ISO 50

[sanj]

@Micheal: Do you mean "the penny dropped"? 

So I am right? But is that not what Neuro has been saying and you disagreeing? Where lies MY confusion...?

Thx guy

[J.R.]

Ok we work the same way it seems. Even though I do not know what ETTR or YMMV mean.

ETTR ... Expose To The Right
YMMV ... Your Mileage May Vary

[neuroanatomist]

ETTR ... Expose To The Right
YMMV ... Your Mileage May Vary

TMBSITT ... Too Much BS In This Thread

I trust I don't need to spell out what BS means...   

[sanj]

[/quote]
Setting ISO 50 'causes' blown highlights only because you change aperture or shutter speed to maintain a metered exposure (relative to ISO 100). Not clear as I am still exposing correctly for both ISO.

The ISO change doesn't directly blow the highlights (if you change from ISO 100 to 50 in M-mode and then press the shutter, your meter will show a stop of underexposure).  Agree, basic even for me.

But when you change aperture/shutter to let in more light, that can blow highlights that would not blow at ISO 100. Dont understand why. As I am still exposing correctly.

Point being, if you're at ISO 100 with almost-blown highlights and need a slower shutter or wider aperture, ISO 50 won't save your highlights - you need an ND filter in that case. Agree. But I would attempt ISO 50 not to save the hightlights but to get even lesser noise.

[/quote]

[MarkII]

So, to summarise, what is happening is:

Camera Setting	Image EXIF Reports	Actual sensor gain	Actual metering gain	net effect
ISO 50	ISO 50	ISO 100	ISO 50	Brighter shadows; blown highlights
ISO 100	ISO 100	ISO 100	ISO 100	Normality
ISO 200 HTP	ISO 200	ISO 100	ISO 200	Highlights preserved; shadows burned

ie - ignoring any small shifts due the possibility that the 'native sensor base ISO is not exactly ISO100 - the only differences between the three modes are the metering and the subsequent processing to correct for the metering error.

If you shoot JPEG, the camera automatically compensates for the difference between the sensor and metering gain. If you shoot RAW, the file contains a flag that allows your RAW processor to do this. You can achieve a similar effect by simply using the exposure compensation setting and correction later - though the in-camera options will give better quality if you shoot JPEG.

The only real difference is in the exposure, metering and post processing. The metering gain changes really do mean that the number of photons hitting the sensor are affected by the mode setting - relative to the actual sensor ISO gain setting [edited for clarity].

Can anyone point out where this is incorrect?

[neuroanatomist]

neuro wrote

Do you understand that the case of enabling HTP when at ISO 100 in a an auto-exposure mode causing a halving of the number of photons is a unique case applicable only when at ISO 100 in a an auto-exposure mode?

yes I do, to create a head room which is described earlier

So, IF you understand that enabling HTP when at ISO 100 in an auto-exposure mode is a unique case only applicable at ISO 100 in an auto-exposure mode, THEN it follows that your explanation of the general mechanism of HTP as a halving of infalling light is WRONG.

Will you admit that?

even here you are missing the point, or do not understand, all started with that I explained it must be created a head room by under expose 100iso. Halving the read out electrons , halving the amount of light who are hitting the sensor. Some of you  " cough cough " start to argue against that. This is way the camera are changing from 100 iso to 200iso and make the exposure time shorter or 1 more F-stop from example F-4 to 5,6.= cutting infallng light by one stop  to hit the sensor
From 200iso and up the head room is created, and for evey iso stop or step  i the head room will be one stop  larger= the photons who are hitting the sensor is halving each  iso step because of shorter  exposure time/  or one more f-stop  aperture  and the  gain is increased  in every step / stop but only to the limit that there are still a head room left , then in the camera the software compensate  with another curve and roling softer in the high lights .

So, your actual answer to my question is, "No, I will not admit that I am wrong."

[neuroanatomist]

Yes, please go back to step one and explain how, at ISO 400 (or, in fact, any ISO other than 100), enabling HTP results in Half The Photons hitting the sensor.

We're waiting.

[marinien]

Yes, please go back to step one and explain how, at ISO 400 (or, in fact, any ISO other than 100), enabling HTP results in Half The Photons hitting the sensor.

We're waiting.

it doesn't, there already a head room created by halving  the signal / e  at 200iso  from 100iso , and agin a halving  from 200 to 400iso  and from 400 to 800 etc  etc , se earlier answer

Now I have a Sigma 35/1,4 to pick up and test/ compare to my canon 35/1.4

[J.R.]

TMBSITT 

[neuroanatomist]

Yes, please go back to step one and explain how, at ISO 400 (or, in fact, any ISO other than 100), enabling HTP results in Half The Photons hitting the sensor.

it doesn't

Finally.  So, before you stated that the mechanism of HTP was a reduction by half in the amount of light /number of photons hitting the sensor.  Now, you are finally admitting that's not true.

Perhaps not quite the mea culpa we could have expected, but it'll have to do.

Enjoy the Sigma 35/1.4 - by all accounts, it's an excellent lens and I expect you'll find it trumps the Canon 35L in many ways.

[Meh]

So, your actual answer to my question is, "No, I will not admit that I am wrong."

Why would he, he now has his "special case" to yammer on about to avoid dealing with his mistakes.  The most entertaining part is that the special case was suggested by someone else as a possible explanation for what he meant and now he adopts it like it's what he was talking about all along.

ETTR ... Expose To The Right
YMMV ... Your Mileage May Vary

TMBSITT ... Too Much BS In This Thread

I trust I don't need to spell out what BS means...   

You should have mentioned.... Too much NPD in this thread

[rpt]

          _______
         /              \
        /                \
       /                  \
      |       R I P     |
      |                    |
      |                    |
^^^~~~~^^^~~~^^^

                   

[sanj]

tre men waiting for a new canon 7d MK2 ?
se you

Hahahaha. Must say this is funny..... really. Good one!

[dlleno]

finally a breakthrough.  I really tried guys I really did.  I tried to get mikael to answer a very specific question and he avoided it with the great skill of an inkfish. 

[neuroanatomist]

So who am I, Oprah?!?