Optical aid to matching lens in post

[Len Guyse]

I have bought an a poor mans Angénieux, the Tokina 28-70 2.8 a-tx pro, the 1994 to 98 series, I think. This will probably be my main lens for a while and suite me most of the time on s35. Occasionally I will need to go wider, and for this I will be using the Rokinon 16, 20 or 24. The Tiffen black promist will almost always be in front of the lens.

I was wondering to what extent does putting diffusion on a lens help matching lens in post. Now here I am referring to poor mans lens not real Cine lens that I can only dream about. Using diffusion or contrast filters as a kind of equalizer.

Edit the title is misleading should be just optical aid to match lens .

 

[M Harvey]

The short answer is that you'll have to do your own testing, of course. A lot of what people think about when matching lenses in post is color, and a diffusion filter isn't going to make two lenses match in color. You may want to get an inexpensive color chart (these can run $10-15) to aid in matching color in post-- shooting a chart with both lenses in the same light can provide more objective information about the color differences.

Otherwise, I can see that a black promist used on both lenses might help a little bit. For starters, even if it the lenses are quite different in character, the halation of a promist may give them a prominent shared characteristic (e.g. their reaction to highlights) that helps the lens package feel a little more cohesive. And the reduction in contrast may give you a little more latitude in matching the footage in post. (It's usually easier to add contrast than take it away.)

Keep in mind that you'll often want different strengths of diffusion filter in front of a wide angle and a telephoto-- the diffusion will read differently.

 

[Len Guyse]

Thankyou your answer is pretty much what l was thinking, you just put it more legibly than I could. I will try post something when I get my want-a-be Angénieux. It is come from Japan and I may have to wait until September.

 

[M Harvey]

Congrats on the new lens, and be sure to share what you learn from your testing!

 

[David Mullen ASC]

I find that the differences between zooms and primes, for example, or older zooms and newer zooms, are slightly less than the lightest diffusion filter made (unless one gets a special order filter of even lighter strength like a 1/16 something) -- it is probably simpler to create some overall LUT to match the difference but usually it means "dumbing everything down" to the softest, lowest-contrast lens. And so many other things affect sharpness / contrast on a shot by shot basis. But if you plan on shooting mostly wide-open, for example, then you can probably get closer to a match with a very light filter on your sharper, more contrasty lenses and then shoot clean on the softer, flatter lens.

 

[Elishua Howard]

I find that the differences between zooms and primes, for example, or older zooms and newer zooms, are slightly less than the lightest diffusion filter made (unless one gets a special order filter of even lighter strength like a 1/16 something) -- it is probably simpler to create some overall LUT to match the difference but usually it means "dumbing everything down" to the softest, lowest-contrast lens. And so many other things affect sharpness / contrast on a shot by shot basis. But if you plan on shooting mostly wide-open, for example, then you can probably get closer to a match with a very light filter on your sharper, more contrasty lenses and then shoot clean on the softer, flatter lens.

It is interesting that the differences are so small. If that's the case what drives the lens obsession a lot of us visual creators have? You have the big deciding factors like focal length, T-stop, and sharpness, but assuming that the choice of lenses are similar in all those respects, what drives the debate...? I've been on the hunt for a lens set that has more "character" or "flavor", be it Leica-R, Zeiss contax, Canon FD, (I'm not at the high end cinema glass level), looking at video after video, and in the end the lenses, to my novice eyes have very little differences, and some of the differences they do have can often me remedied in post, primarily color and contrast -- sharpness, bokeh, and CA not so much. Lately I've been thinking that instead of spending a few thousand dollars on a set of lenses with character, I can spend a few hundred by slapping on differing diffusion filters on my "clean" set of lenses... different look, sure, but I'd have character.

What are some of the things you look at when deciding on a lens set other than focal lengths, T-stop, and sharpness -- You're in charge of large productions so I understand the dynamic may be different, and in your case the small differences in lenses may matter more, but curious about your thoughts!

 

[Michael Tiemann]

There are times when the subject in front of the lens is so perfectly eye-catching that it almost doesn't matter what lens or camera you are using. There are other times when you depend on the action of the lens and/or the resolution of the camera to make the magic. A really nice focus pull, a properly complimentary flare, edges that don't buzz with CA or fizz with coma/spherical aberration: these will test you equipment and your skill. They take time to master, and without taking the time you might judge that it's much ado about nothing. In the end, it's up to you to decide the constraints you want to work within, and to make the most of those constraints. I found I simply could not live within the constraints of prosumer camcorders for what I wanted to do. Others are doing amazing things with their cellphones. To each their own, and more power to all who strive to do their best work and achieve at least a little bit of their creative vision.

 

[Elishua Howard]

There are times when the subject in front of the lens is so perfectly eye-catching that it almost doesn't matter what lens or camera you are using. There are other times when you depend on the action of the lens and/or the resolution of the camera to make the magic. A really nice focus pull, a properly complimentary flare, edges that don't buzz with CA or fizz with coma/spherical aberration: these will test you equipment and your skill. They take time to master, and without taking the time you might judge that it's much ado about nothing. In the end, it's up to you to decide the constraints you want to work within, and to make the most of those constraints. I found I simply could not live within the constraints of prosumer camcorders for what I wanted to do. Others are doing amazing things with their cellphones. To each their own, and more power to all who strive to do their best work and achieve at least a little bit of their creative vision.

Ahhh. Very true. That makes a lot of sense! The more I learn, the more I'll figure out what I can and can't work with, which will dictate my purchasing or renting decisions. I think my biggest issue is doing all of this learning via online video, rather than hands on experience. That'll come with time.

 

[M Harvey]

One thing to keep in mind--as many others have observed-- is that the differences between lenses are often most apparent at the extremes, e.g. performance at or near wide open, or how the wides handle architecture, or the quality of flares (the extreme of having a sufficiently powerful light source in frame). But you're right, when you're at t4, the differences can get subtle.

In cases where we're not choosing a lens set based on performance under extreme conditions, I think that some of us probably are informed by associations that might be invisible to the audience. The most obvious example would be something like choosing Panavision anamorphic lenses because we feel that a piece has some commonality with the 70s/80s Amblin movies. But do we really believe that the triangular bokeh of certain Zeiss super speeds automatically puts our audience in the mind of the 70s/80s horror films we're trying to evoke on another project? Maybe not. But sometimes the artistic process is aided by setting an intention, and using lenses to situate yourself in a lineage can be part of that.

I will say that I do think that contrast, much as you can mess with it in post, is often a distinctive quality of a lens, and therefore something that can justify a lens choice for me.

 

[Elishua Howard]

One thing to keep in mind--as many others have observed-- is that the differences between lenses are often most apparent at the extremes, e.g. performance at or near wide open, or how the wides handle architecture, or the quality of flares (the extreme of having a sufficiently powerful light source in frame). But you're right, when you're at t4, the differences can get subtle.

In cases where we're not choosing a lens set based on performance under extreme conditions, I think that some of us probably are informed by associations that might be invisible to the audience. The most obvious example would be something like choosing Panavision anamorphic lenses because we feel that a piece has some commonality with the 70s/80s Amblin movies. But do we really believe that the triangular bokeh of certain Zeiss super speeds automatically puts our audience in the mind of the 70s/80s horror films we're trying to evoke on another project? Maybe not. But sometimes the artistic process is aided by setting an intention, and using lenses to situate yourself in a lineage can be part of that.

I will say that I do think that contrast, much as you can mess with it in post, is often a distinctive quality of a lens, and therefore something that can justify a lens choice for me.

Interesting -- I'll keep on eye on contrast differences going forward, any distinct qualities that set one lens apart from others is something I'm looking to get better at observing. And that's a good point, the differences are more notable at extremes -- and working in a low budget space, I might find myself working at those extremes more often than higher budget projects might.