Why no compacts with SLR sensors?

[kessler]

i would only have to disagree with the idea that this cam was "very unpopular ". If we only consider those people who don't use a camera then all cameras are "very unpopular". In fact, this camera was widely used.

I guess the quest for long zooms just shows that most people would rather have mediocre pictures of things that are far away than great pictures of world as we see it. In the end, prime cams are exclusively an enthusiast tool.

-m

This was an awesome little camera that could beat a lot of SLR's
with its 35mm/2.8 lens. It was small, cheap, weatherproof and
tough. It was also very unpopular because it did not have a zoom
lens.

With Digital, you need to have a huge zoom range to be considered a
serious camera. That means you will end up with an R1 + sized
camera.

For now, the Epic/Miju niche is filled by the F20. F30. Either of
them will produce low light photos more natural than a number of
SLR's and have a reasonable zoom range.

 

[K1000Photographer]

It was widely known among enthusiasts but Oly did find it to be far less popular than its zoom cameras.

 

[Bob Blount]

Agreed but they will never do it. Why cannibalise profitable lens
sales?

Except that the majority of DSLR purchasers never use anything
other than the kit lens.

Source for this position, please. Very doubtful!
--
Bob,

'We don't make a photograph with a camera; we bring to the act of photography all the books we have read, the movies we have seen, the music we have heard and the people we have loved.' Ansel Adams

Sony R1
Great Pro1
Casio Z750
Nikon 3100

 

[kessler]

To be honest, I don't really have any statistics on this. I was thinking it was more popular then any one zoom camera, but less popular then the whole lot of them. But, I don't even know where I would get this information.

-m

It was widely known among enthusiasts but Oly did find it to be far
less popular than its zoom cameras.

 

[Andre Martins]

aLSO A GREAT 35MM Camera with as REAL Zeiss Tessar F3.5 :

 

[Jerry R]

If you replace the R1 zoom lens with a fast 35mm fixed lens it would not be any larger than many 35mm "good' fixed lens cameras.

 

[nickleback]

Note also how large the lens appears to be, compared to the 35/2.8 of the Oly Stylus Epic.

Do you think that this is because a digital sensor needs lenses to
be fairly telecentric, requiring more bulky retro-focus wide angle
designs rather than the simple, compact symmetrical designs used
for moderate wide angle lenses on film cameras without reflex
mirrors?

Bingo. Offset microlenses could help, though.

The Pentax 21/3.2 DA wide angle pancake is compact itself (25mm
deep), but is mounted about 45mm from the focal plane, so the total
distance form focal plane to from to lens is still quite large
compared to its focal length, about 70mm.

Yes, the body depth allows the lens to be relatively short. It should be possible to make a retractable lens of similar design, but it probably won't be pocketable.

--
Seen in a fortune cookie:
Fear is the darkroom where negatives are developed

 

[BJL]

If such a camera needs a special sensor with off-set micro-lenses (which no-one except Leica and a few MF back makers seem to care about) as well as having the limitations of a fixed focal length moderately wide angle lens, I see a rather limited market for it.

But if there is a market for such a camera, about f/1.4 or at worst f/2 is about what the lens would need to be. Any slower, like f/2.8, and you would probably be better of with a proportionately smaller sensor, focal length and minimum f-stop, giving similar speed and DOF control more compactly and at lower cost.

For example, what could be done with an "APS-C" sized sensor and a f=20mm, f/2.8 could probably just as well done with sensor of half the area, so 1.4x smaller, with an f=14mm, f/2 lens.

More generally, I see little point for digital cameras limited to a primes f/2.8 or slower and/or zooms f/4 or slower, rather than using a somewhat smaller format with lenses of similar maximum effective aperture diameter, at least down to the limit of photo-sites so small that they do not perform well even at minimum ISO speed.

 

[kessler]

Okay, this seems like a stupid question, so someone should be able to give me an inteligent answer rather easily.

Let's say the lens is the same and the number of pixels are the same and we are shifting the CCD relative to the lens to have the CCD capture the same of the total light coming in whichever sensor we are considering. Since the number of photons coming in is the same, why does it matter whether they are captured on a large sensor or a small one?

I guess what I'm asking is: "Is it all about the glass diameter?" "total photons captured"

-m

 

[Andrew dB]

Agreed but they will never do it. Why cannibalise profitable lens
sales?

Except that the majority of DSLR purchasers never use anything
other than the kit lens.

Source for this position, please. Very doubtful!

I wish I could find a link but I have seen quotes that the average number of lenses sold per SLR is something like 1.4. Given how many lenses some people buy, that would mean an awful lot of users only ever use their camera with the kit lens that comes with it.

Anecdotally, this would appear to be true, when I worked in a camera store, the majority of SLR sales would be of a camera with a kit lens and most of those people never came back in to ask about getting more lenses. A minority of more enthusiastic users would buy twin lens kits or come back after their initial purchase to get another lens - usually a cheap 70-300mm or similar. The percentage of purchasers who ever bought more than two lenses was probably in the low single figures.

 

[kessler]

I should have said the lens diameter is the same, not necessarily the lens. My point being that the number of photons/time is the same.
-m

Okay, this seems like a stupid question, so someone should be able
to give me an inteligent answer rather easily.

Let's say the lens is the same and the number of pixels are the
same and we are shifting the CCD relative to the lens to have the
CCD capture the same of the total light coming in whichever sensor
we are considering. Since the number of photons coming in is the
same, why does it matter whether they are captured on a large
sensor or a small one?

I guess what I'm asking is: "Is it all about the glass diameter?"
"total photons captured"

-m

 

[Andrew dB]

Okay, this seems like a stupid question, so someone should be able
to give me an inteligent answer rather easily.

Let's say the lens is the same and the number of pixels are the
same and we are shifting the CCD relative to the lens to have the
CCD capture the same of the total light coming in whichever sensor
we are considering. Since the number of photons coming in is the
same, why does it matter whether they are captured on a large
sensor or a small one?

I guess what I'm asking is: "Is it all about the glass diameter?"
"total photons captured"

A bigger sensor lets you use a bigger lens for the same field of view which for the same f-stop will gather more light and have a higher image resolution. It's mainly about the improved low light performance and noise.

 

[kessler]

A bigger sensor lets you use a bigger lens for the same field of
view which for the same f-stop will gather more light and have a
higher image resolution. It's mainly about the improved low light
performance and noise.

right, but you threw out the constraint of the same diameter lens, so you let in more light and your signal to noise ratio went up. Does a larger sensor inheirently have an improved signal to noise ratio or is it just that they are used with bigger lenses?

I understand there is a field of view issue which could cause someone to prefer a larger or a smaller sensor, but since that is a preference lets leave it out.

 

[Andrew dB]

A bigger sensor lets you use a bigger lens for the same field of
view which for the same f-stop will gather more light and have a
higher image resolution. It's mainly about the improved low light
performance and noise.

right, but you threw out the constraint of the same diameter lens,
so you let in more light and your signal to noise ratio went up.
Does a larger sensor inheirently have an improved signal to noise
ratio or is it just that they are used with bigger lenses?

Applying a constraint of using the same lens diameter would seem to be a bit pointless. Obviously there are practical limits but it would seem odd to restrict the choice to either a 50mm f10 with a large sensor or a 10mm f2 with a small sensor.

Larger pixels can mean improved fill factor and hence light sensitivity since teh size of the photosensor can be increased while maintaining the size of the surrounding circuitry but this assumes that both devices will be manufactured on the same process with the same underlying design which is unlikely to be true.

I understand there is a field of view issue which could cause
someone to prefer a larger or a smaller sensor, but since that is a
preference lets leave it out.

It's not really about field of view, but rather that you could have a small sensor camera that used our hypothetical 10mm f2 lens above and you would scale the whole thing, including sensor up to a 50mm f2 but with the same FOV. What the final FOV of each combination is is a consequence of the relationship between each focal length and it's corresponding sensor size. Obviously the camera is bigger but its performance should show a significant increase.

 

[nickleback]

Applying a constraint of using the same lens diameter would seem to
be a bit pointless.

It isn't if your objective is to make a pocketable camera.

Obviously there are practical limits but it
would seem odd to restrict the choice to either a 50mm f10 with a
large sensor or a 10mm f2 with a small sensor.

That's basically the choice that was made with compact 35mm cameras. Want a big zoom? It'll be f/5.6-13. That's not much different than compacts with f/2.8-4 zooms. Very few compact 35mm cameras broke out of that mold.

--
Seen in a fortune cookie:
Fear is the darkroom where negatives are developed

 

[kessler]

Applying a constraint of using the same lens diameter would seem to
be a bit pointless. Obviously there are practical limits but it
would seem odd to restrict the choice to either a 50mm f10 with a
large sensor or a 10mm f2 with a small sensor.

Larger pixels can mean improved fill factor and hence light
sensitivity since teh size of the photosensor can be increased
while maintaining the size of the surrounding circuitry but this
assumes that both devices will be manufactured on the same process
with the same underlying design which is unlikely to be true.

I see your point that you want to hold image characteristics (i.e. FOV) constaint and then compare the two. You are right, if you do that the larger sensor will have a higher S/N.

However, this still doesn't answer the question of whether the larger sensor has a higher S/N ratio or if it is that the larger sensor allows us to use a lens that lets in more light.

-m

 

[kessler]

Larger pixels can mean improved fill factor and hence light
sensitivity since teh size of the photosensor can be increased
while maintaining the size of the surrounding circuitry but this
assumes that both devices will be manufactured on the same process
with the same underlying design which is unlikely to be true.

yes, this starts to explain why a larger sensor might have improved S/N. Does anyone know what fraction of the surface of a pixel at the different sizes is taken up by circuitry?

Also, I read elsewhere that there are diffraction issues as the pixels get closer together.

Still, I wonder how much of the total S/N improvement between compacts and SLRs is explained by these two things as opposed to letting in gobs more light.

-m

 

[Andrew dB]

Applying a constraint of using the same lens diameter would seem to
be a bit pointless.

It isn't if your objective is to make a pocketable camera.

True, so to get anything approaching a pocketable camera with a fast aperture, it would need to be a fixed lens. Stuffing in zoom would render the whole exercise pointless although obviously not having a zoom would limit the market even if the price didn't do that anyway.

Ultimately if the buyer is looking for a pocketable camera with a decent, fast zoom then they are going to be limited to a small sensor device and I can't see technology changing that one bit.

Obviously there are practical limits but it
would seem odd to restrict the choice to either a 50mm f10 with a
large sensor or a 10mm f2 with a small sensor.

That's basically the choice that was made with compact 35mm
cameras. Want a big zoom? It'll be f/5.6-13. That's not much
different than compacts with f/2.8-4 zooms. Very few compact 35mm
cameras broke out of that mold.

They were pretty rubbish so for a camera of this type to be worthwhile, a zoom would be out of the question unless it had a very small range and iven then, it could be a problem.

 

[Andrew dB]

Applying a constraint of using the same lens diameter would seem to
be a bit pointless. Obviously there are practical limits but it
would seem odd to restrict the choice to either a 50mm f10 with a
large sensor or a 10mm f2 with a small sensor.

Larger pixels can mean improved fill factor and hence light
sensitivity since teh size of the photosensor can be increased
while maintaining the size of the surrounding circuitry but this
assumes that both devices will be manufactured on the same process
with the same underlying design which is unlikely to be true.

I see your point that you want to hold image characteristics (i.e.
FOV) constaint and then compare the two. You are right, if you do
that the larger sensor will have a higher S/N.

However, this still doesn't answer the question of whether the
larger sensor has a higher S/N ratio or if it is that the larger
sensor allows us to use a lens that lets in more light.

Larger pixels will often have much bigger charge capacities but should have similar readout noise so in that respect S/N can be much better.

More photons landing on each pixel from using a larger pixel pitch will reduce photon noise which I understand is the main noise source at low ISOs.

If you keep the lens diameter the same and just increase the focal length (thus increasing the focal ratio) while increasing sensor size, the first benefit may still apply but the second will not since total light received by each pixel should remain constant.

 

[Andrew dB]

Larger pixels can mean improved fill factor and hence light
sensitivity since teh size of the photosensor can be increased
while maintaining the size of the surrounding circuitry but this
assumes that both devices will be manufactured on the same process
with the same underlying design which is unlikely to be true.

yes, this starts to explain why a larger sensor might have improved
S/N. Does anyone know what fraction of the surface of a pixel at
the different sizes is taken up by circuitry?

It varies massively and mainly depends on sensor type and manufacturing process but figures I have seen range from 0% (full frame CCD) to 75% (some CMOS). It's further complicated by the use of microlenses which focus light onto the sensitive part of each pixel and increase its effective sensitivity although the 'well size' of each pixel is not affected so the total number of photoelectrons it can record will not increase which limits S/N to some extent.

Also, I read elsewhere that there are diffraction issues as the
pixels get closer together.

Yes, but I have seen many different arguments about how much of a problem this is. Just because it allows diffraction effects to be seen at 100% magnification, doesn't mean that there is a problem.

Still, I wonder how much of the total S/N improvement between
compacts and SLRs is explained by these two things as opposed to
letting in gobs more light.

It would be interesting to know but I'm afraid I can't say due to there being so many factors and types of technology influencing overall performance. Perhaps one of the posters with more experience in optics and imaging could provide a more definitive answer.