I am working on a how-to book with lots of photos. I have no idea what I'm doing with the photos.
Are photos I take with my iPhone good enough?
Probably not.
I've spent all of my editing life working on non-fiction books, and a good proportion of that time working on highly-illustrated non-fiction. You need very sharp, high-resolution photos if you're going to reproduce them in a book: the papers most commonly used in book production aren't very good for printing pictures on, so the pictures instantly lose a bit of clarity and if they aren't the very best from the start, you're stuffed.
If I decide to send it around to publishers first rather than go straight to self-publishing, can I still just insert the photos where they belong in the text? I'm going to finish the book first either way, although I know I'll still have to send a proposal to potential agents or publishers.
Include a few photos in your proposal, to show your intentions. You don't have to insert them into the text: include them in an appendix, and number them, then add "insert image xii here" at the appropriate point in the text.
If I finish all of this then find out my photos won't work, I'll be so mad. The book won't make any sense without them and they're step-by-step so I really have to find out if iPhone photos are good enough.
I'd find a much better camera if you are going to go ahead with this.
If I wanted to follow orders for money, it would make far more sense for me to just go back to work
Not only is this comment a misrepresentation of how trade publishing works, it's dismissive of writers who take that route.
Since my original post, I've researched dpi required for Createspace and Kindle. If anyone else is wondering, it appears that the iPhone 6 Plus (I don't know about older iPhones) should do the job provided your photos will be no more than 4" x 6" in the book. If it works for CreateSpace, I'd guess it works just as well for any publisher, since they're both printed books. If anyone has more knowledge on that, please share!
DPI is not the only thing to consider. And while the photos you've taken might be acceptable for CreateSpace etc., they aren't going to get you the best results and they might well end up giving you really poor results. The last thing you want to do is publish a book which looks poorly-done, and which relies on blurry ugly greyscale shots to get your message across.
Why not download a dozen of your pictures to CreatSpace now, bung in a bit of random text, and order a proof copy to see how the pictures look? It would show you what to expect, so if the results weren't good enough you'd not lose any more time. And the last time I used CS I didn't have to put the book up for sale, so it's not like anyone will see it.
Also, just an fyi for anyone interested, many publishers do accept nonfiction books directly, which differs from fiction.
They do indeed. But this is changing, and some are moving to an agent-only model.
Now I'm looking up inserting photos on Createspace, which is also a pain. My other how-to books don't have images so this is a PITA I've been avoiding so far. However, not using images really restricts the how-to books I can do so it's a bullet I'll have to bite. If anyone has relevant experience, do share! I'm also interested in info. on images vs. cost.
My only experience of illustrated non-fiction is with trade publishing. I do know that such books are much more expensive to produce than non-illustrated books, so sales have to be higher to make it worth doing.
If self-publishing, there's an additional problem of arranging the images in the text. I won't be hiring anyone for that but I will consult some books with images for pointers. Has anyone done it?
My experience is that inexperienced designers will not produce a good-looking book. Layout of a highly-illustrated book is a very skilled job, not only because one has to ensure text flows properly around the images but because one has to ensure that the book has a good rhythm to it: one doesn't want lots of images on RH pages only sequentially, for example, followed by one on a LH page, and then back to RH. Typesetting and layout for such a book is a huge challenge, as you indicated in your next para:
The problem is of course that when you insert your images where you want them, there's often not enough space left on that page for the whole image to fit, so the image inserts on the next page instead, and you're left with a big gap on the current page. So you have to balance that problem with also having the images flow as seamlessly as possible so the reader doesn't have to constantly flip back and forth and get annoyed.
This takes a lot of skill to get right. I've spent days in designers' offices working with them to get pages to sit right. It's amazing how many details have to be taken into account to do a good job. By all means have a go yourself, but recognise that you're going to miss things and make mistakes. Be prepared to order several rounds of proof copies, and if possible get a few other people to go over those proof copies for you too. It's hard work.