Steve's Digicams Forums

Steve's Digicams Forums (
-   Canon Lenses (
-   -   Tweaking the 24-70 L for 300D (

fsm2i Feb 16, 2004 9:38 AM

Tweaking the 24-70 L for 300D
I bought the 24-70 L as an all around lens and have found it softer than I expected, especially for further away shots. Before buying the lens, I read some reviews which had mentioned the same problem but since the vast majority of reviews waxed on about sharpness, color, contrast, etc. I bought it anyway. While the color and contrast are certainly better than anything I have, sharpness has been disappointing, even if stopped down.

Has anyone had the same experience? Any suggestions on tweaking the auto settings for more consistent sharpness especially at distance (100 yards away and further)?

tuthill Feb 17, 2004 1:45 PM

I too haven't been as enthralled with my 24-70's sharpness as I thought I'd be. Up to now, I suspect that operator error is the culprit but I'll have to see. I see improvements at f4 and above, just not what I'd expected. I think the focusing is a little off as well, but that's probably the digirebel itself. I'm still wanting to also get a 70-200 2.8 IS L but may consider the Sigma 2.8 instead. Less than half the money, same speed but no IS. gary

ohenry Feb 17, 2004 1:55 PM

What parameters are you shooting when you experience "soft" focus? Are you shooting jpg format? Shutter speed? Aperture? ISO? How are you viewing the pictures? Is your monitor crisp normally? Are you printing them out? What camera are you using and what parameters do you have set in the default? Are you using a tripod or handholding the camera?

tuthill Feb 17, 2004 6:43 PM

Whew, from your post ohenry, I'm even more leaning towards operator error. Parameter-wise, I'm at zero (I think). Format is jpeg fine. Shuttter speed has varied quite a bit. When shooting low light/pool swim meets I've been using high speed sync with my 420EX. I've learned from an earlier post that that's been wrong. I see I need to use the regular setting on the flash and the camera's inherent 1/200 second x-sync time. I (my son's) next meet is on Saturday and I'm going to try using that setting and see what happens. My monitor is a Gateway 19" LCD and seems 'crisp' normally. The camera is a digitalrebel. Finally, I'm handholding the camera. I'm not the steadiest person so perhaps a monopod would be benificial? gary

fsm2i Feb 17, 2004 6:46 PM

24-70 L
I have tested the camera under Parameter 1 and different Set up modes experimenting with different combinations of sharpness, color, etc. I have also experimented with differented ISO settings as I have found daytime photos too dark compared to my 18-55, 55-200 and 24-85 (the 24-85 I have since sold). I have also compared all of these lenses using a tripod and with different aperture settings.

So far, I have found that the 55-200 beats the 24-70L for sharpness almost every time. The 24-70 usually wins on color and contrast.

In closer shots--within say 10 feet away--the 24-70 beats the 18-55, but I often have to look really hard at the photos to see a difference. (I view the photos on my laptop's monitors and a separate home monitor.) On portrait photos with flash, the 24-70 L is sharper but I have to be careful to shoot at 35MM or longer as the barrel's shadow appears at wider settings.

However, my $70.00 50mm f/1.8 blows all these lenses away without even trying (meaning I leave it in "P" mode, on normal parameters and don't have to fuss with it at all.)

On wide angle shots, I have not been able to tell any big difference between the 24-70 and the 18-55, although I have to admit I need more testing.

Recently, I thought about comparing photos of 24-70L at ISO 100 versus ISO 200 during bright days. The 24-70 L comes off sometimes as too dark so I figured maybe some light is lost--it is a pretty big barrel--and increased sensitivity should help. I tried this in a limited basis the other day and have found some differences. For one thing, photos stopped at f/6, 8, and 10 are consistently sharper under ISO 200 than ISO 100. Also, the ISO 200 photos were a little brighter without any obvious increase in noise. Still, I have to do more controlled comparisons on a warmer day (it's winter here and I could only stand to be out in the cold for a few minutes so my photos were ad hoc.)

I have yet to really test the camera in the day time within 10-20 feet.

Any thoughts?

fsm2i Feb 17, 2004 6:52 PM

24-70 L additional note
I have noticed in my comparisions in auto mode (P), the 24-70 L consistently shoots at a wide stop differencential, ie photos taken on the 55-200 would be automatically shot at f/10 or f/11. The 24-70 L at the same distance setting--say 55mm--would consistently take the shots at f/8 or f/9. (All else is equal--parameters, ISO at 100, etc.)

I tried to compensate by manually adjusting the aperture, but it gets tedious and the results were also not much different. Lately I tried the same experiment at ISO 200 for the 24-70 (while keeping the 55-200 at ISO 100) and achieved a little bit of an improvement.

ohenry Feb 17, 2004 7:49 PM

Tuthill, shooting jpg you should probably have your parameters set at either 1 or 2 with sRGB or even custom if you want the pictures even sharper, more saturated, or more contrast. I shoot RAW / Adobe RGB and adjust saturation and contrast outside of the camera, so I'm not adept at which parameters do's in the manual. And a tripod/monopod is always helpful, especially when hand holding the lens at slower shutter speeds.

fsm, your issues are a bit more complicated. I don't have the lenses you have, but I do have the 70-200 L and it is incredibly sharp. Since you're comparing lenses, I can only assume that you're not changing settings between lenses so that rules out a bunch of problems. It sounds like you are consistantly seeing softer focus on the L lens than your other lenses and that would seem to indicate a problem. I can only suggest that you take your camera and lens into a camera shop (not BestBuy!) and have them check it out. If you can take in samples showing the problems you're experiencing, I'm sure they can help you figure out the problem. It could be that you have a bad lens or something simple that you're overlooking. Let us know what you find out.

fsm2i Feb 17, 2004 11:32 PM

Thanks for the suggestion OHenry. I may take it to the shop. However, if you like, I can take some photos this weekend and drop them into my website at pbase and you can see for yourself.

I am starting to come to the conclusion that the 24-70 L is just not ideal for the 300D.

It's like with hunting--I hunt--certain rifles like certain types of ammo. My Marlin 45- 70, for example shoots better (at least when I am shooting it) with Remington 45-70 ammo than with Winchester 45-70 ammo even though they are essentially the same. This is not uncommon with shooting. You need to match the rifle with the ammo it likes.

In the same vein, I think you need to match the lens with the camera. I think the 18-55 and the 55-200 were made for the Digital Rebel, while I believe the 24-70 L was made for other cameras, especially film. I could be wrong, but this is the view I am starting to come to. (I got the same sense with the 24-85 which I sold.)

barthold Feb 17, 2004 11:44 PM

The 24-70L is considered the best zoom lens there is. Yes, some primes will be even better, but hey, they are primes :-)

It is always possible the lens and camera combination are out of sync, resulting in out of focus (soft) images. To test this, take several shots, on a tripod (!), with a remote shutter release (or if you don't have that with the self timer) in good day light of the same subject at the same distance at different zoom factors. You can also repeat it with the same subject at different distances, at a fixed zoom. Do use the F2.8 aperture in Av mode to get the smallest DOF.

Examine the pictures and let us know. I'm curious to see the results! If those pictures are fine, then it is most likely 'user error'.


You can look on for more information on the 24-70L .Here's just one link:

From reading the forum it seems that some people experience incorrect AF at infinity and/or too soft pictures at F2.8 at the long end (70mm). But you will typically read more complaints than positive experiences in such a forum, thus drawing the conclusion that the 24-70L is a 'bad' lens is incorrect.


fsm2i Feb 18, 2004 11:20 PM

24-70 L
Thanks Barthold. I'll test it again the way you detailed and will post the photos on my pbase site. Will update maybe by late next week.

All times are GMT -5. The time now is 10:51 PM.