Author Topic: 'People Are Confusing Two Things..' (Read 2776 times)

Panther · « **on:** July 05, 2011, 12:10:12 PM »

"Crop-Factor" & "Zoom Factor" (if there is a such a thing).
Folks hear "600mm 35mm equivalent lens" & think they're getting 600 zoom instead of 600 crop......

popo · « **Reply #1 on:** July 05, 2011, 12:15:36 PM »

You mean zoom ratio? I do find it difficult to explain the concept of focal length instead of "zoom" multiple to compact users when they ask...

adash · « **Reply #2 on:** July 05, 2011, 12:31:27 PM »

People are so used to comparing zoom ratios that they miss to hear that it is not zoom ratio that you are talking about....

E-M5 Pete · « **Reply #3 on:** July 05, 2011, 01:18:19 PM »

I have perfered compairing the wide end to the tele end and then it makes more sence..

14-42 is a 3x zoom ratio, BUT, at 42mm it has the same FOV/Crop of a 84mm on a 35mm FF camera. IE: just shy of a 2x magnification compared to a normal 25mm lens. Which is our eyes viewpoint, or 1x magnified view.

I blame the marketing for this. My wife a 12x zoom with her p/s, but, in terms from starting at the considered normal lens FL, it has a reach of just over 7x, from the 24mm fov though, the tele end of 300mm fov, it is a 12x from one end to the other. But is not a 12x magnification as far as measured from a normal lens. (our eyes viewpoint), The long end is like a 7x binocular view.

voyager · « **Reply #4 on:** July 05, 2011, 01:22:11 PM »

I honestly don't even get why there are numbers on the lens to begin with, especially now that full frame isn't the main standard anymore.

Panther · « **Reply #5 on:** July 05, 2011, 01:32:46 PM »

Quote from: voyager on July 05, 2011, 01:22:11 PM

now that full frame isn't the main standard anymore.

Main standard for what?

voyager · « **Reply #6 on:** July 05, 2011, 01:45:07 PM »

Er, I suppose I should rephrase that. Full Frame isn't the most prominent sensor size used by manufacturers now.

popo · « **Reply #7 on:** July 05, 2011, 01:56:55 PM »

The use of full frame equivalents has been a pet hate of mine for a long time, but only tolerated since it is in effect the default standard for comparing across systems. I guess the problem with what might be a more popular alternative "APS-C equivalence) comes from that Canon are a bit different from Sony/Nikon, and if you really want to be picky they're different between themselves too depending on the model and age. Old 35mm is the nearest thing we have to a stable reliable standard.

Back on the zoom ratio, of course they're defined as the multiplier from shortest to longest focal lengths, but the difficulty comes when the widest may not be the same. I think 28mm equiv. is common on cheaper models, with better models starting around 24mm equiv. While I guess the use of a standard reference would mitigate that, you'd then have difficulty expressing the wide end. What would you describe that as? Unzoom? Wide factor?

It sucks, but it is the least worst of what we have short of making compact users understand focal length and crop factor conversion.

Panther · « **Reply #8 on:** July 05, 2011, 01:57:28 PM »

Quote from: voyager on July 05, 2011, 01:45:07 PM

Er, I suppose I should rephrase that. Full Frame isn't the most prominent sensor size used by manufacturers now.

It never was the most prominent in terms of volume..

popo · « **Reply #9 on:** July 05, 2011, 02:01:17 PM »

Quote from: Panther on July 05, 2011, 01:57:28 PM

It never was the most prominent in terms of volume..

I'd dare say it was just before digital came along. There's a lot of old photographers out there...

E-M5 Pete · « **Reply #10 on:** July 05, 2011, 02:11:07 PM »

Most of us still have 35mm as a standard to compare other formats to... but, in a few generations, every one will have a multiple formats in our heads, all standard for the format we are using.

So, those people will say 14mm w/o saying "the fov of a 28mm on a 35mm" they will just know the fov is 75* on their m4/3.

Panther · « **Reply #11 on:** July 05, 2011, 02:36:16 PM »

Quote from: popo on July 05, 2011, 02:01:17 PM

I'd dare say it was just before digital came along. There's a lot of old photographers out there...

True...
After digital emerged when DSLR's became affordable (D50/D70) no longer prominent in volume...

yotsuba · « **Reply #12 on:** July 05, 2011, 04:03:34 PM »

I have full frame, APS-C and M4/3 sensor cameras, each camera has its own usefulness.

For birding, I use my D90. I will not use my full frame D700 for birding simply because I need the 1.5x crop factor. I don't use my EPL1 for birding as I need the optical VF, overall speed and ease of use.

Other than that, the EPL1 is the camera I grab everytime because its small and light and the colours are just so pleasingly natural.

yotsuba · « **Reply #13 on:** July 05, 2011, 04:09:47 PM »

This is a comparison between full frame and m4/3 sensor.

A full frame camera with a 100mm lens and a m4/3 camera with a 50mm lens. Both cameras were at the same distance from the subject.

This is what the crop factor is all about; x2 crop factor.

E-M5 Pete · « **Reply #14 on:** July 05, 2011, 04:35:51 PM »

Yes, you achieve the same thing by cropping a ff 50mm fov lens to be a 100mm fov

Expect the DOF will be different as your example shows... a 50mm f/2.8 has the same fov as FF 100mm at f/2.8, BUT the DOF of the 50mm f/2.8 (m4/3) is like the DOF of the FF 100mm at f/4. Bit, since you used f/2.8 for both, the 100mm at f/2.8 on a FF, has less DOF.
And, many people confuse this also, thinking they are [losing 2 f/stops of light]. F/2.8, is f/2.8 on any lens as far as light gathering power. because, the iris opening will change according to the focal length, not the sensor size... IE: F/2 on a 100mm (Any format: m4/3, 35mm 6x6) will have a opening of 50mm. The lens may be larger or smaller because of the image circle required by the format, but the iris opening will always be 2/100mm = 50mm opening at f/2

f/2 on a 200mm lens has an iris opening of 100mm, it is still f/2, and lets in the same amount of light as the 100mm lens at f/2, even though the opening is larger. The 200mm telephoto will lose light at double the focal length of the 100mm lens (Inverse square law involved here, with FL other than 1/2x or 2x, the law still applies. I just used 100 and 200 to keep it simple),
2/200mm = 100mm opening at f/2

Panther · « **Reply #15 on:** July 05, 2011, 04:56:09 PM »

Yes but how many people moving up from P&S really understand this?
They think they're getting 600 zoom with a 300 lens

E-M5 Pete · « **Reply #16 on:** July 05, 2011, 05:33:09 PM »

Quote from: Panther on July 05, 2011, 04:56:09 PM

Yes but how many people moving up from P&S really understand this?
They think they're getting 600 zoom with a 300 lens

Not a lot, I'd think, unless they are proficient in photography as one who understands the "why's and wherefore's" of the mechanics of how it all works together. And, there are many degrees of understanding also as one learns the mechanics of photography.

But, many just what to have a better camera that can deliver a better IQ, that's all that matters. And that is OK also.
We, that have a deeper understanding, will be able produce repeatable results over and over, and be able change the camera's options to get a desired result, over and over, because we will know the Why and How to do. And that is OK also.

cosinaphile · « **Reply #17 on:** July 05, 2011, 05:37:54 PM »

i will always think in terms of 35 mmm equivilancies , just as i will always
think of distances in miles and 32 degrees as freezing\212 as boiling...its how i learned , and i cannot seem to un learn it, as i do not want to un learn it

ratobuhler · « **Reply #18 on:** July 05, 2011, 06:56:31 PM »

The 35 mm reference is only meaningful to us old guys that actually used (or are still using) 35 mm Film.

count_zero · « **Reply #19 on:** July 05, 2011, 08:37:11 PM »

Quote

Yes but how many people moving up from P&S really understand this?
They think they're getting 600 zoom with a 300 lens

I hope you're joking. 4/3 sensor and 300mm lens will get you a 12MP photo equivalent to FF 12MP using 600mm lens. Call it 2x crop or crap or zoom or whatever. Point is I can buy a Panasonic 100-300mm f4-5.6 m43 lens for $500 vs a 600mm f4 Nikon lens will cost somewhere around $10,000. Not to mention the 300mm m43 lens will fit in my murse, and I can hold it with one hand.

Is the image quality better? Probably not, but it is better than using 300mm lens on a FF 12MP sensor that is later cropped in photoshop to get 600mm field of view and up-scaled back to 12MP.

cosinaphile · « **Reply #20 on:** July 05, 2011, 08:53:19 PM »

Quote from: count_zero on July 05, 2011, 08:37:11 PM

Quote
Yes but how many people moving up from P&S really understand this?
They think they're getting 600 zoom with a 300 lens

I hope you're joking. 4/3 sensor and 300mm lens will get you a 12MP photo equivalent to FF 12MP using 600mm lens. Call it 2x crop or crap or zoom or whatever. Point is I can buy a Panasonic 100-300mm f4-5.6 m43 lens for $500 vs a 600mm f4 Nikon lens will cost somewhere around $10,000. Not to mention the 300mm m43 lens will fit in my murse, and I can hold it with one hand.

Is the image quality better? Probably not, but it is better than using 300mm lens on a FF 12MP sensor that is later cropped in photoshop to get 600mm field of view and up-scaled back to 12MP.

thats a great point , im amazed at the quality and speed i achieve on m 4\3 with my canon fd 200 2.8
i got the lens years ago mint for about 50 dollars

a 400 2.8 on full frame is a kings ransom

Danny · « **Reply #21 on:** July 05, 2011, 11:26:09 PM »

I always refer to a lens as what it is. A 200mm is a 200mm. A 50mm is a 50mm. As already said, its the sensor thats cropped.

yotsuba · « **Reply #22 on:** July 06, 2011, 04:17:58 AM »

Quote from: ratobuhler on July 05, 2011, 06:56:31 PM

The 35 mm reference is only meaningful to us old guys that actually used (or are still using) 35 mm Film.

But what about younger guys with ff DSLR? lol

adash · « **Reply #23 on:** July 06, 2011, 05:09:58 AM »

I used digital crop much before than I started used 35mm film. Still 35mm equivalence is meaningful as it tells me what to expect. For example if a camera with a given crop factor has a "24mm lens in 35mm equivalence" that is much more meaningful and easy to understand than saying "12mm lens on a 4/3 sensor" or "16mm equivalent in APS-C 1.5x" or "14.5mm equivalence for 1.6x APS-C" or "4.3 mm on a 1/2.33'' sensor". It's sort of an informal standard when so many sensor sizes are available.

Panther · « **Reply #24 on:** July 06, 2011, 08:57:32 AM »

Quote from: ratobuhler on July 05, 2011, 06:56:31 PM

The 35 mm reference is only meaningful to us old guys that actually used (or are still using) 35 mm Film.

Author Topic: 'People Are Confusing Two Things..' (Read 2776 times)

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