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Old 09 March 2008, 08:36   #1
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Thumbs up LCD Monitor Review - ViewSonic VX2835wm 27.5inch

After a lot of research, I finally got an LCD monitor for amiga use.

The one I selected is the 27.5inch Viewsonic VX2835wm. This monitor has the following inputs:
- HDMI (DVI adapter included), Component, VGA, SVideo, Composite.

And has the following resolution and frequency ranges:

- Native 1920x1200, Horiz (24-82KHz), Vertical (50-85Hz), aspect ratio (1:1, 4:3, 16:9, full screen - 16:10)

So how suitable is it for the amiga?

If you have the Amiga's native RGB output, your choices are composite (bad quality), svideo (quite good, close to camera photos of SCART on this board - less distortion, but not as sharp), or VGA.

The VGA input can take scandoubled (from my EZVGA Plus) 31kHz 50Hz just fine. It is quite sharp and clear. Scrolling through the VGA however is not perfect and is a bit stuttery (same output scrolls perfectly on my CRT). The non-smooth scrolling is not due to the actual panel, it appears it may be due to some picture enhancing routine in the monitor's hardware, as svideo or composite do not show the same stuttering. (I have read somehwere that most LCD panels DSPs operate internally at 60Hz so maybe this is a factor) No pointer trails through the VGA. There is barely some vertical lines there, but not like I have seen on other monitors. You only notice it a little bit in Hires modes on workbench, not in Lores.

Svideo is almost perfectly smooth, there is a very small stutter say every 4 seconds or so. There may be very very slight trails (or not). Composite may well be smooth, the stutter in svideo is quite small, can't tell if it is there in composite as the resolution of A1200 output is more blurry. (Can't wait to get the Narmi deluxe!!!) There are pointer trails in composite. I wanted to try the Svideo out of the CD32 (but have no compatible cable), as it may well be my PC Laptop causing the stuttering in SVideo and not the monitor.

NTSC modes are also handled via SVideo and VGA. Haven't tried NTSC composite, but I am sure it would work.

The panel says it can go as low as 24KHz, but it could not display the 24KHz amiga modes through the VGA. It could display the 27KHz ones with huge overscan, although not perfectly. It does not handle many of the non-PAL or NTSC amiga modes mostly due to overscan issues, with some also due to out of sync range. It has preset resolutions for EGA and VGA modes, and tries to fit non-standard resolutions into those. There are some such as Productivity and Productivity Laced which it does. Note that it can do as high as 94KHz for 1600x1200 75Hz, but not recommended as beyond the monitor's specs. It can also sync as low as 47Hz for some of those DBLPal modes, but you need to use the VGAOnly driver to make them usable due to overscan at 47Hz being recognised as a 640x480 mode, whereas with VGAOnly it is recognised correctly as 720x576.

It can also display PAL and NTSC interlaced (i.e. vertical 400/512 lines) 15KHz modes through VGA, but the NTSC is a bit garbled, and the PAL interlace mode produces artifacts when the mouse moves over sharp contrast lines. Using the scandoubler is a much better bet. The non-interlaced 15KHz modes are out of sync range.

The PAL modes are generally converted to 720x576, and NTSC 640x480. This results in NTSC Hires being a bit imperfect as it also shows the overscan area, thus losing some resolution. It should really have used 720x480 for NTSC (which it only uses for 15KHz interlaced NTSC).

Note also because the resolution is 1920x1200, it does those old VESA 320x240, 400x300, 800x600, 1600x1200 modes pixel perfect in 4:3. And VESA 320x200 and 640x400 are perfect in 16:10.

Overall, if you do not have a SCART monitor or cannot get one, I would recommend this LCD. I have a hunch SCART may be slightly better than SVideo (although the jury is out on smooth animation). This panel does not even come close to a PicassoIV at 100Hz on a CRT in terms of colour reproduction or smoothness. It is 262K colours with the rest interpolated. I expected some banding in AGA modes, and it looked like there was. Though there is NO ghosting my eyes could detect. It is a 3ms panel. Though it is again, not like a CRT.

- 31KHz 50Hz through VGA (good if you already have a scandoubler)
- Good Svideo with range of sharpness, contrast controls
- 1920x1200 (better for interpolation and multiple native res) - WinUAE at native 800x600 4:3 full screen looks great
- No ghosting
- 1080p through Component
- PIP (though aspect ratio goes to full screen when used)

- TN panel 6bit + 2bit interpolated (not true 8 bit), and colours change when change viewing angles (looks like causes banding in AGA)
- VGA 50Hz not perfectly smooth (have not tried NTSC 60Hz game)
- May be a problem with WHDLoad on an A1200 through VGA where the screen keeps on blanking. Needs more testing. I hope this is not due to the time delays for certain CPUs put in the WHDLoad games. There is always Svideo of course.
- Buzzing sound when brightness below 80% (something to do with the inverters, like for fluorescent lights). This WILL annoy some people and may not occur on all models.
- Overscan sometimes very severe in some non-standard screen modes
- Sometimes need to select autoadjust to display some modes properly

There is no perfect LCD monitor I know of, but I am happy with this one. Of course, your mileage may vary as you may have very sensitive eyes or higher expectations from LCD. Hopefully the problems due to WHDLoad blanking the screen are isolated to my hardware setup or some games.

And be sure not to get an early build date version. Mine is firmware R30.2, build date 29/10/2007 (latest is R30.6+ in November).
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Old 12 March 2008, 17:31   #2
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Just an update:

The viewing angles are worse than I first thought, with some colours appearing darker on the top third of the screen. This is related to TN panel technology having bad viewing angles. It is worse for darker colours as they tend to blend in to the black near the top of the screen. Increasing contrast and tilting the top of the screen forward and sitting higher improves it slightly. Although the black then starts having a purple tinge to it at the bottom of the screen. Comparing with my laptop, I realised perhaps my laptop has a full 8-bit S-IPS or *VA panel.

Also, some colours all look the same. Example is the intro of Dragons Breath where there should be 3 reds for the Dragons Breath logo. I cannot only make out 2 unless I look at the screen from a crazy angle.

Good news is I used powerstrip and I can get 50Hz for WinUAE. I think it may be a bit smoother than 60Hz, but it is hard to tell without having a CRT simultaneously running alongside (I have the monitor alongside, but only 1 VGA out from the computer).

Regarding smoothness, CRTs have a large phosphor trail after scrolling images, whereas this monitor does not. Will still try and figure out if the smoothness can be improved by running at 60Hz. I just need an appropriate game to use. Recommendations on how to test or a game, anyone?


This monitor can actually go from 24-100KHz, 39.5-92.5Hz using powerstrip. But the specified range is 24-82KHz, 50-85Hz. So therefore one should stay inside the safe range.
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Old 30 March 2008, 09:33   #3
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I worked out why some of the colours appeared to be missing. It is because the gamma of this monitor is off (at least when using my laptop VGA out with it). This was a noted problem in some of the proper reviews on the net. I needed to adjust the gamma upwards from 1 to 2 from my video card driver in Windows. Now I can see all of the colours just fine using WinUAE. However this may be a problem if you are after perfection using an Amiga which cannot adjust the gamma. But maybe the Amiga's default gamma is different so it may not be an issue (more testing required - my original Dragon's Breath disk does not load on the AT 1200 floppy drive, need to write the 100% ADF to disk).

It is on the darker colours that it matters more.

I also have just compared the banding to see how bad it is, and good news is I can barely detect it at all, when using those 256 shade R/G/B to black charts. MUCH MUCH better than 16bit modes and those 16bit scandoublers.

It appears my laptop screen must be an 8bit panel as I cannot detect any banding on it whatsoever. However the colour timbre of Viewsonic's shades of R/G/B appear much better than the laptop screen, and colours are not washed out, black level is better. I actually prefer the less washed out colours over the barely discernible banding.

I did some further testing on 50Hz/60Hz smoothness, and WinUAE was almost perfectly smooth at 60Hz, I think it is my laptop does not have enough horsepower which gives the odd stutter every 10-15 seconds or so (also occurs on my laptop screen at same time). 50Hz still does not look smooth, it is a bit stuttery, although IMO it is slightly better than 50fps at 60Hz.

So can anyone point me to a game that would be a good vertical and horizontal scrolling test in NTSC 60Hz? Someone on EAB should know one.
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