Originally Posted by
William W
The following comment is in respect of Canon DLSR Cameras and based upon my observations and it is a synopsis of my hypothesis of HTP functionality.
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I conclude that HTP does affect the raw file.
It occurs to me that if HTP enabled the camera underexposes by (about) 1 stop. This logically seems to be done by lowering the ISO.
This lowing of the ISO, might be akin to how the camera actions the selection of the “intermediate” ISO, such as: ISO 500 & ISO 640; ISO 125 & ISO320 etc.
This data IS recorded to the RAW file.
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In-Camera JPEG conversion:
When the camera generates the JPEG file it occurs to me that the HTP flag is noted and a curve is applied to boost the shadows and mid-tones without affecting the highlights. HTP is useful for shooting JPEGS, to achieve this effect, SOOC.
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Post Production Programmes:
It occurs to me that when (most) Adobe Products see the HTP flag they automatically boost the exposure slider by one stop.
It occurs to me that Canon DPP manages HTP, slightly differently. When DPP sees the HTP flag set on the underexposed RAW file, it applies a different curve in the RAW conversion which again will selectively boost the shadows and mid-tones by about 1 Stop and not the highlights – this is something like what the camera does when making the JPEG file in-camera.
The value of HTP in regard to shooting JPEG:
If one IS shooting a scene of wide Dynamic Range - there is the potential of the raw data to be recorded in suitable appropriate dynamic range but the highlights being blown when a “standard” JPEG conversion curve is applied to the raw data to generate the JPEG (in-camera).
So, (as per the Canon User Manual), HTP has a useful application for those who use JPEG capture.
I think this is where the concept that ONLY the JPEG data is affected comes about.
But, the fact (my hypothesis) still is - that when using HTP the raw file is indeed, affected.
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The value of HTP in regard to shooting raw ONLY:
One might choose to use HTP for raw capture: if the idea of (generally) underexposing at capture time and then boosting the shadows and mid-tones in post-processing is a good approach. I cannot see that there any end-game advantage in this practice, however.
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The value of HTP in regard to shooting raw + JPEG:
I shoot raw + JPEG(L). I do see an advantage of using HTP, sometimes: this is when I expect that my JPEG file will be used (quickly) SOOC, or with minimal Post Production.
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Although it appears that HTP has a scatty RANGE of responses (outcomes), depending upon the type of lighting on the scene; I have found HTP quite predictable if one often shoots in similar lighting scenarios: which I do.
I think that if you (Steve F) really want to understand HTP and assess any potential value of the function to your Photography, then you need to give it a lot more a go than merely “a brief play at lunchtime” and also I suggest that you need to consider how the HTP function might be applied to which of the (maybe repetitive) specific shooting scenarios in which you find yourself. To that end, I suggest that you first question the reasons for your shooting (only) JPEG.
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There are many discussions about HTP in various forums.
All the conversations which I have read where Photographers have used HTP and have also made specific A/B comparisons of both their raw and JPEG files (and Post Production Programmes): their results concur, along similar lines, to mine which I have outlined above.
I have not seen any definitive paper from Canon, which outlines the detailed functionality of HTP.
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P Mode:
It may have been a tongue on cheek comment, but I shall nonetheless respond:
"P Mode" is the most misunderstood (and also maligned) of all the Automatic Camera Modes.
P Mode can be an exceptionally useful Camera Mode and it would bode well for a complete understanding of the functionality of P Mode, especially if one is charging money to shoot Weddings, using a Canon EOS DLSR: and especially if one is shooting JPEG only.
Perhaps the functionalities and usefulness of "P Mode" ARE indeed understood by you and that was why the comment was made, linking P Mode and Weddings and HTP.
This would indeed make sense to me.
WW