I keep a canon 40mm pancake on both of my Canon full frame DSLRs as a walk-around lens, when I have no particular type of subjects in mind. It is small, lightweight and excellent optically, suitable for most applications when I am “just walking around”, and they were very inexpensive.
When I have some single specific type of subject I am seeking, I will select whatever lens I prefer for that type of subject. I almost never carry a zoom lens, primarily due to personal bias acquired from over 60 years experience in photography. I find this pancake lens the best alternative for what I use it for.

It was just a general question about why people like pancake lenses, but evidently it upset you. I see all sorts of offers for discussion on this forum that I ignore. I have never used a pancake lens, but imagine that they could be handy for grab shots and would help to make the camera you're carrying much more portable. This forum would be rather pointless all we did was send questionaires to each other and then shared the results. Have you used a pancake lens? How did it work for you? Thanks

Pancake is just a term to scribe a very short lens, one shorter than is normally associated with that focal length. The pancake lens is designed to be short and usually there is some compromise in quality - perhaps not much but a landscape photographer would never use a pancake lens. But they are really useful when you want to travel light,
say putting you full frame camera in a briefcase, or fitting an extra lens is a full camera bag, or most importantly,
not being so noticeable to the folks or facility you are photographing. Sometimes a pancake or small lens is used for street photography. The focal length of such lenses is normal or shorter, since the goal is to make the lens small.
There are no telephoto pancake lenses although there are telephotos that are larger and smaller.

Nikon has just announced a Z mount short 28 mm lens that could be considered a pancake lens. There are several that are available for Micro 4/3s. The new Hasselblad 907 system comes with a wide angle lens (about 35 mm in
35mm camera terms) that is quite short and is sometimes called a pancake lens.

So one could summarize by saying that a pancake lens is a short lens that you use in situations where a full size
lens would make photography prohibitive. Having pictures with a less that optimal lens is better than having no
pictures at all.

mks

You are getting a few interesting replies. In my own case, I bought one used along with a used Olympus PEN-F. The main reason I use this combination is that it looks like a cheap point and shoot camera, and it fits in my pocket easily. When I travel to overseas cities, it is the best combination for just walking around, not being obvious, and since the lens is a zoom lens, it is perfect for taking quick, high quality shots. If I’m touring in the country, I do switch to a more standard type zoom lens. JimR