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

Started Apr 26, 2013 | Discussions thread
Great Bustard
Forum ProPosts: 23,234
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And there we have it.
In reply to boggis the cat, Apr 27, 2013

boggis the cat wrote:

Great Bustard wrote:

boggis the cat wrote:

Here is part of it (most of it was lost), regarding clear explanation:

Funny you say that, 'cause when I say it much more simply:

Equivalent photos have the same perspective, framing, and DOF, which will result in the same total amount of light falling on the sensor, which will result in the same noise for equally efficient sensors.

Compare that 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.

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.

You have a huge number of former IDs, Joe.  That should tell you a lot about how effective your 'teaching style' is.

I was hoping you would bring that up.  One of my former ID's, "g r e e n p e a" was permanently banned after responding to this post of yours:

http://www.dpreview.com/forums/post/35689971

The entire content of the reply to that post of yours was:

Not just DOF, boggis, but the total amount of light projected on the sensor, which will result in the same noise for equally efficient sensors.

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?

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?

Ratios are not in dispute, nor is the advantage that a larger sensor can yield.  Creating a dispute takes either incompetent exposition or deliberate intent.  (Or both, I suppose.)

Link and quote where I created a dispute.  Again, in the deleted posts, I was able to link and quote where it was you, not I, who was doing exactly that.  Again, please ask if you need the link.

Refer to above two responses.

I'll take that as a "no can do".

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.

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.

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