MichaelJP

MichaelJP

Lives in United States Palo Alto, CA, United States
Works as a Scientist
Joined on Dec 2, 2003

Comments

Total: 8, showing: 1 – 8
On What is equivalence and why should I care? article (2071 comments in total)
In reply to:

rfsIII: There must be an professor of imaging science out there somewhere who can be hired by DPR to write a nice counterpoint article that will untangle this topic and bring sanity to what is essentially a holy war between two under-informed camps. I would start at http://www.rit.edu/cos/optics-rit and work westward from there.

yes you have; and that is the sensor performance at different ISO,
that is how the sensor behaves with more amplification of the signal from each pixel. It was not so long ago that most sensors would not be used over ISO 400 as the sensor noise would become very noticeable. So perhaps now with the extremely good performance of sensors at low and medium ISO, your suggestion might seem to be a reasonable test, strictly it is not.

Direct link | Posted on Jul 14, 2014 at 10:49 UTC
On What is equivalence and why should I care? article (2071 comments in total)
In reply to:

lumigraphics: Sorry but you guys botched a bunch of this. :sigh:

"Total light" is completely unimportant. Yes, there is less light hitting a smaller sensor, but it doesn't matter because its a smaller total area. Light PER SENSEL is the same.

And lenses don't matter at all. Given a frame-filling grey card (as an example) a 50mm f/4 and 100mm f/4 will give exactly the same 18% grey image on any sensor size. If lenses didn't work that way, you couldn't have external light meters.

Larger digital formats aren't less noisy because they are larger so they collect more light, its because they can have a lower sensel density. In the film days, it was because you didn't have to enlarge so much with a bigger negative.

smdh...and I'm only on page 2.

@Richard Butler

You actually do mention pixels by implication.
The moment you introduce the word image there is an implication that pixels are involved. The only useful measure, Equivalency or otherwise, of Total Light is when normalized by the pixel area, otherwise Total Light captured as a standalone metric without the inclusion of number of pixels is irrelevant to the quality of an image with respect to the lens' F-number or sensor size.
There is one scenario where Total Light becomes a useful metric and that is where you wish to decide maximum printing size, with equivalent noise and resolution, but this still includes the need to consider pixels.

Direct link | Posted on Jul 10, 2014 at 08:34 UTC
On What is equivalence and why should I care? article (2071 comments in total)
In reply to:

rfsIII: There must be an professor of imaging science out there somewhere who can be hired by DPR to write a nice counterpoint article that will untangle this topic and bring sanity to what is essentially a holy war between two under-informed camps. I would start at http://www.rit.edu/cos/optics-rit and work westward from there.

the problem with your comparison is that now you have introduced a non-optical variable - that is the sensor characteristics.
It still remains interesting as a comparison, but not for noise or resolution, unless you wish to compare characteristic between two sensors.

Direct link | Posted on Jul 10, 2014 at 08:09 UTC
On What is equivalence and why should I care? article (2071 comments in total)
In reply to:

SouthElginDad: I don't understand why "total light hitting the sensor" matters. The image is captured by pixels, not by the entire sensor. It seems to me that total light -- per pixel -- is roughly the same, whether or not there are more total pixels on a larger sensor. (Granted, a smaller sensor may have smaller pixels in order to maintain resolution, but that's not what this article is saying -- it's saying that the total light hitting the entire sensor, regardless of how many pixels are on that sensor, is what matters.)

I get the part about the DoF, that makes sense. But I don't understand why total light on the entire sensor makes any difference.

Well, I still do not understand, or i do but feel there is one missing point.
Indeed a larger sensor that uses a lens with the same f-number will capture more total light and true, if you divide that sensor into a high resolution 4-pixel camera each pixel will capture more light, but only by virtue of the pixels being bigger.
If the larger sensor has 16 pixels compared to the ½ size sensor having 4, then the light capturing equivalency is the same.

I think the article is confusing when it discusses this as for the photographer is is irrelevant how much the total light the sensor captures, but that for noise considerations it is really the light per pixel that determines the performance.
It still comes out that in general a larger sensors has better noise characteristics as, for example the pixel numbers for a 35mm sensor is about 24 - 36 million, while a 4/3 sensor is 16 million, so in real life you do get better performance from the larger sensors as their pixels are bigger.

Direct link | Posted on Jul 9, 2014 at 09:22 UTC
In reply to:

Timmbits: I'm not on MFT, but MFT sure gets a nice lens.

Bring out a 20mm f1.2 (40mm equivalent) and I might just take a look at the MFTs.

If your equivalency statements are referring to the light gathering performance then you are incorrect. f/1.4 is equal to f/1.4 on any system
If you are referring to depth of focus then you have a mild argument as a depth of field at f/1.4 or f/0.7 are both very shallow.

Direct link | Posted on Jan 7, 2014 at 09:47 UTC
On Panasonic DMC FZ200 preview (155 comments in total)

Correction: I do believe it was the FZ1 that was the pioneering camera
that created the modern superzoom category for Panasonic.
I still have mine and I still love its more angular shape. 12x with f2.8.

Kudos to Panasonic for developing the FZ200 with the constant aperture f2.8.

Direct link | Posted on Jul 18, 2012 at 16:31 UTC as 54th comment
On Images of Panasonic GF5 start to appear article (118 comments in total)
In reply to:

Almeida: Is this an editorial change that's here to stay? Will we start to have rumors on DPReview?

I would rather not have DPR cite rumours.
I would rather they maintain their tradition of timely news
and early previews.

Direct link | Posted on Mar 20, 2012 at 03:52 UTC
On Antonov 225 Mriya visits Eindhoven in the AIRLINERS challenge (3 comments in total)

...soon it might be a two off...
as another airframe could possibly be finished

Direct link | Posted on Nov 25, 2009 at 03:46 UTC as 2nd comment
Total: 8, showing: 1 – 8