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July 13, 2016 at 8:10 AM #90800
I have a Sony HDR-CX440 and using it to monitor a welding process, particularly the center of the welding. But I’m having trouble with getting a good focus with it. After using ND filters to reduce the brightness, all I get is a blurry ball of light that doesn’t show much else. I need another camera with better focus to be able to view the welding tip clearly. Note that I have little or no prior familiarity with cameras and video-making, I have searched high and low on the internet, and I’ve gotten really bamboozled with the different terminologies (exposure, zoom, image stabilization, lens aperture, shutter…phew!)
I don’t know what features to look out for in getting better focus. Could anyone recommend video camera options that can do the job really well, around the range of $1000?
July 15, 2016 at 10:35 AM #214236JackWolcottParticipant
Of course I can’t be sure, but I suspect the problem is with the welding tip as much as with your camera. I doubt that the circuitry in the camera can handle the tremendous amount of fluctuating light intensity coming from the welding site.
If this were my problem I would go to a camera rental house, discuss the problem with the staff, bring home the camera they recommend and give it a trial.
July 15, 2016 at 11:44 AM #214237paulearsParticipant
The camera cost is about the same as a days rental of the type of camera you need. It’s a point and shoot handicam that takes nice pictures in bright light. It’s performance in a situation where you need a real sense is pretty poor.
The snag you have is dynamic range – In fact, even the naked eye is poor at this one. I assume you’ve seen through a welder’s mask? All you see is the arc, or plasma area, and the immediate work area – perhaps maybe limited to a few cms, the rest is blackness. A camera has nowhere near that ability, so while with welder’s density ND you might see the arc around the workpiece and the rod in sharp focus, the workpiece will vanish. The range between arc and not arc is too much for the camera, so the arc if exposed properly to less than 100%, leaves everything else black, and if you bring up the blacks the arc is just a white circle. Modern cameras can expose the work area and not burn out the sensor, but the white spot problem is not going to be solvable. Proper lenses give you more adjustment over the levels, but a handicam is not going to be controllable in these circumstances.
July 15, 2016 at 1:07 PM #214238Gig FilmerMember
I have no direct experience in filming this subject but, if it were me, I would try the following :-
Multiple exposure: Film the subject a few times with different exposure (brightness) and overlay the clips in your editing programme. You’ll need a rock solid tripod and/or something to line up the edge of your frame. Try gaffer tape on the workbench at 2 opposite corners of the frame.
Manually focus the camera before shutting down the exposure or applying the ND filter(s). The focus shouldn’t change. If you can’t focus with the iris wide open and the lens on extreme wide angle then maybe you are just too close to your subject.
Experiment with manual focus and how it’s affected by the zoom control and exposure/iris/f-stop in a more friendly environment like a flower vase in the middle of the dining room table.
Please excuse my poor English. I’m ………er English 😉
July 15, 2016 at 5:29 PM #214241barnacleParticipant
Have you tried using a piece of welder’s mask glass (#3-4 at hardware stores)
in front of your camera?
July 23, 2016 at 11:18 AM #214278Kevin McMember
Actually, I think you want to go in the other direction. Lose the ND filter, which slows down your shutter speed, making the image even more blurry, and instead, crank your shutter speed way up to make each frame sharper… Now you’ll probably have to open your iris/aperture all of the way, which will reduce your focal length, so pu the camera on a tripod and manually focus it. If the lighting gets too dark with the high shutter speed – add some gain to compensate.
July 27, 2016 at 2:42 PM #214305
Thank you so much @paulears…yes the surrounding work area is all blacked out which is fine, because the interest is in the arc/electrode/base metal junction itself (we have a second camera capturing the “bird’s eye” view. But still the image left is blurry and more like just a small ball of light. I wish I could upload screenshots of what I have and what I need along with my post, I tried but I can’t. I was however able to upload the images on another forum:
If you could take a look, it might give you a clearer picture.
@Gig Filmer, yes, the Sony Handicam I have presently doesn’t look like it can do the job at all. It doesn’t allow one to manually control both the focus AND the exposure. For some reason, once it’s on manual exposure, it’s locked in autofocus. And from suggestions, it seems we’ll need to adjust both manually(?).
Video camera marketers suggested I try Panasonic HC-VX870K camcorder, Canon VIXIA HF G40 camcorder or Canon EOS Rebel T6i DSLR camera. Can anyone tell how fit-for-the-job these are, based on the specifications? (Note that audio is not a priority) Like I said, I’m pretty much a novice and I fear that these marketers could just suggest anything…they want to make sales anyway!
July 27, 2016 at 2:38 PM #214304
July 27, 2016 at 2:55 PM #214306
Thank you for your suggestion @Kevin Mc. It looks like I’ll need a lot of flexibility with the focus/exposure settings to do that, which this camera doesn’t give me. If you check my last comment I described the limitations I’m having in that regard, and other camera options that I have been advised to get. Do you have any thoughts on those cameras suggested?
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