cheap AF-S 55-250 STM sharper than L series AF 70-300 USM

[faustino]

It seems, from the eyes of a 18 megapixel crop sensor, that cheap lenses designed for crop sensor are sharper than L series lenses designed for full frame cameras; I am getting to such a conclusion looking a the comparison from the link below:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=856&Camera=736&Sample=0&FLI=4&API=1&LensComp=738&CameraComp=736&SampleComp=0&FLIComp=3&APIComp=2

I understand there are other lens characteristics beside sharpness; in this specific case, on vignetting and distortion fields, the full frame lens wins hands down. Without mentioning flare, transmission, and the focus motor. If the plastic lens has a motor that can focus, in proportion, the USM lens has a motor that could move a truck.

Anyhow, it seems that to a crop sensor body, I would better couple an sf-s lens, rather than the full frame lens I already own. I would both reduce my bag weight, and get "better" image quality (somewhat).

 

[ajfotofilmagem]

Yes, on a APS-C body 18 (or 20) megapixel, a lens EF-S high quality can result in greater clarity that some L series lenses Indeed, other factors such as vignetting, geometric distortion, light transmission, can not follow the best sharpness. If you consider the price and weight, Canon 55-250 STM is an excellent choice for APS-C cameras. Obviously, L lenses have durability, weather sealed, etc, but they really shine on a full frame body.

 

[bholliman]

Interesting. I knew the 55-250 STM was good, but surprised it's sharper than a well respected L that cost 3x more.

I also compared it to the 70-200 f/2.8 II and the STM appears sharper at the corners, and only very slightly less sharp in the center and mid-frame. Very surprising. I will start recommending the 55-250 STM even more strongly than I have been to people looking for a APS-C tele zoom.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=856&Camera=736&FLI=4&API=1&LensComp=687&Sample=0&SampleComp=0&CameraComp=736&FLIComp=0&APIComp=0

 

[faustino]

It seems that, by designing lenses that cover a smaller image circle, just sufficient for APS-C sensors, Canon was able to increase sharpness.
I am wandering if they could further improve sharpness by designing pro APS-C lenses in super-telephoto focal length range (lets say 200-400mm).

I know the "reach advantage" of APS-C bodies is a myth based on wrong understandings. Anyhow, if Canon could further increase sharpness designing pro APS-C dedicated lenses, then the "reach advantage" could actually take a real life; don't you think so?

 

[faustino]

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=856&Camera=736&FLI=4&API=1&LensComp=687&Sample=0&SampleComp=0&CameraComp=736&FLIComp=0&APIComp=0

The only problem with the comparison above is that it is not at the same aperture. The 55-250 is at f/5.6, while the 70-200 is at f2.8. Closing the 70-200 to f5.6, the image seems to get sharper than the 55-250, but just a little bit.

 

[bholliman]

The only problem with the comparison above is that it is not at the same aperture. The 55-250 is at f/5.6, while the 70-200 is at f2.8. Closing the 70-200 to f5.6, the image seems to get sharper than the 55-250, but just a little bit.

Sorry, I must have copied the URL before I changed the aperture for the 70-200. With both at f/5.6 the 55-250 looks a little sharper to me at the corners and very close at mid frame. I'd give the 70-200 a slight edge in the center. This is very surprising. I took the comparisons a little further and compared the 55-250 to two of the best primes in that range, the 135 f/2L and 200 f/2 L. To me the EF-S zoom looks a little better than the highly regarded 135mm f/2 L at f5.6 and even holds its ground against the legendary 200 f/2 L (a lens that cost 17x more) at that aperture.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=856&Camera=736&Sample=0&FLI=4&API=1&LensComp=458&CameraComp=736&SampleComp=0&FLIComp=0&APIComp=4

Of course, these f/2 and f/2.8 lenses are much faster and have L build quality. But, my conclusion is that the EF-S 55-250 STM is a terrific lens for the money.

 

[Mt Spokane Photography]

How sharp is it at f/4? F/2.8?
What you get for all those $$ are wide apertures and better construction. Sharpness (whatever that is) must be nice.

 

[faustino]

How sharp is it at f/4? F/2.8?

Do you really think we didn't thought about that?
8)


The comparison is between the 70-300 L and the 55-250. I believe it is surprising that the 55-250 is sharper at equal apertures and focal length, I really would like to understand why it is the case. Do you know why the 70-300 L is not as sharp as the lightweight 55-250 STM?

 

[Loswr]

Do you know why the 70-300 L is not as sharp as the lightweight 55-250 STM?

For many lens types, designing a lens for a smaller image circle is easier - lenses can be made at lower cost that deliver as good or better optical results. The 17-55/2.8 is a fast lens that's also optically superior to many L-series lenses (note that made at lower cost ≠ sold at lower cost!), when compared on the same crop body.

The 55-250 is probably at the edge of where a lens with a smaller image circle can benefit. For the most part, telephoto designs do not benefit from a smaller image circle (note that the 50-250 is not a true telephoto lens design).

Also, note that the combination of a the L lens with a FF body is much sharper. You can see that when you compare the approximately equivalent (in terms of framing and DoF) 60D + 55-250 @ 200mm f/5.6 to the 1DsIII + 70-300L @ 300mm f/8 (link).

 

[faustino]

For the most part, telephoto designs do not benefit from a smaller image circle (note that the 50-250 is not a true telephoto lens design).

Thank you! This is the information I was looking for. I still don't understand why telephoto designs do not benefit from a smaller image circle, but most probably such understanding would require too much technical know how in optics (maybe it is due to the fact that, for telephoto lenses, front elements are the "optical bottleneck").

Also, note that the combination of a the L lens with a FF body is much sharper.

Yes it is clear. The reasons for this are also quite easy to understand.
Thanks.

 

[KeithBreazeal]

Interesting lens. I ran it up against the 24-105L and they are almost identical. I was looking for something light weight for hikes or a lens for the "to go bag". I bought a SL-1 for my pole cam and that little camera is actually quite impressive. Maybe the 55-250 might just do it. The price is right, that's for sure.