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07-12-2011, 08:54 AM   #46
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QuoteOriginally posted by mdbrown Quote
Not necessarily as I stated in the previous message. Consider though that 35mm might have longevity but it is going away... sooner rather than later I would guess. I don't think it matters though as this industry seems to hold on to obsolete terminology long after it's necessary or relevant. Case in point, sensor size: 1/2.33"... as I understand it that format is a carryover from long gone video sensors of some kind. APS... a dead film format that wasn't even that popular to begin with. Micro 4/3???

Matters not, things will continue as they are. I just fail to see the logic.
Unlike 35mm which was a design accident and resisted heavily by Kodak, APS was actually an agreed upon format with industry consensus, albeit horrible execution, especially pricing.

07-12-2011, 09:00 AM   #47
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QuoteOriginally posted by RioRico Quote
Usage trumps logic. That's why we still have units of measurement based on barleycorns.
I weigh 12 stone exactly
07-12-2011, 09:02 AM   #48
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QuoteOriginally posted by Aristophanes Quote
Unlike 35mm which was a design accident and resisted heavily by Kodak, APS was actually an agreed upon format with industry consensus, albeit horrible execution, especially pricing.
Kodak introduced the 135 film cartridge for still cameras in 1934. How was that resisting? Kodak was introducing a film format a year in the early 20th Century.

http://camerapedia.wikia.com/wiki/35mm

Last edited by Blue; 07-12-2011 at 09:09 AM.
07-12-2011, 09:29 AM   #49
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QuoteOriginally posted by Marc Sabatella Quote
Same reason most auto companies out names rather than numbers on cars, or that we refer to each other by name and not by, oh, some sort of DNA code designation. People find names easier to deal with in most cases. There's really nothing more to it than that, and it's not new or unique to photography. I mean, we use numbers when there are an ininifte number of possibilites and we need to be precise, but for lumping things onto a handful of standardized categories, names will almost always trump numbers.
In large format it is even more confusing with film formats not only imperial or metric sizes but some of the carry overs like Whole Plate are still made whereas half plate and quarter plate not so much. 67 is much smaller than 5X7 and 2 1/4 may be the same as 66 (or 67,68,69).

To return to the OP when you get to larger formats there were equvalency charts long before there were digital cameras. Simply a useful tool for anyone moving formats. For example if you are a 6X7 shooter and usually use a 75mm lens in landscapes what focal length would you most likely want if you moved up to 5X7. So if you used a 28mm lens most often on a 35 which lens should you buy for your new K5.

I carry a film camera with my digital and do a quick calculation when changing formats. It is not obsolete to use more than one format of image size (film or digital) nor is it unneeded to be able to calculate which lens on my film camera would give me the similiar image on the digital. Or if I was to move up and take a similar shot with the 4X5 to determine which lens I should use or if I should start off by having to move the tripod before I even set up.

The conversion factors are tools for those who need them. If you are only shooting cropped digital (or any one format exclusively) then it is totally useless IMHO. They are very useful to me.

07-12-2011, 09:37 AM   #50
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QuoteOriginally posted by Marc Sabatella Quote
.... but for lumping things onto a handful of standardized categories, names will almost always trump numbers....
Good insight! Precision is not needed much of the time - We often don't want everything to have a different name, and prefer reference by type.
07-12-2011, 10:36 PM   #51
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Of course if the imaging industry had standards and names that actually made sense, we would have much less to discuss on these forums.
07-13-2011, 06:50 AM   #52
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QuoteOriginally posted by RioRico Quote
Of course if the imaging industry had standards and names that actually made sense, we would have much less to discuss on these forums.
So true, FF, APS-C, 4/3, 1/1.7, 1/2.3--Formats that require a dictionary to understand.
07-13-2011, 07:56 AM   #53
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QuoteOriginally posted by mdbrown Quote
In the case of sensors it is, at best, imprecise. For starters, APS is a format that failed in the first place and is long gone in the second. Sensors in digital SLRs vary in size... 23.6x15.7, 22.2x14.8, 28.7x19... as a matter of accuracy it's just not correct. Why not just use the diagonal measurement of the sensor. Same applies to compact digital cameras as well I mean come on... 1/1.7" or 1/2.33"??

I know it won't change but really, it should in this case. Sometimes hanging on to something like that might make sense but I don't see it here.
But it does make sense (at least to some of us) to know the focal length in absolute unambigous units (: milimeters).

For eample, a 1 meter tall pole at 10 meters distance will produce an image 5 milimeters long on mu sensor with a 50 mm lens - irrespective of whether I used an APS-C or an FF-camera. It "may look" larger on your screen as compared to the same image taken with an FF but it isn't! Such absolute measures will often be needed in areas such as astro- and macro photography.

Likewise, if you have a lens with an "equivalent focal length" of 90 mm, what length should an extension tube have to allow you to do macro photography with a magnification of 1:1? Again, you cannot answer that having a loose statement on the FOV or the "equivalent focal length". Only the focal length in true milimeters will give you the answer.

07-13-2011, 08:33 AM   #54
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QuoteOriginally posted by GeneV Quote
So true, FF, APS-C, 4/3, 1/1.7, 1/2.3--Formats that require a dictionary to understand.
And the ambiguity and overlap: FF is full-frame or front-focus or a Freak Brother; MF is manual-focus or medium-format or an obscenity; AOV and FOV are the same, but not for the same lens in different formats; 35mm is a film size (and camera type) or a lens; PF is purple fringing or this forum; etc. Those come immediately to mind. Our terminology has many accretions from many sources, with no Central Authority to normalize / standardize the language.

So, is this just an insoluble problem? Or is it an opportunity to sell dictionaries?
07-13-2011, 09:14 AM   #55
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QuoteOriginally posted by Stone G. Quote
For example, a 1 meter tall pole at 10 meters distance will produce an image 5 milimeters long on mu sensor with a 50 mm lens - irrespective of whether I used an APS-C or an FF-camera.
See, that's where you're wrong: in an APS-C context, that pole is really 1.5 meters tall.
07-13-2011, 12:52 PM   #56
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QuoteOriginally posted by RioRico Quote
And the ambiguity and overlap: FF is full-frame or front-focus or a Freak Brother; MF is manual-focus or medium-format or an obscenity; AOV and FOV are the same, but not for the same lens in different formats; 35mm is a film size (and camera type) or a lens; PF is purple fringing or this forum; etc. Those come immediately to mind. Our terminology has many accretions from many sources, with no Central Authority to normalize / standardize the language.

So, is this just an insoluble problem? Or is it an opportunity to sell dictionaries?

And 35mm, although a film size, is not a format size. Full frame 35mm is 24x36, or close to it. 2 1/4, is, at least, close to that wide.
07-13-2011, 01:32 PM   #57
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QuoteOriginally posted by dadipentak Quote
See, that's where you're wrong: in an APS-C context, that pole is really 1.5 meters tall.
Aha - so I don't need a bigger car after all? I'll just take a snapshot of my current with my K200D!!!
07-13-2011, 04:49 PM   #58
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QuoteOriginally posted by civiletti Quote
And 35mm, although a film size, is not a format size. Full frame 35mm is 24x36, or close to it. 2 1/4, is, at least, close to that wide.
2 1/4in or 6x6cm format has frames actually 56x56mm. Close enough.

Yeah, 35mm / 135 film can be stuffed into all sorts of cameras. I never had a 24x24mm Robot nor a 24x80mm pano, but I have 135/HF (half-frame) and 135/FF (full-frame) cameras, and I put 135 carts into 6x6cm and 6x9cm MFC's for sprocket-hole panos. Plagiarizing Korzybski's THE MAP IS NOT THE TERRITORY, we can say THE FORMAT IS NOT THE FILM. Or something like that.
07-13-2011, 05:27 PM   #59
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to mdbrown given that focal length has a a real physical meaning i.e. distance from lens plane to focal point (nice explanation with pix on wikipedia), on a 50mm lens it is 50mm (not measured in a camera or on film but in space (ok, technically air)!), and never did have anything to do with standardization of 135 as a film format, and thus as a measure or a rating should not be changed going to aps-c any more than it was going from view camera to 120 to 135 (which is not at all). people just shifted their expectations of what a 50mm lens would normally show to match their new camera, as should you i and everyone in between.

of course if we lived in atlantis then that 50mm focal length would be entirely wrong since saltwater has a different refactive index, but unless you're got a liquid filled camera the lens ratings are usually pretty darn close to the true focal length.
07-13-2011, 07:19 PM   #60
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QuoteOriginally posted by Blue Quote
Kodak introduced the 135 film cartridge for still cameras in 1934. How was that resisting? Kodak was introducing a film format a year in the early 20th Century.

35mm film - Camerapedia
Kodak tried to do everything they could to outmaneuver the "open source" 135 format it inadvertently created through the perforation system by tying new camera models for consumers to new film formats proprietary to Kodak. With Kodachrome Kodak kind of threw in the towel and the proprietary films were gradually displaced either by standards based on industry consensus (110 and APS) or low-end (126).

The history of Kodak is also a history of lawyers and lawsuits. Fascinating company.
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