Super Hoods and Sweet Spots
© Steve Sint 2002

As the digital revolution rushes towards high pixeled, full frame, 35 mm sized sensors I’m beginning to think that the smaller sized sensors (in cameras from Nikon, Canon, Fuji, and Sigma) are the way to go. Since July, beginning with my acquisition of a Nikon D100, I have shot about a dozen magazine articles using it and I have not exposed one frame of film!
 
Although all of these smaller chip, “multiplier” cameras suffer when compared to the wide-angle capabilities of full frame digital and film 35’s, there are some unique and obtuse features that the “multiplier” cameras bring to the table.
 
Soon after getting my hands on my D100 I purchased a lens that I thought I would never have to buy again. The ubiquitous 50 mm 1.4, of which I had a manual focus version, became the object of my infatuation. Considering the D100’s 1.5 focal length multiplier factor this inexpensive, lightweight, small filtered, lens offers the perspective of a 75 mm f 1.4…. perfect for intimate portraits. Pretty amazing when you consider it’s about 1/4 the price on Nikon’s 85 1.4 that’s used to accomplish about the same thing on a full frame camera.

 
But there was more to this story. Lighter in weight (MUCH lighter in weight!,)




Smaller filters (like 52’s vs. 77’s!!). and there’s the lens hood. What? As a crafty view camera photographer I realized a lens designed to cover a 24X36 mm frame has much more “coverage” than I need to cover a 15X24 mm sensor! I could care less if a lens hood caused vignetting on the 24X36 mm frame….as long as it didn’t vignette on the camera’s smaller sensor.



 
After some experimenting, the lens hood I’m using on my 50 mm, f 1.4 is from an ancient 105 mm, f 2.5 Nikkor. Although this combination is vignette city on a full frame 35 it doesn’t vignette on the D100. Likewise, my 24 mm, f 2.8 Nikkor is sporting the lenshood from an 85mm, f 1.8 Nikkor without a trace of vignette woes!




 
All this has led me to another discovery. Because the sensor on the multiplier cameras only sees the central part of the lens’ circular projected pattern (a “sweet spot”), lenses that I might avoid because of poor edge performance on a full frame 35mm camera became worthy of a second look. A lens, that resolves details at the edge of a full frame 35 mm camera as if its glass was made from the bottom of a coke bottle, can have central optical performance good enough to suddenly become very interesting.
 
A good case in point is my new Tamron 80-210 mm, f 4.5-5.6 (120-300mm equivalent). While it certainly isn’t up to the optical quality or speed of my 80-200, f 2.8 AFS Nikkor (especially wide open and/or at the edge of the full 35mm format) the fact that it weighs 9.1 oz (compared to the 60 oz. 2.8 Nikkor!!), and costs $ 95 (about one-fourteenth what the AFS 2.8 does!!) is tantalizing. Taking only 52 mm filters (compared to 77 mm filters on the AFS 2.8!!) makes it even more so. Combining it with digital’s ability to pump up the ISO for a few frames and digital’s ability to deal with underexposure makes it a very enticing, lightweight, package!
 
This is in no way to belittle the 80–200 Nikkor that offers the perspective of a 120-300mm, f 2.8 zoom on the D100. With the addition of the 1.4E Nikon tele-converter, it becomes a very reasonably priced auto-focus 420mm, f 4 telephoto on the long end!
 
Lastly, while I used to carry a macro lens as part of my kit, close-up lenses, whose poor edge performance made me pass them over for use on full frame 35 mm lenses, provide very acceptable optical performance in the center of the pattern. With the “multiplier” cameras and a few close up filters (often called “plus” lenses), every one of my lenses is now capable of close-up work. With the “multiplier” cameras a few filters can replace a prime macro lens with little or no loss of image quality.




 
Now that Nikon has announced a new 12-24mm zoom (18-36mm full frame equivalent), designed exclusively for their digital cameras, the wide-angle side of things is finally becoming workable! This digital only lens, combined with the oversized lens hoods, sweet spot lens performance, and close-up lens capability when using traditional, full frame lenses on the small sensor breed of digital SLR are adding fuel to the digital revolution. Considering these added benefits, and the relatively low price of the small sensor digital SLR’s when compared to some of the newest full frame digital SLR’s, these cameras are becoming more attractive everyday.