Re: Compulsory low-energy light-bulbs

On Thu, 15 Mar 2007 22:35:54 +0000 (UTC),
Tim Woodall <devnull@xxxxxxxxxxxxx> wrote:
On Thu, 15 Mar 2007 12:56:08 +0000,
Alex Heney <me8@xxxxxxxxxxx> wrote:

I have also always taken the "equivalent output" with a LARGE pinch of
salt, and tend to use and 18 or 20W to replace a 60W traditional bulb,
and a 23W to replace a 100W bulb.

My tests this evening using a digital camera taking a closeup of the
lampshade deliberately out of focus (because at the distance I was
there's very noticable patterning on the weave of the shade and I didn't
know how that might affect the exposure metering).

f8, 1/100s

Brand new 60W incandescent - the camera thought it was either just right
or overexposed by 1/3 stop.

1 year old 11W CFL with maybe 2min warmup, camera thought it was either
just right or underexposed by 1/3 stop.

I couldn't really tell any difference looking around the room (all the
other lights had been turned off for my tests) between the CFL and the
incandescent. Of course, this could have been a feature of the
lampshade.

I did take some pictures in RAW but I'll have to convert them to a
different form to analyse them to see what the spectral response looks
like. And I'm limited to the CFA on the CCD. I've got no way to measure
the actual spectral response of the CCD.

And here are my "results":

This is with no processing of the raw data from the CCD other than
averaging all the red pixels, the green pixels, and the blue pixels.

R G B Y R/Y G/Y B/Y
11W CFL: 211 153 73 162 1.3 .94 .45
60W GLS: 225 163 100 175 1.3 .93 .57

(Using Y=0.3R + 0.6G + 0.1B)

The camera automatic metering was saying that the GLS was between
correct and 1/3 stop over exposed and the CFL between correct and 1/3
stop underexposed - which is in agreement with these figures. (I'm
assuming that, because the camera is an SLR, the metering is separate
from the CCD)

Tim.


--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t,"
and there was light.

http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/
.

Relevant Pages

  • Re: Astro CCDs still dragging their pixel feet
    ... > Compared to consumer digital cameras, ... > CCD Sensor: High Sensitvity Sony® ... > camera would be a disaster. ... Smaller pixels = less photons gathered per pixel... ...
    (sci.astro.amateur)
  • Re: digital video cam compatable?
    ... Cheapy cameras shoot 16:9 by remapping the CCD, ... Those pixels have been sat on by an elephant. ... It is better to keep the aspect ratio camera native. ... big enough to afford not using the sides when shooting 4:3. ...
    (uk.comp.sys.mac)
  • Re: How many pixels?
    ... This assumes that the camera is parfocal with the oculars (which can ... on the CCD. ... It will not increase the number of resolved elements ... 1000x1000 elements or pixels is accurately imaged onto a CCD ...
    (sci.techniques.microscopy)
  • Re: Astro CCDs still dragging their pixel feet
    ... > Compared to consumer digital cameras, astro CCD cams ... > camera would be a disaster. ... As you shrink the pixels you need to sacrifice these. ...
    (sci.astro.amateur)
  • Re: DPI
    ... The pixel originates in your camera. ... There are roughly eight million Pixels on the sensor in your camera. ... resolution discernable by the human eye. ... Printer resolution is how many dots of ink the ...
    (alt.photography)
Loading