Making a superzoom for a compact is easy, but for a DSLR, it's hard?

Started Oct 7, 2013 | Discussions
Leandros S
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Making a superzoom for a compact is easy, but for a DSLR, it's hard?
Oct 7, 2013

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

MoreorLess
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

I'd guess a combination of smaller sensors being easer to design lenses for and compact users being much less demanding of lens performance, probably not noticing or caring about soft boarders/corners.

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yonsarh
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

That is just another excuse.  Once APS-C chip is getting cheaper, like I would say, someday it will going to be cheap as 2/3" , a better APS-C sized superzoom technology will be available in the future.  but it's just too expensive to make it for right now.

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Leandros S
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Getting to the bottom...
In reply to MoreorLess, Oct 7, 2013

MoreorLess wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

smaller sensors being easer to design lenses for

But why?

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brianj
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

I still have a film SLR camera tamron 28-300mm zoom that is huge but it worked ok when I used to use it.  Are we saying the same cannot be easily done for digital, or are we saying 300mm is not a superzoom?

Brian

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MatsP
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

It is possible to make good and sharp superzooms for all formats. They exist. Take for instance the Canon EF 28-300/3,5-5,6 L IS which is a very sharp superzoom for FF cameras. But it's heavy and expensive, around 3000$ I guess. And for APS-C cameras we have many examples. Many say that the Tamron 18-270 is sharp, and probably the best APS superzoom, but when checking reviews it's obvious that it can't match shorter zooms or primes through it's full range. So with an interchangable lens camera there are always better alternatives regarding sharpness. On a compact you have no choice, and the built-in superzoom is sharp enough for compact camera users, who from start made the choice to sacrifice some IQ for a small and versatile alternative.

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MatsP
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to MatsP, Oct 7, 2013

MatsP wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

It is possible to make good and sharp superzooms for all formats. They exist. Take for instance the Canon EF 28-300/3,5-5,6 L IS which is a very sharp superzoom for FF cameras. But it's heavy and expensive, around 3000$ I guess. And for APS-C cameras we have many examples. Many say that the Tamron 18-270 is sharp, and probably the best APS superzoom, but when checking reviews it's obvious that it can't match shorter zooms or primes through it's full range. So with an interchangable lens camera there are always better alternatives regarding sharpness. On a compact you have no choice, and the built-in superzoom is sharp enough for compact camera users, who from start made the choice to sacrifice some IQ for a small and versatile alternative.

May I add that it's not easier to construct a smaller format superzoom than one for a bigger format. It's rather a question of cost when you scale it up. A lot of glass is needed for a bigger lens, and glass is expensive. In the movie business superzomms are much used, they are designed for 35 mm film format, very sharp and smooth and extremly expensive.

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MoreorLess
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Re: Getting to the bottom...
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

smaller sensors being easer to design lenses for

But why?

A smaller sensor needs a shorter lens with a smaller image circle, these elements make it easier to design.

Again though I'd say expectation likely plays into this a lot. A superzoom for a large sensor camera will be judged by much higher standards than a superzoom compact lens.

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Leandros S
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Re: Getting to the bottom...
In reply to MoreorLess, Oct 7, 2013

MoreorLess wrote:

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

smaller sensors being easer to design lenses for

But why?

A smaller sensor needs a shorter lens with a smaller image circle, these elements make it easier to design.

I still don't find that intuitive. Other than the issue of flange distance, you should be able to scale a bridge camera design up to being an exchangeable lens, and vice versa. Added to that, miniaturising things is technically harder than making them bigger - at least in terms of R&D. At the small scale, imperfections are much more noticeable, so the glass actually needs to be higher quality.

Again though I'd say expectation likely plays into this a lot. A superzoom for a large sensor camera will be judged by much higher standards than a superzoom compact lens.

And yet, I don't hear the superzoom compact reviews droning on about sharpness. In fact, the last time I remember that complaint as referring to the glass rather than the autofocus accuracy was in an HX300V review - that being a 20MP camera!

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Leandros S
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to brianj, Oct 7, 2013

brianj wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

I still have a film SLR camera tamron 28-300mm zoom that is huge but it worked ok when I used to use it. Are we saying the same cannot be easily done for digital, or are we saying 300mm is not a superzoom?

Brian

I don't know. One hypothesis I had was that people have been getting obsessed with lenses having to start at 18mm. 18-250/270mm should be more challenging to design and build than 28-300mm, I would imagine. Fourteen-fold zoom vs. eleven-fold. I guess it's possible that 18-200mm lenses are significantly better than 18-250. I have my doubts though. In any case, 18 seems to be some kind of magical number, presumably b/c consumers tend to buy their ILC with an 18-55 or equivalent lens and want to upgrade to something that seems on the face of it to require no compromise. 18-270 does that whereas 22-300 might not (numbers for illustration only). Consumer psychology?

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Leandros S
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to MatsP, Oct 7, 2013

MatsP wrote:

MatsP wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

It is possible to make good and sharp superzooms for all formats. They exist. Take for instance the Canon EF 28-300/3,5-5,6 L IS which is a very sharp superzoom for FF cameras. But it's heavy and expensive, around 3000$ I guess. And for APS-C cameras we have many examples. Many say that the Tamron 18-270 is sharp, and probably the best APS superzoom, but when checking reviews it's obvious that it can't match shorter zooms or primes through it's full range. So with an interchangable lens camera there are always better alternatives regarding sharpness. On a compact you have no choice, and the built-in superzoom is sharp enough for compact camera users, who from start made the choice to sacrifice some IQ for a small and versatile alternative.

May I add that it's not easier to construct a smaller format superzoom than one for a bigger format. It's rather a question of cost when you scale it up. A lot of glass is needed for a bigger lens, and glass is expensive. In the movie business superzomms are much used, they are designed for 35 mm film format, very sharp and smooth and extremly expensive.

Okay, so the example I found is the Canon CN-E30-300mm, which is still a lot narrower at the wide end than your typical current superzoom compact camera, but retails for 30k British Pounds. Zeiss has a 16.5-110mm that I've seen for 60k USD, but it's rather short... Are there better examples out there? Even so, the price would need explaining...

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MoreorLess
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Re: Getting to the bottom...
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

smaller sensors being easer to design lenses for

But why?

A smaller sensor needs a shorter lens with a smaller image circle, these elements make it easier to design.

I still don't find that intuitive. Other than the issue of flange distance, you should be able to scale a bridge camera design up to being an exchangeable lens, and vice versa. Added to that, miniaturising things is technically harder than making them bigger - at least in terms of R&D. At the small scale, imperfections are much more noticeable, so the glass actually needs to be higher quality.

Look at the sensor size for your typical superzoom, (generally 1/2.3" which is is about 1/15th the size of an ASPC sensor) then imagine how large and expensive an upscaled superzoom lens would be.

Compact camera's might be smaller than larger sensor options but the camera body is larger relative to sensor size so more able to support a long zoom without becoming over sized.

Again though I'd say expectation likely plays into this a lot. A superzoom for a large sensor camera will be judged by much higher standards than a superzoom compact lens.

And yet, I don't hear the superzoom compact reviews droning on about sharpness. In fact, the last time I remember that complaint as referring to the glass rather than the autofocus accuracy was in an HX300V review - that being a 20MP camera!

As I said I think your typical superzoom buyer isn't going to be as hung up on image quality hence the reviews won't tend to focus on it as much.

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headfirst
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to Leandros S, Oct 7, 2013

the CN-E30-300mm is a professional video/cine lens - high quality, high R&D/tooling cost & very low production nos. to recover it.

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Mark B.
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Re: Getting to the bottom...
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

smaller sensors being easer to design lenses for

But why?

Small sensors ==> small glass.  Large sensors ==> large glass.  It's much more expensive to make a superzoom lens for a large sensor because the image circle must project a larger image onto the sensor.  It requires a lot more glass.

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tko
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the easy explanation
In reply to Leandros S, Oct 7, 2013

Optical designers could give you a more complex answer, but the simplest way to visualize it is that a lens is a curved surface. The bigger the lens, the more the surface has to curve.

Visualize half a sphere. Take a small cut of the front. It's almost flat. Take a wider, bigger cut. The curvature is more pronounced. Take a cut almost the diameter of the sphere. You have a very heavy, curved piece of glass.

Worse, that round surface doesn't focus very well. The wider the lens, the more exotic the correction needs to be. It's only nearly flat lenses that can get by with little correction.

A larger sensor needs a bigger lens (well, you could make a slow, small lens for one, but most people wouldn't buy it, because result in compact camera performance.) Those larger sensor lenses are essentially faster, with a bigger front diameter. More $$, more correction, more weight. Now imagine a zoom, with everything sliding and correcting. More compromises, compromises that are harder to achieve with highly curved lens elements.

It's harder to make an elephant do a back flip than a flea. Just a rule of physics. How many medium format zooms are there? In addition, SLR users tend to be a little more picky. Their reference standard is a good prime. Almost by definition, anything else is in second place.

In short, the SLR lens is typically bigger and faster with more highly curved surfaces that need additional correction.

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

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John1940
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Re: Making a superzoom for a compact is easy, but for a DSLR, it's hard?
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

brianj wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

I still have a film SLR camera tamron 28-300mm zoom that is huge but it worked ok when I used to use it. Are we saying the same cannot be easily done for digital, or are we saying 300mm is not a superzoom?

Brian

I don't know. One hypothesis I had was that people have been getting obsessed with lenses having to start at 18mm. 18-250/270mm should be more challenging to design and build than 28-300mm, I would imagine. Fourteen-fold zoom vs. eleven-fold. I guess it's possible that 18-200mm lenses are significantly better than 18-250. I have my doubts though. In any case, 18 seems to be some kind of magical number, presumably b/c consumers tend to buy their ILC with an 18-55 or equivalent lens and want to upgrade to something that seems on the face of it to require no compromise. 18-270 does that whereas 22-300 might not (numbers for illustration only). Consumer psychology?

I have a Sigma 18-200 for Canon APS-C that I have used for 10 years and a cheap Canon 55-200 mm FF EOS lens.  At 200 mm the 55-200 is sharper and I only paid $100 for it many years ago. Neither is anywhere as sharp over the 70-200 zoom range compared to any L lens.

It isn't just a question of difficulty of design. It's a question of zoom range, aperture, sensor size, cost target, sharpness, wight, sealing, constant versus variable length, image stabilization or not, and designing for those parameters. What is the marketing target of the design? My cheap 55-200 (a FF lens) has a plastic body and no IS and sold for $100. Oh, it's also light and small. It's got decent optics for the price. The current 70-200 f/2.8 is Canon's best offering but costs 25 times as much, and is a FF pro lens. The 18-200 Sigma is useful for travel and is small. The new one is even better.

So, which is or was the most difficult to design?

John1940

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Leandros S
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Understanding demand curves
In reply to headfirst, Oct 7, 2013

headfirst wrote:

the CN-E30-300mm is a professional video/cine lens - high quality, high R&D/tooling cost & very low production nos. to recover it.

That explanation is backwards and doesn't satisfy. How many SLR users do we think actually enjoy changing lenses? I certainly don't. And yet, I slavishly continue in that bad habit because I've been told that I won't get good IQ with a travel lens. And the reason I bought an SLR is partly because I wanted that IQ.

So I'm quite convinced that if there were a reasonably good superzoom lens available at a decent price, everyone would go out and buy it.

I will probably buy one anyway eventually, even if reports keep showing that it's not as sharp and has additional distortion/aberration, simply b/c it will mean that I'll always be able to take the shot when it presents itself.

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Leandros S
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Doubtful that glass cost is the issue
In reply to MoreorLess, Oct 7, 2013

MoreorLess wrote:

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

smaller sensors being easer to design lenses for

But why?

A smaller sensor needs a shorter lens with a smaller image circle, these elements make it easier to design.

I still don't find that intuitive. Other than the issue of flange distance, you should be able to scale a bridge camera design up to being an exchangeable lens, and vice versa. Added to that, miniaturising things is technically harder than making them bigger - at least in terms of R&D. At the small scale, imperfections are much more noticeable, so the glass actually needs to be higher quality.

Look at the sensor size for your typical superzoom, (generally 1/2.3" which is is about 1/15th the size of an ASPC sensor) then imagine how large and expensive an upscaled superzoom lens would be.

Compact camera's might be smaller than larger sensor options but the camera body is larger relative to sensor size so more able to support a long zoom without becoming over sized.

As John1940 points out, you can get zoom lenses with a lot of glass in them for a very affordable price. So I don't think the production of lens elements actually enters into the original question in a big way.

Again though I'd say expectation likely plays into this a lot. A superzoom for a large sensor camera will be judged by much higher standards than a superzoom compact lens.

And yet, I don't hear the superzoom compact reviews droning on about sharpness. In fact, the last time I remember that complaint as referring to the glass rather than the autofocus accuracy was in an HX300V review - that being a 20MP camera!

As I said I think your typical superzoom buyer isn't going to be as hung up on image quality hence the reviews won't tend to focus on it as much.

Even looking at the samples as a DSLR user and owner of some reasonably good lenses, I can see that, say, the SX50 doesn't have major problems with sharpness or aberration. I think the Fujifilm X-S1 was the last superzoom bridge camera that some people said was a bit soft (with the exception of the HX300V, which presumably slightly outresolves its lens - forgivable given the 20MP resolution).

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Leandros S
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Re: Getting to the bottom...
In reply to Mark B., Oct 7, 2013

Mark B. wrote:

Leandros S wrote:

MoreorLess wrote:

Leandros S wrote:

People say that interchangeable superzoom ("travel") lenses can't manage good sharpness, yet superzoom compacts do just fine in terms of sharpness. Why is that?

smaller sensors being easer to design lenses for

But why?

Small sensors ==> small glass. Large sensors ==> large glass. It's much more expensive to make a superzoom lens for a large sensor because the image circle must project a larger image onto the sensor. It requires a lot more glass.

So when you say, "more glass", are you referring to overall volume/mass, or the number of lens elements? I'm not sure that superzoom compacts get away with fewer lens elements, and I don't think the glass volume is the problem either, since, as John1940 points out, you can get telezoom DSLR lenses starting at $100.

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headfirst
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Re: Understanding demand curves
In reply to Leandros S, Oct 7, 2013

Leandros S wrote:

headfirst wrote:

the CN-E30-300mm is a professional video/cine lens - high quality, high R&D/tooling cost & very low production nos. to recover it.

That explanation is backwards and doesn't satisfy.

No, it's not. The CN-E30-300 is a specialist lens (it's not a travel zoom) & even if they were a 10th of the price they probably wouldn't sell appreciably more (in fact most users will probably rent rather than buy). It weighs nearly 6Kg & it has a front diameter of over 130mm - there are a lot of heavy glass lenses in it that probably take up to a year to form, polish etc.

You don't get a Ferrari for the price of a Yugo.

Maybe this would suit you better? http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_28_300mm_f_3_5_5_6l_is_usm

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