DX camera lenses???

DaveW

Senior Member
I'm not sure if this is the right place so apologies.

My question is, I don’t understand the DX lenses as in when they say things like a 50mm lens is the same as a 75mm on a DX camera.
Do they mean it’s actually now a 75mm lens or 50mm lens with a narrower angle of view which would be the same as a 75mm lens?
So is it a 50mm lens or a 75mm lens? And if it’s a 50mm lens why do they say it isn’t?

Err confused.....:eek:
 

fotojack

Senior Member
It doesn't really mean it's the same as; rather, it's the equivalent of the lens in question. DX means it's a cropped sensor.........FX is a full sensor. Nikon DX sensors are 1.5 times the value of an FX lens, so multiply the 50mm by 1.5 and you get 75mm. A little clearer now? :)

Click on this link. It will explain it in more detail and make it much clearer to you. http://mansurovs.com/nikon-dx-vs-fx
 
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ThePhotoLegend

Senior Member
By no means am I trying to pick at words here but the general understanding of this subject confuses me slightly. Is it not rather, just the perception of being 1.5 times the value? All things being equal with lens used and position of the shooter, there does not seam to be any true magnification transpiring but rather cropping due to smaller sensor size? When the images taken with a dx and fx are compared side by side you could fit the dx image inside of the fx image with no change to the DOF or perspective that one would expect to see in a value change? I could be way off base here but I tend to think the equivelent values between a dx & fx being discussed is in reference to the immediate cropping that takes place on a DX sensor in comparison with a full frame FX by have a size?
 

Eye-level

Banned
It is an interesting question!

They call it by various names...the magnification factor the crop factor...Canon is 1.6, Nikon is 1.5, micro four thirds is 2X...the one thing they all have in common is the 24X36 standard. The standard 35mm film size.

Format is a word you need to study if you want to really learn about photography. You will discover that many different formats have been used over the years. Oskar developed the 24X36 and revolutionized the camera because he had asthma and needed a compact camera to take along on his hikes. Then there is medium format - bigger than 35mm but smaller than 4.5...believe it or not it is just about as famous as 35mm to pro photographers over the years...all of those photos of Marilyn Monroe and all of the Playboy bunnies were shot in medium format most of the time. The reason why was resolution...we're talking like 40 megapixels. Megapixels is an important part of the OP question ;) But did you know that to this very day there is not a camera made, film or digital, that will make a picture with higher resolution than a Daguerreotype? It is a fact (Wired magazine says 140,000 megapixels - not 14 not 140...140,000MP)! And the Daguerreotype used formats different even than the common 35mm, medium format, and large formats that we still use today. When George Eastman brought the camera to the masses for the first time it used still a different format than any of the above.

My reason for going through all of this stuff?

It doesn't matter what lens focal length you use or what fstop shutter speed or ASA/ISO you have or if it is on automatic program or manual...the crop factor doesn't matter...it doesn't matter if you use DX or FX or film or wet plates or calotypes for that matter...it is just a format of sorts...exploit whatever it is to the best of your ability!!! It is all about the person behind the viewfinder really!

If you really want to understand what the crop factor (in relation to modern DSLR terminology) is all about you must learn about a lot of this other stuff and mainly what the significance of 24X36 is!

Anyone who thinks that FX is inherently superior to DX is misguided in their understanding of photography...same goes for film vs digital..medium format vs 35mm...etc...
 
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DaveW

Senior Member
I'm actually more concerned about what seems a mythical magnification. If all we are talking about is narrower angle then a 100mm lens is not now a 150mm on a dx which is what they advertise?

Lets put it this way, if I want a 90mm magnification then according to the way they advertise lenses, they say a 60mm is equivalent to a 90mm on a dx, which isn't true is it? Its still a 60mm with a narrower angle of view isn't it?
 

Marcel

Happily retired
Staff member
Super Mod
I'm actually more concerned about what seems a mythical magnification. If all we are talking about is narrower angle then a 100mm lens is not now a 150mm on a dx which is what they advertise?

Lets put it this way, if I want a 90mm magnification then according to the way they advertise lenses, they say a 60mm is equivalent to a 90mm on a dx, which isn't true is it? Its still a 60mm with a narrower angle of view isn't it?

You are right on. What they mean is that if let's say you had two camera side by side, one FX and the other DX. Now you want to have a very particular cropping that would cover just a door and a window for example and it would be very important that you exclude everything around it.
In order to have the exact same content on the DX and FX sensor, you would need to have a 1.5 longer lens on the FX than the DX ( 75mm vs 50mm). So this is why they say that the 50 mm on DX is equivalent to 75 on FX. But the fact remains that the 50 mm lens is still 50 mm and will have all the DOF of a 50mm lens for a certain aperture.

Hope this clarifies it for you.
 

Eye-level

Banned
Tune in tomorrow. Same Bat-Time, Same Bat-Channel! :)

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