SURVEY - Do FT / mFT users know the difference from "full frame"? Replies wanted!!

Started Apr 26, 2013 | Discussions thread
boggis the cat
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Compare your explanation to DPR's
In reply to Great Bustard, Apr 27, 2013

Great Bustard wrote:

boggis the cat wrote:

Great Bustard wrote:

Did you, or did you not, say that my explanations were too long and incomprehensible?

An earlier bit from my response to the 'disappeared' post:

Compare the careful and clear wording that DPR used to explain what they meant with respect to the utility of the fast Sigma lens on APS-C with your rambling and incoherent website.

Here's what it says on my "rambling and incoherent website":

http://www.josephjamesphotography.com/equivalence/index.htm#introduction

A 50mm f/1.4 lens is a 50mm f/1.4 lens regardless of the sensor that sits behind it.  However, the effect of 50mm f/1.4, in terms of the visual properties of the recorded photo, depend very much on the sensor that sits behind the lens:

25mm f/1.4 on mFT (4/3) is equivalent to 31mm f/1.8 on 1.6x (Canon APS-C), 33mm f/1.9 on 1.5x (APS-C for everyone else), and 50mm f/2.8 on FF (FX), where "equivalent to" means:

  • The photos all have the same AOV (diagonal angle of view) and aperture (entrance pupil) diameter: 25mm / 1.4 = 31mm / 1.8 = 33mm / 1.9 = 50mm / 2.8 = 18mm.

  • The photos all have the same DOF (as well as diffraction softening) when they have same perspective (subject-camera distance), AOV, aperture diameter, and display size.

  • The photos all have the same motion blur and the same total amount of light falls on the sensor when the aperture diameter and shutter speed are the same. which means the larger the sensor, the lower the exposure (same total light over a larger area) and thus a higher ISO setting for a given brightness).

  • The photos all have the same same noise when the same total amount of light falls on the sensor if the sensors are equally efficient (less noise if the sensor is more efficient, more noise if the sensor is less efficient).

  • Other elements of IQ, such as resolution, bokeh, flare resistance, etc., as well as elements of operation, such as AF speed/accuracy, size, weight, etc., are not covered in this use of the term "equivalent".

Now we have a context for what you consider "rambling" and "incoherent".  I must say, this seems to support what I've been saying about your "perspective" all along.

That appears to be just a small part of the 'introduction' to your rambling and incoherent website.  (This part is fairly coherent now, though.)

Once more, compare this to DPR's explanation:

Sigma's choice of F1.8 as maximum aperture isn't a coincidence; it means that the lens will offer the same control over depth of field as an F2.8 zoom does on full frame. What's more, it will also offer effectively the same light-gathering capability as an F2.8 lens on full frame. By this we mean that it will be able to project an image that's just over twice as bright onto a sensor that's slightly less than half the area, meaning the same total amount of light is used to capture the image. This is important as it's a major determinant of image quality. Essentially it means that APS-C shooters will be able to use lower ISOs when shooting wide open in low light and get similar levels of image noise, substantially negating one of the key advantages of switching to full frame.

You could split that paragraph up into the two points like this:

Sigma's choice of F1.8 as maximum aperture yields the same results as an F2.8 zoom on 135.

  • This lens will offer the same control over depth of field as an F2.8 zoom does on 135.
  • It will also offer effectively the same light-gathering capability as an F2.8 lens on 135.  This is important as it's a major determinant of image quality due to producing similar levels of image noise(It will be able to project an image that's just over twice as bright onto a sensor that's slightly less than half the area, meaning the same total amount of light is used to capture the image.)  Essentially it means that APS-C shooters will be able to use lower ISOs when shooting wide open in low light and get similar levels of image noise, substantially negating one of the key advantages of switching to full frame.

It is the effect covered by the second bullet point that is your particular obsession.  Notice that they didn't have to even mention 'perspective' or 'framing', and 'DOF' has been relegated to a separate note.

Now really, is your explanation easier to understand?

Funny how I was permanently banned for posting that, don't you think?  'Course, that was back in the day when Phil Askey was running the show, and, well, he had problems with not only Equivalence, but understanding pixel density as well.

You were more likely banned for immediately opening a new account after getting banned for misbehaving when using the former.

Quite the coincidence that I was found out while "misbehaving" by responding to your post by explaining that Equivalence was not just about DOF, but the total amount of light projected on the sensor.

I did notice that when you relented and started using a complete explanation for what you mean by 'equivalence' there were suddenly no arguments in the offing.

What you say, and what happened, are two different things, boggis.  Unless you can link and quote an example, I'll just have to say it's another example of someone intentionally misrepresenting me.

If I spend the time hunting down an example you'll simply dispute it.

We'll never know until you post an example.  Would you like me to post one?

Check your database for when you started posting your clarified 'equivalence statement' (recall that rather long thread where I convinced you to amend your usual 'short form' statement?), and look at the responses (and lack of arguments) from that point.

If people understand what you are saying, you'll find that most will have no objections to it, and no objections around the simple ratios involved.  In fact, most people simply understand that larger sensor systems have an advantage based on their light gathering capability, and if you tell them that this is 'two stops' between FT and 135 they will not be particularly surprised.

People are not stupid, and they will acknowledge facts quite readily when they are clearly explained.

Boggis, in the deleted posts, I linked you acting exactly opposite that.  Would you like me to link it again?

Go ahead.  I won't respond though, because it appears that the moderators must be a reincarnation of 'Phil Askey'.

Note to mods:  he did say, "Go ahead."  My, my -- so many to choose from.  Well, let's go with the same from last time.  Here's my OP:

http://www.dpreview.com/forums/post/39612858

Dynamic Range -- what it is, what it's good for, and how much you 'need'

Click on it.  It's a technical thread.  Here's your entry into that thread:

http://www.dpreview.com/forums/post/39616072

What Joe's good for, and how much we don't need him

Hmm.  What does this tell us?

I expect it will 'tell you' something different from me.  Let others trawl through your selected example and see what they make of it, should they so desire.

The OP here is testing your claim that, for some reason, users of small sensor systems are ignorant of the advantages of larger sensors.  I suggest that you let him gather his evidence then you can debate him with your evidence to the contrary.

Honestly, I have no special knowledge of what mFT users know or don't know.  But I do know what I've said, and I do know what you've said.  And let's just say that the evidence clearly supports my side.

However, if you disagree, please, post a link and quote of me making Equivalence "too complicated" or "unclear".

Refer to my reinstated reply above, where I explain why your 'explanation' is both poor (for choosing secondary factors -- "perspective", "framing", "DOF"; when referring to light?)... and misleading (due to those secondary factors causing the reader to focus on them, and missing the actual point: which is about the differing practical effect of exposure on different size sensors).

Classic!  Absolutely classic!  Equivalent photos are photos with the same perspective, framing, DOF, shutter speed, and display size.  A consequence of Equivalent photos is that the same total amount of light will fall on the sensor.  A consequence of the same total amount of light falling on the sensor is that the noise will be the same for equally efficient sensors.

This is where you seem to take a backward view, starting at an 'equivalent photograph' then working back toward the actual point.  (Notice how DPR don't need to do so.)

It makes a lot more sense to simply understand that twice the sensor area ('all else being equal') yields a 'one stop' advantage -- and you get 'one stop' for each extra doubling in area, and proportionately less for a smaller increase, such as from FT to an APS-C variant (two-thirds to three-quarters of a 'stop', essentially).  You can choose to use that advantage by raising the ISO setting, closing down the aperture, reducing the exposure time, or any combination thereof.

Starting from 'same perspective, framing, DOF' while omitting that the comparative advantage in IQ comes from the exposure is daft.

Let's recall your entry into this thread:

http://www.dpreview.com/forums/post/51360288

If they are explained correctly, then nobody disputes facts

Huh.  How about that?

I understand that you disagree, but there is a good reason why 'your genius is not being recognised' -- this seems to be your actual beef.  You'd be better served working on your explanatory methods instead of attempting to start arguments.

Quoting again from your entry into this thread:

The problem is not that most people are ignorant fools, the problem is that some people tend to make simple things convoluted and indecipherable (then resist fiercely when you try to get them to explain what they are on about in comprehensible terms).

I'm seeing a pattern here.

Well, if the "pattern" is that only a select few can decipher what you are talking about, perhaps take a lesson from DPR's approach to explaining how a brighter lens on a smaller sensor system 'closes the advantage' with a larger sensor system.

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