R5 keeps reverting to F7.1 - manual settings

[NancyMac]

Hi All ,

shooting manual settings.  Want to use 4.5 (on 100-500 lens).  Keeps reverting to 7.1.  What am I doing wrong?

I want to control aperture, shutter speed and ISO all in manual settings.  Why is it locking me out of 4.5 or 5.6 etc?   I’m definitely in Manual mode. 

thanks for your help!

Nancy 

[rs-eos · Accepted solution]

Are you using the RF 100-500mm f/4.5 to f/7.1 lens?   If so, note that when you're near or at the 500mm focal length, the minimum aperature will be f/7.1.   This lens is thus a variable aperture lens.   As you move throughout the focal length range of the lens, the minimum aperature will have different values (e.g. at some point it will be f/5.6).

In order to be at f/4.5 for your lens, you'll need to be at or near the 100mm focal length.

Lenses such as the RF 70-200mm f/2.8 would allow you to use f/2.8 at all focal length settings.

[rs-eos · Accepted solution]

There is no workaround to the aperture setting itself.  As you move closer and closer to the 500mm range, the minimum aperture will indeed change.  Lens manufacturer's create such variable-aperture lenses to lower the cost as well as typically lowering the weight of the lens.

Thus, correct in that you'll need to find ways to compensate such as raising ISO and/or slowing the shutter if that's doable.

In terms of another lens option, I'll let others weigh in as the only zoom lens I have is for my cinema camera (an RF 24-70mm f/2.8).  For my DSLR, I only have two prime lenses.   Thus, I cannot readily recommend zoom lenses in your desired focal length range. 

[jrhoffman75 · Accepted solution]

The 100-500 is Canon's longest RF zoom. 

Canon will be releasing a 600mm f/4 prime, but that is a $9000 lens in EF mount and it seems that RF mount lens are costing more for equivalent lens.

You can download a trial version of Topaz Sharpen AI and see how that handles your higher ISOs. I have been pleased with what it does with my 1D X III files.

[rs-eos · Accepted solution]

Are you using the RF 100-500mm f/4.5 to f/7.1 lens?   If so, note that when you're near or at the 500mm focal length, the minimum aperature will be f/7.1.   This lens is thus a variable aperture lens.   As you move throughout the focal length range of the lens, the minimum aperature will have different values (e.g. at some point it will be f/5.6).

In order to be at f/4.5 for your lens, you'll need to be at or near the 100mm focal length.

Lenses such as the RF 70-200mm f/2.8 would allow you to use f/2.8 at all focal length settings.

[NancyMac]

Hi Ricky,

Thanks for explaining that to me.  Causes a bit of a problem in low light situations.  I did have a 2.8 - 70-200 and the 100-300 so I’m bummed out about this?  What’s the work around?  Just bump up my ISO?   Dang!  Wish there was another lens option.  Any suggestions?  Appreciate your help.   Nancy 

[jrhoffman75 · Accepted solution]

The 100-500 is Canon's longest RF zoom. 

Canon will be releasing a 600mm f/4 prime, but that is a $9000 lens in EF mount and it seems that RF mount lens are costing more for equivalent lens.

You can download a trial version of Topaz Sharpen AI and see how that handles your higher ISOs. I have been pleased with what it does with my 1D X III files.

[NancyMac]

Hi John,

Thanks for your info.   I found a work around solution today.  Now that I know that the zoom is causing the aperture change, then I can work around that.  I did well with it today after reading Ricky's email.  A 600 prime won't work for me.  That'll be like holding a rocket launcher.  :))

Thanks again!  

Nancy

[FloridaDrafter · Accepted solution]

---

@NancyMac wrote:

"Thanks for explaining that to me.  Causes a bit of a problem in low light situations.  I did have a 2.8 - 70-200 and the 100-300 so I’m bummed out about this?  What’s the work around?  Just bump up my ISO?   Dang!  Wish there was another lens option.  Any suggestions?  Appreciate your help.   Nancy" 

---

Hello, Nancy.

I've been using this combo for several months now to shoot birds and wildflowers. The R5 handles higher ISO's amazingly, in fact, I don't notice any noise when shooting in low light. Now, what I consider low light is early morning, late evening, forest canopy, and underbrush. I really like f/7.1 as a starting pont because it allows DOF to be a little better. However, by bumping up my ISO, I can get the lens in its "sweet spot". Since I shoot birds, they generally flit around or are constantly moving their body parts even when perched, so I like to keep my SS in the 1/500th to 1/1000th range. Even then, I can usually keep my ISO below 4000, which isn't a problem at all with the R5, or R6 for that matter. I can also keep my aperture where I want it by adjusting ISO. This is considered unconventional, but it works for me. We were all trained that low ISO is the goal, but the R5, IMHO, is an exception to that rule. I've been using high ISO settings since the 5D mark IV, so I'm used to taking advantage of it and frankly, don't see it as a "workaround" in low light. I've seen some shots on this forum from the people that are using the 1D X mark III with some really outrageous ISO settings, even with their f/2ish primes for sports, and they look really good. I'm sure they denoise to some extent, but the point is, high ISO shouldn't be feared with these newer camers, IMHO. I think if you bump up that ISO you will be happy with the results. This lens is fairly sharp at at f/7 but if you bump up the ISO and get it into the f/8 to f/16 range, it's hard to beat.

This Tufted Titmouse was shot at dusk. EOS R5, RF 100-500, f/7, 1/500th, ISO 4000. No post NR and NR in camer is at its default setting. Edited in DPP 4 and cropped for forum. I was approximately 35 feet away.

Same bird and settings cropped in closer.

Yellow-throated Warbler shot under the same conditions. EOS R5, RF 100-500mm, F/8, 1/500th, ISO 6400 (Note that I raised my ISO to get to f/8). Smaller bird (3"), but same distance. Same post settings (no NR).

Newton

[NancyMac]

Hi Newton,

Great pics and I appreciate your input.  At least I understand now why my aperture kept changing when I was in manual mode.  That was so frustrating, but it makes sense now.  Thanks for your reply  🙂 

[rs-eos · Accepted solution]

There is no workaround to the aperture setting itself.  As you move closer and closer to the 500mm range, the minimum aperture will indeed change.  Lens manufacturer's create such variable-aperture lenses to lower the cost as well as typically lowering the weight of the lens.

Thus, correct in that you'll need to find ways to compensate such as raising ISO and/or slowing the shutter if that's doable.

In terms of another lens option, I'll let others weigh in as the only zoom lens I have is for my cinema camera (an RF 24-70mm f/2.8).  For my DSLR, I only have two prime lenses.   Thus, I cannot readily recommend zoom lenses in your desired focal length range. 

[NancyMac]

Hi Ricky,

Thanks for the info.  I LOVED my 24-70mm / 2.8.... It's non repairable now.  It has an sensor error issue and apparently is "too old" for servicing.  Oh well.  I found a work around today by raising the ISO or decreasing the shutter and I just started off at 7.1 to avoid having the lens shift on me unexpectedly.  So thanks for explaining it to me.  I had it happen to me in the Tetons also and someone told me that it was due to a low battery issue.  Then today my battery was fully charged and so I thought I had messed up a setting or something.  Then I put it in AV at 4.5 and it was changing and I was very perplexed!!  So thanks again!  LOVE the lens / camera combo and the focus is so sharp.  Not a huge fan of it changing on me (was used to the 2.8 - 70-200) so on the learning curve now.  Thanks again.  Stay well.  Nancy

[unclejace54]

You could try using the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens with an EF to RF adapter. You still have aperture shift but it's a faster lens. You lose the 500mm focal length too. It would be more expensive I believe.