Take equal parts of rosehips to Apples so if using 2lb of rosehips use 2lb of apples. Chop up the apples (you do not need to peel as the juices will be going through the jelly bag and whizz the rosehips through a food processor until the berries are minced pop the apples and the rosehips into a heavy based pan (not aluminium) and cover with water and bring to the boil until the rosehips and apples are soft. Strain through a jelly bag (if using the rosehips this way this is a necessity as these berries have very tiny hairs/fibres that if not strained off properly will irritate you system to high heaven so straining is a necessity even iif you prepare the rosehips beforehand. Always strain. Remember the innards of what is in the rosehip is the basis of itching powder.
Leave overnight in the jelly bag to drip. Do not interfere with the jelly bag and try and force the ingredients through as this will spoil the effect of the jelly and we want a nice clear jelly that is jewel bright and looks pretty.
To each 1 pint of juice or part thereof add an equal amount of sugar so for 1 pint of juice you would use 1lb of sugar.
Pop into a pan and add the amount of sugar required, bring to the boil and test every so often for a set where a spoonful of jelly popped onto a cold plate wrinkles on the surface and forms a skin when you push it with your finger. You can if it is taking an age add some lemon juice as this aids with the set (some fruits have very low pectin and it varies from batch to batch) If you don't get this effect the jelly is not set and not ready to be taken off the heat. I always take the pan off the heat when testing for a set as we do not want an overset jelly which will go like rubber or indeed the preserve burnt. Once set is achieved decant into warmed sterilised jars, pop on lids and leave to set. If a set is not achieved first time round just pop back into the pan and rewarm through until this is achieved adding a little more lemon juice if necessary.
Pop onto the Pantry shelf and bring out and use with roast meats as a side sauce etc.
Hugh Fearnley Whittingstall also has some very different ideas on how to use fruits from the wild larder. Including a crab apple and sloe sorbet. I do not see why you could not use the crab apple and rosehip jelly in the same way.