On Behalf Of Michael Wilkinson > No , it does not assist. OK I'll bite ;)
> Your comments are rather hazy with > an authority that lacks detail, so please, be more detailed > in your response. I'm not questioning your knowledge, just > the depth /explanation of your response. There are lots of us > who are looking to move on from CRT to LCD screens that > really do need to get the facts before we buy. I am not fully up-to-date on everything technical regarding hardware implementations of CRT vs LCD / TFT screens, so my descriptions have to be a bit hazy. However: FOR CRT's CRTs work by scanning electron beams across, then down the screen. The time that it has to get across the screen is the horizontal refresh rate. The number of times it gets to do this for a whole screen worth is 'one vertical refresh' - so the number of screen refreshes that it gets to do in a second is therefore the vertical refresh rate - normally people are used to seeing 60Hz+... (UK tv's are 50Hz I believe, even though we only get 25 frames per second). For reference there will be three electron guns - one for each R,G,B which is an improvement on most Tv's which will have just one. This means that each gun will only fire to activate phosphors of one colour on the front of the screen. Depending on how many electrons are streamed at a phosphor decides how bright it will glow. Typically, CRT users have always required 70Hz+ vertical refresh because they sit close to the screen so flicker becomes more likely to induce headaches etc. Screen refresh is an issue because I believe the subconscious mind picks up on flicker even when the conscious does not. Peripheral vision is also more sensitive to flicker - and this can be a good way to check if the screen refresh is high enough for you. Flicker is doubtless caused by many things but I believe the main factor is that the phosphors will only glow for so long after being struck by the beam; if they have too much chance to fade before being activated by the beam again, you have flicker. Hence, for CRT's, typically, the higher the refresh rate the better. However, this very disposition of the phosphors to fade quite quickly (I think it may be called latency but the techie term escapes me now) can actually be useful for some things; like moving images. There have been 100Hz TV's available for some time over here, and Fluorescent 100Hz lighting is also easier on the eyes. CRT's receive ANALOG information via (typically for PC users, can't speak for Macs) a VGA cable. Of course, the graphics area on your graphics card is digital, so it needs a RAMDAC or RAM-Digital-to-Analog-Converter to convert that digital info to analog, to feed down the wires. Hence, the bandwidth of the graphics card defines how high a resolution the graphics card can be run at on a CRT screen without noticeable flicker. To complicate matters, the screens often have a 'bandwidth' of sorts too; so even if you buy a CRT that is capable of 1600*1200, say, does not mean it will automatically be able to run at the same refresh rates as a recent, good, graphics card. FOR LCD's / TFT's The whole situation is different. In fact, TFT and LCD technologies are very different... And I believe most of us mean 'LCD' to mean flat-screen, when in fact the good ones are TFT's (which is what we are interested in!). The technical details of how TFT's / LCD's get the picture on the screen is a little beyond me... But due to the different underlying characteristics, it just makes more sense to get a digital representation of the screen image to the monitor so that there is less degratation when compared to the analog signals. This is where the DVI interface steps in. And again, for precise reasons that elude me, the vertical refresh rate of the screen becomes far less important and 60Hz becomes reasonable... If you want some of my ideas on why I think this is possible we should probably take this off-list! (lets just say, the fact the video signal may contain information about any one pixel only 60 times per second, the screen hardware _may_ actually be refreshing that pixel 500 times per second, electronically). The latency on old LCD's can be Awful leaving ghostly trails behind a moving mouse pointer etc. I've never noticed such on my TFT's. More here on monitor recommendations: http://www.mwords.co.uk/pages/cm/profileMonitor.htm#monitor MY OWN RECOMMENDATIONS FOR GRAPHICS CARDS So I think this means that you should look for a VGA / DVI card if you are thinking you may upgrade to a TFT flat screen in the future. Looking for one that states specifically something like '[EMAIL PROTECTED]' is probably a good idea of a reasonable card (if you run your screen at 1600*1200) - though as noted in my previous email, this bandwidth may not be as important to digital displays as much as for CRTs. On RAM quantity, I do not personally believe that more than about 32MB is required per screen you plan to run (Mac Cinema display users may push this boundary). Graphics cards with 128MB+ of memory are typically for '3d specialist' rendering cards which use lots of memory to store textures that the cards then render onto 3d shapes. In this case '3d specialist' means 'graphcis cards for games players' for the vast majority of people. As ever, there is so much more that could be said! Best Regards, nij =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
