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Filming welding from a safe distance

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26 replies to this topic

#1
CWIWelding

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Greetings all, I am a welding Instructor based in Idaho and after thinking long and hard about it our department bought a Nikon D3300 for the purpose of filming welding tutorials.  We chose a lower end camera from the Nikon range thinking that if it worked well we could invest in something better in the long run.  But that aside, on with the question...

 

Welding and getting close to welding can be a pretty nasty environment, so with that in mind we would like to film in close, but from a distance.  By that i mean we would like to keep the camera out of harms way... say 6 feet away from the process, but be able to see a quarter filling the screen.  We would like to get close up shots of the weld puddle from a safe distance.  Now, we have seen all sorts of lens options online, and many have videos showing massive long range shots etc... but we havent seen one yet that shows the minimum focus length on some of the larger lens (by larger i mean longer, ie larger numbers ;).  We bought the 2 lens kit including the standard and 55-200 lenses and obviously they do not give the magnification required, i mean they could if i got in close but we dont really want to melt the camera lol 

 

So in a nutshell, what sort of a lens or lens combo would alow us to be 5-6' away but be able to focus in on a quarter full screen?

 

Secondly, we are looking at a number of options to counteract the brightness of the welding arc... We obviously have straight welding glass available, as well as reactive autodarkening lenses available, and we are looking at various ways of attaching these lenses to the camera for various tests... Also, we have been looking at ND filters and even purchased a variable filter in a hope to find the right sort of density we would need for a solid single density filter, but the graduating marks around the ring, apart from being out of alignment do not identify the density directly, plus the variables have that horrible X pattern of darkness... so we werent able to determine a usable density value.  Has anyone used a solid ND filter to show the weld pool effectively?  Or does anyone have knowledge of what sort of range should we be looking at getting? As in ND400? ND1000?

 

Any advise would be welcomed

 

 

 

 



#2
Merco_61

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The problem is that you need a 1:1.5 reproduction ratio at a long distance. This is not doable AFAIK. You might be able to do something with a long tele lens and some extension rings, but you won't get close to what you want. This would be easier with a camera with a smaller sensor as you wouldn't need the extreme reproduction ratio to fill an industrial CCD or a CX sensor.



#3
Jerry_

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I think that using a consumer market, rather than an industrial, camera on shooting welding with the level of detail that you are looking for can be quite difficult for a number of reasons that have already been mentioned, but also because of the stress that I suppose it will put on the equipment, even so you mention you want to be at a distance that doesn't put it at harm.

In my opinion, the only way to get the captures you want is by getting closer, which causes other issues I am sure you are aware of.

Indeed the heat will be an issue if you are getting to close and will damage the lens. Not only might it have some impact on the plastic parts of the lenses, but also on the glass itself.

Also, having used angle grinders for cutting metal parts in the past next to glass, the sparks are usually that hot that they burn into the glass (here: the lens), so they can't be removed any more.

That being said, there is certainly possibilities to build housings that protect and cool both the camera and the lens and thereby allow you to get closer.

Also having a smaller sized sensor (DX (crop factor 1.5; D3xxx, D5xxx and D7xxx models) or CX (crop factor 2.7; Nikon 1 models f.i.)) will allow you to proportionally increase the distance, for the equivalent of having used an FF camera (which I think would be a bad choice in the type of shootings you plan)

So looking forward to the captures you might already post

#4
TBonz

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Are you looking to produce still images, videos or both?  With still images, you would have the option of cropping the images so that you wouldn't specifically need to get the full magnification in the original shot although you would certainly get better quality images as you get closer to the full frame.  

 

As a starting spot, I'd suggest shooting still images from your 6' distance with the 55-200 and the welding glass to see what kind of images you are able to get - and I would suggest trying various exposure settings above and below to see what works the best.  At a minimum, I would not shoot without something - at least a protective filter - in front of your lens.  Shoot a bunch and review the images to see what works and what doesn't...I expect you'll be able to find some settings that work best...you might also discover that you don't need quite that magnification...or you need more...Theory here being that some testing will eliminate some of the variables and you can post some images that might help us help you to determine a magnification level that would accomplish your goals within a reasonable price level.



#5
Ron

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I can only add this to what's already been said. There's a page in the owner's manuals for all of my digital cameras that warns against aiming it at the sun (or a strong light source) for extended periods of time. You can seriously damage the image sensor that way if you don't use proper (light) protection over the lens. I've done a bit of welding in my time, and have burned my eyes once or twice, so I know how bright a welding arc can be.

 

If I were going to do this (as a still photograph) I would make a composite. One exposure through an appropriate welding glass, which would be the center part of the image. I'd make a second exposure with the center area, that is the area of the arc blocked out completely. Then, in Photoshop, I would combine the two images and adjust for differences in color, etc. 

 

I really don't know how you would go about doing this in video but I've seen enough videos that featured welding to know it's possible.  Google is your friend.

 

--Ron



#6
CWIWelding

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Thank you all for your posts to date :)  and yes, I am well aware of your concerns regarding the heat/smoke/spatter issues that definitely could occur, google has been my friend Ron ;)

 

However lack of knowledge on lenses has been my enemy... what i do know is, i can't get in close enough with the lenses i have, and I have been toying with the idea of extension rings and possibly a less expensive 800mm mirror lens, possibly the Samyang/Rokinon... from what i've read so far it looks like one of the only super telephoto lenses that "could" focus at around 6', I think the extension rings might increase this, but it might be worth a try.  Now the down size of the mirror lens seems to be the filters we would need for the size of the filter that would be required for that type of lens which is a 105mm.

 

Now that alone is going to give us problems even finding something like neutral density filters of the darkness that we would need for the welding arc.  What i do know is the process would require a minimum of a #9 or 10 shade on our welding helmets, that would give is good visibility of the welding arc and the surrounding parent metal, what that actually relates to in an ND filter, I do not have a clue... is there a comparison somewhere that relates shade numbers in a welding lens to ND darkness numbers... like ND400 or ND1000?

 

One comment that I did read was a welding arc is brighter than the sun... what i will state for sure is that statement is incorrect.  It takes at least a #13 or 14 to be able to look at the sun, I know that for a fact as I have those shades and I have done it personally.  I am going to be playing around cheap UV filters (which i only need for the external ring) as I am thinking of getting some welding glass cut to fit it, or obtaining the lee square mount filter attachments that would take a whole welding lens.

 

And in response to the other two posts to date... Yes tbonz we would like to do both, although the real reason we bought this camera was video... the 60fps will enable us to get some decent slo mo.

and yes we will try that, i will set up a weld coupon in position and zoom in with the 55-200 and show you what we are getting so far.  As stated above, we do have filters and will be playing about with more, our concern right now is what can get the shot in close enough... from a distance that will not hard the camera, the brightness of the arc we will play around with later.

 

And yes Jerry its problematic, hence the post... and yes it isn't a simple fix, if it was we probably would already have already found it.  What is for sure is, if we do find a way to do what we want, we want to share that way so everyone will benefit from our work on it, we are educators afterall ;)



#7
Jerry_

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I was interested by your question about the correspondance between welding glass indicators and ND filters and launched a Google search for the following words:
welding shade number to nd filter

One interesting site that was returned is
http://photo.stackex...as-an-nd-filter

Also, it returned a number of articles where welders use welding glass as ND filters.
f.i. Use welding glass as a 10 stops ND filter

The point I came up in my post was to build a housing for protecting your camera and lens. This idea is based on my experience of using cameras underwater, even so I suspect that for your purpose the configuration could be much simpler: a box with a front element of welding glass, a rear element of normal glass, a screw in the bottom to fix the camera and a remote control to trigger the captures.

#8
Ron

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When you mentioned the sun, a little (tiny actually) light bulb came on over my head.

 

What about using a sun filter such as the ones astronomers use on their telescopes? I used to have one many years ago that I used to photograph eclipses with. I can't remember what size it was but it fit over my CAT (mirror) lens. The only downside to it was the way that it attached. It didn't screw into the lens but rather fit over it with thumb screws to secure it... which would have marred the outside of the lens had I not employed rubber caps to protect the lens barrel.  

 

I doubt if you'll find neutral density filters strong enough to be of much help.

 

--Ron



#9
GrayWolf

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I've spent some time inside welding helmets up close and personal to welds. If the conditions inside a helmet are ok for people, I don't see why the environment would harm a camera. I'd get a rubber sunshade, press it up to the filter glass or auto-darkening glass and fire away. If it works, you could monkey up a way to mount the camera against the glass and then the whole thing on a tripod. Shoot from 2-3 feet.
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#10
CWIWelding

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Thank you Jerry, that first link is exactly what i was looking for... I can honestly say that being a professor math doesnt scare me lol, and it looks like it will give me exactly the data i need.  What i will do is grab welding lens data and F stop data and combine them into a usable chart I can post on here, with the caviat of course that welding lens densities vary by manufacturer just as lens filter manufacturers do... but it will be close enough to produce a comparison chart.  Great find.  I had see the second link in my searches, that was a cool site.

 

Hopefully Ron if i can equivalence welding filter densities against F stop or ND values I might be able to use anything given the density values, but not a bad idea... why not tap into the astro side given the fact they already take shots of extremely bright objects like the sun, good point.

 

And yes greywolf, we were thinking the same thing, we were going to make an aluminum shroud that is wide enough at the back so access to controls wasnt impeded yet sealed tight to a clear glass in the front that would protect the camera and lens.  Even if we manage to get in close from a distance, macro's would be nice.

 

Thank you all for your help :) This is a new world for me, never been into photography before this... I'm still learning how to play with shutter speeds and f stops lol



#11
GrayWolf

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You've got compressed air...so what about running some low pressure air into the shroud to cool it. Then you could move in closer / longer.

I'm thinking that as a practical matter, you won't be able to get much closer than a foot or so without your "gadget" blocking the operator's view of what he/she is doing.

You might experiment with various cardboard shrouds enclosing the camera and "pretend weld" the setups you want to video to be sure you aren't wasting time trying to get within inches of the bead.

Or contact Miller, Lincoln, etc to see how they do it.

#12
CWIWelding

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If you remember that old cowboy series with Lorne Green called Bonanza, they had a map of the "ponderosa" on the intro that burst into flames from the middle out, im afraid at the temperatures we are talking about we would have a picaso style camera if we tried it greywolf lol and cardboard im afraid wouldnt survive.  But the shroud idea is already in production out of metal, and any lens will have a sacrificial sheild over the front. Welding of steel means heating the steel to a melting point upwards of 2500 degrees F, plastic (what the lens body is made of) has a melting point of under 400 degrees F, hence the reference to the picaso melting clock :)

 

Primarily we are making the "shroud" to protect it from stray spatter ( stray projected molten metal ), spatter is the trace lines you see on photographs of the welding process, like tracer bullets if you play with the F stop a little, all of this is molten metal being ejected from the weld pool, it can be ejected 4 or 4 feet from the welder, dependant on the position in which you weld it.

 

I have contacted Miller and Lincoln and Hobart, and even a guy that produces welding videos and Ive been given the run around by them all, In one case i was basically told that the camera was sacraficial and only needed for a few shots, so they basically had a few cameras to get the footage, some just refused to answer... I have been given some "this is how i would do it" answers from some photographic companies, and trust me... they are going to get hurt if they try that themselves lol.

 

I have been compiling a master chart based on my initial question regarding ND filters... i found the answer i was looking for earlier in in my searching, but i couldnt resist putting as much info as i could in a single chart.  Its still a work in progress, but this is what i have so far.

 

Weld%20filter%20to%20ND%20comparison.jpg

The shaded rows are commonly used welding lens numbers, as that was my initial focus.

 

Its not complete yet but i thought i would share, in case some other poor deluded soul asks the same question ;)



#13
CWIWelding

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Apart from ND filters and a shroud, ive also ordered a mounting ring and a large screen autodarkening Lincoln viking filter that we will mount like this...

 

CameraWithLens-1024x682.jpg

 

Please excuse the 7D in the picture lol  But you get the idea, and the lens I am going to use is different...

 

It has a 3.74 x 3.34 in. (95 x 85 mm) viewing area like this...

 

LINKP3045-1.jpgKP3045-2.gif



#14
Ron

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That stuff is pretty (pardon the expression) cool! Thanks for taking the time to post it CWIWelding. It certainly looks like you've been doing your homework. My professors always hammered that preparation is the key to success. Just because something looks easy doesn't mean it is. 

 

I sure wish that those auto darkening filters had been available back when I was doing a lot of welding. I probably wouldn't have burned my eyes so much and, as such, probably wouldn't be fighting so many floaters in my eyes these days. Welders today have it nice! LOL

 

The rig on that (cough, cough) Canon looks pretty cool too. Who makes that? Viking?

 

--Ron



#15
GrayWolf

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How close do you figure the camera will be to the arc?

#16
CWIWelding

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lol, yes Viking makes it for Lincoln Ron... I already have the helmet myself, thats why I know i will be happy with the color tint, its more of a goldy kind of green not like some others.  And yes, i definately started welding before they invented autodarkening helmets so i feel your pain lol

 

As close as possible but a safe distance to protect the camera... maybe 6-7 feet if possible with a long lens so that a quarter from that distance would nearly fill the screen.  If that doesnt work then I will protect the camera and get in closer.  Hence the welding lens idea...

 

I have seen a lens that may work, it certainly has the specifications and a wicked zoom at possibly 6 feet, now i take that minimum focus distance with a pinch of salt, its a minimum after all... but heres hoping it lives up to the hype... I know that this lens is made by the same company under different brands (Samyang, Rokinon etc etc) and ive seen that same lens have at least two quoted minimum focus lengths... 6 feet and 11 feet, the ring says 6 so im hoping its correct but in all honesty i'd still be happy with 11 if it can zoom in close enough.

 

Rokinon_800M_B_800_mm_f_8_0_Mirror_13160
 

Its definately marked at 6 feet or 2 meters... If it works as i hope it may be all we need, I need it for video through an ND filter which will probably need light correction anyway, and at under $200 it will well be worth the chance that it would work for what we need it to do... failing that, the camera will have to get close and use the welding lens and shroud to protect it.  The lens above is the 800mm Mirror lens from Rokinon.  Now if i was using this for photography and not looking through the equivalent of an ND4000 filter at a bright blob of weld I might invest in a higher end lens, as it is and given the task... I'm hoping this works :)



#17
CWIWelding

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Then of course I have the next problem... where in the hell do i get an ND4000 filter lol  I have looked everywhere. Is there a way of stacking the ND filters? I know the ones ive seen so far only have the one thread... any idea's? Oh and this lens is 105mm I can get them for smaller sizes up to 95mm, I just cant seem to find one at 105mm



#18
Merco_61

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I don't see how the Samyang would work as a 3° FOV on FX at 6 feet would mean a reproduction ratio of 1:6.5 or so. That said, Lee filters make the 150 system that can stack 150 mm square filters. Their Big stopper is a 10-stop ND and it is available in 150.



#19
CWIWelding

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Ive seen the lee filters, and they are an option, should i need something larger than 105mm , interesting info on the samyang though... being new to all this i'm not even sure how to work all that out, it seemed like a possibility to me, a novice with little to no knowledge of photography.  Hmmm back to doing research again i guess lol 

 

It seems like i need to look at the basic math behind all of this and find a solution, and yes Merco I did read where you said it wasn't doable as far as you knew... but that just makes me want to try to do it even more lol  and yes, as you have obviously guess by my previous comment I have no idea about lenses, reproduction ratios, feilds of view and how it all works... i was simply looking at a long lens with a short minimum focus distance crossing my fingers and hoping it would suffice lol  So first i have to "understand" the problem by learning the math, then being an engineer, solving the problem :)

 

Seems straight forward... ( Where's the tongue in cheek emoticon when you need it haha )



#20
Merco_61

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The problem of getting such a large reproduction ratio at a distance is probably why commercial welding photography solutions are based on 2/3" or smaller CCD cameras instead of larger sensors. With a smaller sensor the need for the large reproduction goes away as the sensor crops the image.







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