For the MR16 bulbs themselves, consider these Soraa LED lights with the available selection of magnetic "snap" filters that change the light beam into a square or rectangle, and/or change the beam width, color temperature, etc. as shown in this video. The Vivid series also give off terrific light quality good for bringing out the color in artwork.

Wow, lee676, thank you!!! I've been researching lighting for fine art like crazy and have not come across this. This sounds like the next best thing to sliced bread. I'm off to check it out.

They sell a 10-piece filter assortment with most of the available filters, so you can experiment with what works best. You start with a reflector bulb with a 10 degree beam spread in your choice of color temperatures - 2700K (warm, like incandescent), 3000K (a bit whiter, like halogen), 4000K (cool white fluorescent tubes, but with better color rendering), or 5000K (cool, matches daylight streaming through windows). The filters can widen the beam spread, which starts out as a narrow spotlight, to a wide spot, narrow flood, or wide flood. There are four sizes and shapes of the squared or rectangular beam shapers. And finally three filters that will "warm" the light, so if you ordered the 4000K bulbs, you could change it to 3500K, 3000K, or 2700K. Doing this slightly reduces the efficiency, so I'd get the lowest color temperature bulb you'll ordinarily use (and they're very efficient - each bulb uses only 7-1/2 watts, but is as bright as a 50 watt halogen bulb).

You also have a choice between 12V low-voltage or 120V line voltage (or 230V in most non-US countries). Using low voltage helped make the old halogen bulbs whiter, but I don't see any advantage to using 12V low voltage for LEDs unless you are converting an existing halogen MR16 setup. If you're installing new lamps, using 120V line voltage (GU10) will save lots of money by not requiring transformers or expensive low-voltage dimmers, and will be less prone to buzzing. They also have two series of bulbs called Vivid VP3 and Brilliant. You want the Vivid/VP3 which has better color rendering (95 CRI in lighting parlance rather than 80), meaning you won't get dull or inaccurate colors like you do with fluorescent/CFL bulbs or lower-quality LEDs.

Filter 10-pack includes:
25ð Beam Spreader
36ð Beam Spreader
60ð Beam Spreader
10ð x 25ð Linear Lens beam shaper
10ð x 36ð Linear Lens beam shaper
25ð x 25ð Flat Top beam shaper
36ð x 36ð Flat Top beam shaper
1/4 CTO Color Temperature Shifter
1/2 CTO Color Temperature Shifter
3/4 CTO Color Temperature Shifter

40ð beam spreader with glare-free louvers sold separately

More links:
Filters
120v line voltage bulb detailed info
12v low-voltage bulb detailed info
Info about color rendering
Info about non-yellowish white rendering

Those last two links aren't technobabble by the way; this company was founded by a guy that won a Nobel Prize for inventing the blue and white LEDs that made LED lighting possible.

I use Soraa bulbs where ever I can. They are a great light quality. I use them in outside light fixtures too. Mr16s and the ar111. Great bulbs!!!

Thanks for the endorsement of the Soraa bulbs, homepro01. I'll certainly keep them in mind for other applications.

Lee676, I have learned the hard way that for lighting a canvas, the color and beam spread filters are needed for the best result, unless one accidentally lucks out with the fixture or guesses correctly with their bulb selection. For example, I'm still trying to get a bulb for a ceiling mounted fixture for a 40 x 30 oil painting above the fireplace. Everything is perfect except about 12 degrees on each side of the canvas remains unlit. I had a MR16 35w halogen bulb with a uv protection rating, 2900k, and a 35 degree beam spread. Also, this bulb only has a 2000 hour rating and lasted just 3 months. I just purchased on the internet an led substitute that has a 60 degree beam spread. To get the wider beam the lumens (brightness) decreased to about half what I had before. However, I had to dim the halogen bulb to about half so the bulb I just ordered may work. If it doesn't, I'm going with the Vivid package. I just used my painting as an example to demonstrate to others reading this post the complexity of lighting fine art. I certainly had no idea.

Lee676, I hugely appreciate all the additional information you have provided. I'm doing some work for business this weekend but may come back with more questions after digesting all this new information. Also, I just posted a question on the lighting forum regarding led tape lighting (2700k vs 3000k) for display cabinets in my family room. If you have time to take a look, I'd appreciate your thoughts. I never cease to be amazed at the wealth of information on GW and the generosity of those who share their knowledge.

Thanks - though the info is mostly cut & paste for me since I deal with lighting specification alot (as you can probably tell). I actually haven't seen these in person yet, though I'm planning to try out the larger PAR30 size that fits 5" cans in my bedroom once the louver attachment becomes available - that way if I look up at the ceiling from the bed the light bulbs will appear dark unless you look straight up at them, which I won't since they're off to the sides of the room. There are some reactions from people who have used them over at Candlepower Forums here and here (yes, there's an entire web forum for high-end flashlight enthusiasts). They don't produce UV that can fade colors which is good.

I saw these and they immediately reminded me of stage lighting, those big spotlights with all sorts of different filters that change the size, shape, and color of the lighting. Like those, you can combine several filters on the Soraa lights to combine their effects. If you're an actor or actress, you know how *hot* those spotlights get, enough to cause problems ranging from sweat rolling down faces to glue melting and causing props to fall apart, so it's not surprising that LEDs are replacing incandescent bulbs there too. I do have a question about how the Soraa filters deal with "keystone distortion" - the trapezoidal shape a square or rectangular filter will yield if aimed from an angle. I assume Soraa took this into account, since these are obviously designed for lighting artwork on walls, and the lights are usually on the ceiling, off to the sides, or on floating arms. Still, different angles will produce different shapes.

I don't have any experience with LED tape lighting, although here too I'd be inclined to only consider high-CRI lighting for good color quality, like these. As for 2700K vs 3000K, it really comes down to personal preference and what color your cabinets and items in it are. I like the warmth of 2700K lighting but in some situations the whiter 3000K light will look better.

Lee, you raise an important issue I hadn't considered regarding possible distortion of light with a filter if the light is at an angle. I'll certainly ask about that aspect. I may consult with a firm here in Houston that specializes in lighting fine art, if I can afford them. My painting will not be back from the framer for another week or two. The lighting consultant I used for my recent remodel likes the House of Troy fixtures for art, the ones with the skinny tubes with led lights that are affixed either to the wall or to the back of the frame. I may try that type first if it is returnable. After checking the internet recently, some online vendors may allow returns but need to clarify further.

Can you link to the Helen of Troy fixtures? I can't find them.