Audio Technica's 815b vs. 897
 

They both cost same. If I could mount it higher above FX1 camera, so it would not extend into picture, which one wiould be better for general use? Would 897 pickup be too narrow? How about fish pole mount? Which one would be better?

I don't know anything about the 815b, but have an 897.I used it on my Canon GL1 ( before I got the XL2) with a K-tek shock mount, which puts it a couple of inches above the camera. It never interfered with the shot. Also excellent sound for the money.
bruce yarock

The 897 is definitely a much newer design with a better signal to noise ratio than the 815b. It's also significantly shorter, so getting into the shot when camera mounted would be less of a problem.
The 897 pattern would be wider than the 815b pickup. The 897 is more like an update of the 835b.
These mics have a mid-level sensitivity and output. With cameras that need a hotter mic or if you're routinely recording quiet subjects, the AT4073a is a much better choice if you can afford it.
The Sennheiser K6/ME66 also has a hot output and falls between the 897 and 4073a in price. It doesn't perform as well all around as either of those mics, but some cameras really must have a hot output mic for quiet situations. The AT mics would be my choice if possible.

Radek - It all depends on what you want from your sound pick-up. If you want a mic that has a long reach and narrow cone of sound, with good reject of sound from the sides and behind, then the AT815b is the one to go for. Superb quality build and sound, with a choice of power sources.

It is a bit long for camera mounting, although I do often mount one on my XL1s (either alone, or beside a Canon mic - one in the hotshoe with a mic adapter, and one gripped inside a Light Waves Systems mini mount. The extra weight of the 815 mic can cause it to slope downward if mounted inside the LWS mini-mount instead of the more rigid hotshoe fitting, but the XLR cable plugged to the back helps balance it better).

The 815 if adjusted correctly, does not intrude into the view of 16X manual lens at it's widest setting, or even when a wide angle lens is fitted on the front.

The AT815ST or AT835ST are the ones to go for if you need a single camera-mounted stereo mic, but I prefer to use two AT815 mono mics for more flexibility. A short XLR is used when I need a single 815 on camera, but by connecting two 815 mics to two long 6m XLR cables, I'm able to position them at greater distances from the camera (and closer to the sound source) using home-made stands and clamps etc, or on a boom pole.

I actually own the earlier AT815a shotgun mics, which are almost exactly the same as the AT815b mics. Both provide the narrow acceptance angle desirable for long-distance sound pickup, with excellent sound rejection from the sides and rear of mic, switchable low-frequency roll-off and pus the added advantages that they operate on battery or phantom power.

I might add, that if you are using the AT815a or 815b mics outdoors, the extended length can be great for isolating sounds at distance, but it also can sometimes pick up wind, so I like to have them not only enclosed inside the foam covers, but also inside a Reinhardt fur windsock.