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dsaptarshi
Joined: 12 Sep 2009
Posts: 9
Location: Cockeysville, MD
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 Posted: Tue Jul 13, 2010 8:27 am Post subject: Amount of Light (Lambet / Lux unit ) required on 10M target |
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Hello Everyone,
Can someone guide me about how much light is required on target for 10M Air rifle? I have been looking for this information on forum but not found any information on this. Is there any standard that is being followed on international competition? I understand that the target should be bright enough so that it can be viewed clearly from 33feet , but is there any scale like lambert or lux unit ,through which I can judge I have enough light on my target and its not too bright or dim as per standard ISSF rules.
I appreciate any help on the above.
Regards
Datta
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David Levene
Joined: 01 Mar 2004
Posts: 2942
Location: England
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| Posted: Tue Jul 13, 2010 8:42 am Post subject: |
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You might find that the attached extract from the ISSF rules answers your question.
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dsaptarshi
Joined: 12 Sep 2009
Posts: 9
Location: Cockeysville, MD
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| Posted: Thu Jul 15, 2010 5:51 am Post subject: |
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| Thanks a lot David, I really appreciate your help and I got the answer I was looking for.
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guidolastra
Joined: 06 Sep 2007
Posts: 68
Location: Columbia, MO
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| Posted: Thu Jul 15, 2010 11:11 am Post subject: |
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| For a home range (I assume this is the case), how to get such lighting, what type of light source (bulbs, etc...) do you think should be used ? I have the same problem, my range is dark.
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GCSInc
Joined: 01 Apr 2005
Posts: 66
Location: Georgia
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| Posted: Thu Jul 15, 2010 8:21 pm Post subject: Light |
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First buy yourself a Light Meter. It is the only way to accurately measure the light. http://www.calright.com/pd_534.aspx $49.00
Then study the Technical Issues.
http://www.reliabilitydirect.com/RDIStorePDF/Gardening%20Lighting%20Facts.pdf
My research shows that a 500 watt Halogen Shop light needs to be 7 feet (about 2 meters) or less to the target to illuminate it to 1000 lumens. It would need to be about 4 - 5 feet (aprox 1.5 meters) to make 1500 lumens. This will get you in the ball park. For three position Air Rifle, the light should be 18 - 24 inches off the floor (about even with kneeling) or you might want to use multiple lights (or move them) for each position.
Best Regards,
Roy McClain
www.OleMillRange.org
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Spencer
Joined: 24 Feb 2006
Posts: 917
Location: Sydney, Australia
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| Posted: Thu Jul 15, 2010 10:49 pm Post subject: |
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| 500W sounds like overkill when an R80 75W reflector light at 300-400mm (adjust the set up with a light meter) will give the needed light level on an ISSF 10m target - that's what is used at most of the World Cups
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robf
Joined: 14 Dec 2006
Posts: 214
Location: South, UK
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| Posted: Fri Jul 16, 2010 12:12 am Post subject: |
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| Spencer wrote: | | 500W sounds like overkill when an R80 75W reflector light at 300-400mm (adjust the set up with a light meter) will give the needed light level on an ISSF 10m target - that's what is used at most of the World Cups |
Light intensity falls off inverse square over distance... so at 1unit of distance away you need 1x of light, at 2, you need 4x of light, and at 3, you need 9x.... so if you need 75w at .4m you actually need 2000w at 2m to get the same luminosity... 2m is 5x the distance away from the target that 0.4m is so 25x more light is needed... if wattage = light (assumed), that's where you end up.
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robf
Joined: 14 Dec 2006
Posts: 214
Location: South, UK
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| Posted: Fri Jul 16, 2010 12:13 am Post subject: |
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| interesting that the doc doesn't specify colour temperature...
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Spencer
Joined: 24 Feb 2006
Posts: 917
Location: Sydney, Australia
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| Posted: Fri Jul 16, 2010 1:41 am Post subject: |
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| robf wrote: | | Light intensity falls off inverse square over distance... so at 1unit of distance away you need 1x of light, at 2, you need 4x of light, and at 3, you need 9x.... so if you need 75w at .4m you actually need 2000w at 2m to get the same luminosity... 2m is 5x the distance away from the target that 0.4m is so 25x more light is needed... if wattage = light (assumed), that's where you end up. |
So? Put the light closer - with a suitable pellet deflector!
I will never be accused of being the world's greatest greenie :), but less power, less weight, less heat, less $$$...
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GCSInc
Joined: 01 Apr 2005
Posts: 66
Location: Georgia
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| Posted: Fri Jul 16, 2010 2:51 pm Post subject: Light issues |
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Spencer,
You are correct, to a point. If you're shooting a single bull target your tiny light works fine. If you're shooting a 3x20, Hanging 6ea AR 5/10s then you'll need more light across a larger area. We put a 500 watt light (20" off the floor) in the gap between each Target holder (for a given number of target holders, you'd need an extra light on each end to even out the light) and that covers all three target heights.
Best Regards,
Roy McClain
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Spencer
Joined: 24 Feb 2006
Posts: 917
Location: Sydney, Australia
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| Posted: Fri Jul 16, 2010 10:02 pm Post subject: |
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| I did put in "...the needed light level on an ISSF 10m target..."
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robf
Joined: 14 Dec 2006
Posts: 214
Location: South, UK
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| Posted: Sun Jul 18, 2010 11:23 am Post subject: |
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| Spencer wrote: | | robf wrote: | | Light intensity falls off inverse square over distance... so at 1unit of distance away you need 1x of light, at 2, you need 4x of light, and at 3, you need 9x.... so if you need 75w at .4m you actually need 2000w at 2m to get the same luminosity... 2m is 5x the distance away from the target that 0.4m is so 25x more light is needed... if wattage = light (assumed), that's where you end up. |
So? Put the light closer - with a suitable pellet deflector!
I will never be accused of being the world's greatest greenie :), but less power, less weight, less heat, less $$$... |
I get your drift ;)
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