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Posts for: Elmerviking
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Jan 22, 2019 14:01:00   #
(Main Photography Discussion)
Myth:- M + Auto ISO isn't manual.
RG..it is even simpler than you say when you,like most more advanced cameras, have command dials(wheels). For example on my Nikon D7100 the front wheel adjust aperture and the rear wheel adjusts shutter speed. With auto ISO you chose what is most important, either aperture (DOF) or shutter speed(camera or subject movement).
For example:
Landscape photography: You probably want more DOF and low ISO with the camera on a tripod.
So what to do
1/ chose aperture
2/Adjust Shutter-Speed until you reach the low ISO (probably base ISO=100)
Take the photo. Check result. Too bright? Set EC to minus take another shot and check and adjust EC if needed.
You have full control just as you say!


In the studio with constant light:
Exactly the same procedure. If nothing changes the auto ISO will not change!
Some here claim that the light is constant in a studio and they therefor don’t need to change ISO.
Auto ISO actually is an advantage even in a studio! The light intensity can vary due to sudden voltage changes. One of the lights can be dimmer without the photographer notice it. Murphy’s law...if anything can go wrong it will sooner or later! Auto ISO will adjust to compensate, which is an advantage.Fixed ISO will need a manual operation, iF YOU DETECT THE DIMMED LIGHT!
If the light suddenly changes ISO will change maybe one step..but nobody can tell the difference in noise!
To sum it up:
There is NONE advantage in choosing a fixed ISO!
It doesn’t matter if the rock has been in the same spot for millions of years...it doesn’t matter if you are in a studio or whatever.
Manual mode with auto ISO gives you full control in most situations!
The only exception I can think of now is when you use spotmetering where the exposure is measured where the focus point is. Then you have to lock in the ISO manually. But...if the light changes you have to adjust shutter speed, aperure or ISO. Handheld you can program a button, for example the Fn button to lock exposure, but you have to press the button down .,hold it pressed and take the photo.
Shortly..I agree with everything you said!
There is unf
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Jan 21, 2019 14:07:46   #
(Main Photography Discussion)
For beginers - Introduction to exposure
BebuLamar wrote:
No I am talking about the ISO rating must be specified with both the old ASA and DIN values not just the ASA value alone. Nowaday, I see most people only specify the old ASA number for example ISO 400 and not ISO 400/27.


It all depends of your background. I am Swedish, and we only talked about DIN, never ASA.
If you check B$H photo for example, they specify TriX as ISO400/21. They do never explain what 21 degrees stand for, but as an old film guy I know that it is the DIN “speed”.
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Jan 21, 2019 13:10:49   #
(Main Photography Discussion)
More Exposure and How It Works - A Beginner's Guide - Part 2
rmalarz wrote:
The key to this is "correct".
--Bob


Let me clarify:
UHH is a “ mutual admiration society “ that seems to hate people with different opinion even if the guy with different opinion is correct.
Many hoggers stick to their opinion even if they are proven wrong! Steve Perry for example pointed out that ISO is not sensor sensitivity but gain or amplification, but you still say that ISO is sensor sensitivity.
Is Steve Perry wrong or could it be that YOU are wrong?
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Jan 21, 2019 12:25:39   #
(Main Photography Discussion)
More Exposure and How It Works - A Beginner's Guide - Part 2
selmslie wrote:
I suggest that you read the article and what I said with an open mind.

I did not mention the Zone System until after Bob brought it up.

If you want to have a hissy fit and stop learning at this point, it's your loss. We will all benefit from your absence.


UHH is just a “ mutual admiration society”. They hate people with different opinion even if it is correct!
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Jan 21, 2019 11:37:52   #
(Main Photography Discussion)
More Exposure and How It Works - A Beginner's Guide - Part 3
I can’t see ANY illustrations! Where are they?
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Jan 20, 2019 15:53:14   #
(Main Photography Discussion)
More Exposure and How It Works - A Beginner's Guide - Part 2
rmalarz wrote:
Elmer, thanks for weighing in on this. That is appreciated.

The glasses represent the sensitivity. The lower sensitivity, taller glass, takes a longer time to fill appropriately. A higher ISO, shorter glass, takes less time to fill with equal flow of water.

The water represents the amount of light. The height of the glass represents ISO. It's going to take longer to fill a tall glass than a short glass. Thus, the tall glass represents the lower ISO.

I hope this clears this up for you.
--Bob
Elmer, thanks for weighing in on this. That is app... (show quote)



As I said, I am experienced (probably more experienced than most ppl here) and totally understand. You don’t have to explain to me. I just thought your description was confusing for a beginner. You don’t have to fill the 100 ISO glass all way up to the rim to get a good exposure. You just adjust to a higher ISO.
Or in other words..you don’t have to saturate the sensor to get a good exposure. Understand what I mean?
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Jan 20, 2019 14:47:52   #
(Main Photography Discussion)
More Exposure and How It Works - A Beginner's Guide - Part 2
rmalarz wrote:
Ok, folks, we’re off on another adventure in photographic exposure. Since a lot of you found the first installment ( https://www.uglyhedgehog.com/t-574357-1.html ) enjoyable and enlightening, let’s do another installment. This time it’s going to get a bit sloppy, as we’ll be using water, various sized containers, and a rather large pipe with some special fittings. The fittings are composed of a device which will permit us to vary an opening through which the water will flow, the DIAMETER fitting, (Aperture). This changes the DiAMETER from fully open to something the size of a soda straw. The other fitting is a VALVE, (Shutter). This VALVE can be opened and closed very quickly controlling how long the water can flow through the DIAMETER we set. These fitting are in line with one another.

Let’s start with our container. Imagine GLASSES Sensor or Film). These are cylindrical and vary in height (ISO), but all are the same size around. This is to keep things simple. For our lab work today, our job is to fill a GLASS. It doesn't matter which one. We just need to fill one. The very tallest GLASS is labeled 100. The next tallest size is 200, the next 400, 800, and finally 1600. The 1600 GLASS is the shortest of the group. The idea is that we need to fill whichever GLASS we choose right to the very brim. We can’t allow any water to run over the top. Nor, can we stop filling the GLASS short of right to the top. So, we don’t want to over fill or under fill whichever GLASS we choose to use.

Now our pipe with an unlimited amount of water is close to being the size of a fire hose. We can vary the inside DIAMETER with one lever marked DIAMETER. The other lever is marked VALVE. These are fitted in line in the delivery nozzle. So, let’s pick a GLASS and place it under the nozzle and start our adventure in filling a GLASS.

We’ll pick the GLASS marked 400. We leave our DIAMETER setting wide open. We take the VALVE lever and pull it open and push it closed. Wow!!! Water all over the place. The water came gushing out of the nozzle, hit the GLASS, overflowed, and it’s clean up time. That didn’t work so well, did it?. How to solve this problem. Let’s close the DIAMETER a bit. Since we don’t want another mess let’s close it quite a bit. We open the VALVE for the same amount of time and water flows at a much more manageable rate but doesn't fill the GLASS right to the top. Hmmm, we need to make another adjustment. We'll leave the VALVE open for a bit longer period of time. Ah, that worked. The GLASS is filled right to the brim and no overflow. Perfect!!!

What we’ve discovered is that the right combination of DIAMETER and VALVE allows us to precisely control the amount of water entering the GLASS and fill it exactly. At this point, we decide to experiment a bit. We notice that if we open the DIAMETER setting a bit, we don’t need to open the VALVE for quite a long to accomplish a satisfactory GLASS fill. We then close the DIAMETER setting a bit and we now need to leave the VALVE open for a longer period of time to accomplish the same satisfactory GLASS fill. So, there is a relationship between how large the DIAMETER is set and how long we need to leave the VALVE open and vice versa.

We have marked this relationship noting the setting indications on the DIAMETER and VALVE. So, let’s change the GLASS. We take the next smallest size, the one marked 200. We place that under our nozzle and have our DIAMETER and VALVE settings the same as with the GLASS marked 400. We open the VALVE and close the VALVE. Wow!!! The water only filled 1/2 of the GLASS. Hmmm. What happened? The GLASS is taller and therefore needs more water to fill it. We need to either open the DIAMETER a bit or open the VALVE for a longer time. It’s a matter of letting more water in, in the same amount of time, or letting the same flow of water in for a longer time.

After mopping up some of our missteps, we take a few minutes to ponder and observe. There seems to be a relationship between how much water is needed to fill the GLASS we choose, the size to which the DIAMETER is set and how long we leave the VALVE open. We also notice that we can fiddle with the DIAMETER and that requires us to fiddle with the VALVE and vice versa. We further notice that if we change the size of the container, we have to adjust the DIAMETER or the VALVE, or both accordingly to obtain a satisfactory fill. With all of this filling we concluded that if we change one item, we have to change something else to accomplish the same perfect fill.

We also notice an oddity here. There seems to be somethings that don’t make intuitive sense. The larger the number on the GLASS the smaller the GLASS. We also notice some setting markings on the DIAMETER and the VALVE. The first marking on the DIAMETER is a small number, but the opening is the largest. As we move to larger numbers the opening gets smaller. It’s odd, but with practice, we’ll know exactly the DIAMETER we’re setting and can repeat that setting whenever we want. The same can be said of the numbers on the VALVE. There's a whole number, 1, followed by fractions. The smaller the number on the bottom of the fraction, the faster the VALVE will open and close.

Well, we’ve been at this quite a while now, and it’s getting late. What’s going on? It seems that the later it gets, the less water pressure we are seeing in the system. No worries, we can still fill our GLASS, but we’ll have to adjust for the less pressure by using a larger DIAMETER or leaving the VALVE open longer. If we really need to get a GLASS filled, we might have to choose one of the ones marked with the larger number. Remember the object is to fill a GLASS, we’re not fussy about which one.

This, very simply put, is the way exposure works in your camera. The light-sensitive material is the SENSOR and ISO (GLASS and its SIZE), it can be set to fill more quickly or slowly as needed. Once set, the SHUTTER (VALVE) allows light to flow through the lens for a precise amount of time and the APERTURE (VALVE) controls how much light can flow through. Working together, under your control, the correct settings are made and the optimum exposure is accomplished.
--Bob
Ok, folks, we’re off on another adventure in photo... (show quote)


I appreciate your effort to explain exposure for beginners. But...it doesn’t work for me if I pretend to think as a beginner. Here is why:
You have same diameter glasses and say that they represent sensor AND ISO. A taller glass represent lower ISO?
That is for a beginner really hard to understand.
The fact is that no matter how you change “the diameter” (aperture) or how long you fill the glass (shutter time) or HOW MUCH YOU FILL THE GLASS (half full or any fraction) you adjust ISO to give you the “correct”exposure.
The size of the glass actually represent amount of light hitting the sensor which has nothing to do with ISO!
As I read it (thinking as a beginner) more volume is lower ISO.?
To a beginner I would say that it doesn’t matter what aperture you use or what shutter speed you use..you can always get a correct exposure by adjusting ISO.
The time might be to long and give you motion blur, the aperture might be to small or too large and give you unwanted depth of field, but that is another issue. Too high ISO will give you unwanted noice etc.
Well, I am very experienced and understand what you are saying, but honestly doubt a beginner will.
I don’t mean to underestimate your effort, I am just giving my opinion...like it or not.
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Jan 20, 2019 12:23:19   #
(Main Photography Discussion)
Exposure and How It Works - A Beginner's Guide - Part 1
ggenova64 wrote:
Thank you Mr. Bob
Now I have a better concrete understanding of the balance.
ISO is Camera.
Aperture (AKA F-Stop) and Shutter Speed is that 1:1 Relationship.


LOL....you got it!
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Jan 20, 2019 01:21:22   #
(Main Photography Discussion)
For beginers - Introduction to exposure
BebuLamar wrote:
It's supposed to be marked that way. Marking only the 100 number is not correct. The ISO has 2 numbers and not 1.



Ha,ha...nobody noticed that I mistyped! The marking is 400/27 degrees there 27 degrees is the old DIN speed.
BebulLamar...what are you talking about? ISO 400 is 27 degrees DIN
ISO 200is marked 200/24 degrees
ISO 100 is 100/21 degrees and so on
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Jan 19, 2019 22:58:37   #
(Main Photography Discussion)
Exposure and How It Works - A Beginner's Guide - Part 1
Are many beginners going to UHH to learn basic understanding of exposure etc.?
Is this the right forum to learn photography?
Just wondering.
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Jan 19, 2019 18:19:05   #
(Main Photography Discussion)
Exposure and How It Works - A Beginner's Guide - Part 1
selmslie wrote:
Then you are not the one who is "totally confused". Maybe my explanation will help johntaylor333.


I’m on your side selmlie!
They complicate it too much, specially for beginners!
It’s simple:
If the picture is to dark you can chose
1/ Higher ISO or
2/ longer shutter speed or
3/ bigger aperture
If the picture is too bright:
Lower ISO or
Faster shutter speed or smaller aperture.
Voila!
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Jan 19, 2019 17:47:17   #
(Main Photography Discussion)
Exposure and How It Works - A Beginner's Guide - Part 1
selmslie wrote:
At a fixed ISO, more exposure collects more photons and record as bigger numeric values in the raw file.

At a fixed exposure (constant number of photons), a higher ISO records bigger numeric values in the raw file.

You can blow out the raw file when you reach the maximum recordable value (16383 or '11111111111111' for a 14-bit raw file). That can happen if the ISO is too high for a given exposure or if the exposure is too much for a given ISO.


That is what I said. Number of photons on the sensor gives a certain input. Higher ISO gives a higher output of the signal from the sensor and vice versa. Too high ISO can give blown out highlights as you said. Maybe we talk about the same thing but in different wording?
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Jan 19, 2019 17:16:20   #
(Main Photography Discussion)
Exposure and How It Works - A Beginner's Guide - Part 1
johntaylor333 wrote:
ISO is similar to film speed, but not quite the same.

When you change the ISO setting on your camera, you are changing "the sensitivity" of the sensor. Basically when you are at a low ISO (e.g. 100), you will have more photons (basic units of light) per pixel and therefore a low noise image. Go to a high ISO (e.g. 6400) and you have fewer photons per pixel and a noisier image. I think of ISO as the time the sensor collects photons (which are converted into electrical charge); it's not the same as the shutter speed but obviously you are only collecting photons for the time the shutter is open (or less if you go to high ISO).

The reason why long sensor integration times give lower noise is that most, but not all, of the noise in a CMOS sensor is thermal (shot) noise and that noise is equal to the square root of the number of photons. So if you double the number of photons, you improve the S/N ratio by 41% and so on.

Is everyone suitably confused yet?
ISO is similar to film speed, but not quite the sa... (show quote)


Yeah...I am totally confused! You are saying that ISO is sensitivity(?) and higher ISO collects less photons?
Sensitivity is either Volt/number of photons or number of photons/V. The sensor sensitivity does not change, what is changing is amplification. Less number of photons need more amplification (higher ISO) to present a viewable picture. The more amplification=the more noice! This has been discussed a number of times here.
ISO is in a way comparable to film speed, but not exactly the same.
It is the amount of light (number of photons)that is collected on the sensor that determines what amplification you need of that “signal” to view the picture. Complicated?
Shortly said:how much light that is hitting the sensor has to be balanced against ISO.
More light=lower ISO
Less light=higher ISO
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Jan 19, 2019 11:08:11   #
(Main Photography Discussion)
Experience with your Nikon 18-140 lens please.
One minor problem is that you have to refocus if you zoom in or out. Not a big deal, you just have to be aware of it.
High end zoom lenses lets you zoom in and set focus and zoom out to what composition you need without refocusing. ( My old Nikkor 80-200 Ai works that way, but that is a professional lens)
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Jan 19, 2019 10:23:53   #
(Main Photography Discussion)
Experience with your Nikon 18-140 lens please.
According to dxo-mark it is the sharpest lens in the category!


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