September 23, 2014, 06:18:04 AM

Author Topic: ISO 50  (Read 36499 times)

neuroanatomist

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Re: ISO 50
« Reply #135 on: January 22, 2013, 09:20:05 PM »
That they gain a head room and a better reproduction of the high lights if they shoot JPG  and don't know raw, under or over  exposure, post processing etc .

no -- that is not the mechanism that is the  benefit.  how will you explain the HTP mechanism, the effect of exposure, and the number of photons striking the sensor.
I have just done that  both by text  and by and illustration. Now its up to you and understand  :)

I don't think you have, Mikael.  Here is the question again:  when the camera's ISO dial is set to something besides 100 (I mean it it is set to 160, 200, 400, or 800 or 1600, etc. etc.) how will you explain the HTT mechanism, the effect upon exposure and the number of photons striking the sensor?

My point from earlier, the explanation is 'right' in the same way a broken analog clock is 'right' twice a day. 
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Re: ISO 50
« Reply #135 on: January 22, 2013, 09:20:05 PM »

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Re: ISO 50
« Reply #136 on: January 22, 2013, 09:28:43 PM »
That they gain a head room and a better reproduction of the high lights if they shoot JPG  and don't know raw, under or over  exposure, post processing etc .

no -- that is not the mechanism that is the  benefit.  how will you explain the HTP mechanism, the effect of exposure, and the number of photons striking the sensor.
I have just done that  both by text  and by and illustration. Now its up to you and understand  :)

I don't think you have, Mikael.  Here is the question again:  when the camera's ISO dial is set to something besides 100 (I mean it it is set to 160, 200, 400, or 800 or 1600, etc. etc.) how will you explain the HTT mechanism, the effect upon exposure and the number of photons striking the sensor?

My point from earlier, the explanation is 'right' in the same way a broken analog clock is 'right' twice a day.
Well, looks like Mikael stands by his Half The Photons theory. Choosing not to communicate on that statement is a communication in itself. Obviously he has a direct channel to the Photon God. So every time he sets his camera to HTP, his request for a reduction in photons is granted by that God...
That is the only logical explanation I can come to...
Over and out
(For now)
Mikael, get some sleep...

neuroanatomist

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Re: ISO 50
« Reply #137 on: January 22, 2013, 09:32:50 PM »
The time 0324 here in Sweden,
if you Neuro tell another person they are wrong
please point at the errors.

I have. Many times  I'd suggest the late hour is affecting your reading comprehension, but since I've told you several times now, at various times, that's not it.

In previous posts, you accused others of not being able to admit when they are wrong, and questioned our ability to read.  Ironic, isn't it...
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rpt

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Re: ISO 50
« Reply #138 on: January 22, 2013, 09:43:45 PM »
My G....   You  two Neuroanatomist  and Rpt  don't know the basic how a sensor works, collecting photons and if you are halving the time= go from 100 iso to 200 iso you are halving  the amount of hitting light/photons on the sensor  and  the amount of read out electrons by half.
God night
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babiesphotos

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Re: ISO 50
« Reply #139 on: January 22, 2013, 10:04:07 PM »
The time 0324 here in Sweden,
if you Neuro tell another person they are wrong
please point at the errors.

I have. Many times  I'd suggest the late hour is affecting your reading comprehension, but since I've told you several times now, at various times, that's not it.

In previous posts, you accused others of not being able to admit when they are wrong, and questioned our ability to read.  Ironic, isn't it...

Hey, I am an ex-eastern European.

Where I used to live, there are no interesting careers, not many opportunities to spend creative energy. Nothing changes ever, everyone is looking for a way to kill time, jobs are being held in perpetuality, and businesses are working on inertia. Wherever you are, whoever you are (unless you're researcher at University, or criminal :) there's no opportunity to get immersed in your work. Instead, one spends eternity in arguments with friends that cannot be won, over drinks, or numberless copes of coffee.

I've been 15 years in Canada, and I've changed a lot. And heck, no matter how much I changed, wife still accuses me that sometimes I argue for the sake of arguing :)

So, I'm guessing:
1. Mikael considers all of you friends :)
2. There is no winning argument with him, because for that he'd need to admit that he lost... :)

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Re: ISO 50
« Reply #140 on: January 22, 2013, 10:11:26 PM »
so regarding of the subject (motive with no high lights = motive with a small DR) you can overexpose and get a benefit of the over exposure in the shadows

That's great information, thanks! I'll certainly use that once I've got a 6d and am doing tripod macro focus stacks with low dr objects.
I do that regularly with my 5D3 to work around the shadow noise. Results are normally great.

Mikael, question to you, do I understand correct that you mean this is best for low DR pictures ie flatter? I learned through reading a couple of articles to also use this in more high DR situations like taking a street picture with the sun low. I have no experience of not being able to recover details from overexposed highlights. Is there something I'm missing here?

yes a picture turn out flat with a large DR  and which shall be presented in 0-256 levels, but you can adjust the motive so it do not look so flat with different kind of post processing, for example chose some parts and make selective adjustments
Thanks. I will play around with this and see what I can learn.

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Re: ISO 50
« Reply #141 on: January 22, 2013, 10:12:48 PM »
My apologies as this comes very late in the thread and may seem like a noob question but I am just curious to understand ...

What decides the number of photons that actually hit the sensor? Is it the Aperture and Shutter Speed Or does the ISO play some role in that?

From what I understood previously was that the photons hitting the sensor are the same for the same Aperture and Shutter Speed setting and an increase in the ISO only boosts the signal from the sensor. in other words, it was only when at a particular Aperture Value and Shutter Speed the available light entering the camera (photons) were less that the ISO would require a cranking up to boost signal from the sensor.

After all this discussion abovein the thread, I am quite confused as I don't have a science / engineering background.
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Re: ISO 50
« Reply #141 on: January 22, 2013, 10:12:48 PM »

neuroanatomist

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Re: ISO 50
« Reply #142 on: January 22, 2013, 10:31:19 PM »
My G....   You  two Neuroanatomist  and Rpt  don't know the basic how a sensor works, collecting photons and if you are halving the time= go from 100 iso to 200 iso you are halving  the amount of hitting light/photons on the sensor  and  the amount of read out electrons by half.
God night

Seriously?  Mikael, explain to us, step by step, how enabling HTP causes a change in the exposure time or the light/number of photons hitting the sensor.

Try this little experiment:

1. Set camera to M mode with HTP off
2. Set ISO 100, and set aperture and shutter speed to achieve a metered exposure.
3. Enable HTP.

Now, tell us - did the shutter speed change?  Did the aperture change?  If they did not change, how is the amount of light falling on the sensor any different?

I'm sure you'll point out that ISO changed to 200, and the meter shows a 1-stop overexposure.  So, if you now change aperture or shutter speed by a stop to again achieve a metered exposure, that secondary change halves the light. But you did that, not HTP.

Now...that was in the very specific case of ISO 100.  Repeat the above three steps, but in step two, set ISO 200 or higher.  Did the shutter speed change?  Did the aperture change? Try it again in P mode at ISO 200. Did the exposure change?  Explain how in those cases, enabling HTP reduced the amount of light hitting the sensor.  After you've explained that, please explain how a situation that arises in only a very limited set of circumstances, i.e. ISO 100 with an auto-exposure mode (Av, Tv, P) selected represents a general description of the 'mechanism of HTP'. After that, feel free to prove the general accuracy of that broken clock.

Or just ignore these questions, as you ignored dlleno's similar questions.  Answering them would mean acknowledging your mistake, something you're evidently incapable of doing.
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neuroanatomist

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Re: ISO 50
« Reply #143 on: January 22, 2013, 10:38:19 PM »
My apologies as this comes very late in the thread and may seem like a noob question but I am just curious to understand ...

What decides the number of photons that actually hit the sensor? Is it the Aperture and Shutter Speed Or does the ISO play some role in that?

From what I understood previously was that the photons hitting the sensor are the same for the same Aperture and Shutter Speed setting and an increase in the ISO only boosts the signal from the sensor. in other words, it was only when at a particular Aperture Value and Shutter Speed the available light entering the camera (photons) were less that the ISO would require a cranking up to boost signal from the sensor.

After all this discussion abovein the thread, I am quite confused as I don't have a science / engineering background.

Your previous understanding is absolutely correct.  Only aperture and shutter speed determine the amount of light (number of photons) reaching the sensor.  Any ISO setting other than base ISO (which differs by camera model, is usually in the 60-200 range, and is often not even a user-selectable value, e.g. ISO 80) is gain (analog or digital) applied after the collected photons are converted to electrons and read out from the photosite.

To be blunt, you can safely ignore the drivel that Mikael is spouting about changing ISO somehow affecting the amount of light or number of photons hitting the sensor.
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J.R.

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Re: ISO 50
« Reply #144 on: January 22, 2013, 10:49:55 PM »
My apologies as this comes very late in the thread and may seem like a noob question but I am just curious to understand ...

What decides the number of photons that actually hit the sensor? Is it the Aperture and Shutter Speed Or does the ISO play some role in that?

From what I understood previously was that the photons hitting the sensor are the same for the same Aperture and Shutter Speed setting and an increase in the ISO only boosts the signal from the sensor. in other words, it was only when at a particular Aperture Value and Shutter Speed the available light entering the camera (photons) were less that the ISO would require a cranking up to boost signal from the sensor.

After all this discussion abovein the thread, I am quite confused as I don't have a science / engineering background.

Your previous understanding is absolutely correct.  Only aperture and shutter speed determine the amount of light (number of photons) reaching the sensor.  Any ISO setting other than base ISO (which differs by camera model, is usually in the 60-200 range, and is often not even a user-selectable value, e.g. ISO 80) is gain (analog or digital) applied after the collected photons are converted to electrons and read out from the photosite.

To be blunt, you can safely ignore the drivel that Mikael is spouting about changing ISO somehow affecting the amount of light or number of photons hitting the sensor.

Thanks for confirming ... It's silly for Mikael to not accept this and defend an incorrect opinion, which in turn misleads others because he does seem to know what he is doing
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sanj

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Re: ISO 50
« Reply #145 on: January 22, 2013, 11:40:58 PM »
Here you have a old link , there is a comparison between the D7000 and one of my 5dmk2 three years ago
It is up to you or me how to handle large dynamic , but one thing is clear, it is  always better to have large DR , you have more freedom, exposure latitude etc etc, I will close the link after a day


https://picasaweb.google.com/106266083120070292876/DR5dmk2VsD7000

In your test Canon does not look as good as Nikon counterpart. I hope Canon fixes this asap. Talking JUST about sensor.
« Last Edit: January 22, 2013, 11:57:10 PM by sanj »

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Re: ISO 50
« Reply #146 on: January 23, 2013, 12:00:59 AM »
Yeah but if I overexpose a little I quickly loose details in highlights. I do not like that. For my tastes I prefer preserved highlights and richer blacks.

But sometimes the blacks are too dark and I want Canon to give me a little room to open up the blacks when I want to without noise increase. I know it already does give me room, but to my eyes Nikon seems to give bit more.

No stress, life goes on, photos get created. But it is nice to know what the other companies are doing. :)

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Re: ISO 50
« Reply #147 on: January 23, 2013, 12:47:53 AM »

In your test Canon does not look as good as Nikon counterpart. I hope Canon fixes this asap.
That is because he is not exposing for each sensors optimum performance, he is exposing them to the same absolute values, as I keep saying, if your goal is maximum dr then you must overexpose the Canon more, there is a lot more headroom in a Canon file than a Nikon file.

Confused about this. When I shoot I want to expose for what the scene demands rather than what my sensor is comfortable with. Don't u agree?

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Re: ISO 50
« Reply #147 on: January 23, 2013, 12:47:53 AM »

J.R.

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Re: ISO 50
« Reply #148 on: January 23, 2013, 01:05:30 AM »

In your test Canon does not look as good as Nikon counterpart. I hope Canon fixes this asap.
That is because he is not exposing for each sensors optimum performance, he is exposing them to the same absolute values, as I keep saying, if your goal is maximum dr then you must overexpose the Canon more, there is a lot more headroom in a Canon file than a Nikon file.

Confused about this. When I shoot I want to expose for what the scene demands rather than what my sensor is comfortable with. Don't u agree?

I don't, unless I'm shooting JPG. For RAW, I go for optimum sensor performance because the image will be post processed anyway and I need as much headroom / DR possible.
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Aglet

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Re: ISO 50
« Reply #149 on: January 23, 2013, 01:22:38 AM »
So for all your talk you can't post one image that demonstrates the totally unusable files you regularly got from real world shooting the 5D MkII? Amazing...........

I've got more important things to do this week than appease your impatience. :P
In the meantime, start formulating how you will describe that the banding i've experienced with my 5D2 is my fault. ;)  Especially the upper midtone range.  I really want an explanation for that one. [/cheeky]

And then outline how I can fix it with advanced PP skills.  i know you are good at this so hopefully you will share some of this knowledge with us.  I'd like to improve some of the shots that I otherwise like but have these little flaws that annoy me.

When I have time to prep the samples I'll be starting a new thread in this section.

Now I have to go retest a Nikon camera that they've serviced 3 times over 4 months and have made only more problems without addressing the initial one.
I'll give them that, Canon service in my area has been FAR superior to Nikon's.

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Re: ISO 50
« Reply #149 on: January 23, 2013, 01:22:38 AM »