The best..?

[Ysarex]

Ysarex,

On the Rawdigger histogram, how did the software know where the EV0 setting was placed? Is it in the Raw Camara data?

I'll have to check out this "Rawdigger" program, as it looks very useful.

Marc

Default is three stops down from the MAX value (14 bit raw file = 16,384) but it's user adjustable.

RawDigger: the best $20 bucks a photographer can spend. Indispensable!

 

[Marc Hildebrant]

I wonder where the three stops value comes from? I understand that the value is adjustable, but I would not know what the camara used.

Maybe the cr3 files contain a value.

Marc

 

[Ysarex]

I wonder where the three stops value comes from? I understand that the value is adjustable, but I would not know what the camara used.

Maybe the cr3 files contain a value.

Marc

I don't think RawDigger's histogram graph in anyway reflects or transfers a value from what the camera's metering system determined. The EV0 position on the graph is based on either the raw data values, or RawDigger's knowledge of the camera's ADC bit depth, or any value you the user wants to set.

The histogram has two basic display modes for the data. The default is laid over a) an EV scale in equal 1 stop units or b) an EV scale in linear 1 stop units (each stop twice as wide as the previous).

Here's the note in the instruction manual concerning the EV scale:

"Auto: automatic calculation of grid zero (gray point position) and setting grid step to 1EV. The zero is located at the level that is 3 stops (8 times) lower than the maximum pixel value rounded up (ceiling) to the nearest power of 2. For example, if the maximum value of all pixels in the photo is 3000, then the nearest power of two greater than this value is 4096 and the EV0 value for this photo will be automatically set to level 512.

The maximum can be determined either as the maximum pixel value in the currently opened frame, or as a theoretical maximum for the given camera. The setting that switches on the choice of the theoretical maximum for the maximum is available in Preferences – Histograms – Set histogram EV0 by (please see the chapter on Preferences below)."

 

[Marc Hildebrant]

With regard to the EX0 setting.

Rawdigger then is still useful as you can clearly see how much of the A to D converters range is used. I would think that with experience, you could set the EV0 location to a value based on your knowledge of your camara.

Marc

 

[Ysarex]

With regard to the EX0 setting.

Rawdigger then is still useful as you can clearly see how much of the A to D converters range is used.

That's the value -- you can analyze the actual raw data.
Back in the good old days when we shot film I had a densitometer that I relied on. When you exposed film how did you know if your exposure/processing was optimum for the film, over or under? Look at the negative? Try and make a print? No, you examined the negative with a densitometer and got hard data values.

When we switched to digital, same question; how do we know if our exposure is optimal for the sensor in the camera. Look at the camera JPEG? I never trusted the camera JPEG and I started working in digital feeling very uneasy. I was standing on sand not solid ground. I hated it but thank heaven along came RawDigger. RawDigger gave me back my densitometer and that gave me access to the sensors in my cameras.

I would think that with experience, you could set the EV0 location to a value based on your knowledge of your camara.

I'm not sure that's very useful because the metering system in the camera is a reflected light reading system. It will always contain a fudge factor based on the degree the scene and metering design vary from average. I no longer rely on my camera's metering system. I set exposure entirely from the camera's highlight alert and never allow the camera's meter to determine exposure.

I only process raw files and so I have no need to concern myself with metering for the curve-adjusted image the camera processor creates.

Marc

 

[Marc Hildebrant]

Ysarex,

Another post of yours mentioned that you use White Balance Set to unity. Does this allow you to then use the Live View to accurately show alerts?

If so, then how do you set the camara to WB unity?

Marc

 

[Ysarex]

Ysarex,

Another post of yours mentioned that you use White Balance Set to unity. Does this allow you to then use the Live View to accurately show alerts?

Yes. The live view highlight alerts in my cameras very closely match what I can expect to get in a raw file. I have to know how the alerts for each specific camera function. Setting an exposure then is the easiest thing I do.

There's a gas utility truck in front of my house right now (neighborhood getting new gas lines/meters). So I grabbed my Fuji X-T2, stepped out on the porch and snapped a photo of the truck. Lighting is hazy sun and the truck is painted gloss white. To set the exposure I first have to know that the highlight alert in my X-T2 is reacting to the simulated RGB JPEG in the EVF. The alert is designed to not fire if only one channel is clipping. It takes two clipped channels to activate the alert.

I have to be able to tell the difference between specular and diffuse highlights. I have both in this photo. Here's the camera SOOC JPEG reduced and annotated to identify the highlights I paid attention to.

And there's your uniWB green. That's what I see in my viewfinder. A lot of people can't deal with that. I spent my first 20 years at this with my head under a black rag looking at an upside down and reversed left to right image on a ground glass -- a green tint is trivial.

So to set the exposure I used the EC control and raised it till the highlight alerts were flashing on the truck's hood (two channels clipped). I adjusted the EC down until the alert was off the hood (I may still have the green channel clipped on diffuse highlights). One more tick down on the EC and diffuse highlights are not clipped and I'm exposing as much as possible -- click. No need to bracket, no need to second guess the meter. I wound up with a +.7 EC and exposure is nailed.

Here's the RawDigger histogram for that raw file:

It's a little hard to see but look inside the yellow circle and you can see a little green tick mark. That's the specular highlights clipping. One third stop more exposure and I'd have diffuse highlights beginning to clip the green channel. I can chose to do that if I know I need every last iota of DR. Software like C1 and LR do a great job at highlight reconstruction and they'll fill in the clipped data in the green channel from the not clipped data in the red and green channels.

In the case of this photo I adjusted so the highlight alert went off on the truck's hood and then minus one more third stop to have as much exposure as possible with no diffuse highlight clipping. I got exactly that. Once you've tested your camera (RawDigger) and know how the highlight alert functions it's foolproof.

Here's the processed photo from the raw file:

A final note about the green tint. It really is too much for a lot of people to handle. Once you white balance the raw file you never see it again but having to see that while taking the photo is arguably too much of a distraction. If instead you leave the camera set to something like auto-WB then the alerts will fire sooner. If you use the alerts in this manner then you'll be close and get excellent raw files to work with but may be underutilizing the sensor by 1/3 to 1/2 stop. I know a fellow who like me shoots with Fuji gear and he leaves the camera in auto-WB, adjusts the exposure until the alerts come on and then click. That's probably getting him very close to the same place I'm getting to and he doesn't have to see the green viewfinder.

If so, then how do you set the camara to WB unity?

Using in-camera histograms for ETTR - the last word

If you're interested in the whole topic, it's probably a good idea to read each section in order. If you just want to do the calibration and have access to Rawdigger, Photoshop, and Excel, read this: Preparing for monitor-based UniWB and do this: A one-step UniWB procedure. Acknowledgments Why...

blog.kasson.com

Marc

 

[Marc Hildebrant]

Ysarex,

Thanks for that example.

Marc

 

[greybeard]

In regards to cameras, is there a brand that is the best? Are there people out there who believe that is the case, or is it a level playing field these days..?

Is there a brand that you just really dislike?

Want to hear your opinions.

It all depends on the shooter's needs and what they are used too. I shoot Nikon because it is what I switched too when Minolta when under back in the day. Because I've been using Nikon for so long, I am most comfortable with their products. But, if I had started with some other brand, I would probably be just as comfortable with it.