I don't understand: what's wrong with Eric Renner's book, Pinhole Photography?

I read the Second Edition. It gives a detailed account of the history of pinhole photography,
with a lot of examples. Then it discusses pinhole techniques, and makes some practical suggestions.
It's well-written and seems to be well-researched.

The only thing I found missing was an explanation of why there are so many diffrent recommendations
for optimal pinhole size (for a given pinhole-to-film distance and wavelength of light): for example,
that reommended by George Airy vs. that recommended by Lord Rayleigh. A post on Photography
StackExchange lists five modern sources with five different sizes--the largest 3
https://photo.stackexchange.com/questions/46489/how-to-calculate-the-optimal-pinhole-size

(BTW, I may have a solution to this problem.)

I continue with pictures taken over the summer. It is still July according to what is on the camera roll.

The first picture shows a debris-carrying lacewing larva. Lacewing larvae are predators of small arthropods, and the best known of these are ‘aphid lions’, since these are stalkers of aphid colonies. But other species are more of a free-lance sort. This one was wandering down a tree trunk in a forest, and in this picture you can see the head with long scimitar-like jaws for piercing prey. The large pile of debris that it is carrying is for concealment and protection from its own enemies like ants. Not sure what the debris is, but perhaps it's the wooly stuff made by some plant galls. I do not know the ID, but according to BugGuide it is probably one of the many species of green lacewings. So family Chrysopidae. I had to use the Raynox 150 on my lens to boost magnification on this picture, and even so it is heavily cropped.
Debris-carrying lacewing larva by Mark Sturtevant, on Flickr

Next is a cellar spider with a meal. Cellar spiders will frequently return to old prey to eak out a meager living, and will even accept dead and dried prey. BugGuide explains that the most likely cellar spiders to be encountered in the U.S. are one of the three introduced species. This seems to be Pholcus phalangoides. The white patch on the abdomen is the cover for one of her respiratory openings. Spiders breathe through a pair of ‘book lungs’, which are stacks of thin respiratory membranes in chambers in the abdomen Similar to fish gills.
Cellar spider by Mark Sturtevant, on Flickr

At the shore of a lake I came across a giant swallowtail butterfly (Papilio cresphontes) that was ‘puddling’ on the wet sand to get nutrients like salt and amino acids. This was a nice surprise since these very large but common butterflies seem to always be flying non-stop. ALL of my other pictures of them are rather blurry as I have never quite figured out how to freeze motion with shutter speed and/or flash.
Giant swallowtail butterfly by Mark Sturtevant, on Flickr

Finally, a few feet away from the giant swallowtail was this perfect red-spotted purple butterfly (Limenitis arthemis). The colors really pop with the camera flash! I am beginning to think that this species is one of the most beautiful of our butterflies.
Red-spotted purple butterfly by Mark Sturtevant, on Flickr

Here are some images of my Pinhole camera from 1980's
Front and back frames Honduras Mahogany scrap sides and "Lens" board plywood scrap, shutter from a junked Kodak folding camera (lens removed) diafram used to hold pinhole "plate"
Only cost $18.00 for the 8X10 film holder.
The camera was built and used as a photography class assignment. The reason for more than a cardboard box was I wanted to be able to take more than one image per outing and didn't want to mess with tape to cover the Pinhole.

Well, what else can I do when it's snow packed outside? Took a few grains of Sea Salt and placed them on a piece of blue paper that I tore out of a magazine for a background.

To my surprise I was able to see the color dot matrix of what appeared to be solid blue of the paper. This image was taken with at about 8X magnification using a microscope objective and bellows extension.

Thanks in advance to those who view and your comments, suggestions and critique are always highly appreciated.