Topic: Lighting at Glass Fairs

[Derek]

Hi All

I seem to attend most of the major glass fairs - hands up anyone who doesn't ! The three most recent major venues I have been to are Gaydon, Bristol and Woking.

At Woking, I picked up one of the Peter McDougall 2006/3 weights (Pink flower surrounded by a swirl of leaves and buds all on a Latticino base) that I had pre-ordered. I was somewhat surprised to see that the colour of the flower was distinctly peach coloured rather than the full pink I had seen in all the photos.

On getting it home however the weight was the correct colour!  even in artificial light both incandescent and flourescent - I can only assume that the lighting in the hall must have had a strong sodium (yellow) element so distorting the apparent colour of the weight.

Gaydon seems to have excellent lighting as I have not noticed any discernable difference. Bristol was an interesting venue with natural light coming in on  one side of the hall and the weights on that side had a good sparkle - something lacking on stalls on the away from the natural light - even when the stall holder had additional spotlights.

Has anyone else noticed this and perhaps KevH can shed some light !! on the reason for the change of colour.

Derek

[Frank]

Fluorescent light has a strong yellow/green element, one of the hardest to compensate for in photography - in fact you can only do it with an extremely expensive colour meter and a pile of filters to get the right one.

Monart used a huge range of colours and there are some that really came to life under fluorescent light but die in normal light, others are better with daylight and yet others with tungsten.

When we all switch to LED lighting the challenge is going to be even greater as they change their colour balance as they age and do not put out any UV. Fortunately, for the vaseline folk, UV emitting versions will also be available.

[KevinH]

Derek surmised:

... perhaps KevH can shed some light !! on the reason for the change of colour.

Err, well ... nope! I can only comment on what I see, and what little I may know about the glass batch, not why it happens. Even with some technical data about UV reactions I can't honestly say why the various colours are seen. Apparently it's all down to "absoption", "reflection", "refraction" and other long words that I don't undertsand too well.

Frank commented:

Fluorescent light has a strong yellow/green element, one of the hardest to compensate for in photography ...

Yeah, tell me about it :!:  I now have a couple of excellent "table-top" studio lamps, each with 12 inch reflectors and containing 3 x 30W "daylight rated" fluorescent bulbs (actual rating 6,400 degrees Kelvin). Along with good diffusors and a "shooting cocoon", I can now get superb results for paperweights ... as long as they don't have much clear glass in the photo view.

Any clear glass shows with a mild green tint, even when the camera (an expensive semi-pro digital) is set to any of its various compensations for white balance etc. I have also tried loads of adjustments in the photo editing software [I use Photoshop Elements] but nothing will do the job properly (at least, not to my satisfaction). The closest I have got to a correction, which gives something aproximating to a grey tone, is a setting of "Flourescent +4" in the camera's "pre-set white balance" range, but I cannot find out what that actually means.

Anyone actually know which type of filter can correct the fluorescent yellow-green tint?

[KevinH]

I have tried out a few options and have found that by switching off the "auto contrast" the result can then be manually enhanced for contrast and brightness to get a good result.

When I have played around a bit more, I may well set up a separate message to show the "before" and "after" results ... using a range of weights including a couple of antique French ones.

[Bernard C]

Derek — The hall lighting at Woking is particularly grim, that's why we are located on the island furthest from the public entrance, close to the door to the stallholders' car park.   We take trips outside with interested potential clients perhaps half a dozen times every fair.   Pinks, peaches, ambers, some yellows and some opalescent colours fare worst at Woking.

Never worry about asking a dealer to see that interesting piece of glass in daylight.   It might take a few minutes to organise a minder, particularly at busy times, but it should be worth the wait.

Bernard C.  

[mjr]

Bernard - for an extreme example of how lighting can change colours, i have a Caithness royal wedding which is coloured clear glass. Under normal lightbulbs it is pink. If it is carried into our hallway which has a long life flourescent bulb it goes light blue.  Kids love to show it off as a magic trick

[Bernard C]

Martin — I've seen those before, they're fun.

Mentioning clear glass reminds me of yet another problem at Woking.    Some clear uncoloured glass goes a really wierd colour.   The worst is 1920s and '30s Pyrex, which goes what could be called puse, or, if you replace the "s" with a "k", that might be more accurate.   Fortunately I only stock it in pewter mounts or bain-maries, so usually the pewter sells it.    That I do have to take outside.

Bernard C.  

[Lustrousstone]

Martin, your colour changing paperweight uses neodymium glass, quite common for Caithness things. There are several other threads on here discussing it and this is the best general link I've found http://www.mindspring.com/~reyne/neowhatsis.html