Lee Jay

Lee Jay

Lives in United States CO, United States
Works as a Electrical Engineer / Wind Energy Research
Joined on Oct 17, 2003

Comments

Total: 624, showing: 201 – 220
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On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mostlyboringphotog: Lastly, F-stop is useful because it indicates "equivalent" amount of light passing per unit time/area regardless of FL or the aperture diameter. Now by creating another derivative, what does it help?

Does it really help to normalize lens performance or its relative merits?

A lot of posters think so and so may be it's useful but I think it comes at a cost of mudding the definition of "F-stop" and understanding DOF.

Is there not a better way to communicate the difference that a sensor size affects your image making?

Again, thank you all for your patience.

It just says half size. It doesn't say if that's linear or areal, and it obviously means linear (i.e. 2x crop).

Direct link | Posted on Jul 8, 2014 at 20:20 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

Lights: I kinda think products like the Metabones adapters for APS-C and M43 are an interesting side-track in the Equivalence debate.

They do, just in reverse. Teleconverter and wideconverter are the same except for which side of "1" you're on.

Direct link | Posted on Jul 8, 2014 at 19:04 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mostlyboringphotog: Lastly, F-stop is useful because it indicates "equivalent" amount of light passing per unit time/area regardless of FL or the aperture diameter. Now by creating another derivative, what does it help?

Does it really help to normalize lens performance or its relative merits?

A lot of posters think so and so may be it's useful but I think it comes at a cost of mudding the definition of "F-stop" and understanding DOF.

Is there not a better way to communicate the difference that a sensor size affects your image making?

Again, thank you all for your patience.

I have a little drawing that's supposed to relate that idea to people:

http://photos.imageevent.com/sipphoto/samplepictures/Format%20drawing.jpg

Direct link | Posted on Jul 8, 2014 at 18:30 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mostlyboringphotog: Lastly, F-stop is useful because it indicates "equivalent" amount of light passing per unit time/area regardless of FL or the aperture diameter. Now by creating another derivative, what does it help?

Does it really help to normalize lens performance or its relative merits?

A lot of posters think so and so may be it's useful but I think it comes at a cost of mudding the definition of "F-stop" and understanding DOF.

Is there not a better way to communicate the difference that a sensor size affects your image making?

Again, thank you all for your patience.

Equivalents are about comparing systems using different formats They aren't about setting exposure in your camera.

Direct link | Posted on Jul 8, 2014 at 15:34 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mostlyboringphotog: Lastly, F-stop is useful because it indicates "equivalent" amount of light passing per unit time/area regardless of FL or the aperture diameter. Now by creating another derivative, what does it help?

Does it really help to normalize lens performance or its relative merits?

A lot of posters think so and so may be it's useful but I think it comes at a cost of mudding the definition of "F-stop" and understanding DOF.

Is there not a better way to communicate the difference that a sensor size affects your image making?

Again, thank you all for your patience.

The important parameters for a lens (the ones that control the image) are angle-of-view and aperture diameter. Yet, we specify focal length and f-stop instead. To get back to what matters, use equivalence. This assures that the angle-of-view is specified (in 35mm equivalent terms) and the the aperture is specified correctly through the equivalent f-stop.

Direct link | Posted on Jul 8, 2014 at 14:35 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mislav: I don't care

"I won't shoot 8x10" and 35 mm to get same size print."

Rational people know that the final print size is often dictated by the customer, not the photographer, and that it's choice has nothing to do with the format used in the camera.

No one is redefining f-number.

f-number = focal length / aperture

If focal length is referenced to 35mm as a base, instead of using optical focal length, then the equation becomes:

f-number (equivalent) = focal length (equivalent) / aperture

The problem comes in when people use an equivalent focal length but not an equivalent f-number (which is what's often done with compact cameras), since that DOES redefine the equation, since the aperture is no longer the actual entrance pupil diameter.

Direct link | Posted on Jul 8, 2014 at 14:32 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mislav: I don't care

mislav, you're extremely lost. At the same final size, you most certainly would get finer grain on the 8x10 contact print than you would on the 35mm enlargement.

Read the article. It's absolutely accurate, and it's been repeatedly verified as accurate by actual tests. If you think it's wrong, than it's your thinking that's wrong.

Direct link | Posted on Jul 8, 2014 at 14:02 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mostlyboringphotog: Lastly, F-stop is useful because it indicates "equivalent" amount of light passing per unit time/area regardless of FL or the aperture diameter. Now by creating another derivative, what does it help?

Does it really help to normalize lens performance or its relative merits?

A lot of posters think so and so may be it's useful but I think it comes at a cost of mudding the definition of "F-stop" and understanding DOF.

Is there not a better way to communicate the difference that a sensor size affects your image making?

Again, thank you all for your patience.

The concept of an f-stop is already very "muddled" in the minds of many people. Just look down at how many people think that f-stop defines the amount of light that passes through the lens and onto the sensor, when it actually controls the light intensity (illuminance) instead.

Direct link | Posted on Jul 8, 2014 at 13:31 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

mislav: I don't care

How can the truth be BS?

Direct link | Posted on Jul 8, 2014 at 12:01 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

WT21: Incredibly useful concept that sadly leads to some of the most boring and droning discussions on photo forum boards.

Good article that will hopefully clear it up for most.

I discovered (or, rather, rediscovered) equivalence on my own in 2005, and it has guided my purchases and shooting when using multiple formats ever since.

Direct link | Posted on Jul 8, 2014 at 12:01 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

Lights: I kinda think products like the Metabones adapters for APS-C and M43 are an interesting side-track in the Equivalence debate.

Why?

Want a short explanation of equivalence?

Crop factor = teleconverter.

Likewise, 1/crop factor = wide converter.

Direct link | Posted on Jul 8, 2014 at 11:56 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

hybert46: So finally what is the more compact, potentially cheapest or easiest lens to produce, a FF 100mm f/4 or a m43 50mm f/2? Both should have a roughly similar size of entrance pupil as it is defined by the ratio of focal length over the f-number. Anyone care to elaborate on this, could be interesting!

A lens need not be as long or longer than its focal length. In fact, the definition of a telephoto lens is a lens that's shorter physically than its focal length.

To answer the question, in most cases for equivalent kits, the larger sensor Lena system is smaller and cheaper.

Direct link | Posted on Jul 8, 2014 at 11:51 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

WT21: Incredibly useful concept that sadly leads to some of the most boring and droning discussions on photo forum boards.

Good article that will hopefully clear it up for most.

It's common for me to shoot with a 24-105/4 on full frame at ISO 1600 and simultaneously shoot with a 70-200/2.8 on crop (112-320/4.5 equivalent) at ISO 800, for this reason.

Direct link | Posted on Jul 8, 2014 at 02:31 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

Lee Jay: "Any two lenses 25mm diameter apertures will give the same depth-of-field of shot at the same shooting distance."

This sentence is still incorrect, Richard.

That works.

Direct link | Posted on Jul 8, 2014 at 02:29 UTC
On What is equivalence and why should I care? article (2130 comments in total)

"Any two lenses 25mm diameter apertures will give the same depth-of-field of shot at the same shooting distance."

This sentence is still incorrect, Richard.

Direct link | Posted on Jul 8, 2014 at 02:04 UTC as 268th comment | 6 replies
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

gtstone: The title of this article took me back to 1966-1967 when I took workshops with Minor White. One of his big themes was the concept of "equivalence" (or sometimes "equivalents") where he would show us image after image of clouds and try to get us to understand that the image of a cloud-scape was "equivalent" to a feeling he wanted to convey. Similarly sea-scapes and rocks.

Here's a link about this:
http://jnevins.com/whitereading.htm

He never talked about photographic technique: he had lab assistants to help us with that. What he wanted to talk in about in class was how we would respond to a print (as opposed to "react").

Another frequent theme was pre-visualization: you don't look for something interesting to photograph, you look for something that will make an interesting photograph. You look around and pre-visualize what a print of what you see before you would look like considering all the steps to get there. I often wonder what he would have done with with Photoshop!

You're assuming finding something that will make an interesting photograph is the goal. What if the subject is already known and fixed? You find an interesting way to photograph it.

Direct link | Posted on Jul 8, 2014 at 00:23 UTC
On What is equivalence and why should I care? article (2130 comments in total)

The article has correct information. If you think the article is wrong, you should read it and learn rather than helping to perpetuate your own false ideas.

Direct link | Posted on Jul 7, 2014 at 19:44 UTC as 311th comment
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

photoguy622: Let's not forget the flip side, that a smaller sensor has the benefit of having a great area in focus.

"Stop down a large-sensor system and, so long as the lens will stop down far enough, you can get the same depth-of-field (and you'll get the same diffraction)."

You don't even need the "so long as..." part. This is because all SLR lenses that I know of are capable of putting you way, way out into diffraction-limited territory. Therefore, if you are already stopped down all the way and need even more DOF, you can just shorten the focal length and get even more DOF without the normal loss of resolution you get from cropping the result. This is because the resolution is lost anyway to diffraction. In other words, you weren't pixel-limited, you were diffraction limited.

Direct link | Posted on Jul 7, 2014 at 19:31 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

lacikuss: Excellent article...

So why then a Sony RX-100 III is priced at $850? It should cost $450 according to this article...

There is no "depth of field advantage", as it states in the article.

Direct link | Posted on Jul 7, 2014 at 19:25 UTC
On What is equivalence and why should I care? article (2130 comments in total)
In reply to:

Alberto Franco: Hi. in General DPReview is a very good site, and while i think The crop factor is an accurate concept to understand the equivalence of focal lenght. the Fnumber equivalence you are trying to explain is BiG mistake since you are mixing apples and oranges. The Fnumber makes refference to the amount of light a lens allows to pass through NOT the amount of deep of field. So say an F2 lens in MFT is equivalent to an F4 FF lens is like saying that you need F2 in MFT to make the same exposition of F4 on a FF and that is TOTALLY wrong. So, what is equivalent is the DEEP OF FIELD, this way you can certainly say to produce the same deep of field of an F4 on FF you need an F2 on MFT.

F-stop = focal length / aperture

F-stop controls the light per unit of area (illuminance) at the sensor plane.

Aperture (for a given angle of view) controls the total light that is passed through the lens.

Direct link | Posted on Jul 7, 2014 at 19:11 UTC
Total: 624, showing: 201 – 220
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