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Does a lens with a bigger max. aperture focus faster than a lens with a smaller max. aperture?

For greater telephoto range, should I use 70-200mm + teleconverter or a longer zoom lens?Does a bigger aperture create better photos?Will using a lens at max aperture (“wide open”) result in poor images?How do I best compare lenses?How to compare the speed of lenses taking transmission into account?Nikon Lens - Stopping down causes over exposure in Aperture Priority modeWhy is there no way to set the aperture with an Albinar 500/8 lens on my D3100?Transmission, Aperture, and Focal Length in Low Light SituationsWhich aperture value determines depth of field on variable aperture lenses?My Tamron 100-400mm f/4.5-6.3 jumps to f/6.7 beyond 360mm

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3

The assertion by a well known photographer is that the Nikon 400mm f/2.8 set to an aperture of f/5.6 will let in 4 times the light compared to a Nikon 500mm f/5.6 lens set to f/5.6, keeping the shutter speeds identical.

The ultimate conclusion from this was that the focus acquisition time was much faster for the 400mm lens at f/5.6 than the 500mm set at f/5.6 due to more light.

While there may be different transmission factors for the glass, especially given one lens is the Nikon 500mm PF, I don’t believe the difference would be 4 times. He seems to be asserting that the faster lens is faster at any aperture when compared to a slower lens.

I would expect that if both lenses are set to f/5.6 and all other settings were the same, there should be less than a 1/2 stop difference in light transmission.

Where does the large difference in the statement of the photographer come from?

lens exposure aperture

share|improve this question

edited 8 hours ago

Saaru Lindestøkke

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asked 8 hours ago

Michael DavisMichael Davis

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Michael Davis is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  All of the answers so far address the misconceptions the op had and how the camera/lens works but i do not see how they address the question of does the amount of light as a result of aperture size during focusing result in appreciably faster focusing times ?
  
  – Alaska Man
  6 hours ago
  
  

  
  
  
  

add a comment | 

3

The assertion by a well known photographer is that the Nikon 400mm f/2.8 set to an aperture of f/5.6 will let in 4 times the light compared to a Nikon 500mm f/5.6 lens set to f/5.6, keeping the shutter speeds identical.

The ultimate conclusion from this was that the focus acquisition time was much faster for the 400mm lens at f/5.6 than the 500mm set at f/5.6 due to more light.

While there may be different transmission factors for the glass, especially given one lens is the Nikon 500mm PF, I don’t believe the difference would be 4 times. He seems to be asserting that the faster lens is faster at any aperture when compared to a slower lens.

I would expect that if both lenses are set to f/5.6 and all other settings were the same, there should be less than a 1/2 stop difference in light transmission.

Where does the large difference in the statement of the photographer come from?

lens exposure aperture

share|improve this question

edited 8 hours ago

Saaru Lindestøkke

4,05522 gold badges2727 silver badges6969 bronze badges

asked 8 hours ago

Michael DavisMichael Davis

1822 bronze badges

New contributor

Michael Davis is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  All of the answers so far address the misconceptions the op had and how the camera/lens works but i do not see how they address the question of does the amount of light as a result of aperture size during focusing result in appreciably faster focusing times ?
  
  – Alaska Man
  6 hours ago
  
  

  
  
  
  

add a comment | 

The assertion by a well known photographer is that the Nikon 400mm f/2.8 set to an aperture of f/5.6 will let in 4 times the light compared to a Nikon 500mm f/5.6 lens set to f/5.6, keeping the shutter speeds identical.

The ultimate conclusion from this was that the focus acquisition time was much faster for the 400mm lens at f/5.6 than the 500mm set at f/5.6 due to more light.

While there may be different transmission factors for the glass, especially given one lens is the Nikon 500mm PF, I don’t believe the difference would be 4 times. He seems to be asserting that the faster lens is faster at any aperture when compared to a slower lens.

I would expect that if both lenses are set to f/5.6 and all other settings were the same, there should be less than a 1/2 stop difference in light transmission.

Where does the large difference in the statement of the photographer come from?

lens exposure aperture

share|improve this question

edited 8 hours ago

Saaru Lindestøkke

4,05522 gold badges2727 silver badges6969 bronze badges

asked 8 hours ago

Michael DavisMichael Davis

1822 bronze badges

New contributor

Michael Davis is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 8 hours ago

Saaru Lindestøkke

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asked 8 hours ago

Michael DavisMichael Davis

1822 bronze badges

New contributor

Michael Davis is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 8 hours ago

Saaru Lindestøkke

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asked 8 hours ago

Michael DavisMichael Davis

1822 bronze badges

New contributor

Michael Davis is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 8 hours ago

Saaru Lindestøkke

4,05522 gold badges2727 silver badges6969 bronze badges

edited 8 hours ago

Saaru Lindestøkke

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asked 8 hours ago

Michael DavisMichael Davis

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Michael Davis is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 8 hours ago

Michael DavisMichael Davis

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3 Answers
3

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6

During focussing, the lens is left at full aperture. It's only when you take the picture that it closes down to the appropriate f-stop. That's so you can see what's going on and so that the camera has enough light to focus. So, yes, a lens with a maximum aperture that's two f-stops larger than another will let in four times as much light during focussing.

Your camera probably has a button you can push to close down the lens to see what it looks like stopped down (Depth of Field preview button). You can play with that to get a better sense of how much light different lenses provide at different apertures.

share|improve this answer

edited 7 hours ago

Hueco

14.3k33 gold badges2929 silver badges6464 bronze badges

answered 8 hours ago

Pete BeckerPete Becker

34811 gold badge22 silver badges77 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Yes, and i should have realized this!
  
  – Michael Davis
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Actually, on phase detection autofocus system (present in most DSLR's, if not all of them), it's not the amount of light but the optimal depth of field, what makes a difference. I haven't tested it to be able to say it's true, but is usually said that f2.8 lenses are the faster focusing ones on phase detection, as wider apertures make DoF too shallow and phase detection gets "confused".
  
  – Lisan
  5 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  In addition to my previous comment, DoF depends not only on diaphragm aperture but also on focal lenght and sensor size, and undoubtely there's difference between phase detectors in DSLR models, so knowing which exactly would be the fastest focusing lens surely needs of much more math than just saying 2.8f is always the fastest.
  
  – Lisan
  5 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Lisan my f/8 lens focuses faster than my f/2.8 lens because it's forced to have more DoF by design said no-one ever.
  
  – Hueco
  1 hour ago
  

  
  
  
  

add a comment | 

1

In general, cameras acquire focus with the lens wide open, so it is certainly true that the f/2.8 lens will be letting in (approximately) four times more light. To see this, half press the shutter to get a focus lock and see how the lens is still wide open.

share|improve this answer

answered 8 hours ago

Philip KendallPhilip Kendall

17k44 gold badges4949 silver badges8484 bronze badges

add a comment | 

0

Two factors:

• The longer the focal length, the harder it is to obtain perfect focus.


• The focusing happens at the max aperture of the lens anyway, so using the f/2.8 lens at f/5.6 doesn't matter, as the other answers noted.

I'm pretty sure these two effects fully explain whatever differences you're seeing.

share|improve this answer

answered 8 hours ago

juhistjuhist

1,40711 silver badge1818 bronze badges

add a comment | 

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6

During focussing, the lens is left at full aperture. It's only when you take the picture that it closes down to the appropriate f-stop. That's so you can see what's going on and so that the camera has enough light to focus. So, yes, a lens with a maximum aperture that's two f-stops larger than another will let in four times as much light during focussing.

Your camera probably has a button you can push to close down the lens to see what it looks like stopped down (Depth of Field preview button). You can play with that to get a better sense of how much light different lenses provide at different apertures.

share|improve this answer

edited 7 hours ago

Hueco

14.3k33 gold badges2929 silver badges6464 bronze badges

answered 8 hours ago

Pete BeckerPete Becker

34811 gold badge22 silver badges77 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Yes, and i should have realized this!
  
  – Michael Davis
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Actually, on phase detection autofocus system (present in most DSLR's, if not all of them), it's not the amount of light but the optimal depth of field, what makes a difference. I haven't tested it to be able to say it's true, but is usually said that f2.8 lenses are the faster focusing ones on phase detection, as wider apertures make DoF too shallow and phase detection gets "confused".
  
  – Lisan
  5 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  In addition to my previous comment, DoF depends not only on diaphragm aperture but also on focal lenght and sensor size, and undoubtely there's difference between phase detectors in DSLR models, so knowing which exactly would be the fastest focusing lens surely needs of much more math than just saying 2.8f is always the fastest.
  
  – Lisan
  5 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Lisan my f/8 lens focuses faster than my f/2.8 lens because it's forced to have more DoF by design said no-one ever.
  
  – Hueco
  1 hour ago
  

  
  
  
  

add a comment | 

6

During focussing, the lens is left at full aperture. It's only when you take the picture that it closes down to the appropriate f-stop. That's so you can see what's going on and so that the camera has enough light to focus. So, yes, a lens with a maximum aperture that's two f-stops larger than another will let in four times as much light during focussing.

Your camera probably has a button you can push to close down the lens to see what it looks like stopped down (Depth of Field preview button). You can play with that to get a better sense of how much light different lenses provide at different apertures.

share|improve this answer

edited 7 hours ago

Hueco

14.3k33 gold badges2929 silver badges6464 bronze badges

answered 8 hours ago

Pete BeckerPete Becker

34811 gold badge22 silver badges77 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Yes, and i should have realized this!
  
  – Michael Davis
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Actually, on phase detection autofocus system (present in most DSLR's, if not all of them), it's not the amount of light but the optimal depth of field, what makes a difference. I haven't tested it to be able to say it's true, but is usually said that f2.8 lenses are the faster focusing ones on phase detection, as wider apertures make DoF too shallow and phase detection gets "confused".
  
  – Lisan
  5 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  In addition to my previous comment, DoF depends not only on diaphragm aperture but also on focal lenght and sensor size, and undoubtely there's difference between phase detectors in DSLR models, so knowing which exactly would be the fastest focusing lens surely needs of much more math than just saying 2.8f is always the fastest.
  
  – Lisan
  5 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Lisan my f/8 lens focuses faster than my f/2.8 lens because it's forced to have more DoF by design said no-one ever.
  
  – Hueco
  1 hour ago
  

  
  
  
  

add a comment | 

During focussing, the lens is left at full aperture. It's only when you take the picture that it closes down to the appropriate f-stop. That's so you can see what's going on and so that the camera has enough light to focus. So, yes, a lens with a maximum aperture that's two f-stops larger than another will let in four times as much light during focussing.

Your camera probably has a button you can push to close down the lens to see what it looks like stopped down (Depth of Field preview button). You can play with that to get a better sense of how much light different lenses provide at different apertures.

share|improve this answer

edited 7 hours ago

Hueco

14.3k33 gold badges2929 silver badges6464 bronze badges

answered 8 hours ago

Pete BeckerPete Becker

34811 gold badge22 silver badges77 bronze badges

share|improve this answer

edited 7 hours ago

Hueco

14.3k33 gold badges2929 silver badges6464 bronze badges

answered 8 hours ago

Pete BeckerPete Becker

34811 gold badge22 silver badges77 bronze badges

edited 7 hours ago

Hueco

14.3k33 gold badges2929 silver badges6464 bronze badges

edited 7 hours ago

Hueco

14.3k33 gold badges2929 silver badges6464 bronze badges

answered 8 hours ago

Pete BeckerPete Becker

34811 gold badge22 silver badges77 bronze badges

answered 8 hours ago

Pete BeckerPete Becker

34811 gold badge22 silver badges77 bronze badges

1

In general, cameras acquire focus with the lens wide open, so it is certainly true that the f/2.8 lens will be letting in (approximately) four times more light. To see this, half press the shutter to get a focus lock and see how the lens is still wide open.

share|improve this answer

answered 8 hours ago

Philip KendallPhilip Kendall

17k44 gold badges4949 silver badges8484 bronze badges

add a comment | 

1

In general, cameras acquire focus with the lens wide open, so it is certainly true that the f/2.8 lens will be letting in (approximately) four times more light. To see this, half press the shutter to get a focus lock and see how the lens is still wide open.

share|improve this answer

answered 8 hours ago

Philip KendallPhilip Kendall

17k44 gold badges4949 silver badges8484 bronze badges

add a comment | 

In general, cameras acquire focus with the lens wide open, so it is certainly true that the f/2.8 lens will be letting in (approximately) four times more light. To see this, half press the shutter to get a focus lock and see how the lens is still wide open.

share|improve this answer

answered 8 hours ago

Philip KendallPhilip Kendall

17k44 gold badges4949 silver badges8484 bronze badges

share|improve this answer

answered 8 hours ago

Philip KendallPhilip Kendall

17k44 gold badges4949 silver badges8484 bronze badges

answered 8 hours ago

Philip KendallPhilip Kendall

17k44 gold badges4949 silver badges8484 bronze badges

answered 8 hours ago

Philip KendallPhilip Kendall

17k44 gold badges4949 silver badges8484 bronze badges

0

Two factors:

• The longer the focal length, the harder it is to obtain perfect focus.


• The focusing happens at the max aperture of the lens anyway, so using the f/2.8 lens at f/5.6 doesn't matter, as the other answers noted.

I'm pretty sure these two effects fully explain whatever differences you're seeing.

share|improve this answer

answered 8 hours ago

juhistjuhist

1,40711 silver badge1818 bronze badges

add a comment | 

0

Two factors:

• The longer the focal length, the harder it is to obtain perfect focus.


• The focusing happens at the max aperture of the lens anyway, so using the f/2.8 lens at f/5.6 doesn't matter, as the other answers noted.

I'm pretty sure these two effects fully explain whatever differences you're seeing.

share|improve this answer

answered 8 hours ago

juhistjuhist

1,40711 silver badge1818 bronze badges

add a comment | 

Two factors:

• The longer the focal length, the harder it is to obtain perfect focus.


• The focusing happens at the max aperture of the lens anyway, so using the f/2.8 lens at f/5.6 doesn't matter, as the other answers noted.

I'm pretty sure these two effects fully explain whatever differences you're seeing.

share|improve this answer

answered 8 hours ago

juhistjuhist

1,40711 silver badge1818 bronze badges

share|improve this answer

answered 8 hours ago

juhistjuhist

1,40711 silver badge1818 bronze badges

answered 8 hours ago

juhistjuhist

1,40711 silver badge1818 bronze badges

answered 8 hours ago

juhistjuhist

1,40711 silver badge1818 bronze badges