Beam shot comparison photos

[Blazinator]

I've seen quite a few misleading photos of light beams on this sub forum that are meant to show the advantage of one light over another (or whatever the purpose), and if the photos are separately photographed, it proves nothing due to the auto-irising of most cameras to regulate the exposure level in the shot, not to mention auto-white balance (which will disguise the color when comparing HID's vs LED's vs Xenon, etc).

In other words, you can literally make a Mag light look brighter than a 50 watt HID if you shoot it right (wrong, actually).

So this is just a reminder to those that shoot and post comparative light beams of two or more different lights in photographs for purpose of comparison: Be sure to show the beams of all lights in question in the SAME photograph, like laying all lights side by side aiming at a garage door, same distance away etc. and get the comparison beams in ONE shot.

And when shooting, don't center the image on a light beam, as this will underexpose the image and you won't see the beam spread angle (if comparing beam angles).

 

[fppf]

Or you could just have an honest person shoot them with a dSLR, with manual white balance, shutter, and aperture. Then you could compare the photo's as they each would have the same camera settings.

 

[Gombessa]

The cameras would also need to be set to identical true ISO and have similar dynamic range.

 

[Blazinator]

Yes, those are definitely the other obvious options, but they require honesty like you mentioned, which is precisely the point of beam shots in the same photo. Good idea to have all those statistics of the photo overlayed onto the pic, if you go that route.

 

[Gombessa]

I've always tried to do this on beam comparison shots:

Same distance, focal length, shutter, aperture and ISO, exposure set to prevent blowing out highlights on the brightest light. With lights of varying intensity, sometimes different exposures are required to show spill coverage versus hotspot.

 

[CompuDude]

You are correct about automatic photo modes producing useless comparison photos, unless all are side-by-side in the same shot (and there is no blown out/clipped hot spot).

Any camera with a manual mode, P&A or DSLR, can produce images that can be compared validly, however. Be wary of anyone who doesn't take care to mention this about their photos, however... overlaying the text on the photo isn't really necessary unless you have reason to doubt the impartiality of the source (such as photos from sales people).

 

[Gombessa]

overlaying the text on the photo isn't really necessary unless you have reason to doubt the impartiality of the source (such as photos from sales people).

I try not to force people to rely on EXIF information that may be stripped out in post-processing, and having the information readily visible makes it easier for others to perform their own comparisons under similar conditions.

 

[CompuDude]

I try not to force people to rely on EXIF information that may be stripped out in post-processing, and having the information readily visible makes it easier for others to perform their own comparisons under similar conditions.

Absolutely. Your shots are great. Just pointing out that it's not necessary.

 

[Gombessa]

Absolutely. Your shots are great. Just pointing out that it's not necessary.

Understood, and thanks! My point is though, that if not disclosed (whether in an overlay or in the post linking to the image), there's always going to a question as to whether the photographer knew what he was doing. For instance, I think my camera auto-ISOs if set, even in manual mode. Since my example doesn't include ISO information, you really can't be certain that the top shot isn't a full stop or four brighter than the bottom. My BS-meter drops only a tad when I see a broad disclaimer such as "pictures shot with identical exposure" versus when no mention is made at all.

I think there are enough tricks and pitfalls involved where more information is always beneficial.