Flash Speedlite YN-467 or YN 465?
I'm an amateur photographer, who is still learning the art of photography and wanna buy a flash for my D40.
it says that YN 467 has auto zoom facility and slave triggers… What are those? Are they important options?
what is good YN 467 or YN 465?
The 'slave' modes are optical slaves - they will automatically fire the flash, when they 'see' a pop from another flash going off. You would still set the flash output manually in this mode. There are two different slave modes (S1 & S2) - one of them ignores any TTL pre-flashes, the other one doesn't.
Remember in my previous answer I mentioned that when a flash is in TTL mode, it sends out pre-flashes to measure exposure? Well if you have a simple optically slaved flash off camera, it can fire during the 'pre-flash' - this is a problem as it then doesn't have time to recharge before the main flash fires (which it's supposed to sync with). The slave modes on the YN467 allow the flash to sensibly ignore any TTL signals in the flash that is controlling it & only fire on the main flash as it should.
You'd use slave mode if for example, you wanted to use the YN467 off camera but did not have any radio triggers. The pop-up flash on your D40 would trigger the slave flash to fire. You could fire your pop-up in TTL (with pre-flashes) or manual mode (no pre-flashes) and the YN467 would be on either S1 (manual) or S2 mode (for TTL use - ignores pre-flashes) & would fire at the correct time.
Optical triggering is quite useful, but can have drawbacks. The 'slave' flash sensor has to be able to physically see the flash from the triggering flash (your pop-up in this case), so there has to be a line of sight between the two. Bright sunlight can also interfere with the optical trigger.
That's why I recommended (previously) radio triggers. RF602's are cheap & reliable and they have a far greater range than an optical system - they can even trigger a flash in a different room! Optical slave functions are always useful to have though - handy as a backup if your other transmitter should fail.
Zoom facility is the ability to 'zoom' the flash head in/out. THe flash will zoom automatically within a certain focal length range when mounted on camera to match the focal length of the lens used. Off camera, you cam adjust the zoom of the flash manually. It basically controls the 'spread' of the flash beam from a fairly wide angle (around 24mm focal length equivalent) to a telephoto (85mm or so equivalent) - think of it like a focus for the flash beam.
A good resource to learn about off camera flash is the Strobist blog;
http://strobist.blogspot.com/2006/02/welcome-to-strobist.html
There's also an associated Flickr group;
lots of threads on there relating to Yongnuo stuff - it's very popular in the Strobist community. Search the threads though before asking a new Q - it's probably been asked before!
A lot of my stuff on my photostream is shot with off camera flash - I always put the lighting details in the comments.
Btw = you have a great camera there (D40) - Strobists love them because they are one of the few DSLR's that have an electronic shutter at high speeds & can therefore sync with flash at a much higher speed than most others. This is handy if you want to reduce the ambient light levels outdoors when shooting a flash/ambient mix.