Bonsia ~ Testing Depth of Field

[Ysarex]

Ermmmm. I think, if I keep ISO as low as possible, get best shot I can, learn from it and constantly look to improve, I am probably on the right track.

Errrrrrrr no. That's one of the faulty ideas my students show up with. They think raising ISO is the source of noise. They don't like noise and so they say to themselves "keep ISO as low as possible." They've also been screwed up by this idea that they can't be real photographers unless they use their camera's in full manual. The scenario: They want to take a photo in low light. Camera ISO is set to 200. They check the meter and discover they need a shutter speed of 1/8 sec. They know they have to raise ISO but that causes noise and so they resist. They figure they need to get the shutter up to 1/125 sec. but that forces the ISO to 3200. That's too high so they settle on a shutter speed of 1/100 sec and set the ISO to 1600 thinking they're close enough and they're holding the noise down. Using the camera in manual they can do that. They get a noisier photo having made matters worse. What they should have done was try the 1/100 sec. if they thought they could manage that but then set the ISO to 3200 or even higher at say 5000. In this case raising the ISO will reduce noise. Bottom line: the noise is coming from the exposure. The correct thinking is keep the exposure as high as possible but then raise the ISO as needed. Take a hard look at that photo I posted above of canning shelves. ISO is 25,600.

Joe

The key being I cannot get a good image from a bad one (as the example previously discussed) so get the best shot(sssss) I can.

Got to go I have a lot to learn.

 

[Designer]

Ermmmm. I think, if I keep ISO as low as possible, get best shot I can, learn from it and constantly look to improve, I am probably on the right track.

Now you're not just misinformed, you're also wrong because of it.

The people who tell you to keep the ISO as low as possible are wrong. Yes, I know that is about 90% of what you see on the internet, so you're going to have to start ignoring that information.

If you haven't already, have a look at Joe's low-light high-ISO photograph.

So now, you are probably wondering what to do with all that ISO stuff. Fair question.

I say for most photography, set your ISO to "auto" without any limit high or low. No need to fiddle with the ISO setting.

 

[TCampbell]

Ermmmm. I think, if I keep ISO as low as possible, get best shot I can, learn from it and constantly look to improve, I am probably on the right track.

Now you're not just misinformed, you're also wrong because of it.

The people who tell you to keep the ISO as low as possible are wrong. Yes, I know that is about 90% of what you see on the internet, so you're going to have to start ignoring that information.

If you haven't already, have a look at Joe's low-light high-ISO photograph.

So now, you are probably wondering what to do with all that ISO stuff. Fair question.

I say for most photography, set your ISO to "auto" without any limit high or low. No need to fiddle with the ISO setting.

As a broad generalization... you DO want to keep ISO low. But things get subjective at some point because what does "as low as possible" really mean?

"As low as possible" could be interpreted to just mean use ISO 100 all the time. But that's probably not realistic. I mean there's nothing stopping you from doing that... but you probably wont be happy with many of your pictures.

Camera lenses each have a finite number of aperture stops possible.

Suppose I meter a shot and determine that at ISO 100, that f/2.8 and 1/60th second would be a good exposure.

If the lowest aperture possible with the lens is f/4 then you can't shoot at f/2.8 -- the camera wont offer you that choice. To compensate, I could just keep the shutter open for twice as long. But suppose I'm hand-holding the camera (and we'll ignore image-stabilization features of lenses) and the slowest shutter speed I think I can safely manage given my lens focal length might be 1/60th sec.

If we keep the ISO at 100 then my f/4 lens limits my choices and the only thing left is to change the shutter speed to 1/30th sec. But the problem is... I can't hold the camera steady enough to get a clean shot at 1/30th sec. I could take it at 1/30th anyway and risk having motion blur (and that's pretty much a lost shot because there isn't much you can do to clean up motion blur).

OR... I could cave on the ISO and raise it to 200... now I can use f/4 and 1/60th and get a clean shot. Honestly... ISO 200 is probably going to look just as good as ISO 100 to most people and with most cameras. But there are limits to how far you can go before you start to notice the noise.

The thing is... we can't do much about the blur in post processing... but we can actually do something about the noise. Modern de-noising software is pretty good about cleaning it up. So given a choice between a blurry shot and a noisy shot, I'll take the noisy shot.

That's an example where refusing to raise the ISO would be detrimental. But what about using high ISOs?

Lets take a radically different approach... I should be able to crank that shutter speed up to 1/2000th sec (so now I definitely don't have motion blur from camera movement). From 1/30th sec... that's 7 stops up. So I crank the shutter up AND I crank the ISO up 7 stops to "compensate" and now I've got ISO 12800.

The problem with this is... you ARE going to see some noise at ISO 12800 (with any camera).

Before you say "But look at Joe's image"... I give you this: Elevating X-Trans? Fujifilm X-T2 Review
Flip the setting to RAW mode, crank it to 25600 (Joe's camera... Joe's ISO setting) and... you have noise (loads of noise). Of course you can flip it back to JPEG mode and much of the noise goes away... at the expense of some loss of detail.

If you value dynamic range, then there are technical reasons to avoid high ISOs. Increases to ISO result in decreases to dynamic range.

I do not (and I hope neither does anyone else on TPF) advocate that you just go out and crank up the ISO because you can and it's an equally valid exposure. Your shots wont look as good if you do that and I certainly hope it wasn't the intention of anyone here at TPF to mislead someone into that way of thinking.

Middle ground

All cameras look great at ISO 100. Most probably look great at ISO 800. Better cameras look great at ISO 1600. Some of the best cameras still look great at ISO 3200. But there is some point with every camera where you finally decide that you're no longer happy with the amount of noise.

I'll flip between low-ish ISO values without giving it too much thought. I wouldn't say you must use the lowest possible ISO. But I would use the lowest reasonable ISO. Even with ISO values that result in noise... there are ways to clean up noise.

You don't need to live in fear of raising the ISO above 100... but you should give consideration to your exposure and keep the ISO low when practical.

 

[Ysarex]

Ermmmm. I think, if I keep ISO as low as possible, get best shot I can, learn from it and constantly look to improve, I am probably on the right track.

Now you're not just misinformed, you're also wrong because of it.

The people who tell you to keep the ISO as low as possible are wrong. Yes, I know that is about 90% of what you see on the internet, so you're going to have to start ignoring that information.

If you haven't already, have a look at Joe's low-light high-ISO photograph.

So now, you are probably wondering what to do with all that ISO stuff. Fair question.

I say for most photography, set your ISO to "auto" without any limit high or low. No need to fiddle with the ISO setting.

As a broad generalization... you DO want to keep ISO low. But things get subjective at some point because what does "as low as possible" really mean?

"As low as possible" could be interpreted to just mean use ISO 100 all the time. But that's probably not realistic. I mean there's nothing stopping you from doing that... but you probably wont be happy with many of your pictures.

Camera lenses each have a finite number of aperture stops possible.

Suppose I meter a shot and determine that at ISO 100, that f/2.8 and 1/60th second would be a good exposure.

If the lowest aperture possible with the lens is f/4 then you can't shoot at f/2.8 -- the camera wont offer you that choice. To compensate, I could just keep the shutter open for twice as long. But suppose I'm hand-holding the camera (and we'll ignore image-stabilization features of lenses) and the slowest shutter speed I think I can safely manage given my lens focal length might be 1/60th sec.

If we keep the ISO at 100 then my f/4 lens limits my choices and the only thing left is to change the shutter speed to 1/30th sec. But the problem is... I can't hold the camera steady enough to get a clean shot at 1/30th sec. I could take it at 1/30th anyway and risk having motion blur (and that's pretty much a lost shot because there isn't much you can do to clean up motion blur).

OR... I could cave on the ISO and raise it to 200... now I can use f/4 and 1/60th and get a clean shot. Honestly... ISO 200 is probably going to look just as good as ISO 100 to most people and with most cameras. But there are limits to how far you can go before you start to notice the noise.

The thing is... we can't do much about the blur in post processing... but we can actually do something about the noise. Modern de-noising software is pretty good about cleaning it up. So given a choice between a blurry shot and a noisy shot, I'll take the noisy shot.

That's an example where refusing to raise the ISO would be detrimental. But what about using high ISOs?

Lets take a radically different approach... I should be able to crank that shutter speed up to 1/2000th sec (so now I definitely don't have motion blur from camera movement). From 1/30th sec... that's 7 stops up. So I crank the shutter up AND I crank the ISO up 7 stops to "compensate" and now I've got ISO 12800.

The problem with this is... you ARE going to see some noise at ISO 12800 (with any camera).

Before you say "But look at Joe's image"... I give you this: Elevating X-Trans? Fujifilm X-T2 Review
Flip the setting to RAW mode, crank it to 25600 (Joe's camera... Joe's ISO setting) and... you have noise (loads of noise). Of course you can flip it back to JPEG mode and much of the noise goes away... at the expense of some loss of detail.

If you value dynamic range, then there are technical reasons to avoid high ISOs. Increases to ISO result in decreases to dynamic range.

I do not (and I hope neither does anyone else on TPF) advocate that you just go out and crank up the ISO because you can and it's an equally valid exposure. Your shots wont look as good if you do that and I certainly hope it wasn't the intention of anyone here at TPF to mislead someone into that way of thinking.

No one was suggesting any such thing. The goal (at least mine) is to help break the thinking that raising ISO causes noise. It doesn't. What ISO does in a camera does not directly cause noise. Raising ISO biases the camera meter to reduce exposure and it's related to noise in that reducing exposure causes noise. The critical point is that the noise is coming from the reduced exposure. What ISO does as the image is processed in fact helps suppress noise and so the user shouldn't fear raising the ISO if indeed the circumstances warrant it. Sometimes the circumstances warrant it.

As for the methodology of setting a camera to auto ISO and letting the camera select it -- that can be a really effective way to work. The camera's programming works to keep the ISO as low as possible and if you want to remove the option from the camera of possibly selecting a compromise just put the shutter & f/stop to full manual -- the camera software won't have a choice then over the ISO.

If you're concerned about noise and loss of DR in a photo then you should think about maximizing exposure. Thinking directly about the cause and effect factors has an advantage over thinking about it circuitously through ISO -- especially for beginners who are more likely to get confused.

NEXT topic: My photo and DPR's testing. I never shoot camera JPEGs and that photo was processed from a raw file. Yes of course it was noise filtered. So six - seven stops of underexposure -- I can do that with my camera now photographing "normal" scenes and processing a raw file to a usable result without appreciable noise. Add a touch of simulated grain which looks good and it masks the noise and you'd be hard pressed to see it. Here's seven stops -- camera ISO set to 12K processed from raw: CDs and film Compare that to the test file at DPR for an X-T2 and I make their result look pitiful. You can download their raw file. I did and I examined it in RawDigger. It's nearly a full stop underexposed for ISO 12K!! No wonder it looks like bleep. I didn't do that with my photo and I have a much less noisy photo than they do -- noise is caused by underexposure. Stops are exponential. Think about how much more exposure I got than they got. If you're trying to avoid noise in your photos the biggest mistake you can make is to further underexpose after you've already underexposed for the ISO increase. That's like getting down on your knees and begging for it.

Joe

Middle ground

All cameras look great at ISO 100. Most probably look great at ISO 800. Better cameras look great at ISO 1600. Some of the best cameras still look great at ISO 3200. But there is some point with every camera where you finally decide that you're no longer happy with the amount of noise.

I'll flip between low-ish ISO values without giving it too much thought. I wouldn't say you must use the lowest possible ISO. But I would use the lowest reasonable ISO. Even with ISO values that result in noise... there are ways to clean up noise.

You don't need to live in fear of raising the ISO above 100... but you should give consideration to your exposure and keep the ISO low when practical.

 

[PJcam]

How easy it is to try describe something then realise one word, or a couple, can cause the message to read differently to that initially intended.

When I stated to keep ISO as low as possible, it didn't mean to set at it's lowest value, 100, when I said as low as possible what I really meant, or should have said, was as low as possible based on the metered values the camera provides. Therefore is the metered values for ISO are say 1600, then I should also consider using ISO 800, and it would be worth also trying ISO 1600. But the priority would be keeping ISO as low as possible (based on the metered values). Thanks for the comment and details you have provided Tim.

As a broad generalization... you DO want to keep ISO low. But things get subjective at some point because what does "as low as possible" really mean?

"As low as possible" could be interpreted to just mean use ISO 100 all the time. But that's probably not realistic. I mean there's nothing stopping you from doing that... but you probably wont be happy with many of your pictures.

Please accept my comments as a new student, what I know, (which is not a lot) I have learned in two weeks, which is not enough time to absorb much at all, so any replies or comments I post, with best intentions, can only be based on considering what I know and what has been stated in reply.

As for the methodology of setting a camera to auto ISO and letting the camera select it -- that can be a really effective way to work. The camera's programming works to keep the ISO as low as possible and if you want to remove the option from the camera of possibly selecting a compromise just put the shutter & f/stop to full manual -- the camera software won't have a choice then over the ISO.

The position I am at at present says to me that, there does appear to be more than one reason for Noise in a shot. I understand what you say Joe about trying to get people to break free from the Triangle Rule and ISO/Noise, but not as an alternative way of thinking but an additional way of thinking, after all there is more than one reason noise is evident in an image.

I say to myself, my camera is a mini computer, a very clever mini computer, but in the end that is what is is, a mini computer for capturing images and processing them. I then read your comment Joe, 'The camera's programming works to keep the ISO as low as possible ', the software in the chip or chips in the camera are... programming to keep ISO as low as possible. So this is saying to me, the manufacturers of cameras, more than one, are programming the cameras the same way, to keep ISO as low as possible.

So listening to the comments mentioned so far, I am thinking, as stated yesterday, I should keep ISO as low as possible, but at the same time, as stated in this message above, as low as possible based on the cameras metering for my shot. Therefore with keeping metering in my mine when taking shots, I should also consider the camera is 'programmed to do this' so I should also consider maybe one stop more than the camera suggested when it metered the shot, e.g. camera suggests ISO 1600, although I may consider ISO 800, or lower, there is nothing wrong with also considering ISO 3200.

I appreciate this post started as a test for DoF, and has changed considerably to ISO and Noise, but I do not see it as a problem as it was only a general test of DoF and the conversation has been mainly ISO and Noise. Maybe the title should be changed to A Test for DoF - ISO and Noise.I don't know how to or if I can change a title to a post.

 

[vintagesnaps]

These threads do tend to go a bit off track! lol It might be worth coming back and rereading it later on, then it might all make more sense. I think it can be a good way to learn by setting up your own shots and experimenting; sometimes what doesn't work can help you figure out what else will work.

I did get a laugh out of Joe's triangulators, or was it triangulars? I don't quite think the triangle is the best way to understand how aperture, shutter speed, and ISO work together. But it's all over the internet... I think there are a lot of places (blogs, Youtube, etc.) where people can put info. out there without necessarily having much expertise, and people learning photography might do better if they could unlearn some of what they learned online. I think what you're talking about is using the lowest ISO needed, rather than setting it higher than necessary. I'm a longtime film photographer and on occasion used higher speed film like 800 or 1000 ISO but never really liked them; the color and quality wasn't as good. Maybe that's along the same lines, I use 100 outdoors and 400 low light or indoors, etc. I don't get the best result using a higher light sensitivity than necessary, shooting film or digitally.

In the photo you posted, I think facing toward a window the meter could have been reading the light behind the subject. Sometimes I aim the camera downward to meter, then reframe. I'd consider backgrounds too, since even if it's out of focus there can be bright colors that can still be visually distracting. Also with your photo, you mentioned the tilt. I think that can work, but with this I wasn't sure if it was framed at a tilt or was just not quite straight. You might be interested in looking at a technique called 'canted' or 'Dutch' angle. (I think it being called Dutch was an inaccurate variation of Deutsch, because it was seen in German expressionist films.) It was used in movies like 'The Third Man', and I like the clip from the film 'The Conformist'; I like the way the car keeps following the guy, and the tilt just throws you more off balance about what is going on.
Columbia Film Language Glossary: Canted Angle (Dutch Angle)
The Third Man | Gene Siskel Film Center


Someone, I think maybe it was JC, mentioned Hedgecoe; I either have/have read the same book or something else by him. Or 'The Photographer's Eye' by john Szarkowski was good (not the book of the same name by Freeman, I wonder if people get them mixed up).