Benefits of Fresnel Lens LED

[barefoot_dp]

Hi All,

Just contemplating adding a few bits and pieces to my lighting kit and was wondering about fresnel lenses. From what I've read (ie what is advertised) they actually increase the light output over the bare bulb by focusing it all on one place - does this mean a COB LED would give more output with a fresnel pointed towards say a 4x4 silk, than it would just mounting a softbox directly on to the light? Or am I missing something?

I can see that being a big benefit, not only for getting the most out of the lights but also being able to put them further away from the subject where fan noise will not be a problem (while still having the diffusion nice and close to the subject).

Anybody got practical experience with this?

[newfoundmass]

1 hour ago, barefoot_dp said:

does this mean a COB LED would give more output with a fresnel pointed towards say a 4x4 silk, than it would just mounting a softbox directly on to the light?

I don't think you'd get the spread you'd want / need since the light would be concentrated in one spot on the silk, though I've never tried it and never heard it being done. 

[scotchtape]

In my experience of trying to maximize efficiency of lights, the answer is no.

In your example, at the same distance if you used the fresnel vs softbox, the fresnel would produce a small hotspot which is totally useless for soft lighting.

If you then moved the light with the fresnel back to cover the same area, it would be farther away and the intensity would greatly decrease.

If I've learned anything about softlighting it's that nothing beats more power.  The most effective way to get more soft light is to literally get more lights.

 

 

[newfoundmass]

39 minutes ago, scotchtape said:

If I've learned anything about softlighting it's that nothing beats more power.  The most effective way to get more soft light is to literally get more lights.

Yes, the bigger the light the better. 

[UncleBobsPhotography]

I like fresnels, they are in my opinion the most flexible type of lighting. However, if you want soft light, an LED panel will usually be more quiet and softer. You can do some nice bounce lighting with fresnels which are impossible with LED panels. Pointing it at a white ceiling or white wall basically produces a light source anywhere, even if it's rather far away. Fresnels are also much better at making hard light. For learning how light properly and to be able to experiment with light, nothing really beats a fresnel light.

Conclusion: fresnels are a lot of fun

[barefoot_dp]

3 hours ago, UncleBobsPhotography said:

However, if you want soft light, an LED panel will usually be more quiet and softer.

I'm yet to find an affordable LED panel that offers the same size source/softness as a 4x4 diffusion frame (let alone a larger butterfly!).

[Grimor]

5 hours ago, UncleBobsPhotography said:

Conclusion: fresnels are a lot of fun

Don´t forget that years ago most cinema lights were fresnel

[newfoundmass]

2 hours ago, barefoot_dp said:

I'm yet to find an affordable LED panel that offers the same size source/softness as a 4x4 diffusion frame (let alone a larger butterfly!).

Caleb reviewed one recently. https://youtu.be/EaYebQm3CpY

[Mark Romero 2]

I think a fresnel could come in handy when:

1) Bouncing light

2) Illuminating through a window or cookie for a hard light / hard shadows.

3) When you need to use more than one light for a diffused key, and you can shoot two (or more) fresnel lights through a scrim (since we can't really fit more than one light in to a softbox, can we???)

4) When you want a spotlight effect

[barefoot_dp]

13 hours ago, newfoundmass said:

Caleb reviewed one recently. https://youtu.be/EaYebQm3CpY

He literally says in that video that the light is too harsh on its own. 

I own and use a couple of 1x1s and they are simply not large enough for a soft key. They're great for backlights, quick 'n' dirty portable/field/battery setups, or even as an eye light outdoors, but if you want soft light they come nowhere near competing with a COB light pushed through a softbox or scrim (at equivalent prices). Of course you can use a panel with a scrim or reflector too but most simply do not have the power. It's fine for his indoor setup, where he doesn't have to balance any ambient light and has a fairly tight frame so the light can be just a few feet from his face, but I doubt the setup he's demonstrating in that video would work in very many real scenarios (eg setting up an interview in front of a window in a cluttered office space).

[barefoot_dp]

5 hours ago, Mark Romero 2 said:

I think a fresnel could come in handy when:

1) Bouncing light

2) Illuminating through a window or cookie for a hard light / hard shadows.

3) When you need to use more than one light for a diffused key, and you can shoot two (or more) fresnel lights through a scrim (since we can't really fit more than one light in to a softbox, can we???)

4) When you want a spotlight effect

Thanks Mark. In regards to points 1 & 3, and taking in to account Scotchtape's comments above, how would a fresnel compare to a bare COB (with a dish)? Would you not run in to the same issue Scotchtape mentions, that you need to back the Fresnel further from the wall or scrim in order to get an acceptable sized beam - resulting in more light loss than if you'd just put the bare COB closer to the bounce/scrim?

[Mark Romero 2]

2 hours ago, barefoot_dp said:

Thanks Mark. In regards to points 1 & 3, and taking in to account Scotchtape's comments above, how would a fresnel compare to a bare COB (with a dish)? Would you not run in to the same issue Scotchtape mentions, that you need to back the Fresnel further from the wall or scrim in order to get an acceptable sized beam - resulting in more light loss than if you'd just put the bare COB closer to the bounce/scrim?

I think that when shooting through a scrim, you are correct. Moving the light far back enough to get an even spread is going to make the lights more or less equal, regardless if it is a fresnel or a cob with a dish. 

On the other hand, if you are actually shooting in a softbox, you are actually bouncing the light around so that the light can be closer to the diffusion material and still cover the entire area of the front diffusion.

Plus if the COB light is in an enclosed softbox, you won't have the spill that you would have from bouncing it off of a scrim. All that spill is just wasted light. I don't know the exact mathematics but I am pretty certain that when inside a softbox, the light that is bounced off the front diffusion material (and bounced around the softbox), eventually makes its way out to the subject, but at some reduced amount.

In terms of bouncing light off the wall or a ceiling, I guess that yes, you would have to back the fresnel or COB with dish further from the wall. This could be good or bad. If bouncing off a wall, you would probably want to use a COB with dish to get the light further away from the talent (and further from the mic) as you could move it closer to the wall than a fresnel.

When bouncing off a HIGH ceiling, it might be easier to use a fresnel because you wouldn't have to raise the light as high to achieve the same light spread. This would be applicable in a place with high ceilings. But in a place with low ceilings, the fresnel might be at a disadvantage as you might not be able to get it low enough to get the amount of spread you want.

Ideally, I think the best solution would be to get a COB light with an optional fresnel attachment.

Also, a disclaimer: all of my practical experience with fresnel lenses / attachments is from shooting flash photography with strobes. The AD-200 and other strobes I use allow for either a bare bulb or fresnel head on the same light, so the only variable is the actual head. 

[tupp]

On 11/11/2021 at 5:34 AM, barefoot_dp said:

From what I've read (ie what is advertised) they actually increase the light output over the bare bulb by focusing it all on one place

Fresnels don't focus all of the output in one place -- such fixtures can only focus the light that hits the lens.  The light that hits the inside of the housing is wasted.

In this sense, many open-faced fixtures are more efficient than Fresnel fixtures as almost all of the light from an open-faced fixture comes out the front of the unit.

 

On 11/11/2021 at 5:34 AM, barefoot_dp said:

- does this mean a COB LED would give more output with a fresnel pointed towards say a 4x4 silk, than it would just mounting a softbox directly on to the light? Or am I missing something?

No.  The Fresnel will be dimmer than using the exposed LED with a reflector.

By the way, softboxes are generally a lot more efficient and controllable than naked diffusers.  Naked diffusers also generate a lot of spill light.

 

 

On 11/11/2021 at 6:42 AM, newfoundmass said:

I don't think you'd get the spread you'd want / need since the light would be concentrated in one spot on the silk,

On 11/11/2021 at 2:43 PM, scotchtape said:

In your example, at the same distance if you used the fresnel vs softbox, the fresnel would produce a small hotspot which is totally useless for soft lighting.

Folks, Fresnel lights on set generally have a continuous "focus" range of beam angles from "spot" to "flood."  The range of those beam angles varies with each fixture.

I can't recall all the times I've seen someone illuminate a diffuser with a Fresnel light, but almost always they focused the light to "full flood" to completely illuminate the diffuser.

 

17 hours ago, Grimor said:

Don´t forget that years ago most cinema lights were fresnel

Fresnels are used all the time on film sets.

 

9 hours ago, Mark Romero 2 said:

I think a fresnel could come in handy when:

1) Bouncing light

2) Illuminating through a window or cookie for a hard light / hard shadows.

3) When you need to use more than one light for a diffused key, and you can shoot two (or more) fresnel lights through a scrim (since we can't really fit more than one light in to a softbox, can we???)

4) When you want a spotlight effect

I use Fresnels and open-faced focusable fixtures directly on people and sets.

Keep in mind that the "spotlight" effect from a naked Fresnel will usually give a soft edge to the spot.  If one wants a harder edge on a spot, use a snoot and focus the light to "full flood" (or use a good ellipsoidal/followspot or projection fixture that has minimal fringing).

 

3 hours ago, barefoot_dp said:

He literally says in that video that the light is too harsh on its own. 

A lot depends on what you are trying to do.   I could use that panel fixture naked in a lot of shoots.

 

3 hours ago, barefoot_dp said:

I own and use a couple of 1x1s and they are simply not large enough for a soft key. They're great for backlights, quick 'n' dirty portable/field/battery setups, or even as an eye light outdoors, but if you want soft light they come nowhere near competing with a COB light pushed through a softbox or scrim (at equivalent prices).

Softness in lighting is a matter of degree between a point source and completely surrounding your subject with a smooth light source.  There is not definitive "soft light" and "hard light."

By the way, you can use a panel light in a soft box.

 

3 hours ago, barefoot_dp said:

Thanks Mark. In regards to points 1 & 3, and taking in to account Scotchtape's comments above, how would a fresnel compare to a bare COB (with a dish)? Would you not run in to the same issue Scotchtape mentions, that you need to back the Fresnel further from the wall or scrim in order to get an acceptable sized beam - resulting in more light loss than if you'd just put the bare COB closer to the bounce/scrim?

A lot depends on the optics in front of the LED, but, again, open-faced fixtures are almost always more efficient than fixtures using Fresnel/plano-convex lenses.

 

[tupp]

13 minutes ago, Mark Romero 2 said:

I think that when shooting through a scrim,

You call a diffuser a "scrim" -- do you have a background in still photography?

 

9 minutes ago, Mark Romero 2 said:

think that when shooting through a scrim, you are correct. Moving the light far back enough to get an even spread is going to make the lights more or less equal, regardless if it is a fresnel or a cob with a dish. 

Generally, a Fresnel will be significantly less efficient than an open-face fixture.  A lot of the light is lost when it strikes the inside of the housing of the Fresnel fixture/attachment.

 

14 minutes ago, Mark Romero 2 said:

When bouncing off a HIGH ceiling, it might be easier to use a fresnel because you wouldn't have to raise the light as high to achieve the same light spread.

An open-faced focusable source would be better and more efficient in this situation.

 

 

[newfoundmass]

4 hours ago, barefoot_dp said:

He literally says in that video that the light is too harsh on its own. 

I own and use a couple of 1x1s and they are simply not large enough for a soft key. They're great for backlights, quick 'n' dirty portable/field/battery setups, or even as an eye light outdoors, but if you want soft light they come nowhere near competing with a COB light pushed through a softbox or scrim (at equivalent prices). Of course you can use a panel with a scrim or reflector too but most simply do not have the power. It's fine for his indoor setup, where he doesn't have to balance any ambient light and has a fairly tight frame so the light can be just a few feet from his face, but I doubt the setup he's demonstrating in that video would work in very many real scenarios (eg setting up an interview in front of a window in a cluttered office space).

I thought you meant an LED panel to use with diffusion, my bad. 

[newfoundmass]

1 hour ago, tupp said:

Folks, Fresnel lights on set generally have a continuous "focus" range of beam angles from "spot" to "flood."  The range of those beam angles varies with each fixture.

I can't recall all the times I've seen someone illuminate a diffuser with a Fresnel light, but almost always they focused the light to "full flood" to completely illuminate the diffuser

My fresnel attachment that I use on my Godox COB lights doesn't really do a good job in "full flood", though it works great when in spotlight (which is my primary use for it.) I imagine you'd get better results from a nicer one then? 

I'm not on major sets, just small commercial ones, and I've never seen a fresnel attachment being used with diffusion, so I find that interesting. I still feel like the op would be better off using more lights instead of a fresnel attachment. Not to say he shouldn't get one, as they're very fun to play around with and good to have in your kit, I'm just not sure that it's the solution he'd want to go with for diffusion?

[Mark Romero 2]

9 hours ago, tupp said:

You call a diffuser a "scrim" -- do you have a background in still photography?

Yes!

9 hours ago, tupp said:

Generally, a Fresnel will be significantly less efficient than an open-face fixture.  A lot of the light is lost when it strikes the inside of the housing of the Fresnel fixture/attachment.

Thanks. Good to know. I certainly wasn't aware of that.

 

9 hours ago, tupp said:

An open-faced focusable source would be better and more efficient in this situation

Again, good to know. Thanks.

That raises two questions though:

1) When would you choose the Fresnel over an open-faced focusable source?

2) Can you give us an example of a (more-or-less affordable) open-faced focusable light (or modifier)?

[tupp]

7 hours ago, newfoundmass said:

My fresnel attachment that I use on my Godox COB lights doesn't really do a good job in "full flood", though it works great when in spotlight (which is my primary use for it.) I imagine you'd get better results from a nicer one then? 

Not sure what is meant by "doesn't really do a good job in 'full flood,'"  A Fresnel attachment on an LED fixture might be disappointing to one having experience with tungsten and HMI Fresnels.

Regardless, the range of beam angles from a focusable fixture/attachment depends on a few variables.

With Fresnel fixtures, the source is always closest to the lens in the full flood setting.  So, if the Fresnel attachment doesn't allow the LED to get close to lens, then the beam angle will not reach its widest potential.  Of course, there are safety reasons why the light source should not get too close to the lens.

On the other hand, if one can just remove the lens/attachment, then it's best to just use the fixture without the lens, one wants to go really wide and use all of the output from the source.

By the way, it is dangerous to run a tungsten or HMI Fresnel without its lens.

 

8 hours ago, newfoundmass said:

I'm not on major sets, just small commercial ones, and I've never seen a fresnel attachment being used with diffusion, so I find that interesting. I still feel like the op would be better off using more lights instead of a fresnel attachment. Not to say he shouldn't get one, as they're very fun to play around with and good to have in your kit, I'm just not sure that it's the solution he'd want to go with for diffusion?

I don't advocate using Fresnels to illuminate diffusion -- it doesn't make a lot of sense to do so.  However, I see it on set often.

Fresnels and other focusable fixtures are more than "fun to play around with."  If one knows how to use them, they are a valuable tool that "play" often on set.

[Mark Romero 2]

9 hours ago, tupp said:

Softness in lighting is a matter of degree between a point source and completely surrounding your subject with a smooth light source.  There is not definitive "soft light" and "hard light."

By the way, you can use a panel light in a soft box.

I am a little confused by this (Again, I come from a photography background, but I haven't seen anything to contradict this).

In terms of shadows, I understand that softness  "is a matter of degree between a point source and completely surrounding your subject with a smooth light source."

But wouldn't there still be a difference in specular highlights? I know that (in still photography) when a silver-lined umbrella is used, the specular highlights are stronger (more pronounced / more contrasty) than when a white-lined reflective umbrella is used. (And they are even more contrasty when using a non-bounced light.)

P.S. Wanted to say thank you again for your input in this conversation. 

[tupp]

1 minute ago, Mark Romero 2 said:

1) When would you choose the Fresnel over an open-faced focusable source?

Some open-faced focusable sources can produce a double cast shadow in the outer parts of the beam, when focused to "spot."  So, cutting into the beam with barndoors or a flag can sometimes not give a clean edge as with a Fresnel.

I tend to use open faced fixtures, as that double cast shadow usually is not apparent, and because they are more compact and lightweight than Fresnels.

 

13 minutes ago, Mark Romero 2 said:

2) Can you give us an example of a (more-or-less affordable) open-faced focusable light (or modifier)?

The Lowel Omni light.  A great, lightweight, compact, powerful and exceedingly versatile fixture.  It's focusing range is greater than many Fresnels.  Always use a protective screen on the front of the fixture.  Use FTK bulbs with a filament support, and avoid off-brand bulbs.  The focusing mechanism is very fast and can break the bulb's filament if one is not careful.