Sony effio chipset and exview sensor is pretty average technology found in many different manufacturers of CCTV and for $100 it is a great camera.
http://www.sony.net/Products/SC-HP/cx_news/vol66/pdf/cxd5148_40gg.pdf
http://www.sony.net/Products/SC-HP/effiowld/products/ccd.html
The number of TVL only applies if you are viewing on an analog monitor to compare with another camera, but everyone can judge the resolution subjectively. It is difficult to notice a significant difference between 650-800 tvl unless they use a large high definition CRT monitor. Using a TV lines chart helps, but it is just an approximate measure of quality. While viewing remotely, the resolution is limited by the DVR/network constraints. Most DVRs that record high resolution stream in lower resolution.
For more info about resolution, read this previous post: http://www.cctvforum.com/viewtopic.php?f=5&t=9035
Marketing and advertising tactics describe the product's resolution subjectively, but large manufacturers like Sony are selling their name and don't need to fudge the numbers.
http://pro.sony.com/bbsc/ssr/cat-securitycameras/cat-cctv/product-SSCCB564R/
In general, the cctv camera market is very crowded and many "e-bay sellers" and manufacturers either falsify or exaggerate the specifications. That is why there are 4-channel kits being sold for under $100 to target residential users/DIY...we call them "fischer price toys" while professional installations can cost more than $500 PER camera.
As an installer, I can save my client money by selling reasonably priced cameras with IDENTICAL technology. There is a place for the most expensive highest resolution cameras, but a lot of residential end-users demand value over having a Sony logo on their cameras. the camera ECL-580 is professional-quality WITHOUT the high cost.
