Railfan Technology > Bright lights cause stars

Is there anything I can do to get rid of the stars caused by bright lights? I've tried using a 50-135mm Nikkor manual zoom on a Nikon D7200, and I see these stars far more often than when I used film. Yes, I know it is only on certain angles (mostly close to straight on), but I am curious if a new UV filter might help. I've been using Hoya HMC UV(C) filters with no trouble on my other lenses, yet this lens seems to have the stars. (I know I can go from F8 to F5.6 to help some, but I like the greater depth of field at F8.)
Thanks in advance for any help.
Bob

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Ditch the cheap filter. 

Every addtional piece of glass between the subject and the sensor degrades the image somewhat.  Part of the reason that lenses for your camera has multiple elements inside is to correct the imperfections and distortions caused by the element in front of it.  Adding 2 glass-to-air transitions with a filter in front only adds to the distortions, diffractions, fringing, you-name-it before the light enters the front of your lens.  

It's also well-documented that the less costly the filter, the more aberrations and other problems it will cause.  Hoya makes a number of different quality filters for each category.  In the case of a 72mm filter I happened upon, here's what B&H Photo (my favorite camera gear store!) carries...EIGHTEEN (18) of them varying in cost from $125 to $17. B&H Photo Hoya 72mm UV filters   Just like lenses that cost $1000 on up vs those under $300, the added costs are the result of better quality glass, coatings, and design.  Filters follow the same principle.

If you want to see just 'how bad can it get' with cheap filters, here's a blog from the owner of Lensrentals.Com (a great place to rent lenses!  Outstanding service, too!) about a test he did with a bunch of cheap filters...Good times with bad filters - Lensrentals.com

For what it's worth, using 'protective' filters more than likely will cause more lens problems if damaged than had an object hit the front element of your lens!  There's a number of Youtube videos where people hit the front element with a hammer and no visible damage is found.  The tiny shards of a broken filter can be very problematic to a lens if they get inside.  The more easily bent mounting ring on the filter can make even the slightest whack cause it to bend and make removal  quite difficult.  Starting out in photography more than 50 years ago, I was taught to always keep a 'protective' filter on my lenses.  It was less than 10 years ago I finally read about the pitfalls of so-called protective filters and removed mine.  My photos were noticably more sharp and that was using 'high priced' protective filters!  A lens hood, even a cheap generic one, is a far better investment for improved photographs and various side-bangs here and there.  If your lens(es) don't have a hood, check if there's one available from the manufacturer for that lens, or, buy one that fits but will not 'cut off' the corners of the frame, especially on wider angle shots. 
   
 

Thanks for the information. I'll look into better filters.
Bob

The phenomenon is a variation on what is called "Fraunhofer Diffraction".  It is caused primarily by the shape and the number of blades in the lens, used to adjust the aperture.   To a lesser degree, shorter exposure times can diminish the effect.  

Don't use filters at all when shooting digital.  They cause reflections from the sensor that result in stars or inverted ghost images of the headlights/ditchlights.  Ditch the filters completely.

KG

That’s what the world looks like after LASIK surgery.  ;))

I agree that you remove the filter entirely shooting digital. 

Take a look at Nikkors with "Nano" coating.
Works like a dream, but very pricey.

Heh! I keep a polarizer on my lenses unless I'm
shooting at night. Makes a difference with color
contrast. I've got decent filters and don't notice
a difference. Once in a while, with or without a
filter, I'd pick up ghost reflections from head and
ditch lights that were coming at just the right
angle to cause the ghosts.

John.

I'd agree with the advice to get rid of the filters. I managed to improve things quite a bit by moving to a very expensive filter but the issue still wasn't completely removed. Eliminating the filter eliminated my ghost-stars.

I get the same effect wearing polycarbinate eye lenses.
So, I am stuck wearing I think what the call hi-index plastic lenses.
It was so bad the first time I wore polycarbinate lenses at night it was like my glasses were fogged up when it was very dark and approaching car headlights.
It made it unsafe to drive a night.

Pat
South Austin, TX

TOTALLY WRONG!  Can't believe that many posts nobody got it right! Come on TO's.
The star effect is because the older Nikon lens has straight apertures blades, which looks like your has seven of them.
Because they are straight and not rounded like most new lenses you get that star effect especially when you stop down the aperture smaller setting and are shooting with bright lights in the picture.
This is the effect of ghosting due to using a filter with bright lights in the photo.
 

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Thank you to all who have given advice. Here's hoping I can try it out soon.
Bob

I tried my other 50-135mm zoom and got the same resuts. I think it is a problem compounded by the newer higher-output lights locomotives seem to have now.
Bob

Next I'll try removing the filter.
Bob

Thanks to nssd70m2 for the answer. I tried using a different filter and no filter at all but had the stars with both. It must be the straight aperature blades. 
Thankfully the lens is great if I am at an angle to the train and not head on.
Bob

sptno Wrote:
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> I get the same effect wearing polycarbinate eye
> lenses.
> So, I am stuck wearing I think what the call
> hi-index plastic lenses.
> It was so bad the first time I wore polycarbinate
> lenses at night it was like my glasses were fogged
> up when it was very dark and approaching car
> headlights.
> It made it unsafe to drive a night.

For many years I thought it was just me. But then my optometrist finally diagnosed me with a rare condition called "poly non-adapt". Sometimes lenses made from virgin or high grade polycarbonate will reduce the effects but for me wearing most inexpensive polycarbonate lenses is a bit like looking through a fishbowl. High index plastic is better, but provides no ANSI Z87.1 impact resistance. I have a set of custom safety glasses made from PPG Trivex lenses, which is far superior optically to polycarb and Z87.1 safety rated, but the lenses are very expensive. For daily use I've found Crossfire safety glasses to be the best, low-cost, poly safety glasses on the market. I use them for work (railroad), shooting, and just as my daily sunglasses.

refarkas Wrote:
-------------------------------------------------------
> Thanks to nssd70m2 for the answer. I tried using a
> different filter and no filter at all but had the
> stars with both. It must be the straight aperature
> blades. 
> Thankfully the lens is great if I am at an angle
> to the train and not head on.
> Bob

I and at least one other poster I think assumed that you meant the ghosting effect rather than stars, because I don't think most people would have a problem with the star effect. It is only slight and actually looks quite aesthetically pleasing in my opinion i.e. it gives the impression of intense brightness, which is real.
The stars seem to be apparent on the vast majority of photos I see when you're looking quite head on, with all cameras...

I think you identified the cause and solution in your question.  If you look into articles/posts on lens settings, you will find that an f8 aperture tends to create the star effect with bright lights.  Wider apertures will reduce the effect, while smaller apertures will probably make it more pronounced, but also add diffraction issues.  If you can shoot at f5.6, you might be better off (f4 might be better again if your lens is that fast), but of course you will lose depth of field, so focus will need to be tight.  Also, I have found that if the locomotive's nose is well lit - in other words, the less bright the headlights are relative to the scene, the effect is diminished or even eliminated.  I think you should have less issues on sunny days than cloudy or dark conditions, but that doesn't help if you're there at the time I suppose!