Wide angle exposure at DVinfo.net

Franck Ler · July 26th, 2004, 10:36 AM

Hello everyone,

This board seems the best place to post this question. Would the use of a wide angle increase the amount of light entering the optics?
in other words, due to its wider lens, will it allow for more light to come in and therefore at night be a good solution to have better low light performance?

thanks for explaining where I am wrong if so.

(already took u guys advice of having a cheapy camcorder to use as a vcr and save my gl2)

Ken Tanaka · July 26th, 2004, 11:37 AM

Good photographic question, Franck!

The basic answer: No.

The fundamental light-limiting factor for all camera lenses is their iris, rather like your eye's iris. That is, a given lens' maximum effective aperture remains unaffected by the field of view. (Conversely, its minimum effective aperture can be reduced by the use of telephoto adapters, thus admitting less light.)

In the case of the GL2's built-in lens, the addition of a wide-angle adapter will, to some degree, actually reduce the amount of light that passes through the lens. The degree of this reduction will depend on the the quality of the glass in the adapter. Poor glass and lens designs will lose light through uncontrolled diffraction and reflection, not to mention lack of accurate focus design.

As a loose analogy, think of any lens as a sink with its drain being like an iris. Adding a larger faucet will not increase the rate at which water will drain from the sink.

Hope this helps.

Franck Ler · July 27th, 2004, 07:36 PM

thx for the quick answer.

now another question. how can you know so much about videography if your training is in a different field??
Are you so quick to get answers somewhere else??
In any case, thx again!! Ever thought of helping out videography magazines? they sure could use the knowledge.

Tom Hardwick · July 28th, 2004, 01:09 AM

Franck's thoughts that adding a wide-angle 'increases the light' is a very common one, and Ken's reply is spot on. I know where the idea comes from of course. You film in the garden on a tripod and your camera readout is f5.6 say. Then you screw in the w/a converter and suddenly the reading for the same viewpoint is f8. What's happened?

Usually the simplest answer is that the wider field of view takes in the bright sky or the white painted wall, and this means that the light meter takes this into account. Of course your subject sitting quietly in front of your camera is now under-exposed by a stop simply because you fitted the w/a and left the exposure on auto.

Another very good reason to always use manual exposure.

tom.

Don Palomaki · July 28th, 2004, 04:09 AM

Most material prepared for magazines, news papers, etc. is produced by writers working under a deadline, not be technicians. scientists, engineers , (or obsessed hobbiests) with strong techncial background inthe subject and thus are likely to have a more precise understanding of what is going on. The writers work from what ever material they happen to find, which maybe limited to marketing handouts and (gasp), other writrers output. So it is not surprising that printed commonly matreial contains misstatements and errors of omission that are repeated.

And if many who lurk here spent time writing for mags as well as their day jobs ther wouldn't be much time left to lurk here <g>.

July 26th, 2004, 10:36 AM	#1
Franck Ler New Boot Join Date: Jan 2004 Location: Rouen France, Irvine CA Posts: 8	Wide angle exposure Hello everyone, This board seems the best place to post this question. Would the use of a wide angle increase the amount of light entering the optics? in other words, due to its wider lens, will it allow for more light to come in and therefore at night be a good solution to have better low light performance? thanks for explaining where I am wrong if so. (already took u guys advice of having a cheapy camcorder to use as a vcr and save my gl2) __________________ voir, c'est croire

July 26th, 2004, 11:37 AM	#2
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	Good photographic question, Franck! The basic answer: No. The fundamental light-limiting factor for all camera lenses is their iris, rather like your eye's iris. That is, a given lens' maximum effective aperture remains unaffected by the field of view. (Conversely, its minimum effective aperture can be reduced by the use of telephoto adapters, thus admitting less light.) In the case of the GL2's built-in lens, the addition of a wide-angle adapter will, to some degree, actually reduce the amount of light that passes through the lens. The degree of this reduction will depend on the the quality of the glass in the adapter. Poor glass and lens designs will lose light through uncontrolled diffraction and reflection, not to mention lack of accurate focus design. As a loose analogy, think of any lens as a sink with its drain being like an iris. Adding a larger faucet will not increase the rate at which water will drain from the sink. Hope this helps. __________________ Lady X Films: A lady with a boring wardrobe...and a global mission. Hey, you don't have enough stuff! Buy with confidence from our sponsors. Hand-picked as the best in the business...Really! See some of my work one frame at a time: www.KenTanaka.com

July 27th, 2004, 07:36 PM	#3
Franck Ler New Boot Join Date: Jan 2004 Location: Rouen France, Irvine CA Posts: 8	great thx for the quick answer. now another question. how can you know so much about videography if your training is in a different field?? Are you so quick to get answers somewhere else?? In any case, thx again!! Ever thought of helping out videography magazines? they sure could use the knowledge. __________________ voir, c'est croire

July 28th, 2004, 04:09 AM	#5
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,488	Most material prepared for magazines, news papers, etc. is produced by writers working under a deadline, not be technicians. scientists, engineers , (or obsessed hobbiests) with strong techncial background inthe subject and thus are likely to have a more precise understanding of what is going on. The writers work from what ever material they happen to find, which maybe limited to marketing handouts and (gasp), other writrers output. So it is not surprising that printed commonly matreial contains misstatements and errors of omission that are repeated. And if many who lurk here spent time writing for mags as well as their day jobs ther wouldn't be much time left to lurk here <g>. __________________ dpalomaki@dspalomaki.com

July 28th, 2004, 01:09 AM	#4
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Franck's thoughts that adding a wide-angle 'increases the light' is a very common one, and Ken's reply is spot on. I know where the idea comes from of course. You film in the garden on a tripod and your camera readout is f5.6 say. Then you screw in the w/a converter and suddenly the reading for the same viewpoint is f8. What's happened? Usually the simplest answer is that the wider field of view takes in the bright sky or the white painted wall, and this means that the light meter takes this into account. Of course your subject sitting quietly in front of your camera is now under-exposed by a stop simply because you fitted the w/a and left the exposure on auto. Another very good reason to always use manual exposure. tom.