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10-23-2016, 03:09 PM   #61
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QuoteOriginally posted by Nicolas06 Quote
What count is the result, the K1 shot is darker than the K3 and the K3 image are sligly more burned highligh (in the white feathers) than the K3. Exposure isn't the same, whatever the way you got this setting the K1 image got less exposure. There should be 1EV difference to equate dof, not 2EV.
This is precisely my point that the noise difference is not do to the FF vs cropped or even the noise performance of the sensors at question but rather the noise comes from one camera capturing 2x more light over they other.

10-23-2016, 03:15 PM   #62
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QuoteOriginally posted by Ian Stuart Forsyth Quote
This is precisely my point that the noise difference is not do to the FF vs cropped or even the noise performance of the sensors at question but rather the noise comes from one camera capturing 2x more light over they other.
That is precisely the assumption I'm questioning here. By the way, for equivalent DoF, they capture the same amount of light. The difference in intensity is double in favour of APS-c and half in terms of FF, it's a saw off. Same DOF, same shutter speed, double the intensity of light collected, half the sensor size. Same total light. The FF has to increase it's ISO to make use of the lower light level.
10-23-2016, 03:16 PM   #63
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QuoteOriginally posted by normhead Quote
What I'm seeing however is more than .7 stop in terms of noise. However that's subjective... even with the .7 stop added in, I still would have expected the K-1 image to be better. It should be more than covered by the 2 extra EV of DR in the K-1 over the K-3. It's a mitigating circumstance, but I don't believe it entirely explains the difference. But, it is also completely possible that the difference in EV could have made the difference in noise. It would take further testing to tell. To day it is what made the difference would be getting ahead of the tests.

As person who regularly shoots up to -3 EV and plus 2 EV,my experience says something else is going on. .7 shouldn't be noticeable, especially in bright light, like these images.
Except there not only that. the photosites of the K1 are not 2.3 time bigger, only 1.5 time bigger. We are speaking of a 36MP FF, not a 24MP FF. So if you look at 100% crop, you don't see 2.3 larger surface area on the K1 but only 1.5 time wider area so you only benefit from 0.5 stop gain. The stop gain of FF apply on full image. On crop this only depend of the photosites size, not sensor size.

From what we see on exif 1/650 f/5.6 vs 1/1250 f/8 there 2 stops. Not 0.7. Not 1.3. there 2 stops. Then there the fact we look at 100% crop so we don't see 2.3 time greater surface on FF at all. But 1.5 time. The gain is only 0.5EV. Total difference is 1.5 stop of total light, that quite huge. That the difference between f/5.6 and f/3.2 !

The sensor are same technology, same vendor. This not even the D810 tweaked sensor with more dynamic range and iso 50 support or the 42MP BSI sensor. This is really same technology. So there no way to hide 1.5 stop difference. There no magic here. An FF body perform better because the sensor area is bigger. But on 100% crop sensor total sensor area doesn't count at all.

Last edited by Nicolas06; 10-23-2016 at 03:26 PM.
10-23-2016, 03:21 PM   #64
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QuoteOriginally posted by normhead Quote
What I'm seeing however is more than .7 stop in terms of noise. However that's subjective... even with the .7 stop added in, I still would have expected the K-1 image to be better. It should be more than covered by the 2 extra EV of DR in the K-1 over the K-3. It's a mitigating circumstance, but I don't believe it entirely explains the difference. But, it is also completely possible that the difference in EV could have made the difference in noise. It would take further testing to tell. To day it is what made the difference would be getting ahead of the tests.

As person who regularly shoots up to -3 EV and plus 2 EV,my experience says something else is going on. .7 shouldn't be noticeable, especially in bright light, like these images.
DR and noise performance is directly related to how much total light that you put into the image and for the K3 image it received 2 times more light with the longer exposure time over the K1, The meter on both cameras are irrelevant as the backgrounds are slightly different being that the k1 shot has more white and light grey in it, along with the -1ev override caused the K1 camera to select an exposure time half as long. So basically your comparison really is comparing iso 400 for the K3 to Iso 1600 on the K1

---------- Post added 10-23-2016 at 03:25 PM ----------

QuoteOriginally posted by normhead Quote
That is precisely the assumption I'm questioning here. By the way, for equivalent DoF, they capture the same amount of light. The difference in intensity is double in favour of APS-c and half in terms of FF, it's a saw off. Same DOF, same shutter speed, double the intensity of light collected, half the sensor size. Same total light. The FF has to increase it's ISO to make use of the lower light level.
and in your examples the K1 image had received half the total light of the K3 thus more noise

10-23-2016, 03:27 PM   #65
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QuoteOriginally posted by Ian Stuart Forsyth Quote
DR and noise performance is directly related to how much total light that you put into the image and for the K3 image it received 2 times more light with the longer exposure time over the K1, The meter on both cameras are irrelevant as the backgrounds are slightly different being that the k1 shot has more white and light grey in it, along with the -1ev override caused the K1 camera to select an exposure time half as long. So basically your comparison really is comparing iso 400 for the K3 to Iso 1600 on the K1
Is the k-1sensor isoinvariant?
10-23-2016, 03:28 PM   #66
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QuoteOriginally posted by normhead Quote
That is precisely the assumption I'm questioning here. By the way, for equivalent DoF, they capture the same amount of light.
Only if the shutter speed is the same, the transmitance is the same and the lighting condition didn't change.

In many cases you can just use a lower shutter speed and keep the iso the same, say iso 100. This what can be done in most situations. Even there even if iso 100 was too low, you could have kept iso 400 and settled for 1/320s...
10-23-2016, 03:32 PM   #67
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QuoteOriginally posted by normhead Quote
If Ian had any technical training at all, I suspect he would realize that shooting a K-3 with a 200mm lens and a K-1 with a 300mm lens, from the same distance, you have to stop the 300mm lens down a stop to achieve the same DoF. That makes it the same picture. Shooting with different DoFs produces a different picture. Does shooting a K-1 at the same ƒ-stop as the K-1 affect my DoF sparrow image. Hell yes it does. The birds tail is already out of focus. Shooting the 300 on the K-1 even more of the bird will be out of focus.
I did not see this remark but your welcome to it.
But when someone with less technical training can not see that the exposure time is different and that is where the noise is coming from and not the sensors in question, they might want to rethink their theory when someone has too point this out to them several times.

---------- Post added 10-23-2016 at 03:33 PM ----------

QuoteOriginally posted by UncleVanya Quote
Is the k-1sensor isoinvariant?
past iso 800 from the data that I can find

10-23-2016, 03:35 PM - 1 Like   #68
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Thanks, Norm, for all your efforts and for starting this interesting discussion.
And thanks to everyone else (certainly including the "skeptics") for propelling the discussion forward...
10-23-2016, 03:36 PM   #69
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mmm.... would it be safe to assume that the one f stop was to normalise DOF between formats, so ..... given an identicle lens then one stop of ISO needs to be traded for Norms approach. However in this case, lenses were not identicle (but maybe equivelent).... so a likely "t" stop difference between lenses resulted in a different shutter speed to maintain exposure?
10-23-2016, 03:42 PM   #70
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QuoteOriginally posted by noelpolar Quote
mmm.... would it be safe to assume that the one f stop was to normalise DOF between formats, so ..... given an identicle lens then one stop of ISO needs to be traded for Norms approach. However in this case, lenses were not identicle (but maybe equivelent).... so a likely "t" stop difference between lenses resulted in a different shutter speed to maintain exposure?
It was the -1 ev override and the lighter background of the K1 shot that caused the caused the shorter exposure

It takes a complex lens design to see a 1 T stop varies and with the 3 300mm F 2.8 lenses I have used under controlled light I have never had a 1 stop variance, something like the 150-450 and the 150-600 yes but to get to a full stop variance seldom.

Last edited by Ian Stuart Forsyth; 10-23-2016 at 03:58 PM.
10-23-2016, 04:24 PM   #71
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Great discussion—I do wish I better understood why ISO 800 produces less noise than ISO 100.
10-23-2016, 04:34 PM   #72
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Norm,
I took a look at your pics. I purposely ignored methodology and all that and just looked at them as images as they appear on my calibrated screens. After all at the end of the day that's all I really had to go by.

Conclusion: to me I didn't see enough of a consistent difference between the two sets to lose any sleep over.
Perhaps others do I did not.

My advice - grab one or the other and get out there and point it at something beautiful before you are snowed in.

Last edited by wildman; 10-24-2016 at 03:29 AM.
10-23-2016, 04:55 PM   #73
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Thanks to Norm for this interesting thread.

QuoteOriginally posted by noelpolar Quote
From experience the DFA150-450 costs a stop or so at 300mm over my F*300/4.5
So from your experience Noel, how would you rate K-3 + F*300 v K-1 + 150-450 at 450 for birding? On Norm's field test, I would expect the K-3 combo to do at least as well, if not better.

Let's bear in mind we are talking say $A2000 v $5800 here. Even if we said DA*300 instead of F*300, we'd still be talking no more than say $2500.

QuoteOriginally posted by noelpolar Quote
mmm.... would it be safe to assume that the one f stop was to normalise DOF between formats, so ..... given an identicle lens then one stop of ISO needs to be traded for Norms approach. However in this case, lenses were not identicle (but maybe equivelent).... so a likely "t" stop difference between lenses resulted in a different shutter speed to maintain exposure?
Would a fairer comparison be 150-450 on each: at 300 f4.5 (or is it 299mm f4.5?) on K-3 and at 450 f5.6 (or should it be f6.3, for one stop difference?) on K-1.

Of course it isn't the whole story, even for wildlife. But at the moment, for wildlife, I'm thinking that the next APS-C flagship (with flippy screen, pixel shift, faster AF, and other tech improvements) is more worth saving for than the K-1. None of this is a knock on the K-1, even for my preferred uses. It's just that the APS-C flagship with a premium lens looks like great value for money.

Last edited by Des; 10-23-2016 at 05:12 PM.
10-23-2016, 05:43 PM - 1 Like   #74
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QuoteOriginally posted by Des Quote
Would a fairer comparison be 150-450 on each: at 300 f4.5 (or is it 299mm f4.5?) on K-3 and at 450 f5.6 (or should it be f6.3, for one stop difference?) on K-1.

Of course it isn't the whole story, even for wildlife. But at the moment, for wildlife, I'm thinking that the next APS-C flagship (with flippy screen, pixel shift, faster AF, and other tech improvements) is more worth saving for than the K-1. None of this is a knock on the K-1, even for my preferred uses. It's just that the APS-C flagship with a premium lens looks like great value for money.
I think it would be a comparison with less unknowns... I think 290mm is the last F4.5 stop..... however.... I'd not do it wide open anyway.... maybe better say just one stop apart and at least one stop or two from wide open as a starting point on the K3.... (my 150-450 improves quite a bit from one stop down.... so you'd want to reduce this impact on a test.... would favour IQ of the K-1 to much.... which it sorta does in the real world I guess.... maybe a reason why I much preffre the K-1 on the 150-450... )

I don't do fixed distance little bird stuff much..... I'm mostly a walk in the bush kinda person.... so the flexability of the zoom suits me..... and the "prime quality loss" is sort of made up by the K-1 (IQ to some extent, but mostly higher iso usability.... translated into shutter speed during good light and less noise in not so good light..... always an exposure triangle call..... (I've also come to terms with the endless desire for longer focal lengths)

I'll buy a "K-1'd version of a K-3.... if and when it arrives (I'd want flippy screen, K5 DR, better AF.... wouldn't mind the OBF back as well.....)... but the way pentax pricing in Australia is going.... it wouldn't surprise me if the K4 hits at $1890.... that'd stop me in my tracks.... $1200 not so much

My F*300/4.5 will never go.... it's so small and the IQ is right up there.... so it fits right in as a convenient part of a more mobile kit.

Last edited by noelpolar; 10-23-2016 at 05:55 PM.
10-23-2016, 07:24 PM - 1 Like   #75
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QuoteOriginally posted by les3547 Quote
Great discussion—I do wish I better understood why ISO 800 produces less noise than ISO 100.
I think that refers to read noise, which I believe is a minor contributor to total noise compared to shot noise.
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