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I'm trying to take a photo of the Christmas tree in the dark, so that the Christmas lights are the only source of light (or at least the only apparent source of light). I can get a nice short from a tripod by combining a series of photos into an HDR image, however the only problem is that there's strong lens flare/diffraction spikes around the light source:

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Is it possible to avoid this effect and make the lights appear as small dots? Perhaps a more sophisticated HDR tool can acheive it or do I need a flash setup for proper lighting?

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    I'm struggling to see what you're trying to achieve with this shot [I understand this is unlikely to be your intended framing] but it all looks overblown. The entire idea of xmas lights being the only illumination is that it generally all looks dark, not like the house lights are on too. – Tetsujin Dec 22 '17 at 16:33
  • @Tetsujin I'm trying to make the lights look like dots, not as mini flashes. And yes, that's just a small crop of the full picture :) – JonathanReez Dec 22 '17 at 16:45
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    It just looks like the entire exposure needs winding back a long way. – Tetsujin Dec 22 '17 at 16:54
  • @Tetsujin but then the Christmas tree won't be illuminated properly, as the Christmas lights are the only source of illumination. The photo in my post is an HDR shot, combining exposures up until the whole tree is fully visible. – JonathanReez Dec 22 '17 at 20:42
  • @NikitaSokolsky I think Tetsujin's point is that the end result should probably look a little less bright overall to get the effect you're after. – Michael C Dec 22 '17 at 20:47
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The "diffraction spikes" you are seeing is the result of using a narrow aperture. Some folks refer to such effects as "sunstars." The light travelling through your lens' aperture diaphragm is interacting with the blades of the aperture. The number of spikes you see is determined by the number of aperture blades. Lenses with even numbers of blades have the same number of spikes as the number of blades. Lenses with odd numbers of blades have twice as many spikes as the number of blades. (In actuality, even numbers of blades also have twice as many spikes but half of them are lined up directly over the other half.) It looks like you are using a lens with seven aperture blades.

To make the lights look rounder you need to open the aperture by selecting a lower f-number. You can also make the lights look a little rounder by slightly defocusing. To decrease the influence of the ambient lights you also need to shorten the length of your exposure(s) and/or reduce your ISO setting by more than enough to offset the wider aperture.

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Dim the lights using a dimming electrical devise available at hardware stores. Depending on the type of lamps, you can find a dimmer that will do this deed.

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