My idiot question of the week: Do WA adapters let more light in?
 

If you've never seen my other idiot questions, don't worry. I keep them to myself so that no one knows what a pillock I really am. (grin)

The specific question is, will a good quality wide angle adapter bring in more light thru the lens than the same camera without one? My uninformed guess is yes, maybe... I know there will be light loss because of the WA adapter. The f value of the adapter would help me figure that out but that whole chain of math is really lost on me.

Here are the specifics. Century Optics 37mm .55WA attached to either a Canon HV10 or HF100. Shooting outdoors under marginal artificial light. Motor racing, of course.

The reason I ask is that I'm now using the adapter on the HF100 for a locked off speed shot right past the finishing line. With the adapter, the field of view is the whole finishing line all the way back to turn four. Without it, I lose either the whole line or part of turn four. Either wouldn't be optimal.

So far the adapter works well there from late afternoon through night, capturing great twilight skies as a racing backdrop. So I don't expect to change it. I was just very curious if I was gaining or losing a lot of light by using it.

TIA.

Tripp:

Lock the camera down, set the iris manually with the wide angle in place, then remove it. What happens to the exposure?

Just to my eye, the extra incidence of gathered light with a wide angle is generally off set just a bit by the extra glass it passes through, making the camera just a tad less light sensitive, but I'd be willing to go either way, based on your camera and the quality of the wide angle lens.

Bill... Your suggestion would provide much more practical information than the answer to my theoretical question. In a moment of pre-caffine clarity I realized that the WA adapter could result in significantly less overall light getting in if the increased field of view contains a lower average light level.

In theory, it would seem that if the camera was focused on a solid middle gray wall, the light let into the camera would be the same with the adapter as without, less the loss induced by the adapter itself. Since few of us shoot monochromatic backgrounds I think the technical answer to my theoretical question would not provide much useful information overall.