Peer Reviews-Navitar Screenstar SSW08/SST120Peer Reviews-Navitar Screenstar SSW08/SST120; Price: $990 MSRP 3/01/2005 5:45 AM Eastern
Peer Reviews-Navitar Screenstar SSW08/SST120
Peer Reviews-Navitar Screenstar SSW08/SST120; Price: $990 MSRP
Product:Navitar ScreenStar SSW08 and SST120 projector conversion lenses
Price: $990 each
Plus: Easy way to change focal length on a projector
Minus: Lenses must be permanently mounted; could be costly for small projectors
NAVITAR HAS been making high-quality projection lenses for some time. I used its slide projector lenses exclusively in my previous rental & staging career, and its X-Y adjustment, short-throw Gold Series lenses were ideal for aligning and converging stacks of 35 mm slide projectors.
Navitar got into the LCD and DLP projector game by purchasing Buhl Optical of Pittsburgh, PA, a number of years back. Buhl had a nice business with after-market lenses for installation LCD and DLP projectors for many years. However, there are an awful lot of LCD and DLP projectors out there with fixed lenses, and chances are many of the people who bought them really wish that a shorter or longer lens had been available at the time.
Navitar's ScreenStar conversion lenses are intended for LCD and DLP projectors that don't offer interchangeable lenses. They come in four sizes, including a .65x and a 1.5x model. All four versions must be securely mounted in front of the original projector lens.Design
The majority of low-cost projectors are usually equipped with a varifocal lens that provides a limited zoom ratio of 1.2:1 or 1.3:1. Navitar's solution is to provide what we used to call a telextender lens element — it's not a true zoom or telephoto lens, just a screw-on front element that changes the focal length. Here, the design is simply an extender lens with a thin bracket that can be attached to any surface with a couple of small screws.
Of course, you have to make sure that the rear lens element on any of these extenders is aligned correctly with the projector's front lens element. That may require some ingenuity on your part to devise a support for the lens extender bracket. Unfortunately, Navitar can't make direct projector brackets —there are just too many different models out there to support.Performance
I hooked up the two test lenses in front of an Optoma H30 compact DLP projector. Once I was able to come up with a secure mount for the lenses, I had to use a fine text pattern and grid pattern to make sure the extender and projector lens elements were centered and parallel to each other.
A couple things happen to projected images when using extender lenses, and one of them is entirely predictable. First, the light output will change as more lens elements are added. With the “un-extended” Optoma projector, I measured 185 lux on my office screen. Adding the SSW08 dropped light output to 130 lux, but expanded the image size from 68 inches to 82 inches.
Switching to the SST120 lens reduced the image size to 55 inches and resulted in a brightness reading of 251 lux. Brightness uniformity measured 74.8 percent with the SSW08 and measured 78.3 percent with the SST120, so you won't see a noticeable drop-off in image brightness when using either extender lens.
Secondly, white balance should be pretty constant if the lens coatings are consistent. To verify this, I also took color temperature measurements. With the stock Optoma projector, my Minolta CL-200 color temperature meter measured a full white field at 6,420 degrees K.
Adding the SSW08 dropped that a scant 38 degrees, but the SST120 pulled white balance down by a substantial 280 degrees K. That would indicate a difference in optical coatings between the two lenses, one that would definitely be noticed in a home theater application and one that I wouldn't expect with this price tag.
(Editor's Note: When this measurement variation was pointed out to Navitar, it replicated the results and determined that the lenses used for this review were early prototype models. According to Navitar, current production models do not exhibit such variations.)
In all cases, text and fine detail in my images was crisp all the way across the image except in two of the corners. That was probably due to my inability to precisely mount the rear lens element square to the projector's front lens element.Value
It's hard to put a value on lens converters. Anyone who wants specific focal lengths in a projector will usually buy a model that lets you swap out lenses and install the one you want. To be sure, you'll pay extra for that option, although Navitar will gladly sell you a Buhl aftermarket lens for your projector. In fact, Navitar aftermarket lenses can be fitted to many (but not all) projectors with fixed lens designs.
The real market for this product would seem to be smaller business and home projectors with compact optics and lenses that aren't easily replaced, or can't be replaced. However, some of those projectors are available for as little as $1,000 these days. Adding either of these two Navitar lenses would effectively double the price. (The .65x and 1.5x versions are more costly at $1,497 each.)
For people with older projectors that use fixed lenses, the cost of a Navitar extender may be a relative bargain compared to the purchase of a new model that could cost $4,000 to $8,000 to replace altogether. That includes older desktop and small installation projectors that are being put to new uses and aren't quite ready to retire yet. If you have such a projector (probably two to five years old), then this product is worth a closer look.
Pete Putman is a contributing editor for Pro AV and president of ROAM Consulting, Doylestown, PA. Especially well known for the product testing/development services he provides manufacturers of projectors, monitors, integrated TVs, and display interfaces, he has also authored hundreds of technical articles, reviews, and columns for industry trade and consumer magazines over the last two decades. You can reach him at firstname.lastname@example.org.