I put one roll of print film through my camera to test my new lens, Nikkor 17-35/2.8 AF-S. To my surprise, more than 90% of prints were vignetted or had awful uneven blue sky (caused by light fall off ??). All images are tack sharp, colors and contrast are very pleasing. How to avoid those vignetting and uneven blue sky is a challenge. Would experienced user share your tips with me? Your input is highly appreciated. Equipment I used: Nikon N-70, Nikkor 17-35/2.8 AF-S, the lens shade and a Hoya 77 mm Super multicoated circular polarizer were always on the zoom lens (it could be the roots of the problem, I think), Fuji ISO 100 print film. Sunny day, but I did not shoot in the sun, always used the sunlight from behind me. Sometimes, the angle between sunlight and the optical axis of the lens was 70 to 90 degree, but never less than 70 degree. Could the problem was caused by the lens shade because there were a patch of blue sky in the middle of the pictures which is darker than those at left and right. Do I have to use a rectangular polarizer instead of a circular one to avoid vignetting if it is caused by the CP?

Thank you in advance. Ronald

-- Ronald Shu (isssr@isc.ucsb.edu), June 30, 2000

Answers

The polarizer is the suspect for both the vignetting and uneven blue sky. You will need a "slim" type polarizer, or use no filter at all if you are using the hood. Good luck, and how about showing a pix?

-- Sean (stnoonan@yahoo.com), June 30, 2000.

Sorry, I forgot attach the sample pictures for my post. Here is the URL http://128.111.124.11/ssr/critique.htm

-- Ronald Shu (isssr@isc.ucsb.edu), July 01, 2000.

Your URL: http://128.111.124.11/ss r/critique.htm. This sounds like a question for the www.photo.net Q&A board, especially since your images are of a house and not nature (this being the Nature Critique board and all).

Anyway, your problem is not with the lens, but the sky -- blue skies are not uniformly blue, especially when shooting at 17mm with a polarizer. Polarizers always have a more pronounced effect 90 degrees in the sky from the sun's position; this effect lessens the further you get from 90 degrees in either direction (towards or away from the sun). It always happens with ultrawides and the sky; learn to live with it.

By the way, there is no such thing as a "rectangular" polarizer. You're thinking of a linear polarizer. In any case, it won't give you any different effects as far as polarization. Since you're using an autofocus camera, you need to stick with a circular polarizer; otherwise you will mess up your metering if you use a linear polarizer.

As for vignetting, your polarizers may be too thick to use with such a wide-angle lens. Most polarizers get pretty thick around 77mm. Lool at your lens shade -- notice how shallow it is? It may even be cut away at the corners. Also, look at how close the front element of the lens is to the filter ring -- it's probably barely recessed. This is how ultrawides are built, and it makes 'em prone to flare and vignetting. Unfortunately, there's not much you can do about it other than accepting it as a limitation with which you must work. You may not be able to use a polarizer and your lens shade at 17mm without vignetting. You might consider picking up a wide-angle polarizer -- these are made ultra-thin to avoid vignetting.

Good luck -- ultrawides can be great when you figure out when and where to use 'em. Next week, why not post a print of a natural image so we can see how you're doing?

-- Christian Deichert (torgophile@aol.com), July 01, 2000.

I second Christian's technical as well as "when to use response". It's a predictable action. Whenever a photographer gets their first wide angle they feel obligated to suck in the whold sky. This includes angles in a spectrum close to and far from the 90 degrees from the sun (maximum polarization). Learn and discover the many other creative uses of that fine wide angle lens you now own.

mark

-- Mark LaGrange (mark.lagrange@nml.com), July 04, 2000.

This doesn't look like what I would even call vignetting. Look at your pic2.jpg. The dark patch in the sky is almost in the middle of the top of the picture instead of the corner, and the corner is light. This is due to the polarizer and the angle to the sun.

-- John Foster (johngfoster@hotmail.com), August 05, 2000.

Hoya SMC and only the SMC filters are slim for wide angle. If you are using the bayonet hood form nikon it should not vignet, however if you use a scew in hood with either the filter in front or behind the hood it will bring them out far enough to start vigneting. I agree with some of the others polarizers work best when USED AT 90deg. Try looking at a bright white wall with the filter and hood. If it does vignet it that situation it should be easy to see. Oops I forgot you do not see 100% of the frame in the N70's viewfinder. Maybe stop at a camera store and try it with a F5 where you see 100% of the frame. John

-- john (dogspleen@juno.com), November 02, 2000.