Ah-so! Eye-So!

[Basil]

This guy is one of my favorite YT channels that I follow.

 

[DrEntropy]

I've seen a number of his videos, the intro gets a bit tiresome after about the fourth or fifth one. The slider gets run up to the 1:00 minute mark. Good basic info even though Canon-centric. I've watched more Steve Perry ones. A Nikon guy. Picked up a couple good tips about control settings I'd looked for in the manuals with no joy.

 

[DrEntropy]

I watched his video on metering, his explanation about the 18% gray metering standard. I've mentioned this before; if you're in the same lighting condition as the subject and want a meter reading for overall 18%, use the palm of your hand as a pretty accurate substitute for a gray card.

 

[Basil]

I've seen a number of his videos, the intro gets a bit tiresome after about the fourth or fifth one. The slider gets run up to the 1:00 minute mark. Good basic info even though Canon-centric. I've watched more Steve Perry ones. A Nikon guy. Picked up a couple good tips about control settings I'd looked for in the manuals with no joy.

I skip past the intros on almost all of these YT videos. They all have them, but agree, some of the longer ones get old after you've seen it for a hundred times. Yes, he is a Canon shooter but basic info is usually relevant across the board.

 

[GregW]

I wish he had compared a shot at 200 ISO with the Ferbie at 2:25. Comparing a high ISO to an under exposed shot gives you some information, but two properly exposed shots will show how the noise becomes more obvious. Personally, I shoot as low an ISO that still gets a correct exposure.

 

[DrEntropy]

Still working to understand the capabilities & limits of these APS-C sensors here. And with homage to Zukav; "I Clutch My Ideas." The ISO part of the 'triangle' for me is also the lowest to yield a good exposure. A holdover from the film days, most likely. But also from looking at digital shots at varying ISO settings. That's one of the reasons for doing the "floating ISO" shooting. My nature is to get the shot first, framing in-camera tends to be: "if I have time." So cropping later makes the composition. Not ideal for images at higher ISO's from what I've been able to see. That could be a good argument for a full-frame sensor with high resolution, I s'pose. I get that 'saturating' the sensor with enough light to override the noise is the idea with high ISO, but there seems to be a point of diminishing return. A crop-sensor ISO around 3200~4000 is a 'wall' of sorts from what I've experienced. Keeping it at 800 or lower for most things is what works for me, and faster glass helps as well.

Just read this over, my terminology is Old School! "Resolution" would be determined by pixel count. What is 'noise' now, is 'grain' to my thinking, so lower ISO's equate to fine-grain emulsions. But the correlation is legit.

 

[GregW]

With film, there was a true exposure triangle. Different ASAs affected the exposure. With digital, the sensor has only one sensitivity, always. Digital ISO is more like always shooting 100 ASA film and pushing or pulling the processing. By setting the ISO in a digital camera, you are telling the camera's software what math formula to use on the file once the shutter and aperture have allowed a certain amount of light onto the sensor.

I guess you could say digital cameras only have an exposure line.

 

[Basil]

I used to worry about shooting at as low an ISO as possible, but with current state of the art gear I've learned it's not as big an issue as it once was.

These days I decide what F-stop I want based on lighting and/or how much background blur I want, or how sharp I need it to be corner to corner (f8 seems to be a sweet spot for most of my landscape shooting lenses). Then I decide what shutter speed to shoot depending on what I'm shooting and the conditions (i.e., is it windy causing leaves to blow around, etc). Sometimes shutter speed will take priority depending on the subject. I often (not always) set ISO to auto and don't worry about it (with this R5 camera). Even with higher ISO (10000 and higher), I find that something like Topaz DeNoise or even Lightroom's new DeNoise tool does a great job of greatly reducing noise. If Im shooting a static subject on a tripod, I'll sometimes turn on High ISO Noise Reduction and let the camera produce a low noise image, which works well but only for static subjects.

 

[DrEntropy]

With film, there was a true exposure triangle. Different ASAs affected the exposure. With digital, the sensor has only one sensitivity, always. Digital ISO is more like always shooting 100 ASA film and pushing or pulling the processing.

From that, it would seem 'optimal' to fix the ISO setting at 100. Any other setting would degrade the image to some degree? >kidding!<

By setting the ISO in a digital camera, you are telling the camera's software what math formula to use on the file once the shutter and aperture have allowed a certain amount of light onto the sensor.

So then actually, an 'auto ISO' setting should be a panacea for a proper exposure in about any instance?
Actually, it has yielded some good exposures, as long as 'exposure compensation' is set for the particular overall lighting conditions.

I guess you could say digital cameras only have an exposure line.

That makes the most sense. Triangles are so passé!

 

[GregW]

I went down a dark hole about base ISOs and Native ISOs. A lot of it was beyond me. Apparently, the base is not necessarily 100 depending on the camera model. Sony's F3 cine camera is 800. One thing I did find was dynamic range suffers at higher ISOs by a substantial amount. My camera goes from 13ish stops at 100 ISO down to 7ish at 12800 ISO.

 

[DrEntropy]

One thing I did find was dynamic range suffers at higher ISOs by a substantial amount. My camera goes from 13ish stops at 100 ISO down to 7ish at 12800 ISO.

I've not delved into the sensor details as far as that, but can understand there would be differences between manufacturers, given competition and R&D differences. The dynamic range variation from low to high ISO settings is enough to persuade me to keep to lower ISO's. I would take a WAG that it's even more dramatic in the APS-C sensors. May play around with that to see comparisons.

 

[Basil]

It is true that ISO affects a camera's DR - true for all cameras. The question is whether the reduction in DR matters for a given scene. I always (almost always) use a histogram on the rear of the camera and enable highlight alerts to make sure I'm not clipping highlights or loosing detail (that matters) in the shadows. Most of the time, when I shoot higher ISOs I get very acceptable results except in scenes where the DR of the scene is itself extreme. Most of the time it's not an issue that I notice.

Thomas Eisl here does a good job of demonstrating and explaining why super high dynamic range isn't often necessary. For me, as long as I'm not blowing out my highlights and I can recover details in the shadows in areas where I want detail, then I'm happy. That said, it is a fact that the higher the ISO goes, the lower the DR of the sensor. The question then becomes at what point does that make a meaningful difference in your image?

If you're interested in the DR vs ISO of your camera, check out this site where you can pick your camera (if it's listed) from the list on the right and even do comparisons.

Photographic Dynamic Range versus ISO Setting

www.photonstophotos.net

 

[DrEntropy]

So some doves came into the back yard a few minutes ago, I put the 70~300mm on the D7500 and dialed the ISO up to 2500. 1/800 sec. @ ∱5.6 Flat lighting (cloud cover).

Full frame:



Serious cropping:



Highlights all blown out but an 18% gray bird with spot-metering. The noise is there but considering crop factor, not horrible, IMO.

 

[Basil]

The brown leafs sort of cause the doves to blend in

 

[DrEntropy]

Eisl's final comments reminded me I used to refer to myself as "a panderer in reflected light images."

 

[GregW]

A followup video.

 

[DrEntropy]

Really like his: "sacrifice DR to get the shot" statement.

 

[waltesefalcon]

I'll be following him now.