Problem with close-up photos showing light/dark banding pattern
August 15, 2017 9:43 AM   Subscribe

I use my iPhone to take close-up photos. When I swapped-out my old incandescent bulbs for LED bulbs, I started seeing light/dark bands (stripes) on the photos. How do I fix this problem?

Here is an example photo which displays the banding effect. For illumination, I'm using two desk lamps with LED bulbs in them (but I used only one of the lamps to take the sample photo above).

An Internet search has identified others who have encountered the same problem, but my Google foo has failed to find a simple solution. I do see that eBay has a small number of old-fashioned incandescent bulbs listed for sale, but I wonder if there is an easier, cheaper fix.

When taking photos, I use the standard, built-in camera app on my iPhone. If possible, I'd rather avoid doing something complicated with manually setting shutter speeds, etc.
posted by akk2014 to Technology (17 answers total) 1 user marked this as a favorite
Using something to diffuse the light may help, a photo tent it even just some sheer white fabric between the light and objects. Bouncing the light off a matte white flat surface may also work (like mat board)
posted by RustyBrooks at 9:48 AM on August 15, 2017

Actually, reading some of these links, if it's a pwm problem then the answer unfortunately is probably messing with exposure time
posted by RustyBrooks at 9:49 AM on August 15, 2017

The LEDs in the bulbs aren't on 100% of the time, they're turning on/off at some high rate, but its not completely on/off because the phosphor that glows white has a slight fade, so you don't see complete white/black bands.

This effect combines with the camera photo sensor not capturing at exactly the same instant, instead it reads top to bottom (possibly in parallel groups) so the light bands are when the LED's are on and the dark bands are very slightly later when the LED's are off.

Your incandescent bulbs are on all the time, so you don't get this effect.

Not all LED bulbs are made this way, but other than reviews online, theres no way to tell from the product description if its on all the time.

Fluorescents have the same effect, but at a much slower duty cycle, so you're more likely to just get an under/overexposed photo.
posted by TheAdamist at 9:50 AM on August 15, 2017 [3 favorites]

If your LEDs are dimmable, turning them up to full brightness can help a lot. As others have noted, the problem is that your iPhone camera works by scanning the scene, and the LEDs do dimming by flickering on and off. The dimmer they are, the more time they spend off.

(We hit this problem when we were spec'ing the lights for the Shotbox...)
posted by straw at 9:55 AM on August 15, 2017 [1 favorite]

The bulbs are not dimmable. Or, at least, the desk lamps are not equipped with dimmer switches.

If anyone has specific models of bulbs that they can recommend, I'm all ears. I do see this one listed on Amazon, but it's rather expensive (and I'd need two of them). Thanks.
posted by akk2014 at 10:01 AM on August 15, 2017

If the issue is the scanning of a single picture, could you try turning on the phone's auto-HDR? I'm not sure how htis works on a phone, but non-auto-HDR works by combining multiple images. Since it's unlikely all images would get the light in the exact sample places, this might blend it out.
posted by If only I had a penguin... at 10:03 AM on August 15, 2017 [1 favorite]

You could try manually setting your iPhone's shutter speed using an app like Camera+. I bet longer shutter speeds will reduce or eliminate the banding.
posted by reeddavid at 10:05 AM on August 15, 2017 [1 favorite]

Other folks are right, either buy new bulbs or mess around with the shutter speed.

If you look on Amazon for bulbs that say photo/video in the name, and then look at reviews and make sure they don't say 'banding' or 'flicker'.

Longer term you might want to buy some fancier lights. I've got a pair of these LED panels they're dimmable and you can adjust the color temperature. I've never seen banding or flickering.
posted by gregr at 10:52 AM on August 15, 2017

This video recommends either synchronizing your shutter speed to the line frequency (60Hz for north america or 50Hz for Europe, or a multiple of these numbers respectively), or dimming the lights to force a shutter speed below that frequency if you can't change it manually.
posted by JoeZydeco at 11:08 AM on August 15, 2017

Why not just go back to using incandescents? Specifically, halogen incandescents, which are still sold. They won't flicker, and incandescent bulbs have better (perfect) color rendering than other bulb types. These factors rarely matter, but photography is one of the cases where they do.

Alternatively, buy bulbs specifically designed for the photography market. They will be pricy, but should fix your problems.
posted by Anticipation Of A New Lover's Arrival, The at 11:23 AM on August 15, 2017

OK, I ordered these bulbs, because someone in the reviews section said that he or she used them for photography. I'll report back here to state whether the new bulbs fixed the problem.

By the way, using the HDR setting didn't work at all. I also tried the Camera+ app – and it sort-of worked, but it was too much of a hassle to fiddle with the exposure settings every time I wanted to take a photo.

Thanks for everyone's help.
posted by akk2014 at 12:07 PM on August 15, 2017

As mentioned North American alternating current (AC) domestic electricity pulses (or cycles) on and off 60 times each second.

You've solved your problem to some degree by choosing a CFL (fluorescent) bulb. They also flicker but due to the phosphor in the bulb they don't go completely black like an LED will. Incandescent bulbs flicker the least because the heat keeps the filament glowing until the next pulse of electricity. AC powered LED's that don't flicker are more expensive to make and since humans can't detect the flickering there's more profit in making less expensive lamps. Battery powered (DC) LED's won't flicker since DC power is non cyclical unlike AC power. So consider using an LED flashlight or camping lantern.

You can get a free app for your phone to measure the relative flicker of various light sources.
posted by Zedcaster at 3:31 PM on August 15, 2017

Reporting back on my purchase of the fluorescent compact bulbs: Unfortunately, they didn't work. Same problem with the banding effect. I'm actually surprised that the Internet has so little discussion of this problem, since I would imagine that many people take pictures of smallish items to sell on eBay. I'll have to do more searching for a suitable model.
posted by akk2014 at 10:48 AM on August 20, 2017

Just an update. I'm about to give up on this quest. I've tried four different types of bulbs (including these compact fluorescent bulbs that are explicitly marketed as being flicker-free and designed for photography). They all exhibit the same light/dark banding problem. I'm starting to wonder if there is something about my iPhone that is causing this. However, I don't see this effect when using natural lighting.
posted by akk2014 at 6:28 AM on August 30, 2017

Possibly try DC LEDs? Maybe start with flashlights?

Some of the LED strip lights still use PWM for brightness, but even though the ones I've played with banded when dimmed, they still worked okay at full brightness.
posted by straw at 12:41 PM on August 30, 2017

Have you tried the same bulbs in multiple fixtures? I wonder if the fixture you're using has a built-in dimmer, or an electronic switch of some sort that's causing the flicker?
posted by reeddavid at 10:21 PM on August 30, 2017

@straw: I will follow your suggestion about using DC LEDs. I'm going to order this battery-powered lamp from Amazon.
posted by akk2014 at 9:57 AM on September 4, 2017

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