Does "Crop Factor" still apply when using a "crop lens" (a specialty lens designed specifically for crop sensor cameras) on a crop sensor camera?

[BradS]

Thanks to @OAPOli and @MattKing for solving this conundrum in post #46 and post #47 respectively.

 

[Tom-Thomas]

his is incorrect and the source of your confusion.

Magnification is independent of sensor size.

That is so NOT what I posted. Again, please read my post carefully. Though I can understand why you misunderstood my words.

First, please note in my post that I enclosed the word magnification with quotation marks. I did that because it was the word YOU used and at the time I didn't agree with your use of the word but since I understand what you was trying to say with that word, I put it in quotation marks and go with it, instead of arguing about the word.

What I did say was that:

The "magnification" is determined by the AoV the sensor is capturing

The same sensor can capture different AoV. Again, with the example of a lens with a Metabones installed. Without changing the sensor size, the same sensor captures a wider AoV when a Metabones is installed than without a Metabones. This has NOTHING to do with sensor size, but rather, what matters, in this case, is the smaller image circle size. This is what I have been trying to explain all along.

 

[Tom-Thomas]

A speed booster reduces the focal length of the lens it is attached to.

Not so. Pperhaps this is just semantics, but, in reality, a Metabones does NOT reduce the focal length of the lens, but rather it alters the focal length of the "system", which is to say, the optical system created by combining lens+Metabones. Metabones is very particular and careful in the usage of this term. If you read the Metabones white paper I posted earlier, you will see that they are very explicit when referring to changes in the the focal lengths of the "system", but the focal length of the lens .

 

[BradS]

That is so NOT what I posted. Again, please read my post carefully. Though I can understand why you misunderstood my words.

First, please note in my post that I enclosed the word magnification with quotation marks. I did that because it was the word YOU used and at the time I didn't agree with your use of the word but since I understand what you was trying to say with that word, I put it in quotation marks and go with it, instead of arguing about the word.

What I did say was that:

The same sensor can capture different AoV. Again, with the example of a lens with a Metabones installed. Without changing the sensor size, the same sensor captures a wider AoV when a Metabones is installed than without a Metabones. This has NOTHING to do with sensor size, but rather, what matters, in this case, is the smaller image circle size. This is what I have been trying to explain all along.

What you need to understand is that the Metabones thing you keep talking about is changing the overall focal length so you're no longer comparing two identical focal lengths....which obviously conflicts with the original question.

but, yeah, the angle of view changes because adding the metabones thingy changes the focal length...invalidating your original premise.

 

[Tom-Thomas]

Oh boys, this is exhausting. Back in the days, the terms "crop factor" and "equivalent focal length" didn't exist. We just knew and understood that as the film size you use increase, you need longer lenses to get the same FoV as when you used a smaller film size. And, back then, a lens is a lens. Nobody made lenses specially designated for different film sizes (note that I said different film sizes, not different format cameras). I blame the marketing departments of camera manufacturers.

 

[xkaes]

The same sensor can capture different AoV.

Sensors do not have angles of view. Lenses do.

 

[xkaes]

Not so. Pperhaps this is just semantics, but, in reality, a Metabones does NOT reduce the focal length of the lens, but rather it alters the focal length of the "system", which is to say, the optical system created by combining lens+Metabones. Metabones is very particular and careful in the usage of this term. If you read the Metabones white paper I posted earlier, you will see that they are very explicit when referring to changes in the the focal lengths of the "system", but the focal length of the lens .

Now that's semantics. Of course a tele-converter does no change the focal length of the lens, but together the focal length of the combination is increased. Call it a "system" if you want, but a 2X converter effectively doubles the focal length of the lens being used.

The Metabones are the opposite of tele-converters (which are glorified NEGATIVE diopter optics). A POSITIVE diopter optic, such as a "Close-up" filter/lens shortens the focal length of the lens to which it is attached -- or as you & Metabones prefer to say "Shortens the focal length of the SYSTEM".

 

[Tom-Thomas]

but this is exactly the cognitive dissonance the OP is suffering

A " cognitive dissonance" that I am "suffering" from? Wow! That's so rude and so uncalled for. Do we have to insult each other with words like these? I may have argued in a passionate and blunt manner here but I have never used insults on another member. Wow. Simply unbelievable.

 

[MattKing]

And, back then, a lens is a lens. Nobody made lenses specially designated for different film sizes (note that I said different film sizes, not different format cameras).

Sure they did.
Half frame film.
Olympus made lenses for that.
As did Konica for the original Auto-Reflex which could shift back and forth between half frame and full frame.
All of which were used with the same film.
As of course there were all those motion picture camera lenses for cameras that were using the same35mm film - just different frame sizes on it.

 

[MattKing]

A " cognitive dissonance" that I am "suffering" from? Wow! That's so rude and so uncalled for. Do we have to insult each other with words like these? I may have argued in a passionate and blunt manner here but I have never used insults on another member. Wow. Simply unbelievable.

Actually "cognitive dissonance" is probably incorrect, as your belief is consonant with your conclusions.
Which together don't actually match the factual realities.
However, if what you are asking about is whether the way poorly informed people on the internet bandy about the phrase "crop factor" or the label "crop lenses" is consistently correct, the answer is no.

 

[MattKing]

Sure they did.
Half frame film.
Olympus made lenses for that.
As did Konica for the original Auto-Reflex which could shift back and forth between half frame and full frame.
All of which were used with the same film.
As of course there were all those motion picture camera lenses for cameras that were using the same35mm film - just different frame sizes on it.

At the risk of quoting myself, the world of cinema film is actually a good thing to consider, because things like anamorphic lenses are perfect examples of where a lens actually distorts the image in order to squeeze it into a smaller frame of film. The difference being, of course, that the anamorphic lens only squeezes things in one direction - horizontally.
Anamorphic lenses are truly "crop lenses" in that way - it is just that for use they need to be combined with projection lenses that reverse the effect.
See here: https://en.wikipedia.org/wiki/Anamorphic_format

 

[BradS]

... Nobody made lenses specially designated for different film sizes (note that I said different film sizes, not different format cameras). I blame the marketing departments of camera manufacturers.

Of course they did.

Nikon made a 180mm f/2.8 ED AIS Nikkor for small format 35mm film and the 180mm f/5.6 Nikkor-W for large format 4x5 film...and of course, Mamiya made a 180mm lenses for medium format. That's just one example. There are many, many more.

 

[Tom-Thomas]

Olympus made lenses for that.

I did say, "... lenses specially designated for different film sizes (note that I said different film sizes, not different format cameras). Did the Olympus lens you mentioned had a designation saying it is specially for half film film? Tell me what this Olympus lens is, so I cam look it up.

As did Konica for the original Auto-Reflex which could shift back and forth between half frame and full frame.

I did say, "... lenses specially designated for different film sizes (note that I said different film sizes, not different format cameras). I am not familiar with this Konica Auto-Reflex. I take your words that it can shift back and forth half frame and full frame, but that's the camera, not the lens. did Konica make lenses that they designated them for using on half frame format. Which ones? I will lokk them up.

As of course there were all those motion picture camera lenses for cameras that were using the same35mm film

There were lenses designated for 16mm films, 35mm films, 72mm films, or different frame sizes using 35mm films? May you give some examples of lenses which the manufacturers marketed (designated) them for use specially for a certain film format?

 

[Tom-Thomas]

Of course they did.

Nikon made a 180mm f/2.8 ED AIS Nikkor for small format 35mm film and the 180mm f/5.6 Nikkor-W for large format 4x5 film...and of course, Mamiya made a 180mm lenses for medium format. That's just one example. There are many, many more.

But did Nikon (market) designate that 180mm f/2.8 ED AIS Nikkor as it is specifically for 35mm?

Of course that 180mm f/2.8 ED AIS 180mm f/5.6 Nikkor-W is used for a 4x5 camera because of the lens mount, which will not fit their 35mm camera. But are you saying that even without the lens mount issue, optically it cannot be used on other formats?

I did say, "... lenses specially designated for different film sizes (note that I said different film sizes, not different format cameras).

 

[Tom-Thomas]

At the risk of quoting myself, the world of cinema film is actually a good thing to consider, because things like anamorphic lenses are perfect examples of where a lens actually distorts the image in order to squeeze it into a smaller frame of film. The difference being, of course, that the anamorphic lens only squeezes things in one direction - horizontally.
Anamorphic lenses are truly "crop lenses" in that way - it is just that for use they need to be combined with projection lenses that reverse the effect.
See here: https://en.wikipedia.org/wiki/Anamorphic_format

I understand how a anamorphic lens squeezes the image. But the squeeze has nothing to do with the film format. It doesn't know nor care what film is in load in the camera, it squeeze the image just the same.

 

[BradS]

But did Nikon (market) designate that 180mm f/2.8 ED AIS Nikkor as it is specifically for 35mm?

Of course that 180mm f/2.8 ED AIS 180mm f/5.6 Nikkor-W is used for a 4x5 camera because of the lens mount, which will not fit their 35mm camera. But are you saying that even without the lens mount issue, optically it cannot be used on other formats?

I did say, "... lenses specially designated for different film sizes (note that I said different film sizes, not different format cameras).

the argument room is two doors down on the left.

EDIT: The answer to your questions are readily available. I invite you to do your own research - both reading the Nikon marketing literature and trying some of these things for yourself. I get the feeling you wouldn't take my word for it anyway but rather just find some further minutia to argue about.

 

[Tom-Thomas]

Actually "cognitive dissonance" is probably incorrect, as your belief is consonant with your conclusions.
Which together don't actually match the factual realities.
However, if what you are asking about is whether the way poorly informed people on the internet bandy about the phrase "crop factor" or the label "crop lenses" is consistently correct, the answer is no.

Sounds to me that you don't consider it an insult when one member says that another member is suffering from cognitive dissonance.

Your standard is certainly differ from mine. but since you are a moderator on this forum, I guess I will have to go with your standard. Well, as the risk of being banned here, I am asking you, the moderator, where the line is drawn. Would calling another member "stupid", "delusional", "incompetence", "slow-witted", etc. be acceptable here. Really, I want to know the standard here.

 

[Dwight Anderson]

As mentioned by others, you can prove this yourself by taking a picture with both a "crop" lens and a full frame lens of the same focal length on a "cropped sensor camera. You will find that the images are the same. I have a 90mm tessar lens that is marked 2 1/4 x 3 1/4, so that is the size film it is designed for. You can also get a 90mm Super Angulon lens that is designed for 4 x 5 cameras. The tessar will produce the same size image on the film, but not cover all of the 4x5 film, the corners will be black.

We are all trying to explain this in different ways, somehow you think we are all wrong, maybe you are the one not reading our messages.

 

[BradS]

Sounds to me that you don't consider it an insult when one member says that another member is suffering from cognitive dissonance.

Your standard is certainly differ from mine. but since you are a moderator on this forum, I guess I will have to go with your standard. Well, as the risk of being banned here, I am asking you, the moderator, where the line is drawn. Would calling another member "stupid", "delusional", "incompetence", "slow-witted", etc. be acceptable here. Really, I want to know the standard here.

Sorry. No insult was intended. It simply seemed to me that you were suffering discomfort due to believing two contradicting thoughts...which is just about the definition of cognitive dissonance. Any negative connotation is yours entirely.

 

[Tom-Thomas]

EDIT: The answer to your question is readily available. I invite you to do your own research - both reading the Nikon marketing literature and trying some of these things for yourself. I get the feeling you wouldn't take my word for it anyway but rather just find some further minutia to argue about.

Since when the responsibility of supporting a statement one makes rests on the reader/audience rather than than on the statement maker himself? Consider this scenario:

"Ladies and gentlemen of the jury, my client was not at the crime scene when the crime happened. I am not saying anything more but I invite you to do your own investigation on it."

Oh, well, that's just great.

 

[Tom-Thomas]

Sorry. No insult was intended. It simply seemed to me that you were suffering discomfort due to believing two contradicting thoughts...which is just about the definition of cognitive dissonance. Any negative connotation is yours entirely.

You probably will use the same argument if "cognitive dissonance" is replaced by any other insulting words. It's never your fault, of course. It's all on me, because I am easily offended. I am too thin skin. Sure. Why not.

 

[BrianShaw]

You must be a really fun person to chat with at a cocktail party!

 

[Dwight Anderson]

what is so special about a crop lens?

Nothing, it is just a lens designed with a smaller image circle, typically to make it smaller and lighter. If you don't need a larger image circle required by a larger sensor, why not make the lens smaller? They will both have the same image on the smaller sensor.

 

[MattKing]

Sounds to me that you don't consider it an insult when one member says that another member is suffering from cognitive dissonance.

Your standard is certainly differ from mine. but since you are a moderator on this forum, I guess I will have to go with your standard. Well, as the risk of being banned here, I am asking you, the moderator, where the line is drawn. Would calling another member "stupid", "delusional", "incompetence", "slow-witted", etc. be acceptable here. Really, I want to know the standard here.

Not in the least.
Cognitive dissonance is a reasonable description of an observable behavior, although I don't think @BradS and I agree about its applicability here.
If someone calls you "stupid" in a post, please report that, as it would be against the rules.

 

[MattKing]

I understand how a anamorphic lens squeezes the image. But the squeeze has nothing to do with the film format. It doesn't know nor care what film is in load in the camera, it squeeze the image just the same.

An anamorphic lens squeezes a wider image to fit on a single frame of 35mm motion picture film. The size of the film frame determines the amount of squeezing.
I wouldn't be surprised if there weren't similar lenses designed for 16mm film - perhaps even the various versions of 8mm film as well.
And certainly there were non-anamorphic lenses made for and marketed for the various video formats like professional Betamax and all the broadcast television video formats - at much higher prices than anything made for digital still cameras today.
Of course, there certainly were many lenses as well that were designed to satisfy the needs of many different users, employing equipment that used a variety of "sensor/film frame" film frame sizes. The vast number of C mount lenses come to mind.