how to compare camera to mobile phone?

Started 1 month ago | Discussions thread
PhotoTeach2 Senior Member • Posts: 9,784
Re: Same settings.....

Tony Beach wrote:

PhotoTeach2 wrote:

The result was less than 1-stop discrepancy, which can easily be within margin-of-error considering it was indeed a phone w/ probably less-accurate ISO calibration, (compared to "real" camera where ISO calibration would be more accurate).

I'm sure you meant ISO "calibration," which is a misnomer as ISO is whatever the camera company says it is and does not reflect a standard of "accuracy."

Well, no ... there is a "standard"

What is the standard? I know it, but do you? It's arbitrary and it even says so.

Then why can I pick up a 50yo (properly working/calibrated) hand-held light meter, use it to arrive at proper "settings" on my brand-new digital, (or even cell-phone).

... and HE just PROVED it was closer than we had first assumed.

You assumed.

No I actually didn't "ass-u-me" ...

I made a mistake and missed f/2 thus incorrectly calculated I was (only) 2stops off and could not immediately account for the FACT his (camera) shot was additionally having to use ISO-2400 instead of 1200.

Thank You for noticing .... (should not make posts in bed w/ cell-phone @ 3am).

And here you mention "less than 1-stop discrepancy".

The additional doubling of ISO (1200 to 2400) would normally be another stop, (causing that image to be "1" stop lighter/brighter)

So since his (available "M") f/stop was MORE than "2" stops, and he could ONLY GAIN "2" stops w/ his LONGER SHUTTER-SPEEDS (from 1/4-second "to" 1/2s, "to" 1-second), he NEEDED that extra (1-stop from 1200 "to" 2400), ISO (lightness) boost.

He could shoot at about 2.5 stops higher ISO with his camera over the phone and get the same results.

The POINT is that he didn't have to make ANY (exposure/lightness) "setting" changes ... IF ... his "M" lens simply had f/1.7, (as phone did).

He could have used ANY combination of f/stops/shutter-speeds/ISO to make the necessary exposure/lightness offsets.

You mean that 2 images LOOK similar to each other to disregard the differences due to ISO calibration?

Yes, I would not trust the accuracy of a phones ISO, (or f/stop-SS), "calibration", so ONLY a 1-stop discrepancy is easily possible within margin-of-error(s).

Ugh -- see above.

Yes ... even less descrepancy

You need to understand what ISO represents, and then you will understand it is not subject to "calibration."

It is a preset "factory" calibration to keep ALL CAMERAS (exposure/lightness) CONSISTENT.

It doesn't apply to Raw, it only applies to Evaluative or Matrix metering, and it only applies to default camera settings. Go read up on the standard and learn what it means.

Just making sure that I understand

Do you understand that even with a Crop-Factor difference of 4.5, (between cell-phone and "M"), the EXPOSURE-SETTINGS did NOT CHANGE, (more than margin-of-error) ???

But you do indeed have a (4.5 stop) longer/deeper DOF and higher-noise w/ phone to "M". (4.5 stop shorter/shallower DOF and lower-noise w/ "M")

And of course there is the 6.1X CF to (FF) equivalent FOCAL-LENGTH.

So I repeat that "equivalence" is over-blown when they imply you cant shoot a smaller-sensor in lower-light.

You just PROVED the cell-phone does it W/ SAME EXPOSURE SETTINGS, (instead of 4.5 stops they want you to think).

Your so wrong it's ridiculous.


Look ... you were RIGHT about me "missing" f/2, (because I wrote it in BED @3am --- I think I correctly included it in an earlier post so I DO KNOW about "f/2") --

But NOW you are CONFUSING a beginner again after HE JUST PROVED YOUR WRONG about everything below.

He "MATCHED" the same "lightness" w/ SAME-OFFSETTING exposure-settings.

There are many ways to match brightness.

He matched it w/ "EQUALLY" offsetting "exposure" f/stops & SS, (& ISO-lightness), settings. They were "equal-offsetting" ... not 4.5-stops different which the "equivalency" gurus maintain it is.

You keep putting equivalency in quotes, and I get your agenda there, and (as I stated above) you are simply wrong about that.

Above I simply meant that for every "+" offset, you have to have an equal "-" offset.

That is exactly the intended way to "offset" f/stops and shutter-speeds for equal/same exposures, (when you want/need to prioritize either aperture or shutter-speeds).

It is exactly the REASON for "A" and "S/Tv" and "P" auto-modes. They will each provide the exact-SAME "exposure" .... but w/ different (offsetting) A and S/Tv settings.

What you are missing is that he can get the same shot shooting his camera at f/7 and raising the ISO to keep the exposure speed constant.

(1) You keep missing the POINT ... he didn't need to make a (total) 4.5-stop shift as the "equivalence" gurus claim.

(2) You keep missing the POINT ... he didn't need to make ANY (setting) changes if he simply had f/1.7 available on his (M) lens.

(3) The EXPOSURE/lightness SETTINGS WERE THE SAME, (after offsetting to simply allow for the different f/stop & SS combinations required).

YES .... the "noise" is 4.5 stops higher on cell-phone and DOF is 4.5 stops shorter/shallower on "M".

DOF and image quality are inextricably related.

Absolutely NOT

You don't understand equivalence, ISO, or have a grasp of image quality.

... in the sense that BOTH longer/deeper and short/shallow DOF have both advantages and disadvantages. (portrait photographers prefer short/shallow but most often longer/deeper is better for family/party/travel photography)

Yada, yada, yada... I could make the same sort of boilerplate statements about shutter speed.

Of course you could ... their are times when BOTH a fast or long shutter-speed is best, and BOTH then also require OFFSETTING corrections to again arrive at same exposure/lightness.

I consider it bad advice to reduce all the decisions a photographer makes to simplistic rules-of-thumb such as this. That said, this has nothing to do with image quality.

BTW, nothing stops a person from stopping down their larger format lens to match the DOF they get with a smaller format lens that has the same FOV.

To get the same DOF I would have on RX10 @ f/16, I would need f/45 on FF. How many (FF) lenses do you have w/ f/45 ???

And if I was using that f/16 in low-light and needed ISO-26,000, what ISO would I need on the FF, (@ same SS) ???

There are PRACTICAL limits -- but an UNNECESSARY discussion out of CONTEXT to this thread.

We are doing nothing but CONFUSING a "beginner" again ...

I do agree that NOISE and Image-Quality can be inextricably related, (IF the noise is objectionably noticeable).

Noise, like DOF, shows up more the closer you look at it. Improving the signal to noise ratio with a fixed shutter speed necessarily means you open up the aperture and correspondingly decrease the DOF. The entire concept of equivalency is that if you get a larger sensor thinking you will automatically have better image quality then you are ignoring real-world constraints such as changing the DOF at a given f-number for a given FOV at a given distance. Now no one says you can ignore the FOV or the perspective and reasonably say that you are taking equivalent photos with two different formats, but you and others who share your POV are arguing that you can ignore or even embrace a different DOF and then just accept the differences in image quality as "inherent" to the format used, and that's simply wrong.

IF/WHEN I want a short/shallow DOF, (or night-shooting in low-light), I select a FF, (simply makes things easier).

IF/WHEN I want a long/deep DOF, (or long-long-long tele), I select a 1/2.3", (simply makes things easier).

I do CHOOSE a 1" (bridge) simply because it is a fast/convenient COMPROMISE, (w/ continuous-zoom and "leaf" shutter that makes FILL-FLASH in SUN-light EASIER / SIMPLIER).

Take away the noise reduction and start from scratch with those files and see what you have. The smaller sensor is collecting less light overall, and that is reflected by the size of the lens pupils used in the f-number comparison where the pupil of the shorter focal length used on the smaller sensor is actually letting less light through than the smaller f-number but larger pupil on the longer focal length being used on the larger sensor.

But equivalence DOES APPLY to Focal-Length, DOF, and noise-level, (but noise may hot-water if below noticeable or objectionable level).

What I find objectionable about the images shown was the level of noise reduction applied, which wiped out resolution. What I find objectionable about your "teaching" here is that you hint at the relationship between equivalence and image quality and then dismiss it as unimportant. The reason equivalence IS NOT overblown is that it gives us a tool that shows that one can indeed match the output from a smaller sensor to a larger one if you understand that the actual pupil size of the lens being used has to be the same on both formats and that you can't match the results if you only match two of the three variables (FOV, shutter speed, and aperture size) that constitute equivalence.

Thank You again for noticing/pointing-out my (f/2) omission, but this is not helping the OP and I will only respond to SergeyAU again in this thread.

He probably could have used his in-camera metering system to arrive at his image, but I think he has LEARNED something from his "experiments" so it was all to a good purpose.

I am happy to continue to help him w/ further endeavors.

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