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Thread: Welding lens filter - proof of concept

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    Member SnowA's Avatar
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    Welding lens filter - proof of concept

    dtoh posted a link about this a week or so ago, and I decided to have a crack at it after ordering the bits and pieces. Taken today at Lane Cove National Park.

    The setup:

    Shade 8 welding glass lens.
    Generic cokin p-series holder and 77mm adaptor ring.
    30D, 17-55mm lens, and cable release.

    At first I tried to fit the welding glass into the p-series holder. While the glass was the right dimensions length/width for the holder unfortunately it was just a bit too thick (by a mm or so) and I didn't have the patience to sand it down. The edges were pretty sharp too - as my poor fingers discovered - I'm still sporting bandages.

    I'd read about light leak issues with the holder as well, so abandoned that idea and set about fitting the glass directly to the adaptor ring. Used blu-tak (or yellow-tak, in my case) - rolled into a long thin piece, and stuck on the filter edge.

    Tip - don't go too close to the inner edge as when you press it down onto the glass it squashes down and if you have it too close it may intrude into the field of view. The bonus of directly attaching like this is you avoid light leaks around the glass.

    Here's the setup (sorry about the poor quality - phone pic):


    and from the other side:


    (you can see I applied some duct tape to save my digits any more impromptu surgery).

    I also ordered shade 10 and shade 12 lenses, but settled on the 8 as it was the first to hand. I've read that a shade 8 is equivalent to about a 9 stop ND, but I'm not really sure how to go about measuring it - any thoughts?

    Focusing through the glass didn't work, so I auto-focused without the welding glass on it, and then switched to MF, then re-attaching the welding lens filter.

    The lens has a strong green cast to it (this is autoWB, out of the camera):


    I'm shooting in RAW, so I could correct it in PP, but it was easier to use this shot as a custom WB. That got rid of most of the green.

    I set aperture at f/18, ISO 100, and turned on long exposure noise reduction. Figuring the exposure time took a bit of trial and error - I started at 30 seconds and worked my way up, checking the histogram on each subsequent exposure and looking for blowouts. I'd read that you also need to cover the viewfinder to stop light leaking through that, so I used a hanky. It fell off on a couple of exposures but that didn't seem to affect things much.

    The day was fairly still so there wasn't the cloud movement that I hoped for, but I think it's worked, and definitely worth pursuing.

    The shot that turned out best was a 105 second exposure. The out of camera shot still had a slight green tinge to it, so I corrected that, and a few other minor tweaks.

    I'm pretty pleased with how it's turned out and had a whole lot of fun to boot, particularly given that the single filter cost, including (redundant) holder and adaptor ring was around $7.

    What do you think?


    I can see myself having some fun with this
    SA

    Canon 7D | Canon 30D | EF-S 17-55mm f/2.8 | EF 50mm f/1.4 | EF 70-200mm f/2.8L (non-IS) | 580EX II

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    The colour is deep and rich. Looks like fun. Good luck
    Homer says, "It's funny, because it's true."

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    Still in the Circle of Confusion Cage's Avatar
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    Hi Snow

    Good result. Was thinking about having a play myself, maybe glueing the glass onto a step-up ring.

    It would be an interesting comparison to see a 'normal' shot of the same scene.

    Cheers

    Kevin

    PS: Have a look at this link. http://cgi.ebay.com/58mm-58-mm-ND-8-...item3efd594265
    The filter is probably cheap and nasty but optical wise may be on a par with the welding glass. Anyway for about $8 it's worth a try.
    Last edited by Cage; 24-07-2010 at 5:44am. Reason: Add link
    Cheers
    Kev

    D600 : D7200 and too much stuff to list

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    I`m gonna get one...and have some fun. Are their differing shades of glass? Are they all the same darkness (maybe a dumb q)?
    Graeme
    "May the good Lord look down and smile upon your face"......Norman Gunston___________________________________________________
    Nikon: D7000, D80, 12-24 f4, 17-55 f2.8, 18-135, 70-300VR, 35f2, SB 400, SB 600, TC-201 2x converter. Tamron: 90 macro 2.8 Kenko ext. tubes. Photoshop CS2.


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    I got some today, $5 each from blacksmith jacks, check the state of the glass to make sure you get a nice piece.
    Good cheap way of trying this type of photography.
    Just clowning around

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    SnowA's Avatar
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    Quote Originally Posted by old dog View Post
    I`m gonna get one...and have some fun. Are their differing shades of glass? Are they all the same darkness (maybe a dumb q)?
    They come in differing shades. I have an 8, 10 and 12 - from what I've read they should approximately be equivalent to an ND 9, 11-12 and 15, respectively.

    I'm going to try the shade 12 next.

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