White point in camconst.json


I have recently determined the white point(s) for my Nikon D800. They are the same as the data shown for Nikon D800E in the camconst file on my installation of RT. So, question: will the D800E data be used for my images despite the slightly altered camera name? Or do I need to edit the camconst file?

(Ingo Weyrich) #2

@mikesan IIRC it should match for this case (D800E contains D800 character-wise)


Hope you are right. After a look at that json file I pale at the thought of trying to edit it.

(Ilias Giarimis) #4

Hi Mike,

You can see if RT uses camconst data for your cameras by looking in console (set verbose=true in your options file).

I read in console that RT is not using D800E data for D800. For this to happen, all you have to change is the “make_model” line to

    "make_model": [ "Nikon D800", "Nikon D800E" ],

Is it hard if I ask for a full set of white samples ?

Ingo, this is how Dcraw works sometimes but not camconst (and I think it’s better this way…)

(Ingo Weyrich) #5

Yes, I confused that.


Hi ilias

I don’t have a full set but plan on filling it out, at least with a selection of ISO values. I will be happy to send it when done.


Hi ilias,
When I open camconst.json in Notepad (win7x64) and make the suggested edit, I am unable to save the edited file. Warning appears stating I am not allowed to edit. Is there a way around this?

(Mica) #8

Can you edit as administrator?


Thanks. Administrator did not work. However I changed “permissions” in file, properties. That worked. I will test it using console.

(Andrew) #10

@mikesan, I tried this last year and got very confused. RT didn’t complain about the edited file but neither did it see the values within it. I concluded that Notepad messes up the file. I downloaded some free s/ware - Notepad++ I think - not at my win PC - and this worked fine (and seemed a nice piece of s/ware). Hopefully you’re aware you don’t need to edit the distributed version, rather you put an edited copy in an appropriate personal folder.

(Ilias Giarimis) #11

It’s better to use Notepad++ for editing camconst.json … this makes editing easier and safe (no format/alingning changes no EOL changes) and permits saving in restricted folders also.



Many thanks to you both for your responses. I have installed Notepad++ and editing the file was easily accomplished.

Can you tell me exactly in which personal folder my edited copy should go?