My first post here: image

rfkiii · 10-30-2015, 05:17 AM

Of course, I can only speak to how I operate and what I have observed, but as 2351HD alludes to, I allow a little clipping when it comes to the sun being in the frame. The image in the OP looks great (sorry, I can't get all super-excited about lifting shadows/underexposures as I have been using Sony sensors in Nikon cameras for a few years now - since the D3x) but I'd like to see it at full size. That's when you'll see the noise, if there is any.

Having said this, I prefer to avoid highlight clipping under normal conditions (sun at the back or peripheries) therefore I keep an eye on the highlight alert in the 645z's LV (since it has been confirmed that the preview comes off the RAW), and lower the EC until the alerts are gone. If it were not for the wide DR at base ISO (and trying to avoid crushing the blacks), it seems that I'd have highlight clipping in a fair number of the images even those not strongly backlit with the sun. This goes beyond lifting a shadow, This is lifting an underexposure of the entire frame. If a highlight clip does occur, it seems like it is harder to recover from with this sensor. Not complaining mind you but I don't work this way with Canon/Nikon products (even Nikon products with Sony sensors). I meter for a middle grey and then bracket and pick the best exposure during the PPing. Very seldom do I not arrive at a good exposure with this method. I use brackets too with the 645z and when I adjust EC to avoid highlight clipping, sometimes there isn't an image in the set that attains the neutral exposure. They are all -EC.

2351HD · 10-30-2015, 10:17 AM

Rfkiii, I agree.

The histogram is lacking on the Z. You can never get a full exposure that is ETTR by using the live view histogram.

I just don't see why they can't give a sensor readout that is accurate, we are only asking for the chip to tell us when a pixel is white.

You can get close, but 0.5 stop still has considerable data in it.

**clackers** · 10-30-2015, 11:28 AM

Originally posted by 2351HD

The histogram is lacking on the Z. You can never get a full exposure that is ETTR by using the live view histogram.

Histograms in cameras are from the JPEG.

You can't trust them.

You 645Z guys have a sensor that goes way beyond an 8-bit data format.

rfkiii · 10-30-2015, 03:35 PM

Clackers, I may be wrong but I remember seeing a thread here where it was determined that the 645z histogram in LV is read from the RAW file.

2351HD, I was not implying that the histogram is lacking (and at this point, I am neither agreeing or disagreeing with you on that issue). In reality, I am not sure how to articulate the difference in exposing with the 645z sensor/meter vs. other typical 35mm sensors/meters so maybe I should shut it.

**clackers** · 10-30-2015, 04:02 PM

Originally posted by rfkiii

Clackers, I may be wrong but I remember seeing a thread here where it was determined that the 645z histogram in LV is read from the RAW file.

If you can find it, Rfkiii, great, but I don't think its true of *any* camera. :-)

It'll be the histogram of the preview JPEG in the RAW file.

It'll say stuff is blown or black, and yet you can recover in post.

2351HD · 10-30-2015, 04:48 PM

Michael from Luminous Landscape in his review said that the live view on screen histogram was pulled from the raw sensor readout.

I usually dial back EC until highlight blinkers disappear then go forward 1/3 stop till they come back and I find that's about right when I get it into LR. Ymmv

**clackers** · 10-31-2015, 02:37 AM

Originally posted by 2351HD

Michael from Luminous Landscape in his review said that the live view on screen histogram was pulled from the raw sensor readout.

Well, he'd be wrong.

Did he give evidence of this?

It would be disingenuous to say that since the histogram is based on the JPEG and since the JPEG is based on the RAW, etc!

There is the small matter of 6 extra bits.

rfkiii · 10-31-2015, 07:49 AM

I first indicated the histogram (and blinkies apparently) was based on the RAW information but actually, Michael Reichmann (who was referenced in the aforementioned Pentax MF forum thread) said it is taken off the sensor (see excerpt below). The RAW file and the sensor may be two different things, I dunno, so, apologies for any confusion created.

https://luminous-landscape.com/pentax-645z-in-depth-review/

Fortunately the 645z has real-time highlight warning blinkies in Live View mode, and this is taken directly from the sensor. In other words, if something blinks red in Live View it’s blown. If it doesn’t, it isn’t. When displayed along with the histogram in Live View (which also has a red line to the right when anything is blown), you will be able to make technically optimum exposures. (Some experiments have shown that the camera’s real-time indication of “blown” coincides almost exactly with that of the histograms in Lightroom or Rawdigger.

10-31-2015, 07:49 AM	#23
rfkiii Senior Member Join Date: Apr 2014 Location: Texas Posts: 130	Possible correction I first indicated the histogram (and blinkies apparently) was based on the RAW information but actually, Michael Reichmann (who was referenced in the aforementioned Pentax MF forum thread) said it is taken off the sensor (see excerpt below). The RAW file and the sensor may be two different things, I dunno, so, apologies for any confusion created. https://luminous-landscape.com/pentax-645z-in-depth-review/ Fortunately the 645z has real-time highlight warning blinkies in Live View mode, and this is taken directly from the sensor. In other words, if something blinks red in Live View it’s blown. If it doesn’t, it isn’t. When displayed along with the histogram in Live View (which also has a red line to the right when anything is blown), you will be able to make technically optimum exposures. (Some experiments have shown that the camera’s real-time indication of “blown” coincides almost exactly with that of the histograms in Lightroom or Rawdigger.

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10-30-2015, 05:17 AM	#16
rfkiii Senior Member Join Date: Apr 2014 Location: Texas Posts: 130	Of course, I can only speak to how I operate and what I have observed, but as 2351HD alludes to, I allow a little clipping when it comes to the sun being in the frame. The image in the OP looks great (sorry, I can't get all super-excited about lifting shadows/underexposures as I have been using Sony sensors in Nikon cameras for a few years now - since the D3x) but I'd like to see it at full size. That's when you'll see the noise, if there is any. Having said this, I prefer to avoid highlight clipping under normal conditions (sun at the back or peripheries) therefore I keep an eye on the highlight alert in the 645z's LV (since it has been confirmed that the preview comes off the RAW), and lower the EC until the alerts are gone. If it were not for the wide DR at base ISO (and trying to avoid crushing the blacks), it seems that I'd have highlight clipping in a fair number of the images even those not strongly backlit with the sun. This goes beyond lifting a shadow, This is lifting an underexposure of the entire frame. If a highlight clip does occur, it seems like it is harder to recover from with this sensor. Not complaining mind you but I don't work this way with Canon/Nikon products (even Nikon products with Sony sensors). I meter for a middle grey and then bracket and pick the best exposure during the PPing. Very seldom do I not arrive at a good exposure with this method. I use brackets too with the 645z and when I adjust EC to avoid highlight clipping, sometimes there isn't an image in the set that attains the neutral exposure. They are all -EC.

10-30-2015, 10:17 AM	#17
2351HD Veteran Member Join Date: Apr 2013 Location: Brisbane, Australia Photos: Albums Posts: 750	Rfkiii, I agree. The histogram is lacking on the Z. You can never get a full exposure that is ETTR by using the live view histogram. I just don't see why they can't give a sensor readout that is accurate, we are only asking for the chip to tell us when a pixel is white. You can get close, but 0.5 stop still has considerable data in it.

10-30-2015, 11:28 AM	#18
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by 2351HD The histogram is lacking on the Z. You can never get a full exposure that is ETTR by using the live view histogram. Histograms in cameras are from the JPEG. You can't trust them. You 645Z guys have a sensor that goes way beyond an 8-bit data format.

10-30-2015, 03:35 PM	#19
rfkiii Senior Member Join Date: Apr 2014 Location: Texas Posts: 130	Clackers, I may be wrong but I remember seeing a thread here where it was determined that the 645z histogram in LV is read from the RAW file. 2351HD, I was not implying that the histogram is lacking (and at this point, I am neither agreeing or disagreeing with you on that issue). In reality, I am not sure how to articulate the difference in exposing with the 645z sensor/meter vs. other typical 35mm sensors/meters so maybe I should shut it.

10-30-2015, 04:02 PM	#20
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by rfkiii Clackers, I may be wrong but I remember seeing a thread here where it was determined that the 645z histogram in LV is read from the RAW file. If you can find it, Rfkiii, great, but I don't think its true of any camera. :-) It'll be the histogram of the preview JPEG in the RAW file. It'll say stuff is blown or black, and yet you can recover in post.

10-30-2015, 04:48 PM	#21
2351HD Veteran Member Join Date: Apr 2013 Location: Brisbane, Australia Photos: Albums Posts: 750	Michael from Luminous Landscape in his review said that the live view on screen histogram was pulled from the raw sensor readout. I usually dial back EC until highlight blinkers disappear then go forward 1/3 stop till they come back and I find that's about right when I get it into LR. Ymmv

10-31-2015, 02:37 AM	#22
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by 2351HD Michael from Luminous Landscape in his review said that the live view on screen histogram was pulled from the raw sensor readout. Well, he'd be wrong. Did he give evidence of this? It would be disingenuous to say that since the histogram is based on the JPEG and since the JPEG is based on the RAW, etc! There is the small matter of 6 extra bits.