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Forum: Pentax Medium Format 08-02-2022, 03:17 PM

Should I buy a 645z or not?
Posted By RICHARD L.

Replies: 56
Views: 3,146

Forum: Pentax DSLR Discussion 05-04-2022, 10:07 PM

RAW: What is it Good For? Absolutely nothing..? Hmm yeah, say it again
Posted By Ian Stuart Forsyth

Replies: 155
Views: 9,845

It really depends on how you are judging the shot. if you are trying to use the camera this can create problems.
When you are going about taking the photo the cameras metering system it is based on the how the final image will appear with regard to the jpg output, if you are shooting raw there is a different way to go about exposure. Most cameras have a built in highlight headroom, also known as the baseline exposure (BLE) this tell the raw converter how much to lighten the raw data to place the tonal range of that raw data into the correct tonal range of outgoing image when using the cameras metering system . many cameras this can be between 1-1.5 stops. This can also vary on what iso setting is used as there can be a different BLE over the iso setting of the camera.

The next problem is how light is converted to that raw data and how the different color channels record that light. For most lighting situations we shoot in red, blue and green record at different levels, this is why we need white balance. If we where to shot a neutral white target and are able to see the raw data ( very few raw converters do not allow you to see this without proper configuration to them ) you would see that the green channel is exposed usually around 2/3 of a stop more to the blue and for the red it can be as much as -1 to -2 stops difference to the green channel (this is dependent on the camera manufacture and the sensor that is used)

here is set of neutral white and grey patch's and how they are being recorded. the circled are corresponds to the furthest right bump in the histogram as you can see that for the red is receiving much less light ( this was shot using ETTR so that the green channel was set for middle gray with an EC of +1.5 for this D800 camera

Next problem is that much of the clipping you might see in your raw converter can be clipping from the outgoing color space you have selected.

How much detail you can bring back really depends how you configure your raw converter, how you set your WB and the color space you select

Here is an example using the Pentax K7

Looking at the raw data there was less than 1/2 % worth of clipping in the green channel
Below is a better representation of how the data was recorded, It has a very strong green color as that was the channel capturing the most amount of light