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Glass Identification - Post here for all ID requests => Glass => Topic started by: dirk. on June 02, 2016, 05:29:05 PM

Title: Photographing clear and translucent glass on a light table
Post by: dirk. on June 02, 2016, 05:29:05 PM
On special request. Someone asked how I achieved my photographs of clear glass.
I use a light table, which I built myself. It simply consists of a 2mm translucent white perspex and a wooden frame.
The perspex was bent using a hot-air gun.
Usually I take all my pictures with just a single 150W bulb, placed just behind the bend so the objects are back-lit.
The table works great on clear and translucent glass, but not very well on opaque objects unless you use additional
lighting.
If you use a small angle for the photographs the perspex gives an additional mirror image of the object.
I´m using irfanview  on most pictures to adjust the colours.
Few examples are added - hope you enjoy!
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on June 02, 2016, 05:32:23 PM
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Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on June 02, 2016, 06:01:51 PM
since it was me that asked the question Dirk, then a big thanks for taking the time to reply. :)

It looks simple enough to construct, so I shall attempt to copy your equipment  -  thanks also for the pictures showing some glass photographed with this method  -  I'm very impressed with the results.

I also use Irfanview, but only for re-sizing  -  for editing the contrast, colour etc., I still use Picasa and seem to get on o.k.

thanks again.
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne on June 02, 2016, 07:44:57 PM
That is so simple yet so effective, Dirk, thanks for showing us. I assume the 2mm perspex is fairly easy to bend to that curve? How does it cope with heavy items, is there any bend in the perspex?
Title: Re: Photographing clear and translucent glass on a light table
Post by: flying free on June 02, 2016, 08:10:56 PM
Perfect photos that show off all the details.  Very envious. :)
m
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on June 03, 2016, 04:57:20 AM
Thank you all!
Measured the perspex again - sorry, it´s 3mm actually.  ::)
You need to make sure it´s the bendable variety of plexiglass. I´ve used the following method to bend it:
https://www.youtube.com/watch?v=aoozlMBLcW4
Make sure you´re only using one clamp! The perspex expands and it might get rippled otherwise.
The strength of the perspex, the frame and the bend make it stable enough for objects of a few kg and
should be ok most of our photographing purposes.
I´ve chosen to make the bend after a third of the whole plate. This way you can use it flat for bowls etc. or
place it the other way for taller objects.
Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on June 03, 2016, 07:25:01 AM
oh no!!!    and I've just been out and bought an expensively large sheet of 2mm  !!  .............     ;) ;) ;D           hope to let you see some results when it's made Dirk. :)
Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on June 03, 2016, 05:46:12 PM
have now found a local supplier of acrylic (which is the formable/bendable type)..........     it would appear that the particular acrylic as described by Dirk, in the U.K. is called Opal 050 in 3mm thickness.          Hope it all goes to plan.
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on June 03, 2016, 07:16:00 PM
Great! Please let us know about the outcome.  :)

Or was it 4mm?? Mmmh, need to measure again....  ;D
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne Tique on June 04, 2016, 11:14:35 AM
Excellent results with the table, looks really professional.

Unfortunately my DIY skills are not ... well, they don't exist... but I'm good at improvising.

I got myself a large, A3 I think, sheet of thick paper with a light, satin finish. I've bend it into a 'U' shape to create an 'endless horizon', and slid it in a large box and attached it with tape, to hold it in place.

The box is then put on one side et voilà  ;D my homemade and improvised photo studio.

I direct the light, like Dirk, towards the back from both sides, to create a sort of halo and white LED light, imo, gives the nicest results.

I then crop the images, play around a little with a programme to enhance quality, colour and light, and my pictures are good to go.

Underneath some results, they're all made in the box.
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne on June 04, 2016, 01:11:36 PM
Anne they work really well too.  I use a sheet of opaque glass stood on four clear glass tot glasses, with a battery operated multi-LED light underneath it at the back, and a sheet of plain white hardboard (rescued backing board from a former bookshelf) stood behind the shelf as the backdrop with a couple of sheets of matt black card stood at either side out of camera view, to give shadows to make cutting or pattern show up clearly... here's some examples...
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne Tique on June 04, 2016, 02:35:08 PM
That's stunning too! I quite like it that on both yours and Dirks' pictures the items don't reflect any direct light from the lamps, like on mine.
It looks very impressive and professional.
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on June 04, 2016, 02:46:29 PM
Wow, good result everyone!  :o :o
Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on June 09, 2016, 05:59:52 PM
in practice 3mm acrylic requires more heat than I imagined in order to make the stuff bend through 90 degrees  -  you can use a wire, but this requires a more complex set up than a simple gun.
The size I chose was one metre square - probably too big  -  as the heat gun reaches the end of 100 cm. the first bit I suspect has lost too much heat before the nozzle returns.
Anyway, mine requires some refinement yet, and I suspect experimenting with the position of the light source might help to improve the brightness where it's wanted.     I've used a modern Energy Saving Halogen bulb rated at 105W, which I was told is the equivalent of the old incandescnent 150W - but not so sure that in practice the light is as bright.            However, it's a vast improvement on my old set up, and a big thanks Dirk for all his help and suggestions. :)
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on June 13, 2016, 03:56:12 PM
Very good results, Paul! Isn´t it amazing how much details show up on cut glass?
You´ll enjoy trying different light settings with your new equipment I´m sure.  :)
Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on June 13, 2016, 09:31:02 PM
hi Dirk  -  yes, I really can't stop playing with it ;)

One important aspect of the light source is that when using a standard incandescent bulb (or even a low energy bulb), the resulting light has a tendency to cast a yellowy/brown glow, whereas using a strip fluorescent type of lighting gives a good white light, and seems to improve the clarity.
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne on June 15, 2016, 04:59:49 PM
Cool white and daylight LEDs give a very clean white light too Paul, as do cold cathode tubes (as used in computer monitors, fish tanks etc). The warm white LEDs tend towards that yellowy tungsten light effect.  There's a handy guide to light temperatures here: https://www.lightbulbs-direct.com/article/colour-temperature
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on June 15, 2016, 05:02:32 PM
Thanks both! My old camera used to have a good function, which helped to easily adjust the light setting.
Unfortunately the new one doesn´t, so I shall try a different light. :thup:
Title: Re: Photographing clear and translucent glass on a light table
Post by: oldglassman on June 15, 2016, 05:43:08 PM
HI ,
           For a long time now I have been using spiral daylight bulbs,they are recommended for photography and also for sad syndrome,so they keep you happy while you work lol

cheers

peter
Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on June 15, 2016, 09:06:04 PM
thanks for the link re light colours Anne, very useful  -  I've been using two angle poise lamps with circular fluorescent tubes - one behind the acrylic and the other underneath.                One was daylight and a good white but the other was casting a less than white look, so have replaced with a 'cool white' LED which according to your list should improve the 'whiteness' - will see how I get on.

Like all obsessive collectors, I get sad syndrome if I don't find anything good for a week ;)
Title: Re: Photographing clear and translucent glass on a light table
Post by: David E on June 21, 2016, 02:23:17 PM
You need to alter the white balance of the camera to adjust for the different types of light. Trouble is, if you're using two different light sources, like tungsten and fluorescent then you'll get two different colours in the image, which is very difficult/impossible to remove.

Another trick for clear glass. If you place two pieces of black card (hey, a book will do!) quite close to the sides of the object, then this refracts the dark light to show up what can otherwise be very pale edges against a white background. Quite useful when the glass is plain and not cut.
Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on June 21, 2016, 03:54:51 PM
thanks David - will give that a go. :)
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne on June 21, 2016, 10:18:06 PM
I said that in my reply #10 earlier. ;)
Title: Re: Photographing clear and translucent glass on a light table
Post by: Pinkspoons on August 15, 2016, 10:19:24 AM
We have a similar set-up - ours uses a large metal frame we put together from parts of a modular exhibition display that I bought in a moment of madness, but it could easily be constructed from timber.

The gubbins are inaccessible without dismantling parts of the table, and I never photographed it whilst putting it together, so I'll have to tell rather than show + diagrams.

It's a ~1m^3 cube with an additional, continuous, cavity underneath (40cm), behind (40cm) and on top (~15cm) that each contain 10 evenly-spaced Osram Lumilux Deluxe 954 fluorescent tubes (so 30 in total - wired to three plugs so they can be operated in blocs) on mounted reflector battens. The outsides of the cavities are boxed in to prevent light-leakage.

The cube is floored with 1m^2 of 25mm clear acrylic, which will take very heavy items, and then a continuous ~3m length of translucent matted film - the type used to print back-lit posters on bus stops and in cinema foyers - is tacked to the top, the back and the floor with double-sided tape, leaving quite a loose curve where it meets corners to avoid jarring lines and shadows from the cube's frame (it's called an infinity curve). The floor is then optionally topped with a 2mm sheet of acrylic (matted/frosted on one side) to protect the film and/or create a reflection (although the films are easy to replace when they get worn) - but this will create a line at the back of the cube where the acrylic refracts shadow, and will need to be 'knocked out' with a couple of GU10 5400k LED spotlights mounted to the front of the cube. They also come in handy for highlighting gilt, enamelling and signatures. If you're only photographing small items, you can also negate it using depth of field with your camera.

Suspended inside the cube on thin wires running parallel to the front opening of the cube are two 'curtains' made from stiff black fabric (I cannibalised a cheap roller blind and stapled the fabric around stripwood at the top and bottom for rigidity and weight) that can be pulled as near as you need to transparent objects to give them something to refract. They're suspended on hooks, so they can be easily removed/replaced.

Opaque items with fiddly shapes might need an additional light source at the front (we've a cheap soft-box on a boom stand), but generally enough light bounces around in there as-is.
Title: Re: Photographing clear and translucent glass on a light table
Post by: Pinkspoons on August 15, 2016, 10:40:20 AM
5 minutes of jiggery-pokery in a photo editor to get rid of any in-shot curtains and smooth out any hiccups, and you've usually got crisp photos of typically awkward glass.

Here's some Holmegaard egg cups that we struggled to photograph previously because of the plain long necks that always vanished against white... and grey... and black... and gradients. They were, once, a complete pain.
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne Tique on August 15, 2016, 10:54:29 AM
I'm not able to follow the explanation of the set up, but that's not your fault ... but what a result ... absolutely stunning!
Title: Re: Photographing clear and translucent glass on a light table
Post by: Paul S. on August 15, 2016, 11:17:52 AM
we do have some clever people here - love those results, and with this 'acrylic' set up there is the added bonus of the mirror reflection which very artistic.  thanks for sharing. :)

Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on August 15, 2016, 05:28:40 PM
Brilliant results indeed - many thanks for your explanation!  :)
Title: Re: Photographing clear and translucent glass on a light table
Post by: WhatHo! on August 22, 2016, 10:48:59 AM
Hi Dirk, I was wondering if you could put up some pics of tall items photo'd via this method, like a 13" decanter or tall vase etc? My light set up is good on small items but not so good on the tall, i tend to get a lot of light at the base and little at the top. How does yours fare? Cheers Wolfie
Title: Re: Photographing clear and translucent glass on a light table
Post by: David E on August 22, 2016, 12:35:39 PM
Having long fluorescent tubes, as described by Nic, will give an even light. However, there are other ways to achieve this with a flash or single light source, such as an umbrella that will produce a soft diffused light with plenty of dispersion.

Another point that I would like to make, with regards to composition, is the perspective. Normally you should stand a good 1 metre away (more if it's a larger item) to prevent fish-eye distortion.

The first photo shows the distortion I see so often, which occurs with the camera just 0.3m away.
The second is with the camera 1.2m away, zoomed in more, and now the top and bottom are more or less parallel.
Lastly (photo 3), try tilting the camera slightly to take the object slightly higher, which removes any doubt.

I hope this helps.

Taken in 2008, with a single 11w flourescent, shining down on the background (backlighting). Yeah, the Photoshopping was rather contrasty!  :-X
Title: Re: Photographing clear and translucent glass on a light table
Post by: KevinH on August 22, 2016, 02:32:54 PM
For trouble with colour tints in photos of clear glass items due to various types of lighting, try the "Remove color" option that should be available in most photo editing applications. It simply creates a "black & white" image, which could be acceptable for many photos.
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on August 23, 2016, 11:06:36 AM
Like David already said it is very helpful to have light-bulbs of different lengths. I´ve used one upright e.g. for a tall Empoli
decanter (pics will follow).
Additionally - I´m switching to LEDs at the moment. They tend to produce less tints in the photos.
Title: Re: Photographing clear and translucent glass on a light table
Post by: David E on August 23, 2016, 12:02:16 PM
Colour tints can also depend on other variables, but it can get rather complex to remove them.

1. If you are using a standard fluorescent light then the colour temperature can vary wildly - such is the importance to use the same bulbs throughout. A 5500-6500K colour temperature is equivalent to a daylight setting and is something I would always prefer. You can get fluorescent lamps with this temperature. See https://en.wikipedia.org/wiki/Color_temperature - it looks as if Nic's lamps are spot on (unless he photoshopped them  ;D )

2. If your tent, or setup, is open to the light (not enclosed) then natural daylight can cause awkward tinting due to different colour temperatures. The solution is to eradicate the daylight with blinds or take the photos at night! But never use room lighting at the same time either, such as incadescent, fluorescent or LED.

3. Your camera settings can make quite a difference too. There may be a white balance setting, but this means setting it up for each session. This is where you 'tell' the camera what the light source is.

4. Photoshop or image editing software can remove any colour anomalies for you, providing it is a single colour cast.
a) Photoshop has Photo Filter setting for warmer (orange) and colder (blue) adjustments - use this in conjunction with the 'Info' panel to check that the whites and greys are equal for R, G and B settings (white is 256, mid-greys are 128, black is 0). Or use the 'Colour Balance' (Ctrl-B) tool to define the colour setting for Shadows, Midtones and Highlights, by boosting the blue values and reducing the red values to make a 'cooler' temperature. Or, the reverse for creating a 'warmer' (orange) image - this can also be used as a crude way to create sepia tints
b) Irvanview has similar settings, but not so easy to use. Just press Shift-G.

There is never the perfect photo and virtually all needs a little tweak along the way. Hope this helps.
Title: Re: Photographing clear and translucent glass on a light table
Post by: dirk. on August 23, 2016, 06:36:37 PM
Here´s the picture of the decanter. I used a ´normal´ tube for the lighting underneath and an LED for
the back light, which gives a nice colour difference.
Title: Re: Photographing clear and translucent glass on a light table
Post by: David E on August 23, 2016, 07:48:26 PM
Very nice, Dirk! Is that a strip of LEDs at the back?
Title: Re: Photographing clear and translucent glass on a light table
Post by: WhatHo! on August 24, 2016, 07:03:27 AM
Thanks Dirk :)
Title: Re: Photographing clear and translucent glass on a light table
Post by: Pinkspoons on August 26, 2016, 11:54:56 AM
Quote
it looks as if Nic's lamps are spot on (unless he photoshopped them  ;D )

Because I buy/sell, and run through lots of photos, I have to make post-production editing as quick and pain-free as possible... so they're definitely spot-on!  :)

Additionally, if going for fluorescent tube lighting and you anticipate photographing coloured glass, always try to get tubes with a high colour rendering index (CRI) - 90, preferably - it will ensure that your colours are as close as possible to real life. Again, saves post-production tweaking time.

It's usually indicated in the coding on the packaging, if not already explicitly outlined - so a 5500k tube with a CRI of 90, say, will be '955', 3500k with 70 CRI is '735', etc...
Title: Re: Photographing clear and translucent glass on a light table
Post by: Anne Tique on February 06, 2018, 11:26:04 AM
Just an update on my progress ...  ::) ...

I recently visited a well known Swedish store (i've bought an island! :D) and I spotted these light panels by coincidence. The light tables i have seen for sale on the internet were a bit expensive for my taste, so I thought I'll give this a try.

Here's the link and I have to add that they are not supplied with a cable, it is just the panel, but the cables are in the same stand and you'll be needing a handy neighbour if you find yourself incapable of connecting the lot, like myself, but I've got a thing when it comes to electricity ... I'm already scared to change a light bulb and a real electrophobic. You can change colour from warmer to colder whites and change the intensity with the supplied dimmer. The lamp is surprisingly strong, I've even tried it with a vase weighing 3,5 kg.

http://www.ikea.com/gb/en/products/lighting/ceiling-lights/floalt-led-light-panel-w-wireless-control-dimmable-white-spectrum-art-40332210/ (http://www.ikea.com/gb/en/products/lighting/ceiling-lights/floalt-led-light-panel-w-wireless-control-dimmable-white-spectrum-art-40332210/)

Here are some results, I have used a darker background for the clear pieces.