why using 25p instead of 50p ?
 

I'm making wedding vids and I'm doing a lot of slowmotion in my editing.
I just purchased the 7D so I will use that for capturing weddings.
Now my opinion is that it's best to use 50p instead of 25p because you can do
better slowmotion. Right ?
a minor thing is that you can't shoot in full HD (1920x1080), but when rendering it for DVD it's not full hd anyways.
So can you help me out why I should use 25p instead of 50p or if it doesn't matter, so I can shoot everything in 50p.

If you do some tests you'll see a lot less aliasing in 1080p25 mode than 720p50 on the 7D. With care, depending on the focus regime used and what's in shot, 720p50 can give excellent results on the 7D, and is especially useful for slowing down in post (as we all know) - but beware of the pitfalls before you shoot any critical shots!

Some test shots I took in Cambridge last week (non-paying "learn the limits of the 7D type stuff") were totally unusable when done in 720p50 mode, and perfectly usable in 1080p25 - so only those made the final short. With my EX3 practically everything in either mode is totally usable, always! The test shots I did were mostly deliberately wide and with deep focus to see just how it would handle this challenge, as well as some low light stuff to test that - College quadrangles/historic architectural shots, The Backs, street scenes, the market square etc. - that kind of stuff. I know what the camera is good at - shallow DOF etc. stuff, I was not shooting that (as that was not the aim in this instance). As a result, I now have a much better understanding of the 7Ds limits and strengths.

The finished 2 minute short is currently on my website (and on YouTube if you want to see the result - 'Cambridge in December'), but like I said, no 720p50 shots made it through the selection process in this quick edit.

Aliasing on the 7D is a real gotcha (and will still look horrible in downconversion to Std Def DVD, often). 1080p25 gives less aliasing than 720p50. That's my opinion/experience so far and others have done exhaustive tests to prove this.

If you are only placing your footage onto normal DVD discs and not Blue-Ray, then it would be better to downconvert to best quality SD. It will be easier then to do the slow-motion clips.

So the best quality of video will be in 1080p.
For the slowmotion, I mostly slow down in Premiere to 75-85%
The thing is, I'm really afraid of screwing up the important shots.
So your suggestion is just to film in 1080p25 and just use to to do some slowmotion aswell ?

Hi Bart. It is not a good idea to use 25p if you are planning to apply slow motion. It almost always looks terrible. Tony's suggestion is good if you have 1080/50i available, but I don't think you have, do you?

Richard