dandi Loc: near Seattle, WA

I just realized that I don’t understand what the difference is between
Light sensitivity and Low light performance.

Here is the example of Nikon D700 vs Nikon D7000 (just an example). These cameras have the same Light sensitivity but Low light performance of D700 is twice better. I copied the numbers from snapsort website.

Light sensitivity 6400 ISO, 6400 ISO
Low light performance 2303 ISO, 1167 ISO

Can somebody explain? Thank you.

jeep_daddy Loc: Prescott AZ

I think what they are saying is that the max ISO sensitivity SETTING is 6400 but they don't perform that well that high, and that the performance drops off (with noise and grainy images) with settings any higher than ISO 2303 and 1167 perspectively. I'm talking about acceptable noise.

Apaflo Loc: Anchorage, Alaska

That is indeed a very good question!

"Light sensitivity" could essentially be defined as what the lowest level of light would be that can be made to produce white levels in an image. Reduce the light more than that, and you get some shade of grey at best.

Of course most cameras can be set to a sensitivity that will make an image in light that is so low the camera cannot produce anything close to a decent image! Too much noise, to put it mildly. So at any given level of sensitivity, say ISO 6400 per your example, "Low light performance" is some measure of how little noise there is. The less noise the better. The usual way to compare two cameras is to list the ISO where the Dynamic Range is at some specified ISO thought to be acceptable.

Here is a chart (which you can change by clicking on cameras listed on the right side) produced by UHH member bclaff.

Photographic Dynamic Range Graphs

This shows 4 graphs, one each for the D7000, the D700, an ideal DX sensor and an ideal DX sensor. Also, if you click on the name of a particular graphed camera, up in the right hand corner of the chart, it presents a list of specific measured PDR values at various ISO levels, plus they give a value labeled as "Low Light ISO Setting". That is a "Low light performance" value based on a PDR of 6.5 fstops. The numbers for those two cameras are different than the ones you cite (nothing to do with dynamic range can ever be directly compared between different sites using different measuring methods), but they indicate pretty much the same thing! The D700 value is 2225, the D7000 value is 1394.

Note that no DX sensor is ever going to be better than the Ideal DX. Hence 3365 is the best a DX sensor will ever have for this performance figure. An FX sensor tops out at 4756. That is due inherently to greater pixel size (these are equalized for sensor with different size but the same number of pixels) of the FX sensor having lower noise. Of course if you have an FX sensor with more pixels, it will have smaller pixels and higher noise too. (It gets complex, eh!)

It's worth checking a few other cameras, to see what has changed in the years since those two were released. A D800 is lightly better than an Ideal DX. No DX camera is ever going to be as good at a D800 in that respect. It's Low Light ISO setting is 3852. But there is one that is a mind boggler too, check out the Nikon D5, with a Low Light ISO setting of 6982! The D5 can take a decent image, with 6.5 fstops of useful dynamic range, at 3 fstops less light than a D7000 can. That absolutely explains why a pro might spend the money a D5 costs!

dandi Loc: near Seattle, WA

- that's how I would summarize it.

I think you both are saying the same thing, thank you, it makes more sense now.

jerryc41 Loc: Catskill Mts of NY

Here's a comparison with cars. A car with 300 HP might be able to outperform one with 400 HP. Or, one car might be able to go 180 MPH, but it's barely controllable at that speed, while another can easily cruise all day at 170 MPH.

In any comparison, what really counts is what's usable.

jerryc41 Loc: Catskill Mts of NY

Right! When I read articles about cameras with ridiculously high ISO ratings, I often see that the higher settings aren't very useful.

amfoto1 Loc: San Jose, Calif. USA

It's the difference between quantity and quality.

Just because a camera is "extra sensitive" and can be set to ISO 102400 (and some actually can now be set even higher than that), doesn't necessarily mean that the image it produces at that setting will be of usable or "acceptable quality" for your purposes.... sensitivity versus performance.

For example, the Canon 7D cameras I bought in 2009 are settable to ISO 12800... but, in general I tried to keep them to ISO 1600 or 3200. I would sometimes use them at ISO 6400, knowing that I'd have to do some extra work on the images in post-processing to make them usable in some limited ways (such as not printed too large... maybe 8x10 instead of 11x14).

In comparison, the Canon 7D Mark II cameras that I shoot with now can be set two full stops higher... up to ISO 51200. But, while I will use them without very much concern at ISO 3200 and 6400... or with some extra post-processing to ISO 8000 and even ISO 16000... I still don't use the full ISO range that's available.

Heck, older cameras I used before the 7D I wouldn't shoot higher than ISO 800 or 1600 in some cases. Some of the earliest digitals I used.... small CCD sensor point 'n' shoots... I kept to ISO 200 max! And, it was actually the same with film. With slides, one of my favorites was ISO 50, though I used some ISO 100 that was quite good too. The fastest slide film I used was ISO 200. Color print film, I used some ISO 400. And with black and white, I used a lot of ISO 400, sometimes "pushed" to 800 or 1600.

Sensitivity versus performance. Quantity versus quality.

So, the next obvious question is.... Why have extra high ISO in a DSLR that you don't use due to quality limitations? I.e., "What good is the quantity, without the quality?"

Well, I'd rather have those higher settings available than not, even if I don't use them today...

First of all, for some purposes they might be partially usable. For example, occasionally I've used a really high ISO and then converted the images to black & whites that look pretty good. In my opinion, black & white tolerates high-ISO noise a lot better than color images. In B&W, image noise looks a little like film grain, which we're somewhat accustomed to seeing.

Plus, you really never know if a new version of post-processing software or camera firmware might offer a breakthrough that makes those higher ISOs usable. There have been significant improvements in noise reduction software over the years. And, I've learned some new tricks with the software, that have made it possible to use higher ISOs, and thus shoot in lower light situations than I'd ever dreamed possible.

toxdoc42

I wonder if someone can revisit this issue today, with the cameras available today. I still have a fundamental problem understanding the performance factor. With my new Z50, it is arguable that at IO 51,200 the photo is acceptable. I tried to remove some noise with PP, but the only program I have that will read the Z50's RAW files is the free Nikon processor and I really prefer Elements, my usual program.

I attached a few photos, I was unable to upload the RAW files, so uploaded the jpgs I made from the RAW files.

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Linda From Maine Loc: Yakima, Washington

You'll probably receive more attention if you start a new topic rather than comment in one that's 3+ years old. The person you used for quote-reply hasn't been on UHH for nearly a year. Many folks use the daily digest or "newest topics," so they won't see this at all, and others may not bother to open an old topic.

toxdoc42

I have been chastised in the past for starting a new post rather than searching for the answer.

I'll try later

Linda From Maine Loc: Yakima, Washington

There are a lot of grumpy old men on UHH. Ignore them (I'm not one 😇).

Also, anyone who suggests using the UHH search function has obviously never tried it themselves.