Nikon & Sigma 105mm macros

I use a 105mm Sigma macro. I've noticed that under some circumstances

the lens produces little stop-sign shaped bokeh. I'm curious about

what the 105mm Nikon does under similar circumstances. Could someone

post some images to show me?

Here's a detail.

This is not Bokeh but lens flare. It appears that the image has had the left portion cropped, otherwise the multiple images of the flare would go through the center of the picture. The "Stop Signs" that you see are out-of-focus images of the aperture diaphragm. If you were using full aperture, they would be circular, and much larger. Possibly the Nikkor has better coatings on its lens elements, but I would bet that it will give you similar images. I use the 105 Micro Nikkor, but I haven't tried shooting directly into the sun with it.

 

Alex

To correct to my previous post, the detail shot of the sun is Bokeh. But since the sun is out of focus, the "stop sign" still images the aperture.

 

Alex

You could wait for a more hazy day (to capture your sunset) or find a lens with better coating to shoot the sun [** taking care to keep from frying your eye and/or your camera's shutter curtain **]

 

Here is one example taken with a F100 and a 1000mm f11 Reflex-Nikkor lens:<div></div>

Thanks, but I'm not sure. The image isn't cropped, and when I took the photo there were highlights on the water that appeared in the as the little stop signs (in other words, these are genuine off-the-water reflections, not lens artifacts). I know that the Sigma has eight blades and yes, the aperture was pretty closed down (it's a macro lensm the rocks were smallish, etc.)--hence the characteristic shape. In any case, I'd sure like to see a similar image (bright, out-focus-pinpoint lights or reflections) taken with the Nikkor.

Barbara,

 

More aperture blades from any brand of lens would give rounder details. I have seen a modified micro lens using a fixed f16 aperture made from a metal disk with a smooth round hole. That effect may be what you are seeking, but of course with that disk the aperture was no longer adjustable. The lens was used for the very special purpose of photographing model railroads, by the way.

 

Then there is the separate issue of bokeh, which most evidently affects the eveness of illumination of out-of-focus highlights. However, I don't see anything particularly wrong with the bokeh of your Sigma lens! Perhaps a particular Nikon or Tamron or Tokina macro lens will give you results you like better than the Sigma, but the best way to get the shape of those stop signs fixed is to get the lens customized with a round aperture.

Barbara,

 

The beauty and smoothness of the image produced by Alex is partly due to the fact that the Reflex-Nikkor lens he used has a ROUND aperture.

The polygons you see in the photo are called ghost not flare. The ghost displays what I�d call average bokeh. Note that the edges of some are a little hot or bright lined but It�s not too obvious. This is typical of a macro lens. Don�t point it out and few people will notice it. The 55/2.8 AIS Micro-Nikkor is less than perfect in this regard. If you want really nice defocused images use a 105/2.5 AI or AIS. Your 70~300ED look quite nice also. You have a couple of shots with the 105 Sigma of a bee and a wasp that look fine. The effect varies due to many conditions.

 

Macro lenses are highly corrected for spherical aberration which contributes. Newer lenses have 9 blade irises which cause out of focus highlights to appear as circles but they can be harsh also so a lens with 9 blades can produce bad bokeh. I wouldn�t worry about it other than if you look at a background and if you see an unpleasant defocused area you might recompose.

 

Hope this helps,

Oops! Those polygons aren�t ghost (or flare). Don�t know what I was thinking?? There just plain old out of focus reflections on the water. <bg> If it were but Halloween I�d have had an excuse.

 

Blush,