Opinions on Extenders, please?

[PajamaGuy]

Extender EF 2x III - or the EF 1.4x III.  Same price.  Other than the obvious, why one over the other?  Are the optics equal?

Thanks!

[ebiggs1]

Oh I see you are a DXO fan.  I am not.  I understand where you are coming from better now.

I have made my case. Take it or leave it.

[TTMartin]

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@ebiggs1 wrote:

Oh I see you are a DXO fan.  I am not.  I understand where you are coming from better now.

I have made my case. Take it or leave it.

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I am NOT a DXO fan and think their measurements are biased due to improper decoding of  the CR2 file, but, sometimes their measurements are the best way to illiustrate a point or concept.

I believe I have made my case.

[ebiggs1]

Full disclosure I am guilty fo citing DXO when it suits or supports my case.  I really don't like DXO.  I will make a gallant effort to avoid doing that in the future.  DXO is agenda driven and really only shares info they want to.

I am not going to debate people who do cite them either.  At least we can remain cordial.  We simply have disagreed on this subject.  This is what I really took exception to, "... the 7D Mk II ... already captures one stop less total light tnan a full frame camera."   But I do believe we are saying nearly the same thing.  Only in a different way.

All the best to you.

[RobertTheFat]

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@ebiggs1 wrote:

Full disclosure I am guilty fo citing DXO when it suits or supports my case.  I really don't like DXO.  I will make a gallant effort to avoid doing that in the future.  DXO is agenda driven and really only shares info they want to.

I am not going to debate people who do cite them either.  At least we can remain cordial.  We simply have disagreed on this subject.  This is what I really took exception to, "... the 7D Mk II ... already captures one stop less total light tnan a full frame camera."   But I do believe we are saying nearly the same thing.  Only in a different way.

All the best to you.

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Here's one point on which we can possibly all agree:

Suppose we define "a" as the amount of incident light falling on an APS-C sensor. Assuming a constant aperture and strength of the light source, the amount of incident light falling on a full-frame sensor is 1.6a, because its surface area is 1.6 times as great. If one insists on expressing that difference in "stops", it's a lot closer to a half stop (1.414a) than it is to a full stop (2a). FWIW.

[TTMartin]

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@RobertTheFat wrote:

Here's one point on which we can possibly all agree:

Suppose we define "a" as the amount of incident light falling on an APS-C sensor. Assuming a constant aperture and strength of the light source, the amount of incident light falling on a full-frame sensor is 1.6a, because its surface area is 1.6 times as great. If one insists on expressing that difference in "stops", it's a lot closer to a half stop (1.414a) than it is to a full stop (2a). FWIW.

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No it is slightly more than 1 full stop, for the same reason a 1.4X TC is one stop and a 2X TC is 2 stops.

It is actually 1.6 squared times a. The 1.6X applies to the length and the width, not just the area. So it is (2.56a) a full stop+.

[ebiggs1]

Bob from Boston,

"Who are those "others" on Tom's side of the argument?"

This is an old concept.  I guess there might be a smidgen of sense here but not what Mr. Martin is claiming.  As I understand him anyway. I have had this debate before (several times) almost as soon as the term "crop camera" was created.  I have discussed it extensively with my buddy Tom Martinez, who was also a Hallmark photographer.  He is an optical expert and gives many lectures.

[ebiggs1]

BTW, the image circle, that you displayed, of the lens is not relevant.  That is the total amount of light in the mirror box.  It has nothing to do with what each pixel receives.  Both sensors, FF and crop, ignore light that falls outside of their individual realm. The total amount of light that falls on each pixel is the same.

[jrhoffman75]

Question for TTMartin.

APS-C crop sensor cameras are called that because the sensor size is close to the APS negative size in the film days.

If what you says holds true about light and area was ISO 100 APS film ISO 200 35mm film cut down in size and rebranded as ISO 100?

[TTMartin]

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@jrhoffman75 wrote:
Question for TTMartin.

APS-C crop sensor cameras are called that because the sensor size is close to the APS negative size in the film days.

If what you says holds true about light and area was ISO 100 APS film ISO 200 35mm film cut down in size and rebranded as ISO 100?

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See Tim's post about how the enlargement process comes into play when you are talking about a completely analog film process. To make the same size print when you are using smaller pieces of film the enlarger head has to be further away, when the enlarger head is further away, you have to increase the exposure time. So while the difference in film size didn't impact the exposure while you were taking the photo, it did impact the exposure when you were making the print.

edit: Were prints from APS film just as good as prints from 35mm film with the same ISO? Are prints from 35mm film just as good as prints form medium format film with the same ISO? 

[jrhoffman75]

Don't bring enlarging into it. A properly exposed negative is a properly exposed negative.

If the APS-C digital sensor needs more amplification to expose properly at a given ISO, f/stop and shutter speed compared to full frame how did APS-C film accomplish that?