Acer V7850 4K DLP Projector Review – Performance

Acer V7850 4K CAPABLE HOME THEATER PROJECTOR – Performance:  Image Brightness, User Color Mode Performance Results, ISF Color Mode Performance Results, UHD Performance, Black Level/Contrast, Noise Level



Image Brightness

The following table shows the measured brightness of the projector for each of the factory preset color/picture modes.  All measurements were made with the lens set to it mid-zoom position and the lamp in in the high mode, except for the “silent” color mode which by default uses low (Eco) lamp mode.

Acer V7850 Brightness
Color Mode Lumens
Bright 1803
Standard 1334
sRGB 968
Rec. 709 958
Movie 1319
Dark Cinema 1332
Sports 1319
Silent 886
User 1310

 

Changing the zoom lens to the maximum setting increased the projector’s light output by 14% and going to minimum zoom decreased the projector’s light output by -15%.  Thus when set to “Bright” color mode and with the zoom set to its maximum value the V7850’s light out goes up to just over 2050 lumens, which is just a little short of the claimed 2200 lumens.  However, the “Bright” color mode has such poor colors I wouldn’t suggest this mode is useful for home theater application.

Changing from high lamp mode to Eco (i.e., low) lamp mode decreased the light output by approx. 34%.

Brightness uniformity was only fair with some visible brightness decrease at the top corners, when the projector was table mounted.

As for color uniformity, when displaying a full white test image I observed some yellow along the bottom edge of the image.

 

User Color Mode Performance Results

The V7850 offers only a limited ability for the owner to calibrate the projector without having a professional calibration from an ISF certified calibrator.  Of the user accessible color (i.e., picture) modes only the single “User” color mode allows for picture adjustments to made and stored for subsequent use.  The available adjustments for the user mode include, in addition to the usual brightness, contrast, etc. adjustments, RGB gain and bias adjustments as well as preset gamma adjustments.  What is lacking is a full color management system (CMS) set of adjustments.  However, a ISF certified calibrator can use a password to gain access to two additional color modes call ISF Day and ISF Night.  For my evaluation of the V7850, I calibrated the projector for the User color mode (color temp./grey scale and gamma) and I also did a full calibration for one of the ISF color modes, more on that below.

PRE-CALIBRATION

The figures below are the measured  grey scale, color gamut and gamma with the factory default settings for the User color mode and using a gamma pre-set of 2.2..

V7850 User Color Mode – pre-calibration grey scale

 

V7850 User Color Mode Gamut – pre-calibration

Color gamut has two elements to it.  The chromaticity is as shown above for saturation levels from 25% to 100% while the luminance errors were reported only for the 100% saturation levels as shown below.  In this case the measurements indicate all 6 of the fully saturated (i.e., 100%) primary and secondary colors were all displayed too dark as compared to the reference white luminance level.  Since in “User Color Mode” there is no CMS adjustments available, these errors could not be significantly corrected.

The measured Gamma using the factory default for 2,2 setting is shown in the figure below.

V7850 User Mode – pre-calibration gamma

GREY SCALE / COLOR TEMPERATURE

I found he grey scale/color temperature could be improved using the available picture adjustments and the results are shown below after the calibration was performed.  Note that measurement errors may account in part the reading at the lowest value (i.e., 10%) on this figure.

V7850 User Color Mode – post-calibration grey scale

The delta E measured under 2.0 across the grey scale for levels from 20% to 100%.  The color temperature varied between 6405K and 6595K over this same range with an average color temperature of 6501K.

GAMMA

V7850 User Color Mode – calibrated gamma

I selected a pre-set gamma value of 2.2 on the projector’s menu and measured a gamma that ranged between 2.15 and 2.25 over this same 20% to 100% range noted above.  I would note that this projector’s gamma tended to droop as the levels approach the black end of the grey scale and this was is probably due to the moderately high native black level of this projector.

BRIGHTNESS

After calibration the projector’s brightness measured over 1200 lumens, which is high enough to support fairly large screen sizes for non-HDR content.  HDR could better be supported with a more reasonable screen size (e.g., 120″) and with some modest gain (e.g., 1.1 to 1.3) where HDR content could be displayed with the brightest highlights perhaps twice the brightness of the reference white level.  However, remember my measurements were made with a new lamp and the lamp’s brightness will drop over its lifetime.

OVERALL RESULTS

Overall this is very good performance for grey scale/color temperature and reasonably good performance for gamma for this class of projector.

Since the V7850 does not offer CMS adjustments in User Color mode there was no means to significantly improve upon the color gamut performance from what is shown in the pre-calibration figures above.  This means a more advanced hobbyist that does have the skills and tools to perform a CMS calibration will not be able to do so without access to the required password for getting into the ISF menus.

As it is, with the out-of-the-box performance for color gamut, the colors are fairly accurate, but they could be improved upon with a calibration of the primary and secondary color points.  More on this topic when I discuss the ISF performance results below.

ISF Color Mode Results

As noted above the two available ISF Color Modes are intended to be used by ISF certified calibrators and the associated menus on the V7850 require a password for access.  Only the ISF modes offer access to the projector’s CMS, which allows for calibration of the color gamut.  I would note this projector does not offer means to perform a calibration of gamma, as only a number of preset gamma settings are offered.  I only performed a calibration for one of the ISF color modes.

GREY SCALE / COLOR TEMPERATURE

The following figure shows the grey scale performance after the calibration.

V7850 ISF Mode – calibrated grey scale

The following figure shows the dE values measured across the grey scale for the ISF Color mode.  After calibration the dE did not exceed 2.1 for levels of 20% and above.  Note that for all of the charts presented in this review the accuracy for the measurements for levels below 20% may not be as accurate.

Acer V7850 ISF mode dE across grey scale

GAMMA

For the ISF mode calibration, I used the projector’s gamma preset for BT. 1886 (the default for the projector’s ISF color mode).  This projector has no provisions for creating a custom gamma curve or for fine tuning one of the existing preset values.   However, the calibration of the grey scale and gamut can impact the gamma results for post-calibration.  The figure below show pre and post-calibration results for gamma.

Acer V7850 ISF Color Mode Gamma

The gamma results show less than ideal tracking across the grey scale with a droop in gamma below the reference level when dark greys are displayed.  This is probably due to the relatively high native black level of this projector and the limited native contrast ratio.

COLOR GAMUT

The following figure shows the post-calibration color gamut results for Rec. 709 reference color space.  The color points and tracking proved to have good accuracy all the way to 100% saturation level for the 3 primary colors (i.e., RGB) and thru 75% for the 3 secondary colors (I.e., CYM),  However, some hue errors were noted at the 100% saturation level for the secondary colors.

V6740 ISF Mode – calibrated gamut

Color gamut has two elements to it.  The chromaticity results are as discussed above for saturation levels from 25% to 100% while the post-calibration luminance errors are reported in the figure below only for the 100% saturation levels (i.e., where the gamut errors tended to the greatest).

I preformed the CMS calibration using a 75% saturation level as the reference and the post-calibration dE values for all of the primary and secondary colors were under 1.0 at that saturation level and did not exceed 2.5 at lower saturation levels.  However, at 100% saturation levels the errors increased and while the primary colors (RGB) dE values remained under 2.5, the dE values for the secondary colors (CYM) increased to as high as 6 (for magenta).  The pre and post-calibration results for the dE for gamut are shown in the figure below.

Acer V7850 Gamut dE results

BRIGHTNESS

For calibrated ISF mode the projector’s brightness measured 1112 lumens which is bright enough for use with rather large screen sizes if displaying HDR is not a concern.  With a more moderate screen size (e.g., 120″) and with some modest gain (e.g., 1.1 to 1.3) HDR content could be displayed with the brightest highlights displayed at perhaps 2 times the brightness of a reference white level.  However, remember my measurements were made with a new lamp and the lamp’s brightness will drop over its lifetime.

OVERALL RESULTS

I would consider this level of color performance, overall, to be very good for this class of projector, but certainly not as good as the best overall performers in this price range (1080p and 1080p w/pixel shifting models).  There was some remaining color errors for fully saturated colors, especially for magenta and cyan that could not be fully corrected and there is no means provided to optimize the gamma curve.  Overall, the color accuracy for the calibrated ISF Color Mode was an improvement from the calibrated User Color Mode described above, which In turn was a step up from the best of factory present color modes.

UHD Performance

UHD includes 3 areas of picture enhancement beyond what is offered with regular HD video.  First there is the increased resolution, second there is the Wide Color Gamut (WCG) and third there is support for displaying High Dynamic Range (HDR).

As discussed earlier in this review the V7850 projector, like all of the other DLP 4K pixel shifting projectors introduced in 2017, uses display chips with 4 Mpixels and displays two images shifted by 1/2 pixel to display UHD image with their native 8 Mpixel resolution.  This works fairly well but because of the overlap of adjacent pixels these projectors are unable to correctly display a native 8 Mpixel black and white checkboard test pattern.  Instead of the pixel color alternating between black and white, all pixels are displayed as grey.  I verified this is the case with the V7850.  Does it make much difference when viewing real UHD video from a UHD Blu-ray disc or  UHD from a streaming video service?  As compared to viewing the same high quality UHD source on a native 4K display, the difference is rather subtle and only visible with the best quality source material.  In any case V7850 falls just one notch short of providing the visible resolution of a native 4K projectors.  However, I would note that assumes the native 4K projector has excellent alignment between its red, blue and green sub-images, since RGB misalignment can soften the image and potentially negate any resolution advantage.

Wide Color Gamut (WCG) is the second enhancement offered by UHD video sources and V7850 is really a Rec. 709 projector even though their literature talks about compatibility with wider color spaces.  The following figure shows the native color space I measured for the V7805.  The outer triangle shows the stardard for full Rec. 2020 color space and the inner triangle represents the standard for Rec. 709 color space.  The DCI-P3 color space is not shown in the figure, but it falls between the two triangles that are shown.  The circles are the measured color points for the V7850’s primary and secondary colors.

Acer V7850 Native Color Gamut

As shown in the figure above, the native color gamut (i.e., color space) is just a little wider than Rec. 709 (103.1%), the HD video standard, and only 76% of the color gamut (i.e., DCI-P3) used for many movies being released on UHD Blu-rays and some UHD streaming content.  Finally, the V7850’s native color gamut is only 54.6% of full Rec. 2020 color gamut.  The bottom line is the V7805, and other 4K DLP lamp based models we have recently reviewed, while accepting a UHD input signal that uses a wide color gamut, actually displays the video with the more limited Rec. 709 color gamut.

The third leg of the UHD set of enhancements is support for HDR.  We have discussed in previous reviews of 4K projector as well in our Blogs, the consumer HDR standards were designed around the capabilities of high brightness flat panel displays while the peak brightness levels possible with a typical home theater projector paired with a moderate to large screen (e.g., 110 to 150 inches diagonal) can be expected to produce a peak brightness that is perhaps between 10% and 20% of what is possible for a HDR capable flat panel display.  The V7850 supports only HDR-10 for its HDR input and offers a user menu input to select “HDR OFF” or 4 different levels of HDR processing (basically 4 different gamma curves).  The user will need to select the HDR setting that produces to the best picture accounting not only for their particular projector/screen setup but also for the specific HDR video source.  Different HDR enabled 4K movies have been encoded for display at different peak brightness levels, therefore no one HDR setting/calibration will work for all HDR enabled movies.

For the UHD/HDR movies that I viewed using Ultra HD Blu-ray discs as the source, I found a HDR setting of 1 or 2 on the V7850’s menu provided the best results in my specific setup.  The results with HDR content was discussed earlier in the this review.

OVERALL UHD/HDR PERFORMANCE

The V7850 does a very good job at displaying the increased resolution coming from quality 4K/UHD video sources.  However, it lacks support for more the vivid, highly saturated colors offered from the UHD sources that are supporting a wide color gamut and I felt the HDR performance was being constrained by the moderately high black level and relatively modest contrast capabilities of this projector.

To be fair, I must note this is an entry-level first generation 4K DLP projector and future models will probably evolve to address at least some of the weaknesses this current generation of 4K DLP projectors.

Black Level/Contrast

I noted earlier in this review that the Acer V7850 has moderately high native black levels and a limited contrast ratio (CR).  I measured the native contrast ratio using the factory preset color modes for “Movie” and “Dark Cinema” at 1314:1.  While this value is not out of line with the native CR for a entry level 1080p DLP projector, it does fall short of what is being offered by certain other non-DLP home theater class projectors in this price range.  The V7850 does not include a dynamic iris to visually improve black levels during dark scenes.  The Acer literature for this projector claims a dynamic CR of a whopping 1.2 million to 1 thru the use of dynamic lamp dimming.  However, I have not seen any projector where lamp dimming is actually effective when viewing video since it requires far too long to dim or brighten a lamp to be effective for this purpose.  Projectors using laser light engines may be able to change the laser’s light output fast enough to be an effective alternative to using a dynamic iris, but that’s not applicable to the V7850 or other lamp based projectors.   By comparison the native CR of the V7850 is perhaps 1/3 to 1/4 that of the Epson UB series of projectors using 3LCD technology, 1/8 that of the entry level LCoS home theater projectors and less than 1/20 that of the best (in terms of native CR)  home theater LCoS projectors, and that’s with those other projector’s dynamic iris turned off and the iris manually set to fully open.  For me this is the greatest weakness of the V7850 and other similar 4K DLP models, especially those lacking a dynamic iris or a  laser light engine with effective dynamic laser dimming.

1/8/2018 UPDATE: 

In direct comparison to a similar price Optoma 4K DLP projector the Acer V7850 proved to have somewhat lower black levels and overall better performance on dark scenes.  That’s not to say the Acer’s performance to really good, in terms of black levels, since it falls well short of you would get with, for example, an Epson Home Cinema 5040UB or a JVC DLA-RS440.  However, it does seem that in terms of black level it is visually a step up the performance scale from some of its primary 4K DLP competitors in the $2.5K (and under) price range.

Noise Level

The Acer V7850 is rated at 29 dB noise level when operating in high lamp mode.  I found the noise level to be audible, but not excessive for use in a home theater and no greater than typical for this class of projector.  In Eco mode (i.e., low lamp) the noise level dropped noticeably and was fairly quiet and certainly could be used in home theaters using small to moderate screen sizes where the approx. 1/3 decease in brightness (below high lamp mode) is not an issue, or is desirable.

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