You’ve not said anything about the space, so I’d use the two Neumanns in the piano, and the 414 on the voice and arrange placement do the piano is in a null. Distance depends on the room. If it adds positives then a little more distance but closer if the room is poor. I’d probably use one of the spare mics as an extra vocal channel for blend. So much here relies on the piano. Grands record well if looked after but even decent uprights can be troublesome in a poor sounding room. EDIT I just noticed the word film. If visuals are important then maybe swap the 414 for one of the slimmer condensers and use that as the closer mic and the 414 for the less close mic on one of its narrower settings?

wrote: You’ve not said anything about the space

The room is an old barn with a high ceiling, rebuild as a nice sounding concert/recording room with good acoustics but without an audience I don't know how reverberant it will be.To pickup the room ambience I was planning to use some room mics. For room mics would an Omni pair be any good or are cardioid mics the best option? https://www.drentme…

Does the room really sound good? For a project I have been researching piece of music and there are some simply awful YouTube recordings of very good performers (and some bad ones too). Some of the venues are wonderful, yet the recordings are good examples of how mics in wrong places wreck good rooms. Most are too distant and too live, unbalanced and just awful. Room mics, cardioids or omni often make these spaces sound bad. Stereo recording, or individual mics that get mixed and balanced can sound amazing or terrible, and my belief is the only real variable that makes the difference is the technique you use and the room you have to deal with. Go to YouTube and search for Edward Macdowell to a wild rose. It's usually a piano and a soloist so should be simple, but listening to the recordings you'll hear some real issues. Most are too much room, or more accurately too much bad room, or video stereo mics in totally the wrong place. I think listening to the bad ones can only improve what you do.

I found a good example of how to do simple mic placement that works in a good space. Two mics for the double bass - I suspect one wider than the other, just for blend in the mix, and a couple of mics for the piano. The piano is blended a little distant for my taste, but the DB is of course meant to be the focus instrument, so it does work. It's not clear what the mics are, but the placement is very obvious. With decent sound sources and the space - multi-mics like this sound very real. It's a nice video too.

I've had a good time recording the musicians last weekend. I tried different options but eventually I used a OC818 with dual capsules and 2 Neumann km184 in stereo setup for the vocal. The piano was recorded using 2 line audio OM1 at 1 meter, spaced about 50 cm. Now time to tweek the sound.

Nice work, very balanced. When the singer moved his head to look at the pianist, I thought... wow...I hardly noticed the move. The room is a bit too live for me, however I know this is what classical recording is all about as well. I would love to hear how the reflections and room ambience could be tamed down/ improved but overall... really nice balance and sound. Thanks for sharing your work. 👍🏼

I rather liked his voice capture. I loved the ambience - I think it was dead right for the piece, but I hated the piano. Not the recording of it - but it's one of those instruments that doesn't live happily in the space. Steinways are always a bit bright, and unless you have a space in the church to set up a pair of speakers for playback, you don't notice until you review the recordings. EQ rarely sounds 'right' as a fix for this. It has that right hand jangliness, that probably leaked into the vocals and the pair near the singer.

It has a very nice feel to this recording - quite realistic. That rotten piano (if you can call a very expensive Steinway rotten) wasn't doing the singer or the pianist any favours - but I bet there, you didn't get the warning sounds. Below middle C, it's quite sympathetic, then those little defects leap out and get captured.

Tell us what you would do differently, next time in the same venue and with the same performers (and piano) after you worked on it. Hindsight is great. I'd not have done it the same, so I'm very interested in which mics made the mix and which you discarded when you heard what they captured.

I've not had a chance to try yet, but I bought a set of extension tubes for my 451s so next outing I'm going to be more video friendly - and try not to get mics in shot. A slim tube with the capsule on the end will look much better and 451s sound nice. 

I would have liked some mics under the lid of the piano just to have some more mixing options. I did put 2 akg414 in a kind of blumlein setup in the room to capture the ambiance, but in the mix it was a bit overkill, so I left those out. During the recording I had to concentrate on operating a camera . The Austrian Audio OC818 was in dual capsule mode and gave me something to fiddle in the mix by using the polar designer software. The 2 Neumann KM184 mic's turned out to be more directional which is nice to get a "closer" sound. The next time recording in this room I would separate the singer a bit more more from the piano so there is less spill and more control. On the other hand it can be a tradeoff between camera placement and audiorecording. Well, some lessons learned.

Every recording is a learning event, isn't it!