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05-27-2009, 09:20 PM   #1
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Ken Rockwell's latest... does it make sense?

So I find Ken Rockwell's rants highly amusing, but this one I don't understand:

QuoteQuote:
The magnification of a DX finder varies with model anywhere from 0.44x to 0.53x, NOT the 0.94x claimed for many Nikon cameras.

What? Simple: Nikon attempts to deceive and specifies them with a 50mm lens. A 50mm lens is a telephoto on DX!

When measured with a 28mm lens, which is normal (the diagonal of the sensor), DX finder specs look as dismally tiny as they really are.
Is he off his rocker? Or does he have a point? (Both happen frequently, AFAICT.)

05-27-2009, 09:52 PM   #2
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QuoteOriginally posted by rpriedhorsky Quote
Is he off his rocker? Or does he have a point? (Both happen frequently, AFAICT.)
I couldn't find any point in the original article, besides APS-C viewfinders are smaller than FX or 35mm film camera viewfinders. His choice of a 28mm lens because it matches the APS-C diagonal should mean that 50mm was always wrong and always slightly telephoto. The correct lens for a 24x36mm format is a 43mm. It has not caused a great tragedy so far to use 50mm as a comparison standard.
05-27-2009, 11:35 PM   #3
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Is he off his rocker??

don't know about the technical merits crop camera VF size but anyone who uses the term "Real Raw" instead of film is a W**k*r of the highest order.

Cheers
Shang
05-28-2009, 12:52 AM   #4
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I've noticed the viewfinder shows miles of difference on a full frame film (The RealRaw ) camera vs APS and I think Ken has a point lol.

All photos shot equal distance from the monitor with a Panasonic DMC-LZ10 to the viewfinder. The lighting changed because my table top tripod broke and I had to move the light to fix it. (its a P-O-S. lol)










I forgot to test the effect of the O-ME53 on the K200D. Leave it for next time I guess.


Last edited by FotoPete; 05-28-2009 at 01:00 AM.
05-28-2009, 01:04 AM   #5
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I think he's got a perfectly valid point. I don't think I'm wrong in suggesting that most people aren't really as interested in the magnification of the viewfinder as they are in its apparent size. Let's face it, magnification is completely dependent on the lens you're using, and the viewfinder is no worse to use just because you slap on a superwide lens and suddenly the "magnification" is down to 0.3X or so.

An APS-C viewfinder that gives the same magnification with a 50mm lens as a full-frame camera is going to have a lot smaller apparent size (because the 50mm covers a lot less area on a cropped APS-C sensor) - that's what really makes a difference.
05-28-2009, 01:04 AM   #6
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Thanks Pete, that's impressive!
05-28-2009, 02:56 AM   #7
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APS-C cameras have small viewfinders, news at 11
05-28-2009, 10:03 AM   #8
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QuoteOriginally posted by Sean Nelson Quote
I think he's got a perfectly valid point. I don't think I'm wrong in suggesting that most people aren't really as interested in the magnification of the viewfinder as they are in its apparent size. Let's face it, magnification is completely dependent on the lens you're using, ...

Sorry but I don't get it. I always understood that maginification of the viewfinder was a percentage of the size of the image on the focusing screen relative to the size of the sensor. i.e. a 0.92 magnification means the size of the image on the focusing screen is 8% smaller than the actual size of the sensor; hence why the 0.92x of an APS-C sized image is much smaller than a 0.92x of a FF sensor image. Coverage is the percentage of the image viewed relative to the one that is captured by the sensor. i.e. a 0.92 Coverage means that the image viewed is missing 8% of the actual image captured. The Apparent size of the image will be the Coverage multiplied by the Magnification and it has nothing to do what-so-ever with the lens used. A 100% magnified image with a 100% coverage will be as if you were looking directly at the sensor instead of the focusing screen. Maybe I was wrong all along, but to me a magnification of the viewfinder image seen as a relative relation to the lens used makes absolutely no practical sense.

05-28-2009, 11:23 AM   #9
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QuoteOriginally posted by regor Quote
A 100% magnified image with a 100% coverage will be as if you were looking directly at the sensor instead of the focusing screen. Maybe I was wrong all along, but to me a magnification of the viewfinder image seen as a relative relation to the lens used makes absolutely no practical sense.
My understanding is the same as yours.

I believe what is argued here is the actual size of the viewfinder image (eg. 0.72x of a 24x36 sensor is physically larger than 0.95x of a 24x16 sensor).

To which all I can reply is: well, duh !
05-28-2009, 11:41 AM   #10
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QuoteOriginally posted by regor Quote
Sorry but I don't get it. I always understood that maginification of the viewfinder was a percentage of the size of the image on the focusing screen relative to the size of the sensor. i.e. a 0.92 magnification means the size of the image on the focusing screen is 8% smaller than the actual size of the sensor; hence why the 0.92x of an APS-C sized image is much smaller than a 0.92x of a FF sensor image. Coverage is the percentage of the image viewed relative to the one that is captured by the sensor. i.e. a 0.92 Coverage means that the image viewed is missing 8% of the actual image captured. The Apparent size of the image will be the Coverage multiplied by the Magnification and it has nothing to do what-so-ever with the lens used. A 100% magnified image with a 100% coverage will be as if you were looking directly at the sensor instead of the focusing screen. Maybe I was wrong all along, but to me a magnification of the viewfinder image seen as a relative relation to the lens used makes absolutely no practical sense.
That is logical regor, but I don't think that viewfinders are spec'ed that way. I think "viewfinder magnification" refers to the relative size of what you see in the viewfinder using a 50mm lens, compared to what you would see with the naked eye. In other words, a 1.0 magnification would mean that if you looked through the viewfinder at a subject, and then removed the camera and looked with the naked eye, the size of the object would be exactly the same. It has nothing to do with the sensor size or a resulting picture. Simply how big something looks through the viewfinder. The same way you would rate magnification of binoculars.

I guess his argument is semantics to a certain point. It depends on how you define viewfinder magnification. He seems to think it depends on the size of the image. It is the argument between "crop" and "magnify" when using smaller sensors. I personally don't agree that using the smaller sensor "magnifies" the image. In other words the "telephoto" effect of APS-C. There is no telephoto effect! It just appears to be telephoto since a large portion of the image is cropped away by using the smaller sensor!

Last edited by PentaxPoke; 05-28-2009 at 11:59 AM.
05-28-2009, 12:00 PM   #11
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time to separate things out.

Fact 1 - DSLR finders are physically smaller than film finders.

Fact 2 - most finders, regardless of size only show between the upper 80% range to perhaps on some models 100% of the image.

As a result, when you combine fact 1 with fact 2 and put an equivelent FOV lens on a DSLR the image and ultimate magnification through the optical viewing system is much smaller than on a film body.

That is the only point being made. but unless you switch back and forth between different formats you won't notice. I looked through my KX today for the first time in years, and yes, the viewfinder is really big in comparsion.
05-28-2009, 12:07 PM   #12
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QuoteOriginally posted by Lowell Goudge Quote

As a result, when you combine fact 1 with fact 2 and put an equivelent FOV lens on a DSLR the image and ultimate magnification through the optical viewing system is much smaller than on a film body.
That is the key isn't it Lowell; some people define magnification based on Field of View (FOV). That is where the confusion arises. FOV depends on the size of the sensor and the cropping of the viewfinder. If you define magnification using FOV, you have two things dependent on each other. My understanding is that FOV and magnification are independent properties. Defined as such (my post above), the type of sensor doesn't effect viewfinder magnification.

Defined this way:

Magnification: How large something looks through the viewfinder (using a 50mm lens) relative to the naked eye.

Coverage (FOV): How much of the resulting image that is taken, is viewable in the viewfinder.
05-28-2009, 12:12 PM   #13
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yeah, "the madman" has a point, once in a while . as pentaxpoke explained. the point is, summing it up, that it is pointless and misleading to give these figures for 50mm lens on aps-c cameras, just because it happened to be common practice for 35mm film slrs (for obvious reasons), and thus it is pointless to compare these figures between different formats (medium format vs aps-c, or aps-c vs 35mm film). it is debatable if camera manufacturers should use the "normal" focal length for all formats, not whatever suiths the marketing department (hmm, i guess it's obvious what my opinion on this is), as things are now, again, these figures are only useful for comparing cameras of the same format.

edit: this means you cannot compare directly 35mm, aps-c, canon entry, canon almost-35mm-dslr, and four thirds, so, for most intents and purposes, it's bloody wrong.
05-28-2009, 12:20 PM   #14
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regor: notice that all manufacturers will specify, besides the figures for viewfinder magnification "with Xmm lens" (and sometimes even aperture, but that's rather irrelevant, except for how bright it looks), for aps-c, they specify with 50mm, the same for 35mm (because it was the normal lens, so it obviously made sense) i am curious how they specify for medium format (wild guess? )
05-28-2009, 12:24 PM   #15
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yes nanok, there is so much confusion now amongst consumers as to what magnification and coverage actually mean, that it seems pointless to continue to rate them this way. I almost wish they would simply switch to rating the viewfinders on diagonal dimension, like they do for the LCD. Then the manufacturers would all be scrambling to make larger viewfinders.
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