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9th February 2019, 06:09 PM #1006GOLD MEMBER
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Do light calcs include a factor for age? Oldies need about three times the light than younger people.
CHRIS
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9th February 2019 06:09 PM # ADSGoogle Adsense Advertisement
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9th February 2019, 07:13 PM #1007
Well, two things to note:
1. If you don't buy enough, you can always get more. If you buy too many you may be able to sell them.
2. There is almost no such thing as too much light. You may find that if you make it too bright then you can switch some off most of the time and then just turn them on when you need some extra light. Also note that during the day you need more artificial light than you do at night - depends on how much night work you do as to whether you need to be able to switch some off.
I really think it will be impossible to accurately engineer it. Your eyes will be different to mine, our brains work things differently, and our life experience makes differences as well. What I mean is that as a pro-photog I may have a different expectation of lighting than some people, in colour temp, shadow penumbras, brightness and variability. That doesn't make their opinions any less valid - they just may not be as fussy.
Another example of preferences making a difference: fletty likes "Daylight" colour temperature, although that is unspecified as to what °K "Daylight" is (and that can vary from <5000°K to 6500°K - which is putrid blue IMO). My preference is for slightly warm at around 3400°K, aka "Warm White" but I could be satisfied with up to around 4000°K. I find that to be very human friendly, but for me fluorescent is abhorrent - hideously cold light. Your mileage can, AND WILL vary!
If you do get a couple of panels too many then you could prolly use them somewhere else anyway.
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9th February 2019, 10:12 PM #1008.
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I agree, above my electronics work bench I have the 4 x 20W CFLs from my photographic copy stand plus 2 x 10W LED spots.
They are all are sort of spots as the are rear shaded with white reflectors.
When they are all on and angled to the same area I can have about 6000 lumens all in about the square metre of area that I mainly work in, and even then that might not be enough so I have a small LED torch that I shine close up onto small electronics components to see model numbers etc.
I made that setup 5 years ago - because they get warm sometime I will eventually swap the CFLs for LEDs maybe some 14W'ers.
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10th February 2019, 02:55 PM #1009
I was going to edit and expand my previous post (#1000), but given it was the last post on the particular page, I've decided to post anew
What follows is drawn from Lighting for the 40+ | About Lux which, according to the original original author, is a rehash of information within these two publications ANSI/IES RP-28-07 Lighting and the visual environment for senior living, 2007, (2011 reprint) and The IES Lighting Handbook, 10th Edition, 2011
Many of us forumites have “older eyes” which take longer to adjust to changes in light levels. The adaptation time is much greater when transitioning from light to dark. Also as we get older, we are increasingly sensitive to glare. Excessive contrast and harsh shadows increase visual fatigue and impair the ability to recognize and navigate changes in elevation and obstructions.
So when it comes to our sheds and man spaces the surface brightness of ceiling-to-wall or immediate-surround-to-task “luminance ratio” should be within 3:1. Which means that avoiding dark walls and corners in our sheds.
Also as we age, the eye’s pupil becomes smaller which means that significantly less light reaches the retina. Aging also slowly clouds the human lens which leads to increased light scattering and glare. (see the following chart)
Aging eyes are more sensitive to glare, so avoiding enhanced light directed to the eyes and bright light sources in the field of view becomes essential to maintaining maximum visual performance.
Another consequence of getting older is that the eye’s lens darkens, filtering out short blue-violet visible light making whites appear yellow and colours less vivid. In particular it becomes more difficult for an older person to distinguish between blue and green.
In partial summary, contrast sensitivity to both brightness and colour decreases as we age. Quoting from ANSI/IES RP-28-07 Lighting and the visual environment for senior living “It is estimated that a normal 65-year-old requires about 2.5 times as much task contrast as does a 20-year-old to see equally well”. There’s a bit more about how particular light sources help with rendering deep reds, cyan and violet – all of which help the older eye to render faces, food, fabric, furniture and finishes more naturally and vividly. In terms of what we might buy from Bunnings or a lighting store, the author comments that short-wavelength blue violet light makes white whiter, thus increasing overall colour contrast and clarity.
If one wishes, you can wander through various technical discussions and papers, such as:
- https://www.noao.edu/education/QLTki...oor+indoor.pdf
- the engineering tool box https://www.engineeringtoolbox.com/l...oms-d_708.html
- https://www.healthandsafetyatwork.co...ing-light-work
The UK Government publication on Lighting at Work http://www.hse.gov.uk/pubnS/priced/hsg38.pdf has some good diagrams on page 15 describing the differences between Generalised lighting, localised lighting and local lighting – in particular look at how close the dark cones come to the work surface when your lighting is “localised” or “Local”.
In summary, the “recommended” light levels for a “working shed” – as opposed to a shed where the user is mostly seeking solace from SWMBO and the kids – is a minimum of 200 lux at bench height through to a maximum of around 500 lux. Allowing for the lower performance of older eyes, a comfortable lighting level might be in the range of 600 to 1000 lux at bench height.
In terms of how to arrange light fixtures so that the lights you buy adequately illuminate your work space, I came across this web page https://www.woodmagazine.com/woodwor...re-positioning To save you following yet another link the page refers to the use of fluoro tubes or similar (i.e. LED tubes or panels) and advises:
- To ensure adequate illumination without shadows or dark spots, you should firstly measure the distance (A) from your main work surfaces to the ceiling or to the desired height of suspended light fixtures. Usually the ceiling will be between 2.4 and 3.0 m above the floor, so after taking away the height of your bench (A) would normally be in the range of 1.6 to 2.2 metres.
- Arrange the light fixtures so that the distance between them (B) is equal to or no more than 1.5 times (A)
- The distance between a fixture and the wall (C) should be no more than one third to one half (B)
In terms of Graeme's question about lighting design software, in my travels around the web I’ve come across this http://www.visual-3d.com/software/downloadvisual.aspx
Lastly, in answer to Graeme’s plea
With a standard fluoro tube or LED replacement tube the light is emitted in a 360 degree fan with the fixture allowing about 25% of the emitted light to go sideways. So a 4000 lumen LED tube in a standard fluoro fixture might only be sending 75% of those lumens (i.e. 3000 lumens) down towards the work surface.
I have one of those fittings, but I also have a LED fixture where the emitted light is “constrained” to a 120 degree fan – well that is what the writing on the box says – meaning that with a bit of geometry I can work out how many lumens reach my bench and then determine how many lux that represents.
Doing the maths –
4000 lumens over a 1.2 metre length is roughly 3300 lumens per metre – what I don’t know is whether these lumens are measured at the fixture’s surface or at a distance of 1 metre. I’m guessing it’s at the emitting surface.
If the distance from my bench to the light is 1.2 metres, the 120 degree fan will result in the light spreading over an arc width of about 4 metres – giving me about 825 lumens per sq.m. which is 825 lux.
(For the pedants, and because when I originally wrote the above, I was yet to have breakfast, I’m ignoring the refinement of converting the arc length to a flat surface – this can be calculated, but is more easily approximated by changing the assumed distance from the light to the work surface to average out the arc. And besides, a result that is +/- 100 lux is more than good enough for the purpose.)
For now, I’m finding that level of lighting more than comfortable.regards from Alberta, Canada
ian
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10th February 2019, 03:13 PM #1010
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10th February 2019, 03:51 PM #1011
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10th February 2019, 04:08 PM #1012
Thanks FF
We are basically in agreement.
That graph of Ian's illustrates the downward trend of our eyesight. Or the need to add more light panels every copule of years, and ominously it stops at age 75 years.
Basically, I do not like the hassles of rewiring to take another light pan and re-arranging the old panels so we have a reasonaby intelligent spacing. Perhaps a line a power sockets across the ceiling so I can just plug them - on second thoughts, that's not all that silly an idea.
I also prefer warm fluoros to daylight. My wife does needlework which involves some incredibly fine colour selections. She was very unimpressed when I put daylight globes in her study to assist - get those hideous things out of here ! - I responded quickly.
Fair Winds
Graeme
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10th February 2019, 04:13 PM #1013
Hi,
Not only humans, fluros dim with age too.
RegardsHugh
Enough is enough, more than enough is too much.
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10th February 2019, 05:13 PM #1014
When ‘the bowman’ wired the shed extension, he insisted on connecting the light fittings via plugs and sockets AND on installing spare sockets. I must thank him again because fitting extra lights has been SO easy as has installing ceiling fans and dust collectors which come on with the lights! Thanks Tony.
a rock is an obsolete tool ......... until you don’t have a hammer!
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10th February 2019, 10:01 PM #1015
Good Morning Ian
Thanks for such an incredibly detailed and thorough posting. I need time to study it and absorb the detail before I reply.
Fair Winds
Graeme
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10th February 2019, 11:14 PM #1016GOLD MEMBER
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That was the single best thing my electrician mate did when he wired my shed over 30 years ago. I don't know how many iterations of light I have since used but it is quite a few and it is about to get another make over. It is so easy to put a 3 pin plug on a fixture and plug it in.
CHRIS
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19th February 2019, 07:36 PM #1017
As an interesting expansion to Ian’s incredibly comprehensive reply, I have recently had an incredibly personal, and rare, chance to experience exactly what has been described above! I have for many years suffered from an optical aberration in my right eye. I was diagnosed with keritaconis which is where the cornea is more conical than hemispherical. This resulted in me being legally blind in my right eye. There is the cure of corneal transplant but, as my other eye was reasonable, I never progressed far enough up the list to be eligible for a very rare donor cornea. As time went on, my optometrist starting muttering about “cataracts” in my good eye? Cataracts are, in fletty-speak, floaties inside the lens in my eye. These floaties caused all of the issues noted above of which the most visible are a clouding and yellowing of all vision. However, as this happens progressively, I was not aware of the changes to my colour perception because the wonderful human brain compensates. Well, late last year I was sent off to a specialist for A potential cataract operation in my better eye. I was literally stunned when he asked if I would like him to also fix the poor keritaconised eye as well! I blurted out YES and began a fascinating journey that climaxed last week. I must stress however that the words used by the specialist, but missed by me, were to “correct for” the keritaconis. A cataract operation is the removal of the deteriorated lens in the eye and replacement by an artificial lens. By using a very special toroidal replacement lens in lieu of a standard spherical lens, the aberration caused by the conical cornea can be largely corrected. The result for me was to instantly progress from legally blind in the right eye to being able to read down to the third line of a standard eye chart! In addition, whites were now WHITE and colours were VIVID. When I looked at anything white, vision from my corrected eye was now pure white, whereas the perception of my uncorrected eye of the same colour was, at best beige and, in photographic terms at least a full stop darker! Over a few weeks, the brain learned to accept binocular vision and seemed to give preference to the colour perception of the corrected eye?
Last week I had the cataract operation on my previously better eye. My binocular vision is now much sharper, at least a full stop brighter and whites are now white. WHITE is the new beige!
I would suggest that my position on the age curve above has been reversed back from about 70 to 45? The operation is virtually painless, a mild discomfort basically overnight, the immediate result for me was stunning and, if my earlier experience is a guide, this stunning result will continue to improve further for about another 3 weeks!
And yet, I’m still buying more lights ?a rock is an obsolete tool ......... until you don’t have a hammer!
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19th February 2019, 07:44 PM #1018
Fletty
That's an amazing improvement.
Regards
PaulBushmiller;
"Power tends to corrupt. Absolute power corrupts, absolutely!"
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19th February 2019, 08:27 PM #1019
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19th February 2019, 09:02 PM #1020
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