Are T-stop lenses better than f-stop lenses?

Plush Photo · Nov 3, 2018

I heard they do more testing on them to insure they are accurate, and thus they are a little more expensive.

But do you get a sharper image from T-stop lenses? Are the colors better? This may sound dumb but I also heard T-stop lenses are used for cinema and f-stop are used for photography. Why? If T-stop is a better lens, then why not use it for both?

Plush Photo

Plush Photo · Nov 3, 2018

What exactly does a lens govern? In the previous post I asked about color (that's what I meant when I said that might sound dumb. Is color relevant to the lens you get, or is it just governed by the camera?)

I know the aperture and shutter speed, bokeh and sharpness, are all governed largely by the lens you get. But is that it? Just checking.

Plush Photo

Tom Axford · Nov 3, 2018

There are different requirements for cine lenses. Overall, you get what you pay for.

petrochemist · Nov 3, 2018

Plush Photo said:
I heard they do more testing on them to insure they are accurate, and thus they are a little more expensive.

But do you get a sharper image from T-stop lenses? Are the colors better? This may sound dumb but I also heard T-stop lenses are used for cinema and f-stop are used for photography. Why? If T-stop is a better lens, then why not use it for both?

Plush Photo

T stops are useful for video, but of no real help for stills photographers. F-stops allow you to work out DOF precisely, being based on the physical size of the opening (compared to the focal length).

While t-stops are measured light transmission, they are usually close to the f-stops but are concerned with precise light values rather than precise apertures. this allows the aperture to be changed between shots while still getting exactly the same image brightness.

Actual transmission is rarely relevant for stills shots, even if TTL metering is not being used the differences are not significant. The only occasion I can think of where lens transmission becomes relevant is when using the lens outside the usual visual wavelength range (particularly for UV imaging) T-stops won't tell you anything about lens transmission here as it is dependent on the wavelength & the lens. Very few photographic lenses transmit even 10% of the light at 350nm so the changes here are far more drastic

There is no correlation between which is used & lens sharpness.

mamallama · Nov 3, 2018

Plush Photo said:
I heard they do more testing on them to insure they are accurate, and thus they are a little more expensive.

But do you get a sharper image from T-stop lenses? Are the colors better? This may sound dumb but I also heard T-stop lenses are used for cinema and f-stop are used for photography. Why? If T-stop is a better lens, then why not use it for both?

Plush Photo

All lens have both an f- stop and a T-stop. The T-stop is the f-stop adjusted for the light transmission loss through the lens.

The T-stop is generally not measured and labelled because it is an added expense and really not important. Most cameras have TTL metering which, in effect, takes into account the light transmission loss through the lens automatically.

Plush Photo · Nov 3, 2018

mamallama said:
Plush Photo said:

I heard they do more testing on them to insure they are accurate, and thus they are a little more expensive.

But do you get a sharper image from T-stop lenses? Are the colors better? This may sound dumb but I also heard T-stop lenses are used for cinema and f-stop are used for photography. Why? If T-stop is a better lens, then why not use it for both?

Plush Photo

Click to expand...

All lens have both an f- stop and a T-stop. The T-stop is the f-stop adjusted for the light transmission loss through the lens.

The T-stop is generally not measured and labelled because it is an added expense and really not important. Most cameras have TTL metering which, in effect, takes into account the light transmission loss through the lens automatically.

So will a T-stop lens tell me my f-stop number, or will it only list the T-stop scale? I bought an 85mm T1.5 lens because I want to shoot both photos and video. Right now I'm just shooting photos, but eventually I'd like to try video as well.

Plush Photo

mamallama · Nov 3, 2018

Plush Photo said:
mamallama said:

Plush Photo said:

I heard they do more testing on them to insure they are accurate, and thus they are a little more expensive.

But do you get a sharper image from T-stop lenses? Are the colors better? This may sound dumb but I also heard T-stop lenses are used for cinema and f-stop are used for photography. Why? If T-stop is a better lens, then why not use it for both?

Plush Photo

Click to expand...

All lens have both an f- stop and a T-stop. The T-stop is the f-stop adjusted for the light transmission loss through the lens.

The T-stop is generally not measured and labelled because it is an added expense and really not important. Most cameras have TTL metering which, in effect, takes into account the light transmission loss through the lens automatically.

Click to expand...

So will a T-stop lens tell me my f-stop number, or will it only list the T-stop scale? I bought an 85mm T1.5 lens because I want to shoot both photos and video. Right now I'm just shooting photos, but eventually I'd like to try video as well.

Plush Photo

The difference between a lens T-stop and its f-stop is the light transmission through the lens. If there were no transmission loss the T-stop would be equal the f-stop. The lower the transmission loss the closer the T-stop will be to the f-stop.

Knowing the T-stops of lens was very important during the old days of filming movies when the scene brightness was measured with external (non TTL) exposure meters and it was important to make the scene look the same when changing or using different lens. It is not that important now when using modern TTL metering and digital cameras.

I believe there is a company which post online the T-stops and f-stops of certain lens. I've seen it but don't remember what it is.

jjdp · Nov 3, 2018

If you're thinking of Rokinon/Samyang in the mid-hundreds range, I'm 99.99% sure the f-stop & t-stop lenses of the same focal length are exactly the same except for t-stop lenses having cine style gears and markings on the side. Example:

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www.bhphotovideo.com

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www.bhphotovideo.com

So I'm guessing their cine lenses won't offer a better picture compared to the f-stop versions in that price range, and don't have the rigorous testing associated with cine/t-stop lenses. Theoretically, compared to the f-stop versions they can offer more consistency between shots with different lenses simply because the aperture rings are declicked, but in practice I don't know how precise you could get. I think they're a great idea. They essentially make 1 lens at every focal length, and just change the mount and/or focal and aperture rings.

Plush Photo · Nov 3, 2018

jjdp said:
If you're thinking of Rokinon/Samyang in the mid-hundreds range, I'm 99.99% sure the f-stop & t-stop lenses of the same focal length are exactly the same except for t-stop lenses having cine style gears and markings on the side. Example:

https://www.bhphotovideo.com/c/product/769362-REG/Rokinon_85M_C_85mm_f_1_4_Aspherical_Lens.html

https://www.bhphotovideo.com/c/product/895598-REG/Rokinon_cv85c_85mm_T1_5_Cine_AS.html

So I'm guessing their cine lenses won't offer a better picture compared to the f-stop versions in that price range, and don't have the rigorous testing associated with cine/t-stop lenses. Theoretically, compared to the f-stop versions they can offer more consistency between shots with different lenses simply because the aperture rings are declicked, but in practice I don't know how precise you could get. I think they're a great idea. They essentially make 1 lens at every focal length, and just change the mount and/or focal and aperture rings.

That's the exact lens I just purchased. The Rokinon 85mm T1.5. I figured since I do photos and video it would be best for both.

Can you explain what is meant by "declicked". I have an idea of what that means but I'm not sure...

Also how is that a benefit?

FrancoD · Nov 3, 2018

Plush Photo said:
jjdp said:

If you're thinking of Rokinon/Samyang in the mid-hundreds range, I'm 99.99% sure the f-stop & t-stop lenses of the same focal length are exactly the same except for t-stop lenses having cine style gears and markings on the side. Example:

https://www.bhphotovideo.com/c/product/769362-REG/Rokinon_85M_C_85mm_f_1_4_Aspherical_Lens.html

https://www.bhphotovideo.com/c/product/895598-REG/Rokinon_cv85c_85mm_T1_5_Cine_AS.html

So I'm guessing their cine lenses won't offer a better picture compared to the f-stop versions in that price range, and don't have the rigorous testing associated with cine/t-stop lenses. Theoretically, compared to the f-stop versions they can offer more consistency between shots with different lenses simply because the aperture rings are declicked, but in practice I don't know how precise you could get. I think they're a great idea. They essentially make 1 lens at every focal length, and just change the mount and/or focal and aperture rings.

Click to expand...

That's the exact lens I just purchased. The Rokinon 85mm T1.5. I figured since I do photos and video it would be best for both.

Can you explain what is meant by "declicked". I have an idea of what that means but I'm not sure...

Also how is that a benefit?

It only makes any difference (and for video only) if you set your exposure manually and change lenses.

Otherwise a perfectly crappy lens could be sold having T stops. That by it self does not give any IQ whatsoever.

MarshallG · Nov 3, 2018

It’s only how the lens Aperture ring is labeled. The scale is the same.

In video/cinema, it’s common to shoot the same scene through two or three cameras, and the director switches back and forth in the edit. The T-Stop scale lets them have better lighting consistency when they cut back-and-forth.

I’m still photography, we’ve always used f-stops, and I suppose it’s a little better because we care a lot more about depth of field then transmission loss. The f-stop, not the t-stop, is the most accurate depth of field measurement.

“Cine” lenses are expensive because they’re super-sharp. It’s about lens quality. The label on the lens doesn’t make it cost more.

FrancoD · Nov 3, 2018

MarshallG said:
It’s only how the lens Aperture ring is labeled. The scale is the same.

In video/cinema, it’s common to shoot the same scene through two or three cameras, and the director switches back and forth in the edit. The T-Stop scale lets them have better lighting consistency when they cut back-and-forth.

I’m still photography, we’ve always used f-stops, and I suppose it’s a little better because we care a lot more about depth of field then transmission loss. The f-stop, not the t-stop, is the most accurate depth of field measurement.

“Cine” lenses are expensive because they’re super-sharp. It’s about lens quality. The label on the lens doesn’t make it cost more.

Still lenses can be sharper.

Cine lenses need to eliminate 'breathing" and to be parfocal. Those two and smooth focusing make them very expensive to design and build.

Lack of breathing : the image size (focal length) remains the same when you focus.

Parfocal : the lens remains in focus when you zoom.

thebustos · Nov 3, 2018

Still lenses with aperture rings have a "click" at each aperture marking so you can feel when you've set it to a different stop. For video this physical "click" can introduce movement when you change the aperture while recording video, so cine lenses will generally be "de-clicked" so you get a smooth physical transition when changing aperture.

PhotoTeach2 · Nov 3, 2018

(Big Screen) Movies are done with "multiple" cameras, (maybe even "10" or more), and it is essential that they all "match" in f/stop & color.

Note than none need to be, (nor can be), better than any other. So no reason to expect them to be "better", (except are more expensive because being "matched").

mamallama · Nov 4, 2018

PhotoTeach2 said:
(Big Screen) Movies are done with "multiple" cameras, (maybe even "10" or more), and it is essential that they all "match" in f/stop & color.

Note than none need to be, (nor can be), better than any other. So no reason to expect them to be "better", (except are more expensive because being "matched").

Matching can now be readily done in post processing with digital whereas it was near impossible to do with film even though filmed movies were shot in negative and transferred to positive for projection.

bobn2 · Nov 4, 2018

Plush Photo said:
mamallama said:

Plush Photo said:

I heard they do more testing on them to insure they are accurate, and thus they are a little more expensive.

But do you get a sharper image from T-stop lenses? Are the colors better? This may sound dumb but I also heard T-stop lenses are used for cinema and f-stop are used for photography. Why? If T-stop is a better lens, then why not use it for both?

Plush Photo

Click to expand...

All lens have both an f- stop and a T-stop. The T-stop is the f-stop adjusted for the light transmission loss through the lens.

The T-stop is generally not measured and labelled because it is an added expense and really not important. Most cameras have TTL metering which, in effect, takes into account the light transmission loss through the lens automatically.

Click to expand...

So will a T-stop lens tell me my f-stop number, or will it only list the T-stop scale? I bought an 85mm T1.5 lens because I want to shoot both photos and video. Right now I'm just shooting photos, but eventually I'd like to try video as well.

Plush Photo

Sadly, I think you have wasted your money - or some of it, you'll have a good lens but you could have had the same lens or better without the 'declicked' T-stop aperture ring for less money and it would have been just as good for you at this stage in your video career. During the history of TV, video has not used T-stop aperture rings, film production has. And that's a clue to why these lenses sell, people want to play at being film directors. It was important in the days of film production, when there would be several cameras in use for one shot, they didn't have through the lens exposure meters and you wanted to make sure that the lightness of the shot was consistent from camera to camera - otherwise as you cut from long view to close-up (for instance) there would be a disturbing change. So, lenses for cinema production have calibrated, T-stop marked aperture rings which take into account lens transmission. If you're using one camera and lens, have a TTL exposure meter, and will be likely grading your output in post, there really is no reason to have a T-stop marked aperture ring at all.

Mystery member · Nov 4, 2018

Plush Photo said:
Can you explain what is meant by "declicked". I have an idea of what that means but I'm not sure...

Also how is that a benefit?

On older lenses with external f/Number adjustment, there's mechanical detents ("clicks" or "stops"), usually at full stop intervals (f/2.8, f/4, f/5.6, f/8, f11 etc.) which is often enough granularity for standard photography. The Shutter Speed has enough flexibility (1/3 stop, usually) to end up with the correct exposure.

Modern lenses usually have internal electronic f/Number adjustment, often with 1/3 stop intervals.

If you are working with T stops, you obviously need greater precision, so the clicks are not present, and the scale is quite likely to be geared to provide finer adjustment.

To repeat what others have said, T stops are only important for film photography, to maintain exposure during lens changes or with multiple cameras.

Here's an image of a movie lens, note the wide spacing of T stop values. On a typical stills camera, the stops are usually only separated by a few millimetres.

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goo.gl

bobn2 · Nov 4, 2018

thebustos said:
Still lenses with aperture rings have a "click" at each aperture marking so you can feel when you've set it to a different stop. For video this physical "click" can introduce movement when you change the aperture while recording video, so cine lenses will generally be "de-clicked" so you get a smooth physical transition when changing aperture.

I don't think that's the reason. To change aperture while recording you need to be very proficient indeed, mostly, you wouldn't even attempt it. Having to smoothly work past clicks only needs a little more proficiency. As people have said, though, the origin of the de-clicked aperture ring is film production, where you want to be able to match the actual exposure of different cameras very precisely (or at least, did when shooting film) to a fraction of a stop. In that case, clicked aperture stops are an inconvenience, because after setting the aperture will always tend to settle towards a click.

bobn2 · Nov 4, 2018

MarshallG said:
“Cine” lenses are expensive because they’re super-sharp. It’s about lens quality. The label on the lens doesn’t make it cost more.

I think it's more about production volumes than lens quality, to be honest. And now there are many examples of what is clearly the same lens being offered in photographic and cine variants.with the cine one costing a lot more. I think as much as anything, that's just exploiting the vanity of the wannabe film director, who wants to look more 'professional' by having a cine lens on the front of their GH.

jjdp · Nov 4, 2018

bobn2 said:
thebustos said:

Still lenses with aperture rings have a "click" at each aperture marking so you can feel when you've set it to a different stop. For video this physical "click" can introduce movement when you change the aperture while recording video, so cine lenses will generally be "de-clicked" so you get a smooth physical transition when changing aperture.

Click to expand...

I don't think that's the reason. To change aperture while recording you need to be very proficient indeed, mostly, you wouldn't even attempt it. Having to smoothly work past clicks only needs a little more proficiency. As people have said, though, the origin of the de-clicked aperture ring is film production, where you want to be able to match the actual exposure of different cameras very precisely (or at least, did when shooting film) to a fraction of a stop. In that case, clicked aperture stops are an inconvenience, because after setting the aperture will always tend to settle towards a click.

The Rokinon/Samyang clicks are very hard and immediate, like a rotary switch. I think OP made the right choice.

Are T-stop lenses better than f-stop lenses?

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