This review is focused on the LG 65SJ8500, which is a third generation LG Super UHD TV. The LG 65SJ8500 is the 65-inch class model from the SJ8500 series. It uses a nano cell technology, meaning the quantum dots are embedded in the LCD panel cells. This is possible due to the diameter of the nano particles being approximately 1 nanometer. In order to be able to provide spectrally pure primary colors (and wide color gamut), the 65SJ8500 uses quantum dots for filtering wavelenghts that do not match the ones for red, green and blue. This is needed because the backlight itself is not tri-chromatic (i.e. optimized for the red, green and blue filters), meaning without the quantum dots it’s possible that some wavelengths of light that correspond to the secondary colors may inadvertently pass though, which would cause the colors to appear washed-out.
On the other hand, the previous generation of LG Super UHD TVs, such as the 65UH8500, used nano crystals ranging from 2 to 10 nanometers in size. Depending on their size, they emitted light at different wavelengths. Unlike the 65SJ8500, which uses the light absorbing properties of the quantum dots to filter out excessive wavelengths, thus improving the color filters, the 65UH8500 relied on the quantum dot display technology mainly for enhancing the spectrum of its backlight prior to it reaching the color filters. This is why the quantum dots were placed in a separate sheet between the backlight and the LCD panel on the 65UH8500. However, there were some down-sides to this design. Before it could reach the LCD panel, the already optimized light (by the Quantum Dot sheet) had to pass through some more sheets (i.e. Diffuser and Prism) and a Guide Plate, which lead to colors staring to lose saturation when viewed off-axis.
As previously mentioned, the 65SJ8500 utilizes nano particles that are more uniformly-sized, and, crucially, embedded in the LCD panel, so there is no separate Quantum Dot sheet. In other words, the optimization provided by the quantum dots is applied almost directly to the color filters, i.e. after the light had passed through the Diffuser and Prism sheets. As a consequence of that, the 65SJ8500 is able to prevent noticeable color shift from occurring up until 60 degree angle, according to LG. Therefore, the 65SJ8500 has an advantage over the 65UH8500 in terms of color fidelity when viewed off-axis. It needs to be said, though, that both of them use IPS type of panels, so there is no significant raise in black levels at an angle.
There is another benefit to the 65SJ8500’a embedded nano-cell technology in comparison to the UH8500’s separate quantum dot sheet. Due to their close proximity to the front panel, the nano particles on the 65SJ8500 are able to absorb some of the ambient light when the TV is used in bright environments, thus reducing on-screen glare. While the 65UH8500 wasn’t able to do so via the quantum dot sheet, which was slightly further from the front panel, it did use a True Black Panel technology for minimizing reflections.
Since the IPS type of panel that both models utilize doesn’t provide very deep black levels, the 65SJ8500 and 65UH8500 use local dimming technique in order to be able to achieve lower minimum luminance level. However, both TVs are edge-lit, so what they have is a rather limited number of local dimming zones. This leads to a diminished ability to control light in many different areas of the screen. The black level can be lowered, but any highlights that are within the same zone are also affected. However, there are several settings for local dimming, so you can choose the one that is optimal for the content you’re watching.
The Ultra Luminance technology that was used on 65UH8500 is improved for the 65SJ8500. This means that small specular highlights are brighter on the latter model. Since the goal of HDR (High Dynamic Range) is exactly making only small areas brighter rather than the entire image, the picture quality with HDR content is better on the 65SJ8500 vs 65UH8500. The increased peak brightness is not the only reason, though. The 65SJ8500 is able to perform scene-by-scene optimization even when the content has only static metadata (i.e. HDR10), or no metadata at all (i.e. HLG, or Hybrid Log Gamma). This is possible thanks to the Active HDR processing which generates dynamic metadata. As a result, HDR10 content can be optimized not only for scenes with highlights based on the MaxCLL (maximum content light level), which is specified in the static metadata, but also when there are no highlights, in which case compression of bright mid-tones can be avoided thanks to the generated dynamic metadata.
Both models support Dolby Vision content, which includes dynamic metadata that is generated during post-production, so it can natively provide scene-by-scene optimization without having to rely on the Active HDR processing by LG. Therefore, Dolby Vision content was the only format that provided scene-by-scene optimization on the 65UH8500 since this model didn’t use Active HDR processing, and HDR10 format only includes static metadata.
The 65SJ8500 has 4 HDMI inputs whereas the 65UH8500 had 3 HDMI inputs. The remaining connections are identical. Both models have 3 USB ports, an Ethernet port, shared component/composite, an optical, a RS232C (Mini Jack), a RF Input (antenna/cable). The 65SJ8500 omits support for the passive 3D technology that the 65UH8500 was equipped with, so the new model is not able to play any 3D content.