No high brow from me, that's for sure.
Let's work this out.
I am not familiar with that Canon printer except that it is a combination scanner, copier, and printer.
So let's start with some basics.
You are using Canon 4 x 6 paper.
The next question is: will you accept some margins around your prints or are you trying for borderless; I don't know if that Canon model does borderless.
So let's assume for the sake of making progress that you want to print an image as large as you can without cropping.
Telling the printer driver that you are using 4 x 6 paper should yield a report above the top right preview panel that tells you the printable area of that paper.
See snap 24.
It is saying that the printable area on that size paper is 5.685 x 3.73 inches
Therefore if you ask for a 4 x 6 size print, it will not fit in the aforementioned space.
So we tell Qimage  (CUSTOM FIT TO PAGE) that we want to fill the printable area,
Here's the crop part. Turn off the crop scissors located below. See snap 25.
Now add your image.
If the camera produces a 3:2 image it will fit the paper. If the camera produces a 4:3 image, then it will not fit a 4 x 6 ratio, so you will have to have white spaces on the 6" sides of the print.
If you turn on the crop scissors, Qimage will crop some some the shorter side until the longer side fills the space.
One last comment. The print size shown in the View Print Queue, lower left, is the size print that Qimage is sending to the printer.

Let me stop here and see if I am on the right track.

Fred

Fred and Seth,
Thank you for helping me out to solve this print size problem. Although I understand more than before I still have a misunderstanding:
Say my photo shows a size in the View queue of 5,69 x 3,73" and to accomodate this size I put in the print driver a paper size of 7 x 5". In the view page it now tells me that the available paper size is 6,685 x 4,731" which should be ample space to print the photo without any cropping. When I put in Print Properties the 7 x 5" paper size there should be no cropping necessary because the paper to print on is larger than the photo to be printed. But no so. When Auto cropping is on part of the image is being cropped; when "off" I get the complete photo but the print does not fill the complete paper but shows white parts left and right. Why is there auto cropping possible?
I would like to print my photos in such a way that no part is cropped away and that it shows a border of equal sizes around the photo.
Can this be accomplished?
Thanks for your help,
Harry

I will study your reply and in the meantime let you have the resolution of some of my photos: 4272 x 2848.

I don't know whether this will help or not but have a look at the attachment below.
It's a diagram where the green rectangle is the edge of the 5x7 paper (I've ignored borders for this diagram).
Two situations are shown: The whole of the image is shown in both cases.
1. no cropping and fitting the whole image into the 5x7 paper
2. cropping on so that the 5x7 paper is filled with print.
Hopefully you can see that you either get white strips top & bottom (1) or the edges of the print cropped (2).
This occurs because the aspect ratio of the paper (width : height) is different from the image aspect ratio. See Fred's numbers on his previous post.

In (1) or (2), the only way to fill the paper without cropping would be to stretch the image - Qimage will not do that!  
Terry.

I think we are making progress.
Follow this, and you will see what is happening!!
As you point out, the printable area is 5.685 x 3.73.
So Qimage proceeds to fill your request to FIT to Page; assuming you used that method.  Ahhh, it fills out the 3,73 dimension just fine, but cannot go beyond 5.59 unless you give permission to crop a little so Qimage can fill out the long side request.
If you click the crop scissors to on, then Qimage will complete your request.
BTW, the difference between the size print with crop permission and without, is .09 inches. You can easily allow Qimage to crop and it will hardly be noticeable to cover.09 inches of space.

The 4 x 6 print can be made on 4 x 6 paper providing your printer allows borderless printing.

Fred

We look forward to getting you up and running with Qimage and the printer.
I believe that Brian Price, who is on the forum quite often, has a 3800 too, and can help heavily on that end.
Let us know when you are ready.
Fred