Question about reflections in my new 35mm prime

dudara

I recently got a 35mm AF-S DX lens for my D40 and I went out last night for a few mins to try some nighttime photos.

However I noticed that I had reflections in most of the photos, always above a light source. I have no idea why this is happening, can anyone illuminate me?


10 seconds at f/1.8,ISO200


1 second at f/1.8, ISO 200


1/8 second at f/1.8, ISO1250

Ghost Train

Was there any filter on the camera? If so I'd say it was that, definitely looks like its from a flat surface of glass

Thirdfox

Remove UV filter

edit: or call the X-Files people

dudara

I did have a UV filter on - good to know it's something that simple.

But why are there reflections at night, and not during the day?

Tallon

dudara wrote: »

I did have a UV filter on - good to know it's something that simple.

But why are there reflections at night, and not during the day?

UV filter !!!

PCPhoto

not that much UV rays emitted by the sun at night !!! (just hope I'm not making an ass of myself but pretty confident that UV light comes from the sun)

Anyway - guessing problem solved.

EDIT: you should try to open the aperture (F-stop) when shooting at night and use a tripod - that way you get a better exposed image.

try F8, F11 and use timer/remote to take pics.....can also be used to get nice light trails from passing traffic.

dudara

It never occurred to me that there would be less UV at night - but when you think about it, without a moon to reflect sunlight and in street lighting, there's not going to be a lot of UV.

Just found this discussion over on Flickr.

I suppose I tend to think of the UV filter as just a piece of protective glass for the lens. So far, I've not thought too hard about the effect that it has.

Ghost Train

dudara wrote: »

I did have a UV filter on - good to know it's something that simple.

But why are there reflections at night, and not during the day?

lens flare from light sources, if you had the sun or other source in shot during day you'd probably get the same I think

Tallon

dudara wrote: »

It never occurred to me that there would be less UV at night

It's like wearing sunglasses at night! Your cameras finding it hard to see through

dudara

PCPhoto wrote: »

EDIT: you should try to open the aperture (F-stop) when shooting at night and use a tripod - that way you get a better exposed image.

I think all the shots above are at f/1.8 but it's my first time using this lens at night, so I need to familiarise myself with it.

denat

PCPhoto wrote: »

EDIT: you should try to open the aperture (F-stop) when shooting at night and use a tripod - that way you get a better exposed image.

try F8, F11 and use timer/remote to take pics.....can also be used to get nice light trails from passing traffic.

I'm very much a beginner and have been trying to get my head around f numbers - but I thought the lower the number the wider the aperture. So f1.8 would be wider than f8?

dudara

You're right - the smaller the f number, the wider the aperture is. So f/1.8 is wider (and letting in more light) than f/8

Thirdfox

Tallon wrote: »

It's like wearing sunglasses at night! Your cameras finding it hard to see through

Not quite :P - I think you're referring to polarising light - which is what sunglasses do when darkening the image (halving the light transference)...and what circular polariser filters do on a camera lens.

UV filters generally do not darken the image whereas a polariser at maximum strength halves the light levels.

dudara

Thirdfox wrote: »

Not quite :P - I think you're referring to polarising light - which is what sunglasses do when darkening the image (halving the light transference)...and what circular polariser filters do on a camera lens.

UV filters generally do not darken the image whereas a polariser at maximum strength halves the light levels.

Yes and No. Polaroid sunglasses reduce light intensity by polarising the light - essentially removing any light that is not in the plane of polarisation. They are particularly good for reducing glare. Other types of sunglasses that remove UV light do so by blocking (or reducing) light that has a UV frequency/wavelength usually by means of coatings and thin films on the lens.

The effect is roughly the same to the eye, but the physical mechanism is quite different.

Good info here from posters - thanks everyone for your responses.

Thirdfox

Yes - but I was making the point that UV coatings/reduction does not affect light transference levels to any perceptible level. The darkening is a result of polarisation not UV filtering - hence UV filters do not darken the image that a camera "sees".

The only reason why UV filters are needed in the case of non polarised sunglasses is that the darkened plastic/glass of normal glasses only reduce visible light levels and does not block potentially harmful UV light as your retina expands to accommodate for the lower intensity of visible light you are receiving.