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-   -   Is canon the only maker of EF-S (short back focus) lense? (http://www.velocityreviews.com/forums/t605258-is-canon-the-only-maker-of-ef-s-short-back-focus-lense.html)

peter 04-12-2008 03:49 PM

Is canon the only maker of EF-S (short back focus) lense?
 
If I understand correctly, a short back focus lense does not need to bend
light as much to achieve a wide angle lense. And the less you have to bend
light, the better quality/cheaper the lense is.

Is canon DSLRs the only ones that supports short back focus lense?

If yes, does that give canon an advantage in wide angle lenses for non full
frame sensor DSLR?



Doug Jewell 04-12-2008 09:02 PM

Re: Is canon the only maker of EF-S (short back focus) lense?
 
peter wrote:
> If I understand correctly, a short back focus lense does not need to bend
> light as much to achieve a wide angle lense. And the less you have to bend
> light, the better quality/cheaper the lense is.

But at the same time, if you have a short back-focus lens,
the light is hitting the sensor at a greater angle from the
vertical, and therefore more prone to fall-off.
>
> Is canon DSLRs the only ones that supports short back focus lense?

Also Olympus.
>
> If yes, does that give canon an advantage in wide angle lenses for non full
> frame sensor DSLR?

I guess to answer that question you need to look at
available lenses and reviews of them.
Canon only offer 1 lens wider than 17mm in EF-S (the 10-22).
All other lenses in the canon line-up that are shorter than
17mm are EF lenses, so don't offer the short backfocus.

In a few side-by-side comparisons between the Canon 10-22 vs
the Sigma 10-20, the cheaper sigma usually comes out on par
with, or even slightly better, than the Canon lens. The
sigma is available for all major platforms, and isn't
short-backfocus. This is probably about the only meaningful
comparison of a short-backfocus lens vs a regular lens, and
it would appear Canon gain no benefit from it.

If you are a name-brand bigot and refuse to put any third
party lenses on your camera, you will find a better range of
wide and ultra-wide lenses bearing Nikon and Pentax badges
than you will find in Canon. Although they are designed for
the smaller digital sensors, these lenses have regular
backfocus lengths.

In the standard kit 18-50'ish range, the Canon (which is the
only short back-focus model) is reviewed as pretty much the
worst of the bad bunch.

So I would conclude then that Canon gain absolutely no
advantage by having the short backfocus. And if ultra-wide
in crop-sensor DSLR is your thing, then Canon has the
poorest range of lenses available.
>
>


Jufi 04-15-2008 11:32 AM

Re: Is canon the only maker of EF-S (short back focus) lense?
 

"Doug Jewell" <ask@and.maybe.ill.tell.you> wrote in message
news:48012383$0$14284$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
> peter wrote:
>> If I understand correctly, a short back focus lense does not need to bend
>> light as much to achieve a wide angle lense. And the less you have to
>> bend light, the better quality/cheaper the lense is.

> But at the same time, if you have a short back-focus lens, the light is
> hitting the sensor at a greater angle from the vertical, and therefore
> more prone to fall-off.
>>
>> Is canon DSLRs the only ones that supports short back focus lense?

> Also Olympus.
>>
>> If yes, does that give canon an advantage in wide angle lenses for non
>> full frame sensor DSLR?

> I guess to answer that question you need to look at available lenses and
> reviews of them.
> Canon only offer 1 lens wider than 17mm in EF-S (the 10-22). All other
> lenses in the canon line-up that are shorter than 17mm are EF lenses, so
> don't offer the short backfocus.
>
> In a few side-by-side comparisons between the Canon 10-22 vs the Sigma
> 10-20, the cheaper sigma usually comes out on par with, or even slightly
> better, than the Canon lens. The sigma is available for all major
> platforms, and isn't short-backfocus. This is probably about the only
> meaningful comparison of a short-backfocus lens vs a regular lens, and it
> would appear Canon gain no benefit from it.
>
> If you are a name-brand bigot and refuse to put any third party lenses on
> your camera, you will find a better range of wide and ultra-wide lenses
> bearing Nikon and Pentax badges than you will find in Canon. Although they
> are designed for the smaller digital sensors, these lenses have regular
> backfocus lengths.
>
> In the standard kit 18-50'ish range, the Canon (which is the only short
> back-focus model) is reviewed as pretty much the worst of the bad bunch.


The old one, yes. The newer IS version is very good. Still the same build
quality, but very sharp.

>
> So I would conclude then that Canon gain absolutely no advantage by having
> the short backfocus. And if ultra-wide in crop-sensor DSLR is your thing,
> then Canon has the poorest range of lenses available.
>>



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