, it is better in all respects.

 

[John Woodworth]

Not sure if you’re serious or just having fun, but remember the concept of crop factor works both ways. If you can get a frame filling subject of a wildlife subject with a 600mm lens on a full frame (36x24mm) sensor camera you’ll need a substantially longer focal length lens on a medium format sensor camera.

For instance on a camera like a Fuji GFX the effective 35mm crop factor allowing for differing aspect ratio is approximately 0.8. So where you might use a 600mm or 800mm lens on a Full Frame camera you’d need roughly a 750mm or 1000mm lens for the same subject size in frame.

A 750mm f/4 or 1000mm f/5.6 lens would be huge and very expensive compared to a 600mm f/4 or 800mm f/5.6 which are already pretty huge and expensive.

That said, medium format for shorter lens work like landscapes, architecture and portraits can be pretty awesome and is done all the time.

Just trying to kick the discussion off of top-dead-center.

You nailed the fundamentals. These are fundamental limitations in scaling of optical physics...The trickle down is that the subsequent lack of demand leads to reduced lenses and performance required for backcountry wildlife use of larger format cameras.

 

[Steve]

You are ofcourse right but I think the question that was asked was more in the meaning of:
If you crop your image using a 600mm on a FX body, would you gain any benefit when you mount a medium format body on the same setup shooting the same object from the same distance (asuming the photosites on both sensors are equal in size)?
In my opnion you only get bigger files and you have to crop more giving you no benfits at all.

Assuming everything is the same as far as pixel density, there's no benefit. If I'm only use 3000 x 2000 pixels from the middle of the frame, it would be the same if I were shooting DX, FX, or MF with a 600mm (same subject, distance, etc).

 

[macwalter]

I have had both cameras and overall I have found that the z8 generally has better image quality. As I shoot action I like the full frame to give more area to work with knowing I can crop more deeply if necessary. i also have the d850 and I do feel that it is slightly better in terms of image quality but the difference is very small. I have read that mirrorless shutters can be slightly noisier than mechanical ones and I wonder if this could play a part. That being said I love the z8 and the z lenses I have gotten. I still have the 500pf and 1.4tc iii. I can say with confidence that this lens combo works noticeably better on the z8 than on any dslr. I sold my d500 and still have the d850.

 

[bleirer]

According to the photonstophotos DR chart the d850 has about 1/3 stop better max dynamic range than the z8, but the Z8 has a slight edge in low light. Neither makes any practical difference, I'd venture. The D500 has about 3/4 stop less max dynamic range than the z8 and the z8 is about 3/4 stop better in low light.

 

[O]

D850 D500 Z9 in DX mode, which image file is better with lower noise ? and does it matter, answer, IMO, its not really worth worrying about...........

But

I shoot the D850 in DX mode sometimes, hence for myself i don't need the excellent D500, my experience is the D850 D500 in DX mode are almost indistinguishable as far as dynamic range goes, if anything the D850 possibly and understandably looked a tad better than the D500.

I shoot the Z9 in DX mode sometimes, hence i don't need the excellent D500, my experience is the Z9 is largely indistinguishable overall compared to the D500.

The difference in both experiences showed the full frame cameras held up slightly better as the ISO went higher than 6400 ISO.

FWIW DXO figures

D850 DR 14.8 ISO 2660 FF
Z9 DR 14.4 ISO 2451 FF
Z8 DR 14.2 ISO 2548 FF
D500 DR 14 ISO 1324 DX

The outcomes are coal face derived, hands on n the field use, reviewed in post using A B comparisons, by myself and several other club member's, be the results reality or gear sample differences, or even psychosomatic.

The same lens was used 50mm 1.4 G
Summary, FX glass on the D850 then the Z9 with adapter then the D500 shows the D850 overall a whisker better than the Z9 and the D500 image files, why ? i don't know and not worth worrying about.

Once we used the 50mm 1.8s no adapter the difference really changed on the Z9 outcomes, showing that Z glass on a Z body works well and shows more of a difference over the D500 and because of that lens a whisker better than the D850 on the 50mm 1.4 G, hence the Z glass does shine by comparison to many of the FX glass but not in all cases.

FWIW right, wrong or just Psychosomatic FX or DX when DX is set in a good FX camera........the outcomes or differences are not worth worrying about.

D850 Z9 really covers what the D500 delivers other than weight and size and exceeds clearly in ISO over the D500.


Again, FWIW DXO figures

D850 DR 14.8 ISO 2660 FF
Z9 DR 14.4 ISO 2451 FF
Z8 DR 14.2 ISO 2548 FF
D500 DR 14 ISO 1324 DX

If the FX for what ever reasons looses DR going to DX mode its not really noticeable or a game changer, well in this coal face application (field hands on use) at least not with using the unit samples on hand.

Only an opinion