Equivalence

[Steen Bay]

Crop factor = Teleconverter.

Short enough?

Usual assumptions - same final image size, same scene, same sensor
technology, same processing...

They do exactly the same thing - crop the image from the lens and
make that crop the full image. And everyone knows a 1.4x TC
multiplies both FL and F-stop by 1.4x

A little confusing, but yes. If Joe wants images equivalent to 50/1,2 on 20D, then he just use it with a 1,6x TC on 5D, and a really smart thing would be a 0,6x TC that transformed 50/1,2 to a 31/0,75 on 20D

 

[Hung Pham]

Do you have a link to your pictures that you want to share?
Just curious since you've posted lot of theories, but haven't seen any pics.

 

[Hung Pham]

Thanks for the time and effort writing this.
I really enjoy your pics too.

 

[Lee Jay]

My son:















R/C aircraft:











Full-scale aircraft:









Self portraits:







--
Lee Jay
(see profile for equipment)

 

[Hung Pham]

Now seeing your son's pics, I remember that I must have seen them before.
By any chance, are you working for the Airforce?

 

[Lee Jay]

Now seeing your son's pics, I remember that I must have seen them
before.

Thanks.

By any chance, are you working for the Airforce?

Nope. My research wind turbine:



You'll find me here:
http://www.nrel.gov/wind/

--
Lee Jay
(see profile for equipment)

 

[spencermcchester]

http://www.josephjamesphotography.com/equivalence/

So, the moral of the story is:

For portraits, landscapes and perhaps macro photography, you generally want a larger frame (35mm or larger). For telephoto photography, a somewhat smaller frame sensor may actually be best (1.3 or perhaps even 1.6 crops).

Right?

 

[Lee Jay]

http://www.josephjamesphotography.com/equivalence/

So, the moral of the story is:

For portraits, landscapes and perhaps macro photography, you
generally want a larger frame (35mm or larger). For telephoto
photography, a somewhat smaller frame sensor may actually be best
(1.3 or perhaps even 1.6 crops).

You always want a bigger sensor. There's never any IQ advantage to a smaller sensor. Cost and size are other issues.

On the other hand, when you are either focal length or magnification (as in macro) limited, then smaller pixels can be desirable. Frequently (but not always) smaller pixels can be found on smaller sensors. In other words, if the smaller sensors have smaller pixels, they can give you an advantage when you are either focal length or magnification limited.

--
Lee Jay
(see profile for equipment)

 

[joe mama]

http://www.josephjamesphotography.com/equivalence/

So, the moral of the story is:

For portraits, landscapes and perhaps macro photography, you
generally want a larger frame (35mm or larger). For telephoto
photography, a somewhat smaller frame sensor may actually be best
(1.3 or perhaps even 1.6 crops).

Right?

...that there are a lot of variables. In terms of IQ, the larger the sensor, the better. But in terms of operation, this is not necessarily the case. The FF bodies are larger and heavier, for example. Furthermore, the AF sensors of the 5D are not 1 1/3 stops more sensitive than the AF sensors of the 30D, even though the sensor is, so that puts it at a disadvantage when using glass slower than f / 2.8, especially when TCs are required.

Jumping brands, some of the smaller sensor DSLRs have in-camera IS, something FF does not have, so they get IS on all their primes, for example. In addition, some are weather sealed, whereas to get that on FF you need a 1DsII, which is pretty damned big.

So, the moral is to decide how to balance IQ, operation, and cost, and then make the best choice for you.

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

Please feel free to criticize, make suggestions, and edit my photos. If you wish to use any of my photos for any purpose other than editing in these forums, please ask.

 

[joe mama]

This is the first time I've ever seen most of those! : )

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

Please feel free to criticize, make suggestions, and edit my photos. If you wish to use any of my photos for any purpose other than editing in these forums, please ask.

 

[ed rader]

well that certainly violates my 2-paragraph rule .

ed rader

--



'One often has mixed feelings about relatives, but few people could identify serious problems in their relationships with dogs.'

-- Anonymous

 

[Lee Jay]

This is the first time I've ever seen most of those! : )

I think all but one of those have been posted to dpreview before, at one time or another.

The night-fly helicopter shots are really hard to get.

--
Lee Jay
(see profile for equipment)

 

[spencermcchester]

...that there are a lot of variables. In terms of IQ, the larger the
sensor, the better. But in terms of operation, this is not
necessarily the case. The FF bodies are larger and heavier, for
example. Furthermore, the AF sensors of the 5D are not 1 1/3 stops
more sensitive than the AF sensors of the 30D, even though the sensor
is, so that puts it at a disadvantage when using glass slower than f
/ 2.8, especially when TCs are required.

Also, currently Canon has a 1.3 crop sensor camera that stores 14-bit RAW, which is something no other Canon can do yet. That certainly has an effect on image quality. Even though JPEGs are 8-bit, and some LCDs are 6-bit, that won't be the case forever.

When I see portraits with a 50mm f/1.2 L wide open from a 5D, or with the old 200mm f/1.8 L wide open on a 5D, I can tell it's something I cannot achieve with my XTi. And those are shots I want to capture.

 

[joe mama]

Also, currently Canon has a 1.3 crop sensor camera that stores 14-bit
RAW, which is something no other Canon can do yet. That certainly
has an effect on image quality. Even though JPEGs are 8-bit, and
some LCDs are 6-bit, that won't be the case forever.

Of course, as you realize, the further that sensors differ from the same design and generation, the greater the discrepencies between noise, DR, and other image attributes (save DOF and possibly vignetting) there will be. In any event, I don't know if the 14 bits is about the sensor, or the hardware processing.

When I see portraits with a 50mm f/1.2 L wide open from a 5D, or with
the old 200mm f/1.8 L wide open on a 5D, I can tell it's something I
cannot achieve with my XTi. And those are shots I want to capture.

Me, too! However, there is a cost involved in achieving that look. For most, it's not worth it, and for some, it's not even desirable. It could be done on smaller sensor cameras, but the size and weight of such equivalent fast glass, not to mention the cost, makes the larger sensor system the less bulky and expensive option, by far.

For example, consider my lenses:

24 / 1.4L (actually, currently the 16-35 / 2.8L, but this will change soon)
50 / 1.2L
100 / 2
150 / 2.8 macro

How much would their 1.6x equivalents:

15 / 0.9
35 / 0.8
60 / 1.2
90 / 1.8 macro

weigh and cost? That would be insane! : )

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

Please feel free to criticize, make suggestions, and edit my photos. If you wish to use any of my photos for any purpose other than editing in these forums, please ask.

 

[bad_doggie]

Crop factor = Teleconverter.

Short enough?

Usual assumptions - same final image size, same scene, same sensor
technology, same processing...

They do exactly the same thing - crop the image from the lens and
make that crop the full image. And everyone knows a 1.4x TC
multiplies both FL and F-stop by 1.4x

which alters the exposure, which is not the case for the equivalence joe
is talking about.

tsk tsk LJ, u know better.

just as i know better than to stick my toe in this tar pit agin.

 

[Lee Jay]

It has the same effect on the image. I care more about the image than I do the numbers in the EXIF data.

--
Lee Jay
(see profile for equipment)

 

[xandxor]

thanks!

Bookmarked... for dissemination when necessary.

I also like the "crop-factor" == teleconverter vignette.

 

[joe mama]

I like the addition of the 'per pixel noise' and 'total image noise'.

If I may, let me make some brief comments about what causes a lot of confusion:

1) Confusing "f-ratio" with "aperture"
2) Confusing "per-pixel noise" with "total image noise"
3) Confusing "exposure" with "total light"

Those three concepts, all by themselves, if understood (and that's a huge "if"), will allow most to overcome the obstacles to understanding it all in a clear manner.

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

Please feel free to criticize, make suggestions, and edit my photos. If you wish to use any of my photos for any purpose other than editing in these forums, please ask.

 

[joe mama]

well that certainly violates my 2-paragraph rule .

And, you must agree, it most also certainly beats restating the same thing over and over and over in long posts.

From now on, I just link it. If an unexpected situation comes up, I edit the link, and, voila, problem solved.

Well, assuming the naysayers read, and understand, the essay. Give me odds? : )

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

Please feel free to criticize, make suggestions, and edit my photos. If you wish to use any of my photos for any purpose other than editing in these forums, please ask.

 

[Barugon]

I know it's been talked to death in here, but I've been spending some
time writing and perfecting an essay on it so I can cite a single
comprehensive explanation whenever it comes up.

If there are errors, or points that can be explained better, I'd be
pleased to hear your ideas:

http://www.josephjamesphotography.com/equivalence/

If you increase the size of the sensor and leave the photo-sites the same size then you will have exactly the same amplitude of noise. However, since you now have more photo-sites you now have more noise. That's right, you have a larger volume of noise that is exactly the same amplitude. If you print the image the same size as the smaller sensor all you have done is increased the spatial frequency of the noise.

If you increase the size of the photo-site then, and only then, will you improve the signal to noise ratio (provided the amplification hardware is the same). The notion that a larger surface gives you less noise is false. The same is true of film; if you increase the size the grain remains exactly the same, you just now have more of it.

--
Whoever said 'a picture is worth a thousand words' was a cheapskate.

http://www.pbase.com/dot_borg