green light in photo?

jjbacoomba · 12-31-2012, 10:15 PM

Hi I am posting a photo I shot tonight. Practicing night shots with my new/old lens. A Pentax smc-A 28mm f/2.8 on my K100D. I used a tripod,turned off SR and shot in bulb mode. Here is the exif: exposure: 1 sec.
aperture: 3.5
ISO: 400 auto white balance.
I noticed what appear to be green dots/lights in the photo that start from the chair on the porch down to the middle of the image.I also noticed some just to the left of the bush. Can anyone tell me what this is, and what caused this? Of the 20 or so shots I took, I think about 5 did not have this going on. Thanks , Joe

Attached Images

kkoether · 12-31-2012, 10:24 PM

Originally posted by jjbacoomba

Hi I am posting a photo I shot tonight. Practicing night shots with my new/old lens. A Pentax smc-A 28mm f/2.8 on my K100D. I used a tripod,turned off SR and shot in bulb mode. Here is the exif: exposure: 1 sec.
aperture: 3.5
ISO: 400 auto white balance.
I noticed what appear to be green dots/lights in the photo that start from the chair on the porch down to the middle of the image.I also noticed some just to the left of the bush. Can anyone tell me what this is, and what caused this? Of the 20 or so shots I took, I think about 5 did not have this going on. Thanks , Joe

Do you have a filter on your lens? If so that is probably where the reflection is coming from. Remove it and try again.

Salagubang · 12-31-2012, 10:25 PM

It looks like reflection caused by lens filter.

p38arover · 12-31-2012, 10:26 PM

I think they are reflections from the lights to the right of the chair. The dots seem to match.

jjbacoomba · 12-31-2012, 10:53 PM

Wow, thanks guys. yes I do have a filter on the lens. Its a skylight filter. Never occured to me to take it off. Was on the lens when I got it. I guess it was on a as protection kind of filter. I will have another go soon. Thanks again and Happy New Year.

kkoether · 12-31-2012, 11:05 PM

Originally posted by jjbacoomba

Wow, thanks guys. yes I do have a filter on the lens. Its a skylight filter. Never occured to me to take it off. Was on the lens when I got it. I guess it was on a as protection kind of filter. I will have another go soon. Thanks again and Happy New Year.

Glad to help. I myself have quit using filters except for the occasional CP filter. I would like to try a ND filter sometime for the appropriate situation.

**TomB_tx** · 01-01-2013, 05:46 AM - **1 Like**

These reflections are common with cheaper or older filters, but only are obvious in such lighting conditions. After buying a lot of used lenses and cameras I've learned that the ones that have filters on them are nearly always in the best shape (optically), just like the camera bodies that have been in a "never-ready" case tend to be more pristine. When you have good lenses it is a dilemma: do you protect the lens as much as possible, or live with reflections? Besides Pentax I also use Leica, and even the 50mm f2.0 "normal" lens is over $2K, so you do want to protect it!
However, the best multicoated filters reduce reflections to where you won't notice them even in lighting like this. I find the Hoya and B&W top-end multicoated filters are worth it, on expensive lenses. (Lens hoods can also offer good protection from fingerprints and such.)
Filter reflections occur symmetrically opposite the center of the image, due to the curvature of the front element (on most lenses), so I set up a test shot to demonstrate. These are center crops, just to illustrate the effect of coating and filters on such reflections. First is a 50mm f2.0 lens with a good (B&W) UVa filter, but not multi-coated:
Name: 2012Sum_BWProF.jpg
Views: 385
Size: 193.2 KB

Name: 2012Sum_BWProF.jpg
Views: 385
Size: 193.2 KB

Next is the same setup, but with the MRC (multi-coated) version of the same filter:
Name: 2012Sum_BWProF-MRC.jpg
Views: 418
Size: 201.9 KB

And finally the bare lens without filter:
Name: 2012Sum_Bare.jpg
Views: 366
Size: 212.0 KB

Last edited by TomB_tx; 01-01-2013 at 08:08 AM.

Primes4ever · 01-01-2013, 08:24 AM

I use my lens hood to protect the lens and only use a CPOL when it is needed.

jamesm007 · 01-08-2013, 06:26 AM

Originally posted by jjbacoomba

Hi I am posting a photo I shot tonight. Practicing night shots with my new/old lens. A Pentax smc-A 28mm f/2.8 on my K100D. I used a tripod,turned off SR and shot in bulb mode. Here is the exif: exposure: 1 sec.
aperture: 3.5
ISO: 400 auto white balance.
I noticed what appear to be green dots/lights in the photo that start from the chair on the porch down to the middle of the image.I also noticed some just to the left of the bush. Can anyone tell me what this is, and what caused this? Of the 20 or so shots I took, I think about 5 did not have this going on. Thanks , Joe

Believe it or not a bluetooth in your ear can do it. I once had blue dots in some pics I was taking at night. I was like what the heck! I finally figured out it was the blue light from my blue tooth going into the OVF and finding a way down to the mirror chamber. This is what the cover for the OVF is for. To get accurate readings in bright light and just to help keep light out. Technically the mirror should seal it, but its not 100% sealed from light that comes from the OVF.

jjbacoomba · 01-08-2013, 10:54 PM

Thanks for the test shots Tom, they were very helpful.

12-31-2012, 10:15 PM	#1
jjbacoomba Senior Member Join Date: Apr 2011 Location: San Antonio,Texas Photos: Gallery Posts: 284	green light in photo? Hi I am posting a photo I shot tonight. Practicing night shots with my new/old lens. A Pentax smc-A 28mm f/2.8 on my K100D. I used a tripod,turned off SR and shot in bulb mode. Here is the exif: exposure: 1 sec. aperture: 3.5 ISO: 400 auto white balance. I noticed what appear to be green dots/lights in the photo that start from the chair on the porch down to the middle of the image.I also noticed some just to the left of the bush. Can anyone tell me what this is, and what caused this? Of the 20 or so shots I took, I think about 5 did not have this going on. Thanks , Joe Attached Images

01-01-2013, 05:46 AM - 1 Like	#7
TomB_tx Loyal Site Supporter Join Date: Jun 2011 Location: Texas Photos: Gallery Posts: 1,446	These reflections are common with cheaper or older filters, but only are obvious in such lighting conditions. After buying a lot of used lenses and cameras I've learned that the ones that have filters on them are nearly always in the best shape (optically), just like the camera bodies that have been in a "never-ready" case tend to be more pristine. When you have good lenses it is a dilemma: do you protect the lens as much as possible, or live with reflections? Besides Pentax I also use Leica, and even the 50mm f2.0 "normal" lens is over $2K, so you do want to protect it! However, the best multicoated filters reduce reflections to where you won't notice them even in lighting like this. I find the Hoya and B&W top-end multicoated filters are worth it, on expensive lenses. (Lens hoods can also offer good protection from fingerprints and such.) Filter reflections occur symmetrically opposite the center of the image, due to the curvature of the front element (on most lenses), so I set up a test shot to demonstrate. These are center crops, just to illustrate the effect of coating and filters on such reflections. First is a 50mm f2.0 lens with a good (B&W) UVa filter, but not multi-coated: Next is the same setup, but with the MRC (multi-coated) version of the same filter: And finally the bare lens without filter: Last edited by TomB_tx; 01-01-2013 at 08:08 AM.

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12-31-2012, 10:24 PM	#2
kkoether Pentaxian Join Date: Jul 2008 Location: Huber Heights, OH, USA Photos: Gallery \| Albums Posts: 731	Originally posted by jjbacoomba Hi I am posting a photo I shot tonight. Practicing night shots with my new/old lens. A Pentax smc-A 28mm f/2.8 on my K100D. I used a tripod,turned off SR and shot in bulb mode. Here is the exif: exposure: 1 sec. aperture: 3.5 ISO: 400 auto white balance. I noticed what appear to be green dots/lights in the photo that start from the chair on the porch down to the middle of the image.I also noticed some just to the left of the bush. Can anyone tell me what this is, and what caused this? Of the 20 or so shots I took, I think about 5 did not have this going on. Thanks , Joe Do you have a filter on your lens? If so that is probably where the reflection is coming from. Remove it and try again.

12-31-2012, 10:25 PM	#3
Salagubang Senior Member Join Date: Oct 2011 Location: San Jose Del Monte Photos: Gallery \| Albums Posts: 198	It looks like reflection caused by lens filter.

12-31-2012, 10:26 PM	#4
p38arover Veteran Member Join Date: Mar 2012 Location: Western Sydney, Australia Photos: Gallery \| Albums Posts: 3,084	I think they are reflections from the lights to the right of the chair. The dots seem to match.

12-31-2012, 10:53 PM	#5
jjbacoomba Senior Member Join Date: Apr 2011 Location: San Antonio,Texas Photos: Gallery Posts: 284 Original Poster	Wow, thanks guys. yes I do have a filter on the lens. Its a skylight filter. Never occured to me to take it off. Was on the lens when I got it. I guess it was on a as protection kind of filter. I will have another go soon. Thanks again and Happy New Year.

12-31-2012, 11:05 PM	#6
kkoether Pentaxian Join Date: Jul 2008 Location: Huber Heights, OH, USA Photos: Gallery \| Albums Posts: 731	Originally posted by jjbacoomba Wow, thanks guys. yes I do have a filter on the lens. Its a skylight filter. Never occured to me to take it off. Was on the lens when I got it. I guess it was on a as protection kind of filter. I will have another go soon. Thanks again and Happy New Year. Glad to help. I myself have quit using filters except for the occasional CP filter. I would like to try a ND filter sometime for the appropriate situation.

01-01-2013, 08:24 AM	#8
Primes4ever Senior Member Join Date: Oct 2011 Location: Cambridge, Ontario Posts: 179	I use my lens hood to protect the lens and only use a CPOL when it is needed.

01-08-2013, 06:26 AM	#9
jamesm007 Veteran Member Join Date: Jul 2008 Location: Detroit MI, USA Posts: 508	Originally posted by jjbacoomba Hi I am posting a photo I shot tonight. Practicing night shots with my new/old lens. A Pentax smc-A 28mm f/2.8 on my K100D. I used a tripod,turned off SR and shot in bulb mode. Here is the exif: exposure: 1 sec. aperture: 3.5 ISO: 400 auto white balance. I noticed what appear to be green dots/lights in the photo that start from the chair on the porch down to the middle of the image.I also noticed some just to the left of the bush. Can anyone tell me what this is, and what caused this? Of the 20 or so shots I took, I think about 5 did not have this going on. Thanks , Joe Believe it or not a bluetooth in your ear can do it. I once had blue dots in some pics I was taking at night. I was like what the heck! I finally figured out it was the blue light from my blue tooth going into the OVF and finding a way down to the mirror chamber. This is what the cover for the OVF is for. To get accurate readings in bright light and just to help keep light out. Technically the mirror should seal it, but its not 100% sealed from light that comes from the OVF.

01-08-2013, 10:54 PM	#10
jjbacoomba Senior Member Join Date: Apr 2011 Location: San Antonio,Texas Photos: Gallery Posts: 284 Original Poster	Thanks for the test shots Tom, they were very helpful.