The Most Useful ISO, etc. Graph

[Michael Erlewine]

This graph allows you to compare and see the differences between dozens of cameras, including the Nikon D810, Hasselblad X1D, GFX 50s, etc.

I have no idea how accurate, but for the cameras I know, it seems right on the money. It shows how close the Nikon D810 is to the new medium-format mirrorless camers.

http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%201D%20X%20Mark%20II,Nikon%20D5,Sony%20ILCE-9,Sony%20ILCE-9(ES)

[BobShaw]

Meaningless to me. My most used ISO on medium format is 50. If it had 25 I would use that.

[madlantern]

What camera can you shoot iso50 on? Is it native or extended?

[dchew]

IQ3-100 base ISO is 50. IQ180 was 35. Although there was some endless debate as to whether that was "real" or not.

Dave

[BobShaw]

What camera can you shoot iso50 on? Is it native or extended?

Mine is the H3DII but there are others.

[bjanes]

Meaningless to me. My most used ISO on medium format is 50. If it had 25 I would use that.

And why do you like ISO 50 or ISO 25? If you want maximum DR, you want to shoot at the base ISO of the camera where the sensor reaches saturation. In most cases it doesn't matter if the sensor reaches saturation at ISO 25 or ISO 100. In the former case, the sensor likely has a low quantum efficiency and requires more exposure to reach saturation. Unless you are shooting waterfalls where a long shutter speed is desired, a low base ISO is a disadvantage since a low shutter speed limits your ability to freeze motion and limit camera shake.

On many cameras, ISOs less than base merely result in overexposure, since the gain of the amplifier between the sensor and the ADC (analog to digital converter) remains the same. For the Nikon D810 these fake ISOs are shown by open circles as shown here. For me, the charts are quite useful.

[bjanes]

Mine is the H3DII but there are others.

I don't know about your H3DII, but many Hasselblads do not change the amplifier gain as the ISO setting is changed, but merely record the ISO as metadata and the amplifier gain is not changed when you increase ISO. The increased ISO does affect metering and exposure, but in essence you are always shooting at base ISO as shown by this plot on DXO.

[BobShaw]

And why do you like ISO 50 or ISO 25? If you want maximum DR, you want to shoot at the base ISO of the camera where the sensor reaches saturation.

I want a lower ISO for a bigger aperture shooting portraits, particularly outdoors.
Also in the studio it means that I can get the soft boxes closer as often even minimum power is too much.
I don't take much notice of anything I see on DXO.

The leaf shutters are important for high sync speed which helps outdoor flash.

[Paul2660]

I want a lower ISO for a bigger aperture shooting portraits, particularly outdoors.
Also in the studio it means that I can get the soft boxes closer as often even minimum power is too much.
I don't take much notice of anything I see on DXO.

The leaf shutters are important for high sync speed which helps outdoor flash.

It's my understanding thus is true for all CCD backs P1 and Hasselblad and it's never been well covered by either company. The vast majority of photographers still seem to believe the the CCD backs work as the more modern CMOS chips do. P1 does offer pixel binning with the IQ backs which cuts the resolution by 3/4 but does offer better low light performance.

Paul Caldwell