So how did you go about determining the extra dynamic range? Have you done that with your phone? I've been thinking the same thing but hadn't figured out how to go about it yet.
The uniwb and TLC do produce good results but are definitely fussy enough that I don't use them that often. Once I got the proper gel filters from eBay for the TLC, I had to figure out a way to attach them so that they stayed flat and could be easily removed. I tried adding them to a 37mm filter adapter from Moment (I have a Moment case) and adding them inside the case, but both ways the problem was keeping the gels flat. I got the best results by taking two thin pieces of cardboard, cutting holes in them to match the lens opening, using them to sandwich the gels, and then sticking them to the phone case with restickable tape. The gels stayed flat that way, though the cardboard definitely gave a funky look to the phone (not in a good way).
Hi. TRS,
Read this over and. If you would, and. when convenient, point out to me to any areas or points that aren’t clear or require elaboration.
If and when it’s content passes muster I’ll pare it down and condense and post it in continuum of the earlier posted introduction.
In the interim, it should answer your question.
Don’t be surprised when you find that your wide (1x) and tele (2x) cameras have different ERADR at the same ISO. Depending on the camera compared and ISO used, my wife’s and my iPhone cameras may have as much as a one and 1/3 stop difference in ERADR! Accurate testing is the name of the game!
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Is raw really for you?
First, if one’s interest is to display their photographic images only via online venues and as small prints, say no larger than 16x20, and one is not interested in creative/artistic post processing, there is really no reason to consider using raw exposure.
Raw exposure comes into its own when used to produce extra-large prints of high quality that are best viewed at normal viewing distance and under proper illumination. Also, any photographer who enjoys creative and artistic post-exposure processing will greatly enjoy the creative versatility provided by raw image files.
I regret not yet having followed up on my earlier promise to continue the saga of utilization of our cameras’ individual complements of extra raw-accessible dynamic range (ERADR).
So here goes!
It started with the concept of ETTR (Expose to the Right) - the idea proposed in 2003 by the late Michael Reichmann of Luminous Landscape who recounted a conversation with Tom Knoll ( author of Photoshop and Adobe Camera Raw - the basis of Lightroom) that one should expose a raw digital image such that the histogram approaches as closely as possible to the Right End of the camera’s Jpeg histogram frame without actual tripping the highlight clipping warning (blinkies or zebra stripes). In 2004 the late Bruce Fraser was next to expound upon proper raw image data exposure,
Proper raw exposure requires production of the brightest possible image without clipping highlight detail, but coming as close as possible to clipping without actually doing so!
Fraser also pointed out the necessity of determining how much DR there was actually available to use.
This premise of proper raw exposure has been repeated, or stated in words to the same
effect by Jeff Schewe, MartinEvening, John Shaw, D.J. Lloyd and other authorities.
The obvious corollary is that to achieve the stated goal that the entire available dynamic range must be utilized in the raw exposure.
Although many photographers had stumbled over the frequent ability to recover accidentally “overexposed” highlights by utilizing some extra DR to the right of the Jpeg histogram frame ( so-called DR “headroom”), it remained, as it does today, a topic about which the camera manufacturers are loath to discuss. It took a while before some photographers of the curious sort began to actually quantitate that “overhead”.
Long story short - turned out that a few sensors have 1/3 to 2/3 stop of ERADR; and about 75% to 85% have at least one to one and 1/3 stops ... and some have as much as two and 2/3 to three full stops of ERADR. Yes; it’s a crap shoot as to how much ERADR your newly purchased camera has. I have personally tested - or evaluated exposure series from - 45 to 50 interchangeable lens cameras. And, of course, my wife’s and my iPhones (11ProMax) each have the wide (1x) and tele (2x) cameras, each of which have had to be tested. I can confidently attest that the claim that there is no variation in DR among cameras of the same brand and model is total hogwash!
One third stop of ERADR, ‘tho minimal, is, indeed, still useful. The commonly found one full stop of ERADR is a wonderful Godsend in terms of increased image data quality ! And any ERADR beyond that is simply icing on an already exceptional cake allowing even bigger and better enlargements and amazingly increased latitude in post processing.
So....How to determine one’s camera’s ERADR?
Chose a scene under reliably constant lighting with a DR without excessive contrast and the histogram of which fits within the Jpeg histogram frame. An overcast sky or a scene in open shade on a sunny day are ideal.
Use a tripod or other sturdy camera support.
Set camera to capture raw ( with most smartphones use one of the several third-party apps that provide a camera able to deliver raw image data files; I use Lightroom mobile.) Which app you finally choose should provide what you feel to be a reasonably intuitive interface and - that is a highly personal decision).
Set to Manual
Set to some particular WB ( NOT Auto WB)
Set to a low ISO of 25 to 100 - (NOT Auto ISO)
The first requirement (challenge) is to find the ETTR (expose to the right) exposure that just barely fails to trip the highlight clipping warning of the Jpeg-adjusted histogram frame.
Then start a sequence of nine exposures to cover the possibility of actually finding if your sensor really has three full stops of ERADR; what the heck, if you are feeling lucky, shoot a series of twelve exposures). These exposures are quite inexpensive! Each sequential exposure should be incrementally 1/3 stop brighter ( with shutter duration1/3 longer) than the previous exposure.
When the series is complete, open each exposure in your raw converter (on my iPhone I use Lightroom mobile for my raw converter and for editing/post processing.) Tonally normalize each exposure by sliding the Exposure slider to the left.
I still find it amazing how such bright, washed-out images turn into tonally perfect images so easily,
Note that the “clipping” spike at the right end of the histogram disappears as tonal normalization moves the bright end of the histogram to the left.
Sooner or later you will encounter a frame in which that clipping spike persists through attempted tonal normalization.
That’s It! You’re done!
Count the frames between the ETTR exposure and the exposure with the persisting clipping spike and divide by three. The result is the number of full stops and parts thereof that constitute your camera’s ERADR at the ISO used.
Notice that I said: “...at the ISO used”. Although it is often claimed that EBTR must always be used at a low ISO, that simply is not true. It is a fact that as the ISO is increased there will be an irregular rate of decrease in Dynamic Range. The relationship of ISO and DR, although theoretically linear, in practice, and possibly related to the persistent phenomenon of “performance variance”, is anything but linear. It thus is useful to test your camera’s ERADR at ISOs you commonly use. The fact remains that regardless how high an ISO is used, the expected increase in captured noise will nonetheless be reduced if exposure is accomplished by full use of available DR by EBTR!
OK! You now know the camera’s complement of ERADR at the used ISO. Now how do I use it?
Pick a scenic view with a DR that fits within the Jpeg histogram frame; find the ETTR exposure, add the ERADR appropriate to the ISO used, and squeeze the shutter remote release!
That’s it! You have now joined the ranks of those practicing EBTR (Exposing beyond the Right)!
And again.... why do we go to the extra effort to use the maximum available DR?
To assure capture of image data of the greatest possible quality ( S:N ratio and tonal spectrum) permitted by the bit-depth of the file delivered by your camera ( a 12 bit-depth file from your iPhone). The difference between the 256 tonal spectrum of an 8 bit Jpeg file and a 1096 tonal spectrum from your 12 bit-depth iPhone file is amazing in terms of captured discernible detail.
To assure capture of an image file permitting you the greatest potential exercise of artistic/ creative initiative( beyond absolutely assuring accomplishment of the pre-visualized image you had in mind when you are the exposure.
More tonal spectrum means more potential cusps of potentially discernible detail.
Y’want to capture more image information? Go for the highest available bit-depth and be sure to use every bit of the available extra raw-accessible dynamic range!
Consider the contribution of the brightest stop used to produce the final image; it is responsible for at least 50% of the levels of brightness captured inthe entire image file! Failure to use just one stop of available DR forfeits at least 50% of that image’s potential image data quality.
Now go forth and be able to be rightly charged with “EBTR Raw Capture with Exposure Aforethought” ! That’s a definitely creditable charge upon which to be proudly judged “GUILTY AS CHARGED”!