Why do fast primes not have IS?

[Maximilian]

I will try to make an approach, as far as I can handle your question:
IS (Canon) is a moving optical element inside the lens.
http://en.wikipedia.org/wiki/Image_stabilization
To work properly it has to move fast and accurate. To be fast it has to be of low weight.

Fast apertures need a larger image circle over the whole optics compared to narrow apertures.
Therefore the optical elements of the IS should be larger as well. This leads to higher weight which causes loss of speed and higher energy consumption and also to higher prices because of the more expensive optics.
So with IS Canon always compromises between functionality of the IS and useful max. aperture.

This is my conclusion. Maybe someone else can do better.

Superteles with IS have large elements.

Weight and energy consumption should therefore be even greater, per your explanation.

Does the larger housing of the superteles provide more space for the mechanism that moves the elements?

Comments?

Hi Larry!
Superteles have larger FRONT elements and other lager non moving optical elements in their design.
The IS is normaly set at a point where the image circle is very small.
Maybe you are right, that the IS element in the big whites is bigger than inside the 70-200 for example.
But maybe this is also one important reason for the much higher price.

 

[Maximilian]

http://en.wikipedia.org/wiki/Image_stabilization

I also think that there is a degradation that comes with thee things and the companies that are making fast primes are generally going for the best MTF curve they can get. So putting the IS gizmo in there costs them some performance in that regard. Zooms are always a compromise so for those it doesn't matter as much (and they are already big and heavy).

Of course you are right!
I forgot to mention it directly but it was included in the wikipedia article.
I think this degradation is an issue you can handle by QC and higher quality and prices for the IS element.
See the 24-70 IS L II or the 70-200 IS L II. edit: Sorry! Made a mistake!

 

[rs]

See the 24-70 IS L II or the 70-200 IS L II.

I though we're still on the first version of that f4 lens? :

 

[Maximilian]

See the 24-70 IS L II or the 70-200 IS L II.

I though we're still on the first version of that f4 lens? :

touche! :-[
I was dreaming about the EF 24-70mm 2.8L II USM having IS.
Thank you for leting me correct this.

 

[Grumbaki]

By the way, there are *some* fast primes with IS - e.g. Sony makes some 1.8 APS-C e-mount primes that have it (35mm & 50mm; maybe others).

1.8 ASP-C is not really fast glass...

 

[AvTvM]

With FF mirrorless cameras taking over some time soon (I hope ), in-lens IS loses one of it's two advantages over in-body IS: on an EVF, viewfinder image will be stabilized, irrespective of whether IS is implemented in-lens, in-body .. or even in a dual/hybrid way using both. [Second advantage for in-lens IS being the fact that it's specifically tailored to match a specific lens ... and I do not believe this holds much truth any longer against todays in-body IS systems)

So while Canon (and Nikon) had a major advantage with their in-lens IS approach during the (D)SLR era, this is coming to an end.

Personally, I would prefer a Canon FF mirrorless system, of course with new, native, short flange-distance lens mount. Ideally with in-body IS, and lenses without any manual focus gears, only "by-wire" in a really well-implemented fashion. Zoom also "by wire". Either turning rings on lenses or really good, highly ergonomical control points on camera body. Ideally also with non-mechanical aperture ... think of something like a variable, highly transmissive LCD with a perfectly round aperture opening at all openings .. also implemented in body, rather than in evry lens.

To complete my vision of future "solid state" mechanics-free FF-sensored cameras, shutter would be fully electronic.

If the in-body IS could be extended to "6 axis", i.e. adding linear movement in the Z-axis [current 5-axis systems (Oly) allow linear and rotational moves in the X and Y axis and rotational moves around the Z axis] ... then focussing could possibly also take place in the body, without any moving lens elements. With proper lens construction, that is.

This would possibly allow for camera/lens systems with significantly smaller, lighter, simpler, more robust, fully weathersealed, higher IQ [only needs to be adjusted/centered once before leaving factory] lenses ... at significantly lower production cost ... and hopefully prices. 8)

Not sure however, whether I'll live long enough to get it from Canon.


Meanwhile I do expect Canon to come up with in-lens IS in fast primes as well. 50/1.4, 50/1.8, 85/1.8 + 100/2.0 are all very old lens designs and in need of a major overhaul, with the same treatment Canon gave the 24/28/35 IS primes. Not only IS and (corner) sharpness, but also less (lonigtudinal) CAs, please.

 

[GMCPhotographics]

I have a 400mm f2.8 LIS. It's a fast prime and it's got an image stabiliser.
I have a 24mm f1.4 L, it doesn't need and IS unit because it can be shot hand held at 1/25th second easily and due to it's huge light gathering capabilities, it can shoot at light levels several stops below what an f2.8 lens can achieve. So what could an Is offer a 24mm f1.4? Very little.

 

[AvTvM]

I have a 400mm f2.8 LIS. It's a fast prime and it's got an image stabiliser.
I have a 24mm f1.4 L, it doesn't need and IS unit because it can be shot hand held at 1/25th second easily and due to it's huge light gathering capabilities, it can shoot at light levels several stops below what an f2.8 lens can achieve. So what could an Is offer a 24mm f1.4? Very little.

2 stops [2.8 - 2.0 - 1.4] ... to be precise. ;D

IS would not hurt, even on f/1.4 lenses. Not everyone shoots them fully open ALL the time. Sometimes a bit more DOF is desirable. Or 2 stops closed (f/2.8) for IQ. etc.

 

[endiendo]

I think people want absolutely IS, but don't know why..

Cameras have good higher and higher ISO..
Very good lens have a lot of light...

-> you can have enough light for fast speeds (> 1/100 or 150)... So why do we bother for IS....
I was useful when camera couldn't go (good) over ISO400.. but know, IS is more and more useless.

I see utility only for long lenses.

 

[GMCPhotographics]

I have a 400mm f2.8 LIS. It's a fast prime and it's got an image stabiliser.
I have a 24mm f1.4 L, it doesn't need and IS unit because it can be shot hand held at 1/25th second easily and due to it's huge light gathering capabilities, it can shoot at light levels several stops below what an f2.8 lens can achieve. So what could an Is offer a 24mm f1.4? Very little.

2 stops [2.8 - 2.0 - 1.4] ... to be precise. ;D

IS would not hurt, even on f/1.4 lenses. Not everyone shoots them fully open ALL the time. Sometimes a bit more DOF is desirable. Or 2 stops closed (f/2.8) for IQ. etc.

If i wanted sharp stopped down photos I'd use a 24-70IIL.
An is usint would only degrade IQ at f1.4 by introducing extra glass elements into the lens forumla. I was my farst primes as sharp as possible wide open....if not then there's little point to it. if you are going to stop down, then there's no need for a bag od heavy fast primes...a 16-35 and a 24-70 would be lighter, more versatile and cheaper.

 

[GMCPhotographics]

2 stops [2.8 - 2.0 - 1.4] ... to be precise. ;D

Ok, hair splitter....several means more than one...
2 Stops is more than 6 clicks on a dial. It bumps shutter speed to x4 at teh same iso, which is a huge benefit.
So lets take an exposure of f1.4 @ iso 6400 @ f1/25th. at f2.8, I would get a shutter speed of 1/6th of a second....pretty slow.

I shot a wedding by candle light in a church crypt a few years back...f2.8 just wasn't possible. but due to f1.4 and f1.2 glass, I could get shutter speeds of 1/50th and 1/100th second at ios 6400. No flashes were allowed and during the service, shutter speeds of less than 1/50th would have been riddeled with motion blur by the targets in the photos.

 

[Maximilian]

I think people want absolutely IS, but don't know why..

Hi endiendo!

I could also live without IS (most of the time) and so I can understand your opinion.
But if useful tech is available at a reasonable price, size and weight, why avoid it?

I can remember a picture I took of a young Siberian tiger in really dim light at the zoo.
It was at ISO 3200, 400 mm and 1/20 s, handheld.
I still don't know how I and/or the IS could manage to get it quite sharp.
But I am sure that it was not my (non existing) sniper ability but more to the IS.

 

[GMCPhotographics]

I think people want absolutely IS, but don't know why..

Hi endiendo!

I could also live without IS (most of the time) and so I can understand your opinion.
But if useful tech is available at a reasonable price, size and weight, why avoid it?

I can remember a picture I took of a young Siberian tiger in really dim light at the zoo.
It was at ISO 3200, 400 mm and 1/20 s, handheld.
I still don't know how I and/or the IS could manage to get it quite sharp.
But I am sure that it was not my (non existing) sniper ability but more to the IS.

Which again shows that the IS merit is stronger at the longer focal lengths and less so for the wider focal lengths.

 

[AvTvM]

yes, agreed.

I've sold my 2 "fast" primes [50/1.4, 100/2.0] recently and rely solely on my f/2.8 workhorse Zooms [17-55, 70-22 II]. Occasionally I do like the capability for shallow(er) DOF (on APS-C), but got sick and tired of the very high amounts of loCA (bokeh fringing; purple/green) of these old lens designs ... and am not prepared to shell out a grand or more for optically better fast primes [L].
IF I move to FF and stick with Canon, I'll definitely get the 24-70 2.8 II as well. Although IS would really be welcome on that one, too!

 

[Maximilian]

Which again shows that the IS merit is stronger at the longer focal lengths and less so for the wider focal lengths.

I totally agree.
And If I had enough money for the 24-70L 2.8 II then I would preferably take this one instead of its prototype brother with IS because of size and weight.

 

[aznable]

yes, agreed.

I've sold my 2 "fast" primes [50/1.4, 100/2.0] recently and rely solely on my f/2.8 workhorse Zooms [17-55, 70-22 II]. Occasionally I do like the capability for shallow(er) DOF (on APS-C), but got sick and tired of the very high amounts of loCA (bokeh fringing; purple/green) of these old lens designs ... and am not prepared to shell out a grand or more for optically better fast primes [L].

 

[AvTvM]

And If I had enough money for the 24-70L 2.8 II then I would preferably take this one instead of its prototype brother with IS because of size and weight.

urban legend ... just look at the difference in size and weight between EF 70-200/4 L vs. 70-200/4 L IS ... identical in size, 55 grams more weight. And ... even better IQ for the IS version.

4 L ... 76x172mm - 705g
4 L IS ... 76x172mm - 760g

Other than for Super-Teles with huge glass elements, in-lens IS units are quite light, compact do not add a lot of production cost ... although it may add a lot on retail prices. ;-)

 

[Maximilian]

And If I had enough money for the 24-70L 2.8 II then I would preferably take this one instead of its prototype brother with IS because of size and weight.

urban legend ...

Okay. I suppose both of us didn't have one to compare, but the "urban legends" spread here sounded reasonable.

just look at the difference in size and weight between EF 70-200/4 L vs. 70-200/4 L IS ... identical in size, 55 grams more weight. And ... even better IQ for the IS version.

4 L ... 76x172mm - 705g
4 L IS ... 76x172mm - 760g

here you are right.
But if you compare the unequal 17-40/4 L to the 16-35/4 L IS it looks different.

So I would extend my statement to "... instead of its prototype brother with IS because of its expecteted bigger size and weight. Otherwise I would take an IS version, if it's not too expensive and does not lose too much IQ."
More precise now?

 

[GMCPhotographics]

There is an upward trend in weight with the L lenses. I'm ignoring the newer mkII super tele's here. But generally there is an upwards trend. The mkII 70-200 f2.8 LIS is heavier, the 16-35 f4 LIS is heavier and larger than the 17-40L. While the newer 24-70IIL is lighter and smaller, it's a different optical design and the old one was over engineered for sure.
The 70-200 f4 LIS vs the 70-300 LIS....that new lens is actually quite heavy compared to the old 70-200 f4 LIS. The 70-200 f4 LIS is a really sweet lens, it's so impressively light. But I don't think it's upto the ruggedness of the f2.8 version. The f2.8 version has a number of metal parts to it's casing, where as the f4 is all plastic, including where colar to which the hood fits. I'm not putting the f4 lens down, just stating a few observations about it. I think the newer and heavier L's are being built to a higher robustness and are heavier as a consequence. I don't think adding an IS unit to the formula adds much weight, but adding lots of new elements to make it sharper and then making the mechanism stronger by using more metal must increase the weight significantly.

 

[sdsr]

I think people want absolutely IS, but don't know why..

Cameras have good higher and higher ISO..
Very good lens have a lot of light...

-> you can have enough light for fast speeds (> 1/100 or 150)... So why do we bother for IS....
I was useful when camera couldn't go (good) over ISO400.. but know, IS is more and more useless.

I see utility only for long lenses.

While it's true that high ISO performance is good on newer cameras, it's still the case that image quality is better with lower ISOs (esp. if you want or need to crop, and esp. with smaller sensors); so IS/IBIS can be useful even with short, fast primes. Unless there's clear evidence that putting IS in a very fast lens reduces its image quality, I really don't understand why people object to the idea.