GX7 vs E-M1 IQ difference?

Started Dec 17, 2013 | Discussions thread
GeorgianBay1939 Senior Member • Posts: 3,948
Re: Image Quality Stops

GEagle wrote:

Baron LaCat wrote:

Jorginho wrote:

and it’s only -1/3 of a stop in overall image quality behind the 16-Mpix Sony NEX-6.

This STOP jargon really confuses me !!! How is image quality measured in Stops ???

And when folk talk about Stopping Down (with a lens) what do they mean ?

(I almost grasped the idea of Stopping Down on a lens, and now we talk about IQ measured in Stops)!!

And if we can Stop Down on a lens, can we also Stop Up on the lens ??

Thanks in advance


In this context, it usually means ISO-wise - like, 1 stop means that, from a IQ point of view (noise etc.) results at ISO 3200 on a camera are comparable to results at ISO 6400 on another.

This is interesting.  Could you please give us a link to a reference for this interpretation of "stop".


A very good book to better understand the exposure triangle comprising aperture, shutter speed and ISO is, IMHO, Bryan Peterson's Understanding Exposure.

Peterson's book might be helpful for JPEG shooters.  Anyone contemplating shooting RAW files will find it helpful to first read Gollywop's Exposure Vs Brightening to gain a more useful understanding of Exposure (which depends on Scene Luminance, f/, and shutter interval) and which is related to the ISOspeed by the "Exposure Equation ", which calibrates average scene luminance with mid-tone output on (camera) exposure meters.

Hope that helps,


The term "stop", [ which has an interesting history related to physical "aperture stops"  as linked by Hokuto here ] is also used to describe important ratios.  Since human vision (and hearing) is generally logarithmic it has become handy to use "stop" in this manner .

DxO uses a variety of terms , bits, ev, dB,  to measure (ill defined) "quality factors".    Many folks use the terms stop and ev interchangeably as they are both the logarithm (to base 2) of a ratio.  This is very handy in a binary world.

As a relative beginner, I am sympathetic to photogs who simply want to know what the heck is going on (often in spite of the terminology).  It appears that there is a lot of noise in the photographer's lexicon!


 GeorgianBay1939's gear list:GeorgianBay1939's gear list
Panasonic FZ1000 Panasonic Lumix DMC-GH2 Panasonic Lumix DMC-GX7 Panasonic Lumix DMC-GH4 Panasonic Lumix G Vario 7-14mm F4 ASPH +10 more
Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow