There are crabapple trees all over the place here, but only one tree that I've found with edible fruit, (I think it's a "Dolgo", a.k.a. "Pink Glow") and it makes wonderful jelly. It's at the water treatment plant, and in August I start watching when I drive by for the apples to turn red. They turned about a week ago, and I've picked about 8 pounds so far, plus I have about 5 pounds in the freezer. Decided to juice them the old fashioned way instead of using my steam extractor because the steamer seems to water the juice down too much.
I followed the directions in the Certo (pectin) leaflet, except I didn't cut the ends off the crabs. If I recall correctly, it was 3.5 pounds of fruit and 3 cups of water. Cook for 10 minutes, mash with a potato smasher, simmer for 5 more minutes. Then strain thru a jelly bag.
The resulting mash looked about like applesauce (except for the stems and skins.) I dumped it into a 1 gallon paint strainer bag and hung it up to drain. Got just over a cup of juice -- it was supposed to yield more than 5 cups but the fruit just absorbed the water and the applesauce was too thick to drain. I dumped the mash back into the pot and added 2 more cups of water. Then heated it to a simmer and poured it back in the bags and squeezed it. Got almost 2 quarts of clear juice, including the cup or so that I got the first time. I poured it all in tall pitcher and put in the fridge to settle the solids out that slipped through the bag because I squeezed it. (this morning it didn't look like much sediment)
Now I gotta decide whether to boil out the excess water or make jelly just like it is. I will probably boil it briefly to reduce it a little. I think this is still more concentrated than the juice I get from the steamer. It's a nice cranberry color. :)