thanks for the explaination, but i had a play with a friends a7r5 and gave it back after 1 day as the larger pixel count showed no advantage shooting extreme macro, as the stacking programs stack noise into more noise and the a7iv is the only camera i have used that displays no noise at base iso and showed no diffraction, as far as more mpixel cameras displaying more detail that is only true up to iso 320 from there on the a7iv will resolve more detail. this is why no one shows skintone images as test images. the 3 DR charts i posted theres a curve ball in one of the images the pixels are the same size but the sensor is half the size displaying that DR is all about pixel size not sensor size. when i stack 300 images the cleanest single image stacked wins hands down.
Nov. 8, 2025
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Donald, I have no idea what you are talking about. Please stop replying to my posts in this thread.
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Ted, you are talking about DR as signal/noise ratio. Technically this is correct.
Donald talks about possibility to recover highlights and shadows - and not by measuring that, but judging subjectively about results. Much more practical criteria, but not so easily quantifyable.
Of course those approaches are not compatible.Or so did I understood last time and nothing seems different in current thread either :)
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Hello Arvo, I realize that you are trying to bring some sense into the insane conversation between Donald and myself.
No, I am talking about max possible signal divided by minimum acceptable signal (not SNR) usually expressed as EV. In other words, the "official" definition of DR.
In the same way, perhaps I could make up my own definition of camera sensitivity for example and post it in any discussion involving ISO - but still calling my definition "ISO setting" because that is the equivalent of what Donald is doing. He should not call the result of his method "DR" when it is not. Perhaps "RR" (Recoverable Range) ... 😀
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What is the difference between "noise" and "minimum acceptable signal"? In digital they IMO are closely related, often it is assumed that minimum signal equals the noise floor. This is easiest to understand and hardest to misinterpret. Sure this does not apply to processed results, but sensor readings (unaltered raw data).
Well, I didn't click on your links (sorry :)) but I vaguely remember that some sites devised their own measure of "minimum acceptable signal" - as long as they use their definition and methodics consistently, it allows to compare things.
Actually this RR sounds pretty correct :) And it characterizes everyday use better than purely technical DR values.
Anyway we as older Sigma cameras users should not talk about DR so much. 8 stops ought to be enough for anyone :)
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my pentax cameras were the same all around 8 stops, the funny thing is when i process images from my past k100,k10 on modern software shadow recovery is fantastic. back in the day you tested DR actually stopping down the camera and counting the stops of recoverable detail using neutral grey targets, if your shooting 9 stops your at the top level, how cameras are supposidly reaching 15 (eg my a7iv) is beyond provability in my books.
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In the Standard, the minimum acceptable signal is the level of luminance at which the SNR is unity i.e. 1.0 or 0 EV. Outside of the Standard, i.e. here, it is whatever Chuck Norris says it is, ho ho.
Yes, I agree that any consistent method is good enough for the purposes of comparison. For example, I often compare texture with Fourier transforms differently to the CPIQ standard www.imatest.com/imaging/cpiq/Quite so, Arvo. Bill Claff measured my SD9 long ago at 9 and a bit EV.
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Diffraction is a "Law of Nature" thing -- no such thing as "shows no diffraction". In fact, for the same DOF, all systems will show the same amount of diffraction (but not necessarily the same resolution, obviously). Usually, macro photography is well stopped down, so diffraction eats into any resolution advantage more smaller pixels have.
If you can show me photos of the same scene with the same settings displayed at the same size, and, if applicable, made by stacking the same number of photos, then we can discuss the matter in a meaningful way. I mean, c'mon, Don -- you remember when you were saying that a compact camera (Olympus XZ-1) was superior to a FF camera (Canon 5D2), right? And you remember the photos you posted to "prove" that point, right? Well, then you'll understand where I'm coming from on this matter. : )
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i have a very elaborate micro studio 8 years in the making , im shooting live subjects at 10x FF no crop stacking 300 images for me is a piece of cake using identical live spiders hanging from there web, i can post any number of identical stacked images from the a7r5 and the a7iv. stacking 300 images from a sensor totally trashes everyone's theory that pixel size doesn't increase DR which i find beyond logic 😊 microscope objectives are totally different to a macro lens, they are f4 you cant stop them down. i also make my own equipment which is what pisses alot of people off because i have chosen not to show anyone my set up I invented, and its not electronic but hand machined to my specs. i can stack more detail with my own tube lens design and lighting with a 50yo objective than that of the most expensive mitty objectives. again its all about the light is all im saying get rid of lens flare and a none coated vintage objective obliterates a coated objective 😊 no one can actually question my theories because they cant produce what im doing 😁 when they can they can enter the realm of extreme shooting. you all keep quoting others information instead of actually experimenting and looking outside the box. i had someone last year try to out do what im doing with MF he posted an image he thought was spectacular, so i posted the same subject and oops maybe i shouldn't of 😁
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always like a challenge
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One of the biggest hurdles that you are facing is that the image you are showing really do not have a high dynamic range, most can easily fit within the standard 8 bit jpg.
Until you start using the term DR in the context that 99% of the photographing community use it. With your images the last several stops of DR the camera is able to record is being clipped by the container you are placing them in so there is clearly not a DR problem.Until this is resolved I feel that we will be going around in circles just as we have done in the past
dprevived.com/t/iso-dynamic-range-what-is-going-on/7370/post/104469/
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DR has nothing to do with 8 bit 10 bit or 14 bit. 12 volt is the same as 12.00000000000000 volt unless you can show me it isnt 🤔 any image can be made to have 15 stops of DR in post 🤔 or is it only 8 to 9 🤔
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Everyone will go around in circles until he gets off his tangent. But I'm not sure that will happen anytime soon...
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Just ignore the thread then. It's not harming anyone 😂
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Piece of cake, Donald ...
"12-Volt" is a NOMINAL voltage rating which for a lead-acid car battery can be anywhere between about 11 V and about 16 V in practice, stupid decimals or not, and for a lithium-ion battery will be something completely different a la Monty Python ....
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Equivalence at its best. Just for you GB now tell me that the canon shot was better than a point and shoot 🤣 notice the 300% crop the canon couldnt even AF accurately, but it was the same in the twin studios as well that i shot side by side with my k7, the K7 destroyed it. looking back 13 years ago the gear was crap compared to now, auto focus was so bad revisiting some old pro shoots. canon colors were so off "red" tint compared to sony sensors.
