Is there something wrong with this RF lens?

[stevejamesbishop@g]

HI all,

I have an my RF 24-105 f4 for about 6 months. I have noticed smeary corners in photos from time to time, but just put it down to camera shake (although I shoot mostly on a tripod). I decided to print out a big focus chart and test my lenses.

To me it looks like the top and especially top right have ghosting issues. It's worse at 50mm than at wide open. Even on f8 it's ghosting a lot compared to the left bottom corner. This image is f8 at 50mm, where it appears worse (also bad at around 35mm). It's a little cleaner at 24 and 105mm.

Here's a link to the full size image: https://ibb.co/QQP4HmT

 

[dwarven]

The corners look fine to me, but I don't usually care about corners anyway. I've found most perceived defects in gear are almost always due to user error rather than actually having a defective item from the factory. I trust Canon's QC and manufacturing processes more than my own eyes lol. It could also be that you just had higher expectations for the lens. It wasn't too long ago that most lenses were smooshy all the way down to f/8. Being able to shoot a lens wide open and have it be sharp edge to edge is a very new thing.

edit:
After downloading your full res image, yeah, the corners are as sharp as you'll get with that lens. They look completely fine. The top right looks a little softer most likely because of inconsistent lighting or because it looks like the paper is crinkled and uneven. If I had this lens in my high school photography class several years ago, the instructor would have wondered whether or not I was a magician.

 

[stevejamesbishop@g]

Thanks for taking a look. The top right being soft was what I kept noticing in my images, and lead to the test so I think the top right is softer rather than it being just on that image. I guess it's not worth sending back to Canon then if its always like this?

I think I need to buy a decent prime lens then. I'm getting into artwork reproduction and the corners of the frame are near the edges of the paintings, and you can really see if they are blurry or not!

 

[dwarven]

Thanks for taking a look. The top right being soft was what I kept noticing in my images, and lead to the test so I think the top right is softer rather than it being just on that image. I guess it's not worth sending back to Canon then if its always like this?

I think I need to buy a decent prime lens then. I'm getting into artwork reproduction and the corners of the frame are near the edges of the paintings, and you can really see if they are blurry or not!

If you absolutely need pristine, edge to edge sharpness I think the RF 50mm f/1.2 is going to be your best bet. It's one of the sharpest lenses money can buy right now.

 

[stevejamesbishop@g]

If you absolutely need pristine, edge to edge sharpness I think the RF 50mm f/1.2 is going to be your best bet. It's one of the sharpest lenses money can buy right now.

Thanks for the recommendation. Due to the nature of art reproduction and printing fairly large format, edge sharpness is really important. I have a Canon EF 35mm f2 and it's so much sharper than the £1200 RF 24-105 zoom lens. Even my EF 15-35 f4 is slightly sharper than the RF lens, which is disappointing. The 35mm is sharp enough for what I need (at my level) but I need a 50mm really (85mm is too much). I've read about the Sigma 50mm Art lens that seems to get good reviews. I'm literally needing a super sharp to the edge 50mm lens for shooting pretty much only at f8 100% of the time. Have you had experience with this lens?

 

[Maximilian]

... I need a 50mm really (85mm is too much). I've read about the Sigma 50mm Art lens that seems to get good reviews. I'm literally needing a super sharp to the edge 50mm lens for shooting pretty much only at f8 100% of the time. Have you had experience with this lens?

Hi Steve.

If you have such detailled expectations for your purposes, best to take a look at TDPs lens comparison tools.
I've selected a EF35 IS vs. Sigma Art 50 mm at f/8 comparison for you. To me the Sigma seems to perform even better at the edges.
Just for fun I also compared the EF35 IS to the RF50 STM as well. At f/8 I cannot find much to complain about this 50. Wide open of course you can see its weaknesses.
If you play with that tools, please keep in mind

• to compare lens with bodies with similar sensor size and resolution
• to compare at the same aperture and
• that a lens is more than just center and corner sharpness.

I hope that can help you with your decission.

 

[dwarven]

Thanks for the recommendation. Due to the nature of art reproduction and printing fairly large format, edge sharpness is really important. I have a Canon EF 35mm f2 and it's so much sharper than the £1200 RF 24-105 zoom lens. Even my EF 15-35 f4 is slightly sharper than the RF lens, which is disappointing. The 35mm is sharp enough for what I need (at my level) but I need a 50mm really (85mm is too much). I've read about the Sigma 50mm Art lens that seems to get good reviews. I'm literally needing a super sharp to the edge 50mm lens for shooting pretty much only at f8 100% of the time. Have you had experience with this lens?

If you can’t afford the RF 50 f/1.2 (I certainly can’t), then yeah I’d get the Sigma. Haven’t used that specific lens, but I have used many other Sigma EF lenses and they have all been phenomenal.

 

[stevejamesbishop@g]

Hi Steve.

If you have such detailled expectations for your purposes, best to take a look at TDPs lens comparison tools.
I've selected a EF35 IS vs. Sigma Art 50 mm at f/8 comparison for you. To me the Sigma seems to perform even better at the edges.
Just for fun I also compared the EF35 IS to the RF50 STM as well. At f/8 I cannot find much to complain about this 50. Wide open of course you can see its weaknesses.
If you play with that tools, please keep in mind

• to compare lens with bodies with similar sensor size and resolution
• to compare at the same aperture and
• that a lens is more than just center and corner sharpness.

I hope that can help you with your decission.

Hi Maximilian,
Thanks a lot for the link to that website. I didn't know about it before. IT's really helpful.
Although did you mean the wide open weakness for the RF 50mm or Sigma? Comparing the 50 Sigma and 50 RF, the Sigma is the one that looks like it has quite apparent weaknesses wide open. The Canon is surprisingly good at f1.2! No wonder it costs a lot...

 

[stevejamesbishop@g]

If you can’t afford the RF 50 f/1.2 (I certainly can’t), then yeah I’d get the Sigma. Haven’t used that specific lens, but I have used many other Sigma EF lenses and they have all been phenomenal.

Ok that's good to know! With regards to my £500 EF 35mm f2 lens being a lot sharper than my £1200 RF 24-105 f4 lens. Is that just the nature of prime lenses even if they cost a lot less? It make me dubious of people saying the £3200 RF 28-70 behemoth 'replacing all of their primes its so sharp'. Surely it can't be.

 

[Maximilian]

Hi Maximilian,
Thanks a lot for the link to that website. I didn't know about it before. IT's really helpful.

Good to know I could help

Although did you mean the wide open weakness for the RF 50mm or Sigma? Comparing the 50 Sigma and 50 RF, the Sigma is the one that looks like it has quite apparent weaknesses wide open. The Canon is surprisingly good at f1.2! No wonder it costs a lot...

I was talking about the weaknesses of the cheapo RF50 STM. Of course the RF50L is playing in a different league.
And even the Sigma is getting weaker and a little bit blurry at f/1.4.
But hey! f/1.4 is a really wide aperture. You will always have some tradeoffs gathering so much light.

I only wanted to show, that stopping down to f/5.6 or f/8 is making a cheapo lens like the 50 STMs quite respectable - either the RF and the EF.
Of course color rendering, contrast and aberation are things that are more to the Sig Art or the L lenses.

 

[Del Paso]

If you are into art-reproduction, I wouldn't suggest a wide-angle, a zoom or even the RF 1,2/50, but rather a flat-field optimized macro, like an adapted EF 2,8/50 TSE macro.
Absolutely corner-sharp!
Or, for far less money, the Zeiss Macro Planar 50mm f2, you could get a used one for less than 500...