How good is the FX7 auto-focus? at DVinfo.net

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Sony HVR-V1 / HDR-FX7
Pro and consumer versions of this Sony 3-CMOS HDV camcorder.


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Old July 23rd, 2007, 01:55 PM   #1
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How good is the FX7 auto-focus?

I know what you're thinking, who uses AF. I do most of the time. I shoot figure skating competitions and some ice hockey. The ability of the AF to follow the skaters is important, especially when they are coming directly at me or moving directly away from me.

I currently use a VX-2100 and couldn't be happier with the AF. It flawlessly tracks the subject even when the background is busy. I sometimes am forced to shoot ice hockey through the glass (clean spot) and the VX2100 will track a hockey player coming at me full steam right up till he crashes into the glass in front of me.

Has anyone used the FX7 in a similar fashion? The majority of my delivery is still SD but I would like to start shooting native 16:9 and at some point delivering HD content on something like Blu-ray.

But the AF performance of the FX7 has me concerned. I also keep reading about issues with rolling shutter on the CMOS cameras. For skating I'm usually positioned mid-way in the rink and as the skater zooms past me I am required to do a very rapid pan to keep them in the cross hairs. While the skater's movement in the viewfinder is minimal the background pans by very quickly. Is this likely to induce the rolling shutter diagonals?

I thought it would be easy to purchase the HD-equivalent of my beloved VX2100 but I'm finding no clear answer. Comments welcome.
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Old July 23rd, 2007, 02:17 PM   #2
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In good lighting conditions, the AF capabilies of the V1 (and presumably also FX7) are awesome. Additionally, the AF Assist function is a great bonus which helps correct the camera when it's focused on something else than you wanted...
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Old July 23rd, 2007, 02:29 PM   #3
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Originally Posted by Piotr Wozniacki View Post
In good lighting conditions, the AF capabilies of the V1 (and presumably also FX7) are awesome. Additionally, the AF Assist function is a great bonus which helps correct the camera when it's focused on something else than you wanted...
I guess that is why I am concerned. Skating rink lighting has never been what I would call "good".
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Old July 23rd, 2007, 02:29 PM   #4
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Agree. My FX7's auto gives me no problems at all in decent lighting conditions.

In less than optimum light, the focus assist and peaking functions work very well.

Compared this to another, much higher pricetag HDV camera that belongs to my partner - the screens shows sharp and the peaking lines show sharp - and the final images? well, not quite, not exactly, sharp, not all the time.

Very frustrating.

So I'm back to using my "consumer" camera that gives me tack sharp results every time.
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Old July 23rd, 2007, 03:22 PM   #5
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The auto focus on my V1 is very good.
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Old July 23rd, 2007, 03:24 PM   #6
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I guess that is why I am concerned. Skating rink lighting has never been what I would call "good".
I'd have thought there'd be no problem at all really.

Why? Because cams use contrast in the image to focus on, and to have a (relatively) dark skater against a white background all the time (assuming you are shooting slightly down onto the ice..) should give the camcorder some really good contrast to focus on, even if the light isn't that great.

Never personally tried shooting in a skating rink but i would say, as long as you stay high enough in the stands to keep the background ice, rather than seating benches on the other side of the stadium, i'd think it will work well.
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Old July 23rd, 2007, 03:34 PM   #7
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I'd concur with Stu on that one.

I've shot cars on Los Angeles streets at night, auto with my FX7.

Of course, there's headlights for the camera to focus on, but even when the cars went by (from infinity to around 12 feet away) the auto focus still held well -- I'd expect it to let go entirely after it stopped seeing headlights.
And that's exterior night under dim street lights.

So when I say "bad lighting conditions" I mean "can't see the subject well".

If I've had to peer and squint to see more clearly (with my presbyopia and astigmatism), then I'd say shoot manual focus. Otherwise...
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Old July 23rd, 2007, 04:02 PM   #8
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I'd have thought there'd be no problem at all really.

Never personally tried shooting in a skating rink but i would say, as long as you stay high enough in the stands to keep the background ice, rather than seating benches on the other side of the stadium, i'd think it will work well.
When I am there as the event videographer I am setup at the edge of the rink with the tripod strapped to the rink wall, normally from one of the hockey team boxes. This puts my angle of view level with the skater so that I am looking directly across at them (no ice in the background). The only thing in the background is the walls with all the advertisements on them. When the skater is half-rink or closer it's not an issue but when shooting into the far corners and the skater is hugging the wall there is only a couple feet between the skater and the wall. So it would be easy for the camera to get confused between the contrast of the wall and the skater. This is where cameras other than the VX2100 get fooled easily and starting hunting with the AF. Thus my concerns about the FX7 and how it's AF compares to the VX2100.

This is also why I mentioned hockey. I shoot hockey from ice level through the glass. So I'm looking directly into the chest of the hockey player coming right at me. :-)
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Old July 23rd, 2007, 04:16 PM   #9
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John

Don't forget that even a manual focus tweak between, say, 60ft and 63ft away from the lens is hardly a major factor, considering the camera's small sensor size and consequent inherent depth of field.

However, what you don't want is for the auto-focus to pump away after totally losing its subject.

If that's what you're worried about, I've not had that happen yet on my FX7.
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Old July 23rd, 2007, 04:23 PM   #10
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John

Don't forget that even a manual focus tweak between, say, 60ft and 63ft away from the lens is hardly a major factor, considering the camera's small sensor size and consequent inherent depth of field.

However, what you don't want is for the auto-focus to pump away after totally losing its subject.

If that's what you're worried about, I've not had that happen yet on my FX7.
This I wouldn't count on. Low light makes getting sharp picture harder for two reasons:

- the AF has not enough information to function quickly and resolutely
- the iris needs to be wide open, which decreases the DOF

But anyway, with good shooting technique, those machines can perform very well in this regard.
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Old July 23rd, 2007, 04:39 PM   #11
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Piotr

In principle I agree with you, and in practice the FX7 I've been using in night conditions just hasn't started hunting and pecking its autofocus like other cameras have, I don't know exactly why.

Other Sonys I've used have given up entirely and started hunting and pecking all over their focus ranges to try and get something, anything sharp. So you'll get a subject tracking okay, then it loses it and everything goes soft, sharp, soft, sharp while the focus hunts.

What I've seen in the FX7 is what you've mentioned - the auto focus is definitely not as quick and a resolute as in good lighting conditions, (and obviously I've not tried tracking skaters around at night), but I have to say, it's not at all bad, especially when you look at the results on a large screen.

I guess it depends on your quality standards. For me, if a fast moving subject goes into relative darkness and the camera loses focus for an instant, or goes slightly soft while the follow focus catches up, well that's sometimes acceptable, depending on the shot.

If not, then I'd suggest a manual focus pull anyway, to nail the shot properly.

BTW, I've also had a VX and know its low light performance well.
While the FX7 isn't quite up to that standard (and presumably it will be awhile before the HDV cameras in general catch up to SD low light standards), it's not far enough away to say "no good, don't try it", at least not in my book.

You mileage, of course, may vary.
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Old July 23rd, 2007, 08:07 PM   #12
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I have also come from VX 2000s to a FX 7, and doing low light wedding receptions and concerts have found that it will hunt for focus, especially when a dark subject is in front of a light background, it will go for the light every time.

The manual override is very useful and necessary with this camera in these situations, however it will go back to focussing on the lighter area, so you end up using it on manual anyway.

The only advice I can give you is to rent/borrow a unit and try it out.

I am not going to buy a 2nd (needed) FX 7 and am waiting for the XDCam EX, to see if solves some of these issues.

In good light, the picture is fantastic, sharp as a tack, but for indoor event -run and gun style - with a moving target, it will struggle.

Cheers Vaughan
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Old July 23rd, 2007, 08:19 PM   #13
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Agreed. It goes for the light every time, which is probably not good for weddings, especially the grooms, but maybe okay for skaters.
I too am waiting for the EX, as is probably half this board :)
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Old July 23rd, 2007, 08:39 PM   #14
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Originally Posted by Vaughan Wood View Post
I have also come from VX 2000s to a FX 7, and doing low light wedding receptions and concerts have found that it will hunt for focus, especially when a dark subject is in front of a light background, it will go for the light every time.
Oh geesh, that is not what I wanted to hear. You see, the walls surrounding the ice rink are typically bright white. Skaters costumes can be a variety of colors but a lot of them are dark.

I've always been pleasantly amazed how the VX2100 manages to stay locked on the skater even when they are very close to the bright white wall. The walls often have bright sponser ad signs which gives the camera even more of a bright target... but the VX2100 stays locked. Simply amazing.

Manual focus is out of the question due to the speed of the skaters. It sounds like I may need to continue to use my VX2100 and wait for the next generation cams. I wouldn't even mind spending more money if it meant having a camera with the focus power of the VX2100. Does such a camera exist for less than $5000?
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Old July 23rd, 2007, 09:08 PM   #15
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John

You may well be right. The white walls will most probably put paid to that idea, sorry. Most of my discussion above was definitely based on a lighter subject against a darker background.

If you're not delivering in HD, there really isn't any need to go there.

I recently worked on two reality TV pilot shows on DVXs plus produced one in DVX anamorphic, and two out of the three are making air in the coming season.

Plus, out of the five other programs I've shot so far with the FX7 since I've had it, only one of them is actually finishing HD - the rest all went to SD.

So I might as well have hung on to my DVXs (except for the one HD job, of course, which was demanding enough (and paid enough) to make the cross over, camera and post equipment, to HD).

As you may have gathered, I really do like the FX7, but in this instance, I'd say stick to what works until you really have to change it.
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