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10-18-2014, 02:15 AM   #91
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A mode on the 645z to lower its performance to the Q-S1's level? How useful!

10-18-2014, 09:04 AM   #92
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QuoteOriginally posted by Kunzite Quote
A mode on the 645z to lower its performance to the Q-S1's level? How useful!

No, the Q will just start off at EISO 800 and work upwards from there. The 645Z will start off at EISO 80.
10-18-2014, 09:27 AM   #93
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Never heard of EISO, and Wikipedia isn't helping either:
Eiso - Wikipedia, the free encyclopedia
10-18-2014, 09:45 AM   #94
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EISO is pronounced just like ISO, and EF is pronounced just like F. You can use them exactly the same way, too, and there's no reason to mislead customers or have internet debates about which format is better.

10-18-2014, 10:21 AM   #95
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QuoteOriginally posted by rawr Quote
I trust any new Pentax full-frame will have a setting to adjust for 'Equivalence' on the mode dial, and be able to meter for 'Total Light', as well as Matrix, Centre-weighted and Spot.
It's called the aperture control

(It's OK, post-purchase you don't have to understand what it's really doing.)
10-18-2014, 10:28 AM   #96
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QuoteOriginally posted by jsherman999 Quote
It's called the aperture control

(It's OK, post-purchase you don't have to understand what it's really doing.)

I want to take some pics in low light, say, between 150 and 200mm.

Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop? Which will provide the best SNR? Sharpness?

This is a real scenario in which I'm working right now, very-low-light type stuff.



...and it's all post-purchase, and it's relevant to APS-C, FF, whatever.
10-18-2014, 12:05 PM   #97
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QuoteOriginally posted by ElJamoquio Quote
EISO is pronounced just like ISO, and EF is pronounced just like F. You can use them exactly the same way, too, and there's no reason to mislead customers or have internet debates about which format is better.
Something that can be used exactly like ISO 12232:2006? Come on, tell me, what is it?

Do you think it's the lens basic specifications (i.e. just focal length and f-number) that gives you an accurate SNR value and sharpness?
10-18-2014, 02:01 PM   #98
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QuoteOriginally posted by ElJamoquio Quote
I want to take some pics in low light, say, between 150 and 200mm.

Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop? Which will provide the best SNR? Sharpness?

This is a real scenario in which I'm working right now, very-low-light type stuff.



...and it's all post-purchase, and it's relevant to APS-C, FF, whatever.
Yep, good example. But once an equivalence-based decision is baked into the purchase decision, the shooter can also reap benefits from that even when shooting blind thereafter.

For example, not buying that 28-300 f/2.8 "equivalent" superzoom because someone told them it will have the same exposure as an aps-c camera at f/2.8 through that equivalent FL range. Someone not accepting that as the full story is happy thereafter, if IQ matters to them

10-18-2014, 03:41 PM   #99
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QuoteOriginally posted by Kunzite Quote
Something that can be used exactly like ISO 12232:2006?
Yes.

QuoteOriginally posted by Kunzite Quote
Do you think it's the lens basic specifications (i.e. just focal length and f-number) that gives you an accurate SNR value and sharpness?
Wow, you think I'm incredibly, moronically stupid.
10-18-2014, 04:26 PM   #100
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No way, I wouldn't even bother to talk with "incredibly, moronically stupid" people - and I really don't think we have such creatures here on PF.
If anything, you are stubbornly clinging to an idea; and you did say:
QuoteOriginally posted by ElJamoquio Quote
Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop? Which will provide the best SNR? Sharpness?
So... do we really have the necessary elements in order to respond to your question? (and yes, it's a 10%-ish crop you're talking about)
10-18-2014, 05:45 PM   #101
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QuoteOriginally posted by ElJamoquio Quote
Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop?
Assuming we are talking about simple lens choices on one format, here I would start by examining the candidate lenses on DxOMark. I'd start by examining the light transmission info for each lens to see if, in fact, one lens may be 'darker' than the other due to it being (perhaps) an older design or a more complex optical structure, thus negating the real-world value of the wider aperture. A 'dark' f2 lens may effectively function like a f2.8 or f3.2 lens.

I would then look at lens sharpness, at the focal lengths you are interested in using. If the 70-200 is soft wide open at your target focal lengths (eg at 200mm, like the Nikon 70-200 f2.8 VR ED can be), but the 135 f2 prime is sharp across the frame, even wide-open (like the Nikon 135mm f2 is), and the difference is big enough to measure, there may be no acutance loss in cropping the 135 prime output to match the field of view of the 200mm. Or dropping the 135mm onto a crop body.

Last edited by rawr; 10-18-2014 at 05:52 PM.
10-18-2014, 06:00 PM   #102
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QuoteOriginally posted by rawr Quote
Assuming we are talking about simple lens choices on one format, here I would start by examining the candidate lenses on DxOMark. I'd start by examining the light transmission info for each lens to see if, in fact, one lens may be 'darker' than the other due to it being (perhaps) an older design or a more complex optical structure, thus negating the real-world value of the wider aperture. A 'dark' f2 lens may effectively function like a f2.8 or f3.2 lens.

I would then look at lens sharpness, at the focal lengths you are interested in using. If the 70-200 is soft wide open at your target focal lengths (eg at 200mm, like the Nikon 70-200 f2.8 VR ED can be), but the 135 f2 prime is sharp across the frame, even wide-open (like the Nikon 135mm f2 is), and the difference is big enough to measure, there may be no acutance loss in cropping the 135 prime output to match the field of view of the 200mm. Or dropping the 135mm onto a crop body.
Very thorough! Of course if you do all that without also including the simple concept of total light it's like going through the trouble of adding 1.34565783456 + 3.26374527 and then saying the answer is "probably something under 5."
10-18-2014, 09:27 PM   #103
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QuoteOriginally posted by Kunzite Quote
So... do we really have the necessary elements in order to respond to your question?
Yes...
10-19-2014, 05:29 AM   #104
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Thank you for proving my point.
10-19-2014, 07:38 AM   #105
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The answer to my question was quite trivial to find... about fifteen seconds.... because I understand the simplicity of equivalence.


The question posed was rhetorical. I know the answers. The response is "ah yes, equivalence is important, even beyond choosing between camera systems".
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