Why are interchangeable lenses better?

superamazing

superamazing

Something that's bothered me for a while is why interchangeable lenses are considered such an advantage.

I mean, once you have a zoom lens, why would you ever need another lens? You can already get wide angle shots and telephoto shots, and everything in between.

I'm probably missing something big here... I have a feeling that I'm showing my newbie to you all. Reminds me of when I discovered that they sold $150 1080p cameras--and it took me weeks of research to find out why they weren't as good as the more expensive ones.
 
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There's not really such a thing as a great "all-around" lens. Aside from focal length (measured in mm, the smaller the number the wider the angle) lenses are also measured in aperture. Displayed as f/X or t/X, it measures how much light the lens lets in. The smaller the number X is, the "faster" the lens is and it lets more light in. f/1 is as fast as it gets, letting all the available light in. f/2 lets half, f/4 lets in a quarter, etc. Generally, the more light you let in the better. Cheap zoom lenses usually aren't any faster than f/3.5 or 4.5 and they're variable aperture, meaning that depending on how far you zoom in you're getting a larger or smaller aperture inside the lens.

There's also the quality of the glass, housing and gears used. Most people in film prefer primes because they're usually faster and have less glass layers inside thus affecting the image less. The problem with primes, is that it's one set focal length. You have to now move the camera in or out to change the image, or swap lenses.

Interchangeable lenses offer more flexibility and access to much better glass. There are some REALLY nice zoom lenses, but the price goes way up. You can buy a 28mm 1.8, 50mm 1.4 and 85mm 1.8 for the price of a 24-70mm 2.8 zoom. Or if you want a really fast zoom lens, they have some that are ridiculous and are something like 25mm-300mm f/1.7... and they cost a few hundred thousand dollars.
 
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Also think of lenses like speakers. If you have a really good stereo system with crappy speakers it won't sound that good. Same as crappy lense on good camera won't look that good.

Owen
 
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I think the craze over interchangeable lenses is fueled mostly by a desire to be able to use shallow depth of field.

You know how in a Hollywood production, during a conversation between two people, the camera will change focus from one person to the next, and then back to the first person again? That's an example of shallow depth of field.

The more shallow your depth of field, the less things are in focus. The more wide the depth of field, the more things are in focus. Though there are ways to manipulate depth of field in any camera, it is only recently that low-budget filmmakers are able to have as narrow a depth of field as is used in Hollywood. I'm oversimplifying, but basically, this was made possible by interchangeable lenses (a camcorder, with a fixed zoom lens, will not have as low an f-stop as a prime lens, which is necessary to acheive really shallow depth of field).

There are many reasons to want interchangeable lenses. At the end of the day, it comes down to being able to control your image to a greater extent.
 
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A wide angle lens is more useful in some instances than a zoom lens. The whole appeal is to be able to get the various lens distortions and angles that match your needs for the shot and scene.

In the case of a camera like the XL1, HD110, XL2, etc. they either didn't make many lenses, or the alternate lenses were more expensive than the camera themselves, so it was something of a joke or a little misleading.

With the whole DSLR craze, it's really cool because alternate lenses and adapters are more readily available, and substantially more affordable. Add with it, the ability to get a shallow depth of field, and you have a lot of visual variation at a reasonable cost.
 
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A few thinks I picked up...

Changing lenses on the shoot is impressive. When you ask the director what lens do you want to use their eyes glaze and they get all dreamy like.. lol

One lens can produces a look completely different then another.

top of the line lenses cost more then the camera body, and always will.
 
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Individual lenses have SO many qualities that effect how they look. Some are soft and dreamy, some are sharp and crisp, some have beautiful bokeh, etc... etc... Those are all tools that can help with visual part of storytelling. It puts another tool in the filmmakers hands.
 
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Yep I consulted on a shoot this past weekend with all "L" series glass, over $2000 worth of lenses. They were amazing, but I still like the look of some of my old Pentax glass. The plan is to use lots of M42 screw mount stuff on my 5D.
 
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Once again we are into subjective territory. Primes are generally considered "cleaner" and are much easier to make as faster lenses (less complexity == less glass == more light) than zooms.

One thing no one has mentioned is that Zooms are much, MUCH larger than primes. Especially for motion picture cameras.

Having said all of that, lots of cases where the Zoom lens is going to come into play for both practical and aesthetic reasons. The look of a zoom is different than that of a prime - and plenty of DPs have shown a general preference for them, if not a specific instance where the look was desired.

Also, ask anyone who as shot 2/3" format how much easier having a zoom makes the day. ;) Honestly, those Fujinon 2/3" lenses are ridiculously good considering the focal ranges they can cover. Counting the extender it's even more silly.
 
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Some practical reasons come to mind.
I remember the first time I made a short film with some friends, which I shot partly in a train, and I wanted a shot where the two people who were sitting in the cabin facing each other were visible; but the (fixed) lens of the camera just wasn't wide enough and not even placing the camera as far away from the people as I could worked; if I had had the opportunity to change the lens (or a wide angle attachment) something like that wouldn't have been a problem at all.
 
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coming from a photography background... LENSES ARE FREAKING IMPORTANT... and the ability to change them mean the difference between isolation in a shot and to much clutter... the same applies from photography into film...

take for example...

this image is shot with a 28mm... i can get a nice wide shot out of it... and make for a decent depth of field and due to the fact i can then also adapt a filter on it... make for a dramatic dark shot in a some what bright over casted day
5460678627_f16327bae8_z.jpg


now this next shot... would not have worked the same way with the 28mm... it needed something that i could zoom up on and create a type of macro shot ... something with like 300mm or more...
5410011603_cd6a7b5c7c_z.jpg


its still a short depth of field... but now being the size of the object it allows for a really short depth of field...

different shots require different lenses... you need to be able to distiguish the difference...

this is an example of a poor shot with to much going on in the image... (granted more than just lense choice is needed to fix this shot... but getting rid of some of the back ground clutter would have been better)

5418452176_0191ae162d_z.jpg


know your lenses like you know your tripod... your crane... your mic and your software...

practice making short little clips and shots all the time... just a thought...
 
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Nice demonstration of the idea. Basically it's about having options. There's usually more to an individual lens than it's speed and focal length though, and that's always something to think about.
 
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David.rhsc said:
Nice demonstration of the idea. Basically it's about having options. There's usually more to an individual lens than it's speed and focal length though, and that's always something to think about.
Click to expand...

to the T... its all about options...

next time you watch a movie... try and figure out what lenses you could use to get a similar shot... or just be amazed like i usually am and say... HOLY CRAP... how did he get that...

Next... learn about filters and there glory...

winters bone is a nice example of why a half ND filter is awesome...
 
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