Ive been trying to find a reasonably priced CRI 95 LED thats 12v and up to 10-15W is fine but many are way overpowered (like 100W or above) and way overpriced!
I did find a bunch of them here, but the postage costs is almost €60!! (I’m from the UK).
I’m happy to order from Aliexpress but theres so many types!
The captures of this thread are made with a similar lamp. I use it as it is, without adding any additional diffuser.
As you can see, it is very cheap, only €1.35. They are also for sale at local DIY stores.
In my opinion 10 W is excessive power. On one occasion I got to try a 7 W lamp. I had to throw it away. The light produced was so intense that it simply saturated the sensor of the HQ camera.
The proposed lamp is 2 W, 170 lm and correct exposures are obtained with times of the order of 4 or 5 ms.
Actually my device is built with an old modified projector and the capture is done with the film stopped and using the Raspberry Pi HQ camera with rolling shutter.
I certainly don’t know how the @bassquake’s scanner works
I want to add an led that’s dimmable but be indirect lighting using a large sphere although haven’t decided yet. Images would be taken one at a time using an HQ Camera.
If I cant find a CRI95 led, can I achieve the same with a RGBW led?
This decision will drive how much light power the LED will need.
The project that you show is 8mm film (Regular and Super 8). Typically the sphere required is not large if it is for 8mm only.
High CRI is somewhat the opposite of discrete RGB LEDs. It may be best to look at the White LED datasheet spectrum profile.
These are the White LEDs I am using (5000K), with a custom designed PCB. The LED subject and quality is a recurring theme in the forum. If the interest (and patience) is there, this may be an opportunity to collaborative design the best form factor for a PCB.
The PCB at the bottom is what I have been using with the LEDs above, first in a small oversided ping-pong ball, and now three in a 90mm metal sphere.
The SMD LED retail cost is about US 35 cents, and PCBs are not that much.
Note that these LEDs have a particularly large Vf of 9V, so typically it will require a 12V power supply (or more if connected in series). In the large sphere above I use a 32V power supply.
PS. As you can see from Manuel results, you can have good results without the complication of building the LED/PCB, so please take the above as an illustration, not a recommendation.
I suppose that with a proper construction, that is, a printed circuit that acts as a support, a good diffuser and, above all, a correct, well-stabilized power supply can give good results.
In my opinion it is advisable to use a color temperature similar to that of the halogen lamps that were used in projectors, around 3000 - 3300 K
The lamp that I use in my device can be powered between 10 and 18 V, that is, it already has the voltage stabilizer built in. In my case it is powered at 12 V by the same power supply as the stepper motor. The light intensity remains substantially constant at all times.
In my opinion it is a good choice for three reasons: