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04-03-2015, 07:40 PM   #106
osv
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QuoteOriginally posted by Wild Mark Quote
Your comment has made me wonder if the use of FF lenses on APS-C cameras is delivering 'extra' light in close proximity to the sensor thus causing IQ losses .... contrast, dynamic range???
you could lock the mirror up and see if there is any bare metal in the light path, next to the sensor??

i've seen speculation that there are reflections bouncing back onto the rear of the lens, for both ff and crop cameras... people have blamed all kinds of things, including reflections inside the adapters, for both the cheap and the expensive adapters.

the a7 has a noticeable sensor reflection problem on long exposures, for example, you shoot a bridge at night, and there might be faint green spots trailing off of some of the lights... i've seen that problem on the bbc sherlock holmes tv series, the opening shot before every episode, so it's not just still cameras.

i compared five 135mm primes on the a7r; canon, pentax, minolta, etc., and pretty much all of 'em had massive pf issues... it was shocking, lol... here is what the 135mm super tak f/3.5 looked like at f/3.5, check out the irrigation pipes... it's defective on the right-hand side, but you get the idea:
https://www.dropbox.com/s/w4vtk7fiufpa04y/135mmSuperTak3point5prime2861.JPG?dl=0

04-03-2015, 08:37 PM   #107
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QuoteOriginally posted by osv Quote
you could lock the mirror up and see if there is any bare metal in the light path, next to the sensor??

This is what I am angling at. Also, I have noted that the genuine adapters have raw (silver) and blackened finish on the mirror box side - thus potentially leading to reflections. Either way, my logic is a FF lens on a APS-C camera is going to potentially behave slightly differently if the 'extra' light is tampering with sensor performance.

I guess my ultimate thought is, if a FF lens is projecting onto a FF sensor then you should see different (better) performance at ISO <400 than the same lens on an APS-C camera shot at ISO 100 (I looked at the equivalence link and have taken on board the dynamic range differences between FF and APS-C sensors). What other benefits there are seem esoteric to me.
04-03-2015, 09:34 PM - 1 Like   #108
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QuoteOriginally posted by mohb Quote
What could be weirder than your strange belief that APSC images MUST be taken with the same FOV and DOF as those taken with a 'full frame?
I'm honestly wondering why you think that's ^ the assertion.

Here, let me try to explain in a different way: If you move to FF from aps-c, will all your images automatically need to get 1.5x wider? Meaning, you will make no adjustments to FL's used, everything will just need to be wider now, because the sensor is bigger and that's just the way it's going to be from now on?

No?

Or will you perhaps frame much as you had before? Meaning, adjust FL accordingly - Instead of using that 50 or 55 for portraits. or setting your zoom at 50-55, you use 75mm - 85mm now, maybe.

There is no *must* there, no-one is forcing you to do that... it's just the way your habits call you, it's the groove you'll fall back into because you know what gives you the best results compositionally, or you know what your subjects expect if they have a stake in the output.

That's framing. As for DOF, it's usually an aps-c Uber alles poster who insists that there's no real advantage to FF, because once you match the aps-c DOF (by stopping FF down,) you've given up the total light/DR/noise advantage - as if that were paramount and a common need - matching the smaller format's deeper DOF. (spoiler: it's not.)

.
04-04-2015, 03:18 AM   #109
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QuoteOriginally posted by fuent104 Quote
Can you explain what you meant by this? I'm curious.
What I mean is that full frame is better at the same iso. If you shoot a shot on full frame at 200mm f2.8 and iso 200 and one on APS-C at 135mm f2.8 and iso 200, the full frame shot will have better dynamic range and less noise. The exposure should be the same though (assuming no fudging of the iso). The thing is that full frame shot will have less depth of field than the APS-C shot. In order to have the same depth of field as the APS-C shot, you would have to stop down to f4 and bump your iso to 400, at which point your noise and dynamic range will be equivalent.

That's what I mean when I say that better full frame performance is linked closely to less depth of field. As long as you want the same exposure and same framing, the reason that full frame has better performance is because it has faster equivalent lenses.

04-04-2015, 03:47 AM   #110
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QuoteOriginally posted by Rondec Quote
What I mean is that full frame is better at the same iso. If you shoot a shot on full frame at 200mm f2.8 and iso 200 and one on APS-C at 135mm f2.8 and iso 200, the full frame shot will have better dynamic range and less noise. The exposure should be the same though (assuming no fudging of the iso). The thing is that full frame shot will have less depth of field than the APS-C shot. In order to have the same depth of field as the APS-C shot, you would have to stop down to f4 and bump your iso to 400, at which point your noise and dynamic range will be equivalent.

That's what I mean when I say that better full frame performance is linked closely to less depth of field. As long as you want the same exposure and same framing, the reason that full frame has better performance is because it has faster equivalent lenses.
Surely in many situations with FF you could double the shutter time instead of increasing the ISO after stopping down to obtain the same DOF on FF as on APS-C? Of course this would often bring too many problems but there must be a fair portion of situations in which it would be fine.
04-04-2015, 06:37 AM   #111
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QuoteOriginally posted by mecrox Quote
Surely in many situations with FF you could double the shutter time instead of increasing the ISO after stopping down to obtain the same DOF on FF as on APS-C? Of course this would often bring too many problems but there must be a fair portion of situations in which it would be fine.
Most of those situations will be low ISO or tripod situations where, while there might be a difference it won't be great.
04-04-2015, 06:38 AM   #112
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One matter lost in this debate is that a FF image is enlarged less than an APC-s image. While an APC-s sensor uses the sweet spot of a FF lens, it enlarges any error 1.5 times. I've never subscribed to extreme cropping as the initial image has to be perfect to survive magnification. To me a 16MP full frame image will more likely have higher IQ than an image from a16MP APC-s camera when viewed at the same size (different magnification)

This is not to say FF is better. The crop sensor has cost advantages, especially for long lenses.

(Retires behind shelter awaiting flaming arrows)......
04-04-2015, 06:55 AM   #113
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QuoteOriginally posted by Timd Quote
One matter lost in this debate is that a FF image is enlarged less than an APC-s image. While an APC-s sensor uses the sweet spot of a FF lens, it enlarges any error 1.5 times. I've never subscribed to extreme cropping as the initial image has to be perfect to survive magnification. To me a 16MP full frame image will more likely have higher IQ than an image from a16MP APC-s camera when viewed at the same size (different magnification)

This is not to say FF is better. The crop sensor has cost advantages, especially for long lenses.

(Retires behind shelter awaiting flaming arrows)......
That assumes that the camera is recording errors. If in fact the lens is providing more sharpness than the sensor can record, which would still seem to be the case, there will be no errors to enlarge. Enlarging with digital is not like enlarging with film. It's a completely different process. No direct comparison can be made. SO while when enlarging film, you just see those grain particles get bigger and bigger, in digital with modern enlarging algorithms the images maintain much more clarity. A sharp 24 Mp APS_c image enlarges just as good as a sharp 24 MP FF image, and in fact the smaller format may give you the sharper looking image, because of the wider DoF and having more of the subject in focus. In the digital world, they are the same and will enlarge equally. If you want better enlargements you have to go to more MP. Currently APS_c goes to 24 Mp and FF goes to 36... so the larger format has an advantage in that you can pack in more pixels.

But for enlargement it's not like film. In the old days you could exceed the output for enlargement of 35 mm 400 ISO Tri-ex by using a fine grain 32 ISO copy film. So even in film days, there was more to "this format beats that format for enlargement" than just what format was used. You had to consider what film was used. Just as the size of the grain mattered then, the size of the pixel matters now.

---------- Post added 04-04-15 at 10:03 AM ----------

QuoteOriginally posted by mecrox Quote
Surely in many situations with FF you could double the shutter time instead of increasing the ISO after stopping down to obtain the same DOF on FF as on APS-C? Of course this would often bring too many problems but there must be a fair portion of situations in which it would be fine.
And in landscape, that's exactly what we do. I shoot base ISO and if my exposures is 1/8 second, I don't care. And at base ISO the difference between FF and APS-c is negligible in any case. I keep saying, your best image on APS_c can be as good as your best image on FF. Not always, but for landscape yes, for wildlife with heavy cropping, it can be better. I know everyone wants FF to be better for everything the APS-c is, but, even talking straight IQ, it's not true.

04-04-2015, 07:10 AM   #114
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QuoteOriginally posted by Rondec Quote
What I mean is that full frame is better at the same iso. If you shoot a shot on full frame at 200mm f2.8 and iso 200 and one on APS-C at 135mm f2.8 and iso 200, the full frame shot will have better dynamic range and less noise. The exposure should be the same though (assuming no fudging of the iso). The thing is that full frame shot will have less depth of field than the APS-C shot. In order to have the same depth of field as the APS-C shot, you would have to stop down to f4 and bump your iso to 400, at which point your noise and dynamic range will be equivalent.

That's what I mean when I say that better full frame performance is linked closely to less depth of field. As long as you want the same exposure and same framing, the reason that full frame has better performance is because it has faster equivalent lenses.
Very good!
04-04-2015, 07:13 AM   #115
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QuoteOriginally posted by Rondec Quote
That's what I mean when I say that better full frame performance is linked closely to less depth of field. As long as you want the same exposure and same framing, the reason that full frame has better performance is because it has faster equivalent lenses.
Exactly.... as soon as you have to match depth of field, the performance advantage disappears. So a shooter who does a lot of shooting with wide DOF images will probably be happier on APS-c, smaller , lighter, those tiny LTD lenses and equivalent IQ, unless you want the extra MP.... then you just have to live with FF.

It's funny the difference of opinion, those of us brought up on large format cameras were always struggling to getting enough DoF. I guess with the smaller formats, getting shallow DoF is an issue, for those who want that.

Last edited by normhead; 04-04-2015 at 07:20 AM.
04-04-2015, 07:13 AM   #116
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QuoteOriginally posted by jeff knight Quote
Let's support the Pentax FF and not devolve into warring APS-C and FF camps.
I agree with that. I think the Pentax FF will be a great camera, and I do hope lots of people buy it. Just as I hope lots of people buy other Pentax cameras, lenses. That way the system flourishes and eventually I get better technology for a better price
04-04-2015, 07:15 AM   #117
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QuoteOriginally posted by mecrox Quote
Surely in many situations with FF you could double the shutter time instead of increasing the ISO after stopping down to obtain the same DOF on FF as on APS-C? Of course this would often bring too many problems but there must be a fair portion of situations in which it would be fine.
Yes, good point. The scenario Rondec gave was correct but depends on the scenario being shutter-speed constrained, meaning maybe you can't double the shutter speed because you'll get motion blur.
04-04-2015, 07:17 AM   #118
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QuoteOriginally posted by Rondec Quote
The thing is that full frame shot will have less depth of field than the APS-C shot.
QuoteOriginally posted by Rondec Quote
That's what I mean when I say that better full frame performance is linked closely to less depth of field.

Keeping all variables equal except sensor size which has more DoF?
85mm lens
F/4.0
10' subject distance


What is the DoF the K-3? FF? 645z?
04-04-2015, 07:24 AM   #119
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QuoteOriginally posted by normhead Quote
Exactly.... as soon as you have to match depth of field, the performance advantage disappears.
Note what I underlined, and try to think of how many times you will absolutely *have* to match deeper aps-c DOF or the image will suffer. It's really much, much less often than some people imply, especially when you move into settings windows where some of the 'deep DOF' requirements are handled by hyperfocal effects anyway.
04-04-2015, 07:27 AM   #120
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With regards to the Pentax Full Frame.... I'd encourage anyone who hasn't used one to give it a try if you can afford it. I'd also recommend a 645 sand a 4x5 scanning back. You can never try out too many formats. It just very costly to do so. The one that you settle on if you ever decide to narrow it down to one, might surprise you.

There's obviously less risk if you try out something you already have lenses for. So Pentax having one should be good for those still figuring it all out. But go in looking for improvement where improvements are likely to be realized, and your learning curve will be faster.
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