LED bulb test

BetterSense · Jan 27, 2016

I found these bulbs at Target that are a dead ringer for a PH140. So I bought one and tested it.

In manual mode with my D70, I can center the histogram with 2000s at F22 for the incandescent, and 640 seconds with the LED. So that is about 2 stops slower, which is fine with me since I typically use a 3stop ND film in my filter drawer anyway.

The images show that the LED appears to have more even illumination than the incandescent. And it appears to turn on and off instantly. How will it fare with the VC RC paper I use? Find out in the sequel coming soon!

BetterSense · Jan 27, 2016

Additional pictures of the LED bulb next to the 60 W PH140 bulb and another LED bulb from my fan that I am also testing.

wiltw · Jan 27, 2016

Interesting, a so-called 60W equivalent (LED) has only about 1/4 the light output (-2EV) compared to the incandescent?!

Sounds like the Marketing Department overstates the 'equivalence', less than 40W bulb it would seem, even though the 'instant on' LED should fare better than the incandescent bulb that has to come up to temp.

Looking at a variety of 60W incandescent bulbs offered by an on-line retailer, the 60W outputs between 420-660 lumens while 40W outputs 290 lumens.
'

wildbill · Jan 27, 2016

The output ratings aren't equivelant on any of the led bulbs I've used over the last few years. Most are pretty neutral but show a little green on film. They're all made differently too. Some are glass, some plastic. I usually cut the globe off the plastic ones to see how the leds are distributed. Cutting the top off the globe turns some of them into great work light bulbs.

gone · Jan 28, 2016

Those bulbs are getting very popular, but I've never experienced any problems w/ incandescent bulbs, and they last a long time in a darkroom or an enlarger.

BetterSense · Jan 28, 2016

Well, I'm having problems with heat affecting my negatives in my cheap enlarger, and I can't get spare PH140 locally, and cutting 60W of heat from my small darkroom will be a side binus.

This is marketed as a ”40W equivalent " at 300 lumens. But the fan light is marketed as a 60W equivalent but has like 20% lower lumens than a real 60W incandescent. So yes, they are stretching it sometimes.

I did some print testd last night which were very positive. I will post the results soon.

ME Super · Jan 28, 2016

A 60W incandescent bulb, when new, outputs around 800 lumens. It's really lumen equivalence you should be after, not wattage equivalence.

I bought some 60W equivalent, daylight-balanced, candelabra-base LED bulbs for the living room before Christmas '15 so I could use daylight-balanced film for pictures. These bulbs, unfortunately, only had a 500 lumen output, so they weren't quite 60W bulbs, they were more like 40W bulbs.

There's a very slight green cast on the Portra 400 shots I did. Easily correctable.

BetterSense · Jan 28, 2016

I made 2 prints, one with each bulb, with an Ilford grade 5 filters onto MGIVRC. I didn't match the exposures perfectly but the contrasts appear similar. Then I made two prints trying to get normal contrast with each bulb type. The LED bulb required a grade 3 filter while the incandescent required a grade 2. This seems workable as my main concern was if the bulb would work with multigrade printing.

As expected, LED exposure time was about 4 times as long as the incandescent which I think is a bonus...the exposure time with incandescent was only 2 seconds for this 5x7 print.

BetterSense · Jan 28, 2016

This bulb seems like a big hit to me so far. I wanted to print step wedges and make contrast curves for comparison, but I lost my step wedge.

LED bulb test

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