# Why Magenta and Yellow



## dennyr (Sep 21, 2021)

Wanted to ask about enlargers that have integral filtration.
I realize some enlargers DO use Green and Blue, which seems more intuitive to me.
Though i have never used one.  

However, it seems MOST enlargers use a Magenta and Yellow filter.
Why is that.?
I have never printed color  (by myself)  Is that the reason.?
Are enlargers that use Green and Blue just contrast colors for printing Black and White.?
Again, i have never used a Blue and Green enlarger, so i am not sure if they have a third color or not.

Thank You


----------



## 480sparky (Sep 21, 2021)

Variable contrast paper is sensitive to blue and green........... which are opposite magenta and yellow on the color wheel.


----------



## dxqcanada (Sep 21, 2021)

This is an explainer from Ilford


			https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdf


----------



## dennyr (Sep 21, 2021)

480sparky said:


> Variable contrast paper is sensitive to blue and green........... which are opposite magenta and yellow on the color wheel.


Right, but WHY use  "Magenta" to pass Blue in stead of Blue and why use "Yellow" to pass Green instead of Green.?


----------



## dennyr (Sep 21, 2021)

dxqcanada said:


> This is an explainer from Ilford
> 
> 
> https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdf


I might be missing it, but i do not see where they get into using Magenta and Yellow Vs Blue and Green.


----------



## 480sparky (Sep 21, 2021)

dennyr said:


> Right, but WHY use  "Magenta" to pass Blue in stead of Blue and why use "Yellow" to pass Green instead of Green.?


Magenta will not 'pass' blue.... _blue_ passes blue.  You use magenta to restrict _green._


----------



## dennyr (Sep 21, 2021)

480sparky said:


> Magenta will not 'pass' blue.... _blue_ passes blue.  You use magenta to restrict _green._


Does a Magenta Filter let Blue light hit the paper.?


----------



## 480sparky (Sep 21, 2021)

dennyr said:


> Does a Magenta Filter let Blue light hit the paper.?



Some.  Magenta filters controls the green, yellow filters controls the blue.

If you're shooting b&w film, and want the blue sky to be darker, you use a yellow filter.


----------



## NS: Nikon Shooter (Sep 21, 2021)

-

Maybe, you want to investigate "chromogenic emulsion"
where not only luminance will have effect but chrominan-
ce as well.


----------



## dennyr (Sep 21, 2021)

480sparky said:


> Some.  Magenta filters controls the green, yellow filters controls the blue.


OK
Having Internet problems, sorry..........i will keep playing.
I understand what you are saying. Thank You

I have talked to photographers that use an enlarger that have Blue and Green instead of Magenta and Yellow.
Does using a blue filter (or green) have "The Same" end effect on contrast as a Magenta or Yellow Filter does.?
If so, why do enlarger manufactures choose one method over the other.?


----------



## dxqcanada (Sep 21, 2021)

The Physics of Light and Color - Light Filtration | Olympus LS
					

The Physics of Light and Color - Light Filtration




					www.olympus-lifescience.com


----------



## 480sparky (Sep 21, 2021)

dennyr said:


> OK
> Having Internet problems, sorry..........i will keep playing.
> I understand what you are saying. Thank You
> 
> ...



I assume some enlargers are marked 'blue' and 'green' to remove one mental step in the process.  If you want to control the green sensitive portion of the paper, making an adjustment marked 'green' is a bit more intuitive than, "I want to adjust green, so I have to use the 'magenta' filter."

The only thing a 'true blue' filter can affect is the exposure time needed for the blue-sensitive portion of the paper.


----------



## dennyr (Sep 21, 2021)

dxqcanada said:


> The Physics of Light and Color - Light Filtration | Olympus LS
> 
> 
> The Physics of Light and Color - Light Filtration
> ...


A great link Thank You
Part of my slowness to grasp this is the fact i was a painter.....Painters Union, not artist.
I made hundreds of colors and stains over the years.
So approaching everything with Primary of R Y B has been ingrained in my head.
I appreciate the help. My search for info did not turn up the link you provided.
Thanks Agiam


----------



## dxqcanada (Sep 21, 2021)

I started in art painting before photography ... so I remembered that we look at this a bit differently.


----------



## dennyr (Sep 21, 2021)

480sparky said:


> I assume some enlargers are marked 'blue' and 'green' to remove one mental step in the process.  If you want to control the green sensitive portion of the paper, making an adjustment marked 'green' is a bit more intuitive than, "I want to adjust green, so I have to use the 'magenta' filter."
> 
> The only thing a 'true blue' filter can affect is the exposure time needed for the blue-sensitive portion of the paper.





dennyr said:


> A great link Thank You
> Part of my slowness to grasp this is the fact i was a painter.....Painters Union, not artist.
> I made hundreds of colors and stains over the years.
> So approaching everything with Primary of R Y B has been ingrained in my head.
> ...


I will Thank You Both   right here.
As i say, i was a painter. So not only did i learn the one odd primary  color, we did not think in terms of light passing "Through" anything, or how something  (like film) saw color.
We just dealt with how color was reflected to the human eye.

Well, ONCE in awhile we had to be careful if were were near  ( i worked in a lot of high-rise buildings)  some heavily tinted or heat absorbent glass, THAT could really F with your color matching.

I was shocked at the effect of clear glass. I had to match a stain on a guys coffee table at Charles Schwab . Big corner office. HUGE 9x3 coffee table with 1/2 inch glass. No way i could move it. TWO of us could not safely move it enough to overhang the table to make the color sample.
I burned up four 8x10 inch Cherry Wood samples trying to match the color through the glass. I could not do it.
I forget the guys name, he was next to "Chucks" office.  (he really did  say  "Call me chuck")
Anyway, THAT guy walked in and i explained to him the trouble we were having.
He said, Don't worry the the table is going WAY over there, just get it as close as you can, nobody will ever know.
So that is a glimpse into the exciting world of a painter.

Thanks Again


----------



## webestang64 (Sep 23, 2021)

This will give you an idea of starting points to select contrast for variable-contrast BW papers.
Y-yellow filter, M-magenta filter.


Desired Grade:0001/211-1/2   2  2-1/233-1/244-1/25Durst filter settings (170M)150Y90Y70Y55Y30Y020M45M65M100M140M170MDurst filter settings (130M)120Y70Y50Y40Y25Y010M30M50M75M120M130MKodak filters:199Y90Y70Y50Y30Y05M25M50M80M140M199MMeopta filter settings:150Y90Y70Y55Y30Y020M40M65M85M200M---

Also Ilford has a tech sheet for contrast control.......PDF.....    https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdf


----------



## dennyr (Sep 23, 2021)

webestang64 said:


> This will give you an idea of starting points to select contrast for variable-contrast BW papers.
> Y-yellow filter, M-magenta filter.
> 
> 
> ...


Not that i am THE Greatest at reading negatives.
But if the neg looks  "Normal"  i typically have the M at 20 on my Besseelr-45

Like you say, it is at least some place to start.

Oh Geez....what are then two types,   Diffusion and Condenser.?
For B&W printing i find it easier to use my Non-Color head. But i like the way...the light system...of the color head prints.
I suppose it is like anything else...............if i did it long enough, i would get used to the condenser head enlarger.

For split printing it is arguably easier to use the slide in filters of the condenser head. But again, you adapt to cranking the knobs all the way instead. No big deal.
I am happy i have a darkroom with ANY Enlarger. 
I cannot imagine shooting film without one.

Anyway...............Thanks Again for the replies.
I Appreciate It.


----------

