G6 vs newest sensors: Real difference in high ISO noize

Started 8 months ago | Questions thread
Øyvin Eikeland
Forum MemberPosts: 87Gear list
Like?
Re: G6 vs newest sensors: Real difference in high ISO noize
In reply to Anders W, 8 months ago

Anders W wrote:

11848 along the X-axis. What I do not get is this: How can I find the dynamic range (or SNR) you will get if I set the camera to an ISO of 25600?

If you expose up to the clipping point of the RAW file, the DR of the image would be the value indicated in the graph (6.61 EV). If you expose less than that it would be correspondingly less (one EV less DR for each EV less exposure).

The difference between the E-M5 with a camera ISO of 25600 and a measured ISO of 11848 and another camera, X, with a camera ISO of 25600 and a measured ISO of 25600 is that at the same exposure (and the meter of the two cameras would normally suggest the same exposure) the ADU values in the RAWs of camera X would be slightly more than one EV closer to the clipping point than that of the E-M5.

Consequently, when camera X is at the clipping point of the sensor, the E-M5 is slightly more than one EV below the clipping point. When the E-M5 is at the clipping point, camera X is has slightly more than one EV worth of clipping.

Thanks,

I think I understand more now. Let me try to use this in a couple of examples. _IF_ I assume that you do not want or need the extra headroom that the Olympus E-M5 provides. I then take that you can disregard the extra dynamic range above the clipping point of a "vanilla" camera where ISO 12800 actually is measured to ISO 12800.

E-M5 set at ISO 12800:

Measured ISO: 5953

Manufacturer ISO: 12800

Dynamic Range: 7.5Ev

The usable dynamic range in this case would be:

7.5Ev-log2(100/5953)-log2(100/12800)=6.39Ev

right?

Another example:

E-M5 set at ISO 12800:

Measured ISO: 5953

Manufacturer ISO: 12800

SNR 18%: 20.9dB

The usable SNR in this case would be:

20.9-20*log10(12800/5953)=14.25dB

right?

Again, please don't take this as an attempt to bash olympus or anything. I am simply trying to learn something here.

BR,

Øyvin Eikeland

 Øyvin Eikeland's gear list:Øyvin Eikeland's gear list
Canon PowerShot S95 Panasonic Lumix G 14mm F2.5 ASPH Panasonic Leica Summilux DG 25mm F1.4 Olympus M.Zuiko Digital 45mm 1:1.8 Panasonic 12-35mm F2.8 +3 more
Reply   Reply with quote   Complain
Post (hide subjects)Posted by
NopeNew
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow