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weird lens rendering, nighttime

Noah B

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Hey all, I've been doing a few tests with a couple lenses: Micro Nikkor 55mm f/2.8 AIS and Micro Nikkor 60mm f/2.8 AF. I did a couple night shots tonight and came back with two different renderings of light. The 55mm made the lights into this circular shape, while the 60mm made them into a hex type shape. I'm not sure if this is normal for AIS lenses? If anybody could chime in it'd be great, as I'm pretty confused right now.

55mm -



60mm -

 
It is called flare and the shape is often from the lens iris.
 
Both exposures were 15 seconds in the same position, I thought it was strange how one was different than the other. I thought it might be because the 55mm is an older model. Thanks though.
 
The lens or filter was also slightly dirty or foggy. The shape of the iris determines the number of points of the star as well.
 
That's not weird. That's diffraction on very overexposed lights. The overexposure was necessary to expose deeper into the night scene.

When I built a homebuilt reflector I used a 4 vane spider because with a 4 vane spider you get only 4 diffraction spikes but with a 3 vane spider you get 6 spikes. Such is one effect of diffraction.
 
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Chris, I looked at the blades on the 55mm and they're much rounder than the other lens, which is straighter. I've just never seen a lens render the light like that before.
 
Noah B said:
I've just never seen a lens render the light like that before.
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I think you might not have noticed this effect as much because the lights were not overexposed as much as they were in these photos.

One more thought. Try taking the same photos but with the lenses wide open. That should not show the spikes.
By the way, your 60mm lens has a 7 blade aperture, correct?
 
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One of the strangest lens effect I have ever seen, I dont even want to write about colors. But may be reason for that stars are the modern optics of the street lights. They can be very angular diamond cut like shapes on the light source. If your light source was clean and point light source diffracted like this , this a bad japanese lens. In real optics , point light sources must appear as point images otherwise its a very bad optics. Look for point spread function. Nikon have the worst optics I have ever seen or used.
 
Just curious, but were you shooting through a window? A lot of solar films will cause starlighting.
 

This is simply untrue, and a load of hogwash.

Neither of those images have unusual looking characteristics for a street lamp at night.

The only thing I see is the difference between a straight bladed aperture and a rounded aperture, perhaps used at a different f/stop which would also affect the appearance of the lights.
 
Are you using filters on either lens? The first one,a rendering is a but bizarre but I kinda like the second.
 

The intention was to shoot the same scene, same aperture and exposure. I could care less about over exposing the street lamps. Did you see the difference between the two? One has circular orientation and the other pointed hex shape. I wanted to see if this was normal for the AIS lenses.

I didn't shoot either of them through a window, both lenses didn't have any filters on them. Both lenses have 7 aperture blades, the 55mm aperture has a rounder shape when you stop down, and the 60mm has more of a straight shape when you stop down. I've shot lots of cameras but can't remember ever seeing lights that look circular at nighttime.
 
it is -much- more difficult to get star shaped highlights off a lens that has rounded blades, at any aperture. Straight blade lenses will do it even only two stops down from wide open, if the focus is right.
 

What aperture were you using the lenses at? I ask because, notwithstanding all the nonsense about 'bokeh' and the like, if you are using the lens at maximum aperture, the shape of the iris and number of blades has no effect, as it is open and perfectly round.

It appears that the 55mm is behaving normally with the lights themselves heavily overexposed - showing artifacts you wouldn't usually record; and the 60mm looks like it or the filter may need a cleaning.
 

These were actually both shot at f/8 @ 15 seconds, neither had a filter on, focused at infinity.
 
AgX said:
Has anyone counted those peaks?
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14 in the one from the 60mm lens. Hard to be certain in the first (55mm) one. I still think the 60mm lens could do with a cleaning - perhaps some sort of oily/smeary stuff on it.
 
lxdude said:
Or some condensation.
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Maybe, but in my experience condensation usually gives diffuse halos, not those sharp pointy rays.
I think the 55 is actually pretty well behaved, considering the overexposure (unavoidable) of the lights.
 
Mustafa Umut Sarac said:
In real optics , point light sources must appear as point images otherwise its a very bad optics. Look for point spread function. Nikon have the worst optics I have ever seen or used.
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I'd probably throw the Summicron 28 in the dumpster along with that Nikkor...
Dead Link Removed (Scroll down to where it reads "One thing the 28/2 ASPH does very nicely is beautiful 10-point sunstars")
 
I bet that really hurts! uch:
 
ic-racer said:
I'd probably throw the Summicron 28 in the dumpster along with that Nikkor...
Dead Link Removed (Scroll down to where it reads "One thing the 28/2 ASPH does very nicely is beautiful 10-point sunstars")
Click to expand...

Oh dear, even my 50 dual range with umpteen rounded blades makes some nice stars when closed down all the way...better chuck it.
 
Micro lenses are corrected for use at short distances. They give the best resolution when used for closeups. They can be used for general purpose photography but with less than optimal results.
 
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