RF 24-105 f4-7.1 vs RF 24-70 f2.8 in daylight

[Salamander]

I currently have the R6ii with the RF 24-105 f4-7.1 lens. I’m considering getting the RF 24-70 f2.8. I know the 2.8 will be better in low light. I’m curious if there is much difference in the quality of pictures taken outside in daylight, particularly as you zoom towards 70mm.

 

[neuroanatomist]

Daylight, so maybe say, "F/8 and be there." I presume you mean the RF 24-70/2.8L IS USM. In the center of the frame at 70mm f/8, the L-series lens is a little sharper, away from the center of the frame the L lens is noticeably better.

https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1504&Camera=1508&Sample=0&FLI=3&API=3&LensComp=1415&CameraComp=1508&SampleComp=0&FLIComp=3&APIComp=4

If by some chance you mean the non-L 28-70/2.8 IS STM, you can compare that lens using the above tool as well, and run through more focal lengths and apertures if you like.

 

[Michael Clark]

I currently have the R6ii with the RF 24-105 f4-7.1 lens. I’m considering getting the RF 24-70 f2.8. I know the 2.8 will be better in low light. I’m curious if there is much difference in the quality of pictures taken outside in daylight, particularly as you zoom towards 70mm.

The constant aperture f/2.8 obviously also gives you the option to shoot at wider apertures in brighter light if your camera can shorten exposure times enough to compensate or if you use Neutral Density filters. The minimum exposure time of the R6 Mark II is 1/8,000 with mechanical shutter and 1/16,000 with electronic shutter. "Sunny 16" gives you ISO 100, f/2.8 at 1/6,400.

 

[Salamander]

The constant aperture f/2.8 obviously also gives you the option to shoot at wider apertures in brighter light if your camera can shorten exposure times enough to compensate or if you use Neutral Density filters. The minimum exposure time of the R6 Mark II is 1/8,000 with mechanical shutter and 1/16,000 with electronic shutter. "Sunny 16" gives you ISO 100, f/2.8 at 1/6,400.

I thought I understood the sunny 16 rule, but apparently not. My understanding is if the ISO is 100 then the shutter speed should be 1/100, not 1/6,400. I’m new to this, so I need more help understanding this.

 

[AlanF]

I thought I understood the sunny 16 rule, but apparently not. My understanding is if the ISO is 100 then the shutter speed should be 1/100, not 1/6,400. I’m new to this, so I need more help understanding this.

The sunny 16 rule is that at iso 100 you need 1/100s at f/16. So, at f/11 you need 1/200s. f/8 1/400s etc etc to 1/3200s at f/2.8. (Not 1/6400s).

 

[Salamander]

The sunny 16 rule is that at iso 100 you need 1/100s at f/16. So, at f/11 you need 1/200s. f/8 1/400s etc etc to 1/3200s at f/2.8. (Not 1/6400s).

Thanks. I found a handy chart that further explains it. It’s going to take me some time and practice to get handy at this.

 

[Michael Clark]

The sunny 16 rule is that at iso 100 you need 1/100s at f/16. So, at f/11 you need 1/200s. f/8 1/400s etc etc to 1/3200s at f/2.8. (Not 1/6400s).

To quote Roger Cicala, "I was, er, might have been wrong, ahem... less correct than I originally wrote."

I was underexposing by a stop to protect the highlights with plans to boost the mids and shadows in post while holding back the highlights.

Yeah, that's it! That's the ticket. I was protecting the highlights!

 

[AlanF]

To quote Roger Cicala, "I was, er, might have been wrong, ahem... less correct than I originally wrote."

I was underexposing by a stop to protect the highlights with plans to boost the mids and shadows in post while holding back the highlights.

Yeah, that's it! That's the ticket. I was protecting the highlights!

View attachment 229070

There are some here who would have argued that seriously.

 

[Sporgon]

Thanks. I found a handy chart that further explains it. It’s going to take me some time and practice to get handy at this.

Beware the Sunny 16 rule with digital cameras !
As has been correctly stated, the ‘rule’ is when the subject is lit frontally and evenly in full sunlight, from two hours after sunrise to two hours before, if your shutter speed is the ‘same’ as your iso then f/16 gives the correct exposure.
The problem with this rule and most digital cameras is that their stated iso is not the real iso. So to use the ‘sunny 16’ with a digital camera you have to know what, say 100 iso on your camera really is. This information is available at both dxomark and photonstophotos.
To use a Canon R6 as an example, the camera stating 100 is really 63.
So to use the sunny 16 rule when your R6 is set to 100 iso, on a full sunny front lit day set 1/60th, not 1/100 at f/16 and you’re exposure will be spot on.
On my 5DS the 100 iso setting is really 77.

 

[Salamander]

Beware the Sunny 16 rule with digital cameras !
As has been correctly stated, the ‘rule’ is when the subject is lit frontally and evenly in full sunlight, from two hours after sunrise to two hours before, if your shutter speed is the ‘same’ as your iso then f/16 gives the correct exposure.
The problem with this rule and most digital cameras is that their stated iso is not the real iso. So to use the ‘sunny 16’ with a digital camera you have to know what, say 100 iso on your camera really is. This information is available at both dxomark and photonstophotos.
To use a Canon R6 as an example, the camera stating 100 is really 63.
So to use the sunny 16 rule when your R6 is set to 100 iso, on a full sunny front lit day set 1/60th, not 1/100 at f/16 and you’re exposure will be spot on.
On my 5DS the 100 iso setting is really 77.

Thanks for that update. I have the Canon R6ii. Do you know where on those websites I can find the iso data?

 

[Sporgon]

It looks to me as if DXOmark may have stopped assessing camera sensors, which could be an issue in the future, although it is easy enough to test for yourself.
However, they have tested the R8 which uses the same sensor as the R6II, and at base iso 100 the camera is actually 66. So I would set 1/60th. If you do this you will find that the rule works for you. Remember to give back half or even a full stop if there are significant shadows depending upon how prevent they are and how important detail is in them to you. (This is why the rule works for evenly front lit subjects).
As the ISO climbs the difference between stated ISO and actual gets less. Link is to the DXOmark chart for the R8.
For people only using the camera meter the difference is irrelevant, but if you are using a handheld meter it is very important. (Or the sunny 16 rule !) This is why the latest handheld meters such as the Sekonic 858 can be custom profiled to exactly match your particular camera.

DXOMARK

www.dxomark.com

 

[AlanF]

Thanks for that update. I have the Canon R6ii. Do you know where on those websites I can find the iso data?

I don't think they are on them. I might have missed it, but I don't recall photonstophotos having the data, and I just checked DxoMark and the last Canon they did was the R3 in 2023.

 

[AlanF]

My reply was at the same time as Sporgons!

 

[Salamander]

It looks to me as if DXOmark may have stopped assessing camera sensors, which could be an issue in the future, although it is easy enough to test for yourself.
However, they have tested the R8 which uses the same sensor as the R6II, and at base iso 100 the camera is actually 66. So I would set 1/60th. If you do this you will find that the rule works for you. Remember to give back half or even a full stop if there are significant shadows depending upon how prevent they are and how important detail is in them to you. (This is why the rule works for evenly front lit subjects).
As the ISO climbs the difference between stated ISO and actual gets less. Link is to the DXOmark chart for the R8.
For people only using the camera meter the difference is irrelevant, but if you are using a handheld meter it is very important. (Or the sunny 16 rule !) This is why the latest handheld meters such as the Sekonic 858 can be custom profiled to exactly match your particular camera.

DXOMARK

www.dxomark.com

Thanks