[Oakland Rob]

It's not too bad when you write to a tag exiftool makes a copy and labels the original, original.

Dx0 can only be as complicated as good as the exif information is.

E.g I set a 55mm km lens as a fa 50mm it needed the max aperture and focal length to match and the LensID and a valid fnumber
you can do this in realtime too
e.g the picture is open in dx0 and you change a value it refreshes if it stays gray it doesnt have a matching module if it goes red it has a number of matches and if it is green it matched.

Heh. Clever, good work! More work than I wanna do, but good to know. I have often wondered why DxO doesn't at least allow manual selection of lens profiles (like where you know the lens is simply re-branded but otherwise the same). Nice to know that if necessary one could work around that.

[blackest]

Heh. Clever, good work! More work than I wanna do, but good to know. I have often wondered why DxO doesn't at least allow manual selection of lens profiles (like where you know the lens is simply re-branded but otherwise the same). Nice to know that if necessary one could work around that.

It works for canon too

I have an old hanimex 135mm f2.8 M42.

exiftool -FNumber="11"
exiftool -LensType="Canon EF 135mm f/2.8 soft" _V1H3533.CR2
exiftool -MinFocalLength="135" _V1H3533.CR2
exiftool -MaxFocalLength="135" _V1H3533.CR2
exiftool -AEMaxAperture2="2.8" _V1H3533.CR2
exiftool -MaxFocalLength="135" _V1H3533.CR2

This is what I did but

exiftool -LensType="Canon EF 135mm f/2.8 soft" -MinFocalLength="135" -MaxFocalLength="135" -MaxFocalLength="135" -FNumber="11" _V1H3533.CR2

Would work.

exiftool -LensType="Canon EF 135mm f/2.8 soft" -MinFocalLength="135" -MaxFocalLength="135" -MaxFocalLength="135" .
would have done the whole session
Fnumber I would be better to leave alone. with the chipped adapter i think you can dial it in.

working out the used aperture is a tad tricky

How i think it works is the camera measures the light coming through the lens and calculates an exposure.
green button metering stops down and calculates the difference in ev
and then calculates a difference in shutter speed.

I think the nominal max aperture is 1.2 to calculate a base shutter speed from. lets say its 1/180


stopping down results in a change in metered light lets say 2 EV so the shutter speed needs to be 1/45th

What we actually know is the ev measured at max aperture and the shutter speed used to take the photo.

The value for effective ev might be recorded as -3 but what we don't know is what evectiveEV was for the max aperture value it could be anything

[blackest]

Just an addendum:

With cameras like the K-x, you could also use [the late, great] PhotoMe to produce a JPEG showing a summary of the LV measured in each metering area:

The late great Photome, lives on and is very useful of the 16 metering segments in a k200d

1 is centre spot :12.6
2is centre edge :12.1
3 upper mid right :10.8
4 upper mid left :11.1
5 upper right : 11.0
6 upper left :12.2
7 mid right :10.9
8 mid left :12.9
9 right :11
10 left :12.8
11 lower mid right :13
12 lower mid left : 12.6
13 lower right :12.6
14 lower left :12.8
15 Top :11.4
16 Bottom :12.6

I am thinking that 1,2 are used for spot metering 12.6, 12.1
1,2 , 7,8 for centre weighted 10.9 12.9
all of them for matrix metering. (the rest).

1,2,7,8 = 48.5 total avg 12.125

EffectiveLv was recorded as 13.1
LV was 13.

and Light value ev100, for f8 and 1/125th iso 100 is EV13

next shot

Lightvalue 13.5 55mm 1/180th f8 aperture iso 100 (Exposure Calculator to Compare Any Two Camera Exposures) value is 13.5 which is nice

-2 exposure compensation
segments 1,2 7, 8 11.9, 11, 9.0 9.5 avg = 41.4/4 = 10.35
EffectiveLV 11.5

ho hum seems these are a series of bracketed shots so this one is underexposed 2 EV

Lightvalue 13 1/125 f8 iso 100

12.6 12.4 12.5 12.1 (12.4)
EffectiveEV =13 0 exposure compensation

next
exposure compensation -2
f8 1/500th (15EV)
Lightvalue 13
EffectiveLV 13

12.5 12.2 12.4 12.4 = 12.375

next
Exposure Compensation +2
f8 1/60th (EV12)
LightValue 10.6
EfectiveLV 13

12.6 12.4 12.5 12 = 49.5 = 12.375 ( just tried the -n option works out to 12.4)


Does any of this make any sense?
About the only thing i know for sure i had my camera set to bracket exposure 3 years ago

[geo444]

.
Huge work with exiftool on Pentax EXIF datas, congrats blackest !

... it has a Light Value in EV Calculated from the light...

.
Right, the Light Value at the end of EXIF datas is Calculated,

the formula : LightValue = Log² ( Aperture² * 100 / ( ExposureTime * ISO ) )

keeping ISO at 100, changes to : ExposureValue = Log² ( Aperture² / ExposureTime ) @ ISO 100

I built an utility SW 1st written in Pascal Language... in Delphi-Kylix around year 2k...
Now that every Browser supports the JavaScript Math.lib...
I just rewrote it in HTML JavaScript :

Camera Simulator, Exposure Calculator, Scene Light Value -49 to 69 Ev-Lv.

Please :
- don't change Ev-Step from 1/3 to 1/2 or vice versa...
- don't change back Ev-Step from 1/2 or from 1/3 to 1 Ev...
until I have time to fix the errors giving Non-Normalised Values !

Enjoy !

[blackest]

.
Huge work with exiftool on Pentax EXIF datas, congrats blackest !


.
Right, the Light Value at the end of EXIF datas is Calculated,

the formula : LightValue = Log² ( Aperture² * 100 / ( ExposureTime * ISO ) )

keeping ISO at 100, changes to : ExposureValue = Log² ( Aperture² / ExposureTime ) @ ISO 100

I built an utility SW 1st written in Pascal Language... in Delphi-Kylix around year 2k...
Now that every Browser supports the JavaScript Math.lib...
I just rewrote it in HTML JavaScript :

Camera Simulator, Exposure Calculator, Scene Light Value -49 to 69 Ev-Lv.

Please :
- don't change Ev-Step from 1/3 to 1/2 or vice versa...
- don't change back Ev-Step from 1/2 or from 1/3 to 1 Ev...
until I have time to fix the errors giving Non-Normalised Values !

Enjoy !

Its not pretty but its effective thank you.

[geo444]

Its not pretty but its effective thank you.

.
I'll work on its prettyness as soon as I finish with its effectiveness

the latest advances of the Camera Simulator in efficiency

Enjoy !

[blackest]

.
I'll work on its prettyness as soon as I finish with its effectiveness

the latest advances of the Camera Simulator in efficiency

Enjoy !

How about combining it with a dof calculator ? Link the aperture for the exposure with the dof calculator

what do you think?

[geo444]

How about combining it with a dof calculator ?
Link the aperture for the exposure with the dof calculator
what do you think ?

.
Hi Blackest !
I'm sometimes thinking about it for a while now...
but for the Astro-Photo., I've not so many opportunities to regret not having it

A fast, lightweight, Universal Utility Software such as the Exposure Calculator would be a nice idea,
not a Huge Collection of Constants engraved inside the code like MasterDoF is :
Exposure Calculator would have needed 2 856 Constants

the Exposure Calculator is a ~20 years old story, starting with Pascal, then Delphi-Kylix...
Now, re-written in HTML-Java-Script, so it's able to run on Every System,
I need a little more time to build something in my head...
at night... during Looong Exposuuures......

[blackest]

.
Hi Blackest !
I'm sometimes thinking about it for a while now...
but for the Astro-Photo., I've not so many opportunities to regret not having it

A fast, lightweight, Universal Utility Software such as the Exposure Calculator would be a nice idea,
not a Huge Collection of Constants engraved inside the code like MasterDoF is :
Exposure Calculator would have needed 2 856 Constants

the Exposure Calculator is a ~20 years old story, starting with Pascal, then Delphi-Kylix...
Now, re-written in HTML-Java-Script, so it's able to run on Every System,
I need a little more time to build something in my head...
at night... during Looong Exposuuures......

something like Free Depth of Field Calculator.
maybe

[K1N8]

For HDR i wanted to find all photos that were take using exposure bracketing while the shake reduction is turned off.

I used "exiftool -json" in combination with "jq", to have a little more control over what exactly gets changed. Don't wanna touch the DNG's by accident.

Close darktable and digiKam

Install Requirements

Code:

 sudo apt install exiftool jq

Create a big JSON file with all EXIF data (adjust file pattern as needed)

Code:

 exiftool -json -g 20??/*/IMGP????.DNG > db.json

From the JSON tree select all files that match auto bracketing and disabled shake reduction. (jq is a query language for JSON data.)

Code:

 jq -r '.[] | select(.MakerNotes.ShakeReduction == "Off" and .EXIF.ExposureMode == "Auto bracket") | .SourceFile' db.json > filelist

Given that every DNG file has a existing XMP sidecar file, add a single keyword "forHDR" to allow filtering in digiKam/Darktable.

The XMP "subject" tag might not exists and should not already contain the keyword, to avoid duplicates.


Test the condition without adding the keyword.

Code:

 while read L; do exiftool "${L}.xmp" -if 'not defined $subject or not $subject =~ /forHDR/i' -filename ; done < filelist

WARNING: Add the keyword to all sidecar files

Code:

 while read L; do exiftool "${L}.xmp" -if 'not defined $subject or not $subject =~ /forHDR/i' -XMP-dc:Subject+=forHDR ; done < filelist

Start digiKam / Darktable to re-load the sidecar files.

[angerdan]

An very interesting and techy Thread

Are there any news?