Wanted: temperatures from your cams

[escho]

Hi Alex
I don´t understand very well, what your function does. What is MOD? And where is "-60" ?
Edgar

[a1ex]

MOD is the modulo operation: MOD(a,b) is from 0 to b-1 (a and b both int32_t, b > 1). C has the % operator, but that one gives negative numbers as well, which doesn't match what I've learned in the math class about modulo (see https://en.wikipedia.org/wiki/Modular_arithmetic ). That's why I've defined the MOD macro in imath.h.

And 150 * 40 / 100 = 60.

However, that definition wraps around at 102 degrees to 0, so it will fail at negative temperatures. A better version that works from -20 to 80 degrees is:

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#define EFIC_CELSIUS (MOD(efic_temp - 100, 256) * 40 / 100 - 20)

Before/after (efic_temp from 0 to 255):

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42 42 43 43 44 ... 101 101 102 0 0 0 1 1 2      ... 40 40 41 41 42
42 42 43 43 44 ... 81 81 82 -20 -20 -20 -19 -19 ... 40 40 41 41 42

I'm not sure at which point this number really wraps around, but at least this definition should cover the usual temperature range. If anyone wants to place his EOS M in a freezer or oven for measurements, that data would be welcome, but please be very careful with condensation and/or heat (you can damage the camera). Or, it may be safer to just find the conversion function in Canon code.

[escho]

Thanks for the explanaton, Alex. I must reflect a bit about this, next days...
Edgar

[escho]

I would like to use this one:

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#define EFIC_CELSIUS (MOD(efic_temp - 95, 256) * 40 / 100 - 22)
This would cover a temperature-range between -22°C and  +80"C

Temperatures under -20"C can be possible ( in Sibirien ) but when you turn your cam on, the temperature will rise.
And I guess, Canon will shutdown the cam reaching about 80°C
So this temperature range from -22°C - +80°C should be satisfactory.

Edgar

[escho]

I did some testing with 1200D.
See the table below. (A => RAW; B => EXIF (°C))
Looks like it is close to group 5 (0,6x-65).
What do you think?

Yes, group 5 should be fine:



Edgar

[escho]

The EOS-M temperature jump is fixed. Thankyou Alex 
Edgar

[JohanJ]

@escho
Here is data from 100D/SL1 w/ ML Beta-4a (magiclantern-Nightly.2016Oct05.100D101)
Tried to cool down the cam in the fridge for about an hour. First shot is therefor with lower temp, looks strange in RAW.
I took a picture in LV mode about every minute and tried to keep the cam busy with focusing in between.

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Time    RAW ExifC
0 143 15
1 144 24
2 146 26
3 150 30
4 150 32
5 155 35
6 156 36
7 156 39
8 159 41
9 164 42
10 164 44
11 164 45
12 164 47
13 166 47
14 165 48
15 172 49
16 172 50
17 173 51
18 173 52
19 172 53
20 174 53
21 174 54
22 171 55
23 176 55
24 176 56
25 175 56
26 180 57
27 180 57
28 178 58
29 178 59
30 181 59
31 178 60



[escho]

Thanks Johan

The data look pretty nice. I will have a closer look to them later next week

Edgar

[DeafEyeJedi]

Per @a1ex's request -- I was able to use this command line to spit out Camera Temperatures via exiftool with ease on Mac OS X:

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exiftool -CameraTemperature
rather than diving through the entire block with this:

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exiftool -U
unless you want to go for a swim. 

Anyway here are the results I got from doing the same test as @JohanJ earlier this week coming from @nikfreak's Nightly.2017Jan06.70D112 (with an exception that the body was left in an A/C controlled room at work to begin with for this test purpose):

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Time / RAW / ExifC
0  152 26
1  161 26
2  164 29
3  169 31
4  174 32
5  179 33
6  181 34
7  180 34
8  182 36
9  185 37
10 185 38
11 192 39
12 191 39
13 193 40
14 193 40
15 196 41
16 194 41
17 202 50
18 202 51
19 202 51
20 201 51
21 201 52
22 206 52
23 206 52
24 206 52
25 207 53
26 207 53
27 207 53
28 207 53
29 211 53
30 211 53
31 211 53

[escho]

Find some time to make the graph and formula for 70D: https://seescho.wordpress.com/2016/04/24/temperaturanzeige-mit-magiclantern/
The 70D fits fine to convertion-group 5. So I guess, we will take:

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0,6x - 65
I´m working on 100D

[escho]

And the 100D made its way through LibreOffice Calc, too. Formula and graph is on my website. Same link as one post before: https://seescho.wordpress.com/2016/04/24/temperaturanzeige-mit-magiclantern/

The 100D ist a cam for group 1:

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x - 128

[nikfreak]

thanx for 70D and 100D.

[esas]

Just bought a 70D, coming from a 650D and noticed that temperature was missing in latest nightly.

Here are the results from my test:

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133 6
138 13
141 15
146 16
151 18
156 20
158 22
161 23
162 24
170 25
172 27
175 28
173 29
181 29
183 32
185 34
188 34
189 36
194 37
191 38
194 39
192 39
197 40
196 41
201 42
202 44
206 45
209 47
207 47
210 48
211 50
217 51

I exluded some readings where the raw units changed before/after picture was taken.

[escho]

Thanks for the measurment. I will have a closer look into it next week.

[esas]

Looking at the previous results for 70D I think it's wrong to include several plots with the same values. This will bias the results. If you exclude the duplicates in DeafEyeJedi's test the result from my measurements and DeafEyeJedi's are not that far apart.