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Topic ClosedThe A77 thread (cont'd)

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Direct Link To This Post Posted: 23 June 2011 at 14:57
On the low-ISO function. I, too loved Fuji Velvia-50 and shot some nice negatives on Ektar-25. I think that others are also recalling the sharpness, depth and range extensions that people could get with those films.

I just think that we need to cajole Sony (since they make the sensors for Nikon, Pentax and Sony) to build sensors with extended depth and range, so we can get that again. If you just want to get shallow DOF or portrait-like dreamy images from low f-number lenses, you may need to get those ND-filters in this post-photochemical technology.

Is that about right?
 



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Direct Link To This Post Posted: 23 June 2011 at 15:03
It's technically impossible to go below base ISO of an image sensor. Period.
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Direct Link To This Post Posted: 23 June 2011 at 15:13
Originally posted by sybersitizen sybersitizen wrote:

Well, that's a comfort. Hey, maybe the SLTs will eventually grow NEX-like flash connectors on top for the HVL-F7S and F20S.
But that's pure speculation.
The same way it is possible that a more advance NEX Alpha (call it NEX-7) comes with the iISO hot-shoe.
And it could also be that it comes with build in flash and can wireless trigger the Sony/Minolta D flashes.

Saying "- and no compatiblity with the Minolta/Sony flash system." as a statement means you have insight in Sony's platform plans? ;o)
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Direct Link To This Post Posted: 23 June 2011 at 15:41
That's the problem with using "ISO" rather than "Gain" as a descriptor for digital sensitivity, people try to apply other equally inappropriate film qualities to the sensor.
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Direct Link To This Post Posted: 23 June 2011 at 15:48
Originally posted by Fuzzphoto Fuzzphoto wrote:

It's technically impossible to go below base ISO of an image sensor. Period.


True, but does that mean that a sensor couldn't be made at a lower base ISO in the first place, even if that means some compromise with the high ISO? (or equivalent thereof)
Tim
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Direct Link To This Post Posted: 23 June 2011 at 15:57
Originally posted by sybersitizen sybersitizen wrote:

Hey, maybe the SLTs will eventually grow NEX-like flash connectors on top for the HVL-F7S and F20S.

Originally posted by Sick Sick wrote:

But that's pure speculation.

I wouldn't even call it that. The thought just popped into my head and I let it out.

The same way it is possible that a more advance NEX Alpha (call it NEX-7) comes with the iISO hot-shoe.
And it could also be that it comes with build in flash and can wireless trigger the Sony/Minolta D flashes.

Saying "- and no compatiblity with the Minolta/Sony flash system." as a statement means you have insight in Sony's platform plans? ;o)

If you object to that statement, why did you not also object to some of these?

- slower AF speed than in DSLR/SLT models

- adapter required for mounting A-mount lenses

- with that adapter AF only works with lenses that have builtin motors


All of the above are true with regards to current NEX still cameras and will remain true with upcoming NEX still cameras unless Sony makes significant changes. Sony could invalidate all of those truths at some point in the future. Even the one about the adapter - if they include the adapter in the box, the NEX is 'instantly compatible' with Alpha lenses. I don't see how there can be any reasonable speculation if we constantly allow for the possibility that a future NEX camera might be literally anything and everything. All you would need to do is repeat that last phrase and be done.

Edited by sybersitizen - 23 June 2011 at 16:06
 



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Direct Link To This Post Posted: 23 June 2011 at 16:20
Making 2 models for one change like that would doubtful in cost savings.   Sony didn't bother selling the A55 without GPS in the US, I wonder if they ever sold many of those around the world or quickly just went to the GPS only model. Why make a camera that saves them maybe 5 bucks, yet at the retail end they have to put a much bigger price delta in there, at least 50 bucks.   That means either removing some profit to have the cheaper model, or pricing the GPS model higher than planned or just simply higher and hurting sales.

As is commented many times, there is lots of features in cameras some people don't use. Just the way it is. But the A55 had 2 big things, SLT and GPS.   I'm pretty sure GPS was a big part of it's success.


Originally posted by PhotoTraveler PhotoTraveler wrote:

It's good to here they both have GPS, if Sony blew that one after the success of the A55, that would have been dumbfounding. In interviews reps had said GPS will come on the higher end models in the future, so it's good to see it stays.

I've no need for GPS, so I would like to see a (cheaper) version without the GPS... What about an A75 without GPS?


Edited by PhotoTraveler - 23 June 2011 at 16:22
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Direct Link To This Post Posted: 23 June 2011 at 16:26
yes no,   the sensor can't go below, they doesn't mean you can't PWM it, if it's only running half the time during exposure, you have certainly reduced it's sensitivity.

As was mentioned, it needs to be thought about as Gain, and I think people are making the false assumption that what ever the base ISO of the camera is, is also the point with no Gain Added.    I doubt this to be the case, as pretty sure even the most base ISOs see a good amount of Gain applied to the signal.

Originally posted by Fuzzphoto Fuzzphoto wrote:

It's technically impossible to go below base ISO of an image sensor. Period.
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Direct Link To This Post Posted: 23 June 2011 at 16:39
Originally posted by tigertimb tigertimb wrote:

Originally posted by Fuzzphoto Fuzzphoto wrote:

It's technically impossible to go below base ISO of an image sensor. Period.


True, but does that mean that a sensor couldn't be made at a lower base ISO in the first place, even if that means some compromise with the high ISO? (or equivalent thereof)



Problem is that low ISO in Sensor speak is "High Electron count". High electron count is quite easy in boring old world of CCDs but not so in the exciting new world of densely packed CMOS designs..

Typing out loud...

IIRC from the 7D\5D\Sony sensor spec sheet sheet (looked for it on my HD at work but it seems to be buried somewhere) of 100,000 e' and this yielded ISO 100 (Or low 80) for its base sensitivity.

So empirically to get to ISO 50, you would need 200,000 e' .. I know the CCDs used by phase one and the like can hold 200,000 e and more per photo site..

Conversely it does imply that most CMOS parts are around 50,000e' per node (by the statement that their base sensitivity of ISO 200).

Of course this excludes the inherent non linearity of film to the inherent Linearity of a imaging sensor and charge conversion efficiency of the electrons.
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Direct Link To This Post Posted: 23 June 2011 at 17:13
Originally posted by PhotoTraveler PhotoTraveler wrote:

As was mentioned, it needs to be thought about as Gain, and I think people are making the false assumption that what ever the base ISO of the camera is, is also the point with no Gain Added.    I doubt this to be the case, as pretty sure even the most base ISOs see a good amount of Gain applied to the signal.


Probably true. I consider the base ISO as the ISO at which the DR is maximized, whatever be the gain level. Go above the base ISO and the DR goes down, while the sensitivity goes up with the increase in the gain (along with noise).

I read an article a couple of months back, where they were stating that camera manufacturers are applying a hidden amount of gain onto the sensors and not publishing it. Another point mentioned in the said article, if I remember it correctly, was that there was absolutely nothing to be gained by using super-fast lenses with these digital cameras (unlike say in the film era), and that there is a cut-off point for the aperture size, and lenses with any larger apertures, provide absolutely no benefit to the shooter (and of course has the downside of needing to carry heavier-than-needed lenses).
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Direct Link To This Post Posted: 23 June 2011 at 17:21
Originally posted by PhotoTraveler PhotoTraveler wrote:

Making 2 models for one change like that would doubtful in cost savings.   Sony didn't bother selling the A55 without GPS in the US, I wonder if they ever sold many of those around the world or quickly just went to the GPS only model. Why make a camera that saves them maybe 5 bucks, yet at the retail end they have to put a much bigger price delta in there, at least 50 bucks.   

iirc they can't sell GPS-equipped in China & China is coming to be a major market ...
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Direct Link To This Post Posted: 23 June 2011 at 17:42
Originally posted by PhotoTraveler PhotoTraveler wrote:

Staying on topic is far to constraining for the A77 thread.


Happy shooting,
Yakim.
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Direct Link To This Post Posted: 23 June 2011 at 17:44
Originally posted by roweraay roweraay wrote:


Probably true. I consider the base ISO as the ISO at which the DR is maximized, whatever be the gain level. Go above the base ISO and the DR goes down, while the sensitivity goes up with the increase in the gain (along with noise).


Interesting to note that (for example) both the A700 and A900 supposedly have a base ISO of 200. (not sure if this is official or just popular opinion)

But if you look at the DXOmark measurements for the A900 and the A700 both still show gains in noise, tonal range and dynamic range at ISO 100.

It's certainly a small gain and not linear, but it is an improvement, so maybe this should be considered the base ISO? With good light, I certainly don't hesitate to use ISO 100 now, where initial reports seemed to suggest that it could actually be detrimental!

(and intriguing to see that the more recent A580 shows a much more linear gain at ISO 100 (which is responsible for it scoring better than the A900 for dynamic range, where at every other ISO the A900 is better)
Tim
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Direct Link To This Post Posted: 23 June 2011 at 17:49
Originally posted by bill_bly_ca bill_bly_ca wrote:

Originally posted by tigertimb tigertimb wrote:

Originally posted by Fuzzphoto Fuzzphoto wrote:

It's technically impossible to go below base ISO of an image sensor. Period.


True, but does that mean that a sensor couldn't be made at a lower base ISO in the first place, even if that means some compromise with the high ISO? (or equivalent thereof)



Problem is that low ISO in Sensor speak is "High Electron count". High electron count is quite easy in boring old world of CCDs but not so in the exciting new world of densely packed CMOS designs..

Typing out loud...

IIRC from the 7D\5D\Sony sensor spec sheet sheet (looked for it on my HD at work but it seems to be buried somewhere) of 100,000 e' and this yielded ISO 100 (Or low 80) for its base sensitivity.

So empirically to get to ISO 50, you would need 200,000 e' .. I know the CCDs used by phase one and the like can hold 200,000 e and more per photo site..

Conversely it does imply that most CMOS parts are around 50,000e' per node (by the statement that their base sensitivity of ISO 200).

Of course this excludes the inherent non linearity of film to the inherent Linearity of a imaging sensor and charge conversion efficiency of the electrons.


Always great to benefit from the expertise at Dyxum - thank you

So better low ISO would be feasible if it was made a design priority, but it would no doubt come at considerable cost and alternative compromises?
Tim
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