The (very) old book The Amateur Photographer's Handbook has probably the best explanation of what filters do and how they work as I've seen in any source. One thing to keep in mind is that the filter only subtracts light, it doesn't add anything. It blocks the complimentary color, but it also diminished all the colors in between. So here's the odd part to keep in mind (and which I rarely see discussed): if you use, for example, the red filter, and you do not compensate for exposure, only red light will be exposed correctly, and blue-green light will be blocked. The filter factor (the +3 stops) is basically to bring the exposure of all the other colors back up normal, which results in red light essentially being overexposed. So in your tree photo, if you put on the red filter but did not add extra stops of light, the tree would look essentially the same as in the unfiltered photo, but everything else would become very dark.  This is why in the photo of the buildings the filter has the apparent effect of lightening the building in the foreground.

6:05 The building was probably a brownish orangish type building, so it got brighter as a result despite being in shadow.

That skyscraper shot is really interesting.  It never occurred to me that you could cut out reflections by cutting the color of sky.

A red with a polarizer on a blue sky with clouds really gives the sky a great look.

Best line ever: “I was close to B&H.”  Heaven!

The haze that we see in standard shots between the lens and the subject is clearly not heavy on red because the red filter blocks most of leaving a much clearer and sharper image at depth.

5:47 i guess it is the warm color of the old building in contrast to the Glossy Highrises that mirror the blue sky.

I’m fairly sure there is tape on both ends of 120 so if you took it out and then got it hooked back you could just wind it all the way through again and then it would be back at the start.

Fascinating! Specifically the red tree.

The number of stops for a color filter really depends not only on the intensity of the filter (not all red filters require 3 stops) but also on the spectral sensitivity of the film.  Also, it is wrong to say that a red filter would add more details to portraits because generally skin tones are quite warm, so a red filter would actually smooth out details.  A green or blue filter would actually increase contrast in the details for portraits, so those would be more gritty.

red is the main hue of this filter, that is kept on +0 stop, everything that gets further in the color wheel gets darker at max -3 stops. the furthermost of the colorwheel is the complementary color of the filter, which is probably a light cyan.

Orange is my favourate filter for BW

I use yellow filter with my color photography and using it during golden hour gives amazing results.

At 5:50 my guess would be that the underneath of the ledge is lit mostly with a warm bounce lighting from the material of the building, ground or other surroundings. If so then that bounced lighting could increase the light levels more than the other parts of the facade which is being lit by a more cold light, which would get blocked out by the red filter. So when you increase the stops of light because of the filter, you would also increase the bounced lit shadows proportionally higher. Not sure but that would be my guess.

It makes sense that the filter has this behavior when considering how a lot of digital processing techniques can give improved results when applied to the channels separately rather than all at once. A single channel can give enough information for a good black and white image, so removing the unnecessary noise from the other channels should give stark differences like this.

i think it's fascinating that alot of these happen simply beecause the light bounced by our atmosphere and the sky is blueish

Thanks!

My uncle the professional photographer told me to get those clouds to pop, just attach a red filter to the black and white film. It really works.

I think the reason the pics on 6:03 has such a stark difference  in the clarity is that by blocking a lot of scattered blue light from the sky, you can see more features since most of the red light actually comes from the object reflecting light, and not the environment.

Keep trying Joshua and don't give up.  You definitely understand the principles and with more practice over time you'll see better and better results.  Good job!