Variable aperture lenses

[Peter C.]

I film primarily with camcorders, currently Panasonic UX90. I'm annoyed with variable aperture lenses that are on most if not all camcorders. I was filming behind the scenes dance studio b-roll and then a musical. Every time you zoom in the aperture changes from 2.8 wide to 5.6 zoomed in. The exposure changes significantly then in post you have try to fix the exposure. Seem like it would be a simple thing if they would add a feature that would change the gain when zooming to maintain the same exposure.

Yeah I know I could set the camera to auto but that's not ideal because then the exposure will change based on the background. Your trading exposure changing for a different reason. I'm also aware I could set the aperture to 5.6 then it will remain constant, but that's a lot of light to sacrifice for consistent exposure in dark interior filming conditions. Probably no easy answers.

 

[nutmegger]

I film primarily with camcorders, currently Panasonic UX90. I'm annoyed with variable aperture lenses that are on most if not all camcorders. I was filming behind the scenes dance studio b-roll and then a musical. Every time you zoom in the aperture changes from 2.8 wide to 5.6 zoomed in. The exposure changes significantly then in post you have try to fix the exposure. Seem like it would be a simple thing if they would add a feature that would change the gain when zooming to maintain the same exposure.

Yeah I know I could set the camera to auto but that's not ideal because then the exposure will change based on the background. Your trading exposure changing for a different reason. I'm also aware I could set the aperture to 5.6 then it will remain constant, but that's a lot of light to sacrifice for consistent exposure in dark interior filming conditions. Probably no easy answers.

Occasionally I use a UX90 and own a CX350. As you know the lenses on both cameras ramp from 2.8 to 4.5, based on zoomed amount. I usually try to set the camera’s exposure for f4.8 and live with it. I’m not aware of any camcorder with a longer range zoom lens that has a constant aperture lens. Some people claim the Sony Z280 has a constant aperture lens. I don’t believe this is true.

 

[NorBro]

The Z280 clearly has a f/1.9 constant aperture, but critically-speaking (if that's what you mean by not believing) the amount of light loss - if any - is debatable.

 

[nutmegger]

The Z280 clearly has a f/1.9 constant aperture, but critically-speaking (if that's what you mean by not believing) the amount of light loss - if any - is debatable.

I recall reading in the past that a Z280 user said the camera does ramp a bit, something like f/1.9 to f/2.8. The person that would know for sure is Doug Jensen.

 

[Doug Jensen]

Oh sure, put me on the spot.
Yeah, my Z280 does ramp from f/1.9 to f/2.8 at the very end of the zoom -- even though the display in the viewfinder still says "f/1.9". Shame on Sony for not being truthful. But in the camera's defense, it is only at the very end of the zoom and the Z280 has excellent low-light capability for a 1/2" sensor. At least 2000 ISO at 0db, so even at f/2.8 if still blows away other cameras in its class like the CX350 and Z190. In a totally different league than other camcorders. The Z280 is an FX7mark2 with a smaller sensor and fixed lens.

@ Peter C. You have an excellent grasp of the problem and the potential work-arounds, so I'm sure you already know the solution is to get a better camera . . . or add lighting.

 

[Peter C.]

Thanks for the feedback. z280 sounds nice but it's pricey. Good know I have an alternative. To compound my annoyance FCP doesn't have keyframes for exposure so I have to split the clip and put a transition to bridge the exposure change.

 

[Run&Gun]

It doesn't help you, but if it makes you feel any better, I have cameras and lenses that each cost orders of magnitude more than the UX90 and I still have 'iris ramping' to deal with, with my (~$30K) zooms. It's the trade-off the engineers and designers have to make to give us lenses with wide zoom ranges that are both affordable and portable(compact and lightweight enough to be hand-holdable).

 

[Peter C.]

You'd think the camera manufactures would have by now come up with exposure compensation for variable aperture lenses.

 

[NorBro]

If DSLRs and mirrorless' didn't change the world, these cameras could have been much better.

But it feels like they were mostly abandoned with only about 30 models or so made in the last 10 years (prosumer camcorders, not palm cameras), compared to over 200 DSLRs and mirrorless'.

It's a shame because camcorders can be so useful.

 

[drboffa]

To compound my annoyance FCP doesn't have keyframes for exposure so I have to split the clip and put a transition to bridge the exposure change.

Are you sure you can't keyframe this in FCPX? I swear I've dealt with this in the past by adding a color correction effect to the clip (usually the Wheels) and then keying my corrections there...

 

[NorBro]

You can, it's just a lot of work for a lot of changes.

Easiest way for me is to add a standard color board on the clip and then press 'Control + V' to open up the clip's video animation. And then from there you can make keyframes wherever you want and then adjust the midtones (or any of the other ones) on the keyframes.

So in the example below, my midtones are going from 0 to 25 from the first to the second keyframe (for a slow zoom that ramps from f/2.8 to f/4.5).

You fine-tune accordingly.

 

[Peter C.]

You can, it's just a lot of work for a lot of changes.

Easiest way for me is to add a standard color board on the clip and then press 'Control + V' to open up the clip's video animation. And then from there you can make keyframes wherever you want and then adjust the midtones (or any of the other ones) on the keyframes.

So in the example below, my midtones are going from 0 to 25 from the first to the second keyframe (for a slow zoom that ramps from f/2.8 to f/4.5).

You fine-tune accordingly.

Thanks I didn't know that. For the longest time FCP didn't have key frames for the Color effect. At some point I stopped checking and have been using the old way of splitting the clip, adding a different Color effect to each and using a transition to control the change between the two.

 

[Noel Evans]

It's important to note, and I am sure you are aware, that 2.8 to 4.5 is about 1.3 stops. I'd argue that any wide angle zoom will give a similar result, even if the manufacturer doesn't specifically state it.

 

[nutmegger]

Oh sure, put me on the spot.
Yeah, my Z280 does ramp from f/1.9 to f/2.8 at the very end of the zoom -- even though the display in the viewfinder still says "f/1.9". Shame on Sony for not being truthful. But in the camera's defense, it is only at the very end of the zoom and the Z280 has excellent low-light capability for a 1/2" sensor. At least 2000 ISO at 0db, so even at f/2.8 if still blows away other cameras in its class like the CX350 and Z190. In a totally different league than other camcorders. The Z280 is an FX7mark2 with a smaller sensor and fixed lens.

@ Peter C. You have an excellent grasp of the problem and the potential work-arounds, so I'm sure you already know the solution is to get a better camera . . . or add lighting.

Doug, question about the Z280 media. The camera has 2 ExpressCard/34 slots which take Sony’s SxS cards. Are there any lower cost alternatives, maybe with a ExpressCard/34 adapter that can be used? Also, there seems to be a very limited number of SXS card readers on the market. Read today that Sony announced a Z280 firmware update that will allow HD 120fps recording.

 

[Doug Jensen]

Interesting about the 120 fps in HD, I hadn't heard about the update. I guess some people might like that but the days of me shooting anything whatsoever in HD are long over.

You could use XQD cards in an SxS adapter if you want cheaper media, but Sony discontinued the adapter a couple of years ago so you are unlikely to find even a used one. And if you can find a used one, they sell today for more than when they were new.

Sony does offer a SDXC to SxS adapter but I'm not sure about compatibility with the Z280 right now. I got my Z280 more than 3 years ago and I have plenty of SxS cafds so I haven't bothered to keep up with what other cards are compatible and what are not.
https://www.bhphotovideo.com/c/product/978782-REG/sony_mead_sd02_sdhc_sdxc_card_adaptor.html

I would suggest you give the Mead SD02 a try with some high-end SD cards. The camera might give you an error message and refuse to record XAVC-I 4K codecs. But if it does allow it, I'd give it a try. SD cards have gotten a lot better in recent years. On my FX6 I can shoot XAVC-I 4K @ 120 fps all day long on Sony TOUGH V90 SDXC cards. And that is twice the frame rate that the Z280 is capable of, so I'd have no qualms about using the TOUGH cards in a MEAD SD02 adapter -- if the camera allows you to do it. I don't know if it will. Try it and let us know.
https://www.bhphotovideo.com/c/product/1437901-REG/sony_sf_g128t_t1_128gb_sf_g_series_tough.html

 

[Run&Gun]

You could use XQD cards in an SxS adapter if you want cheaper media, but Sony discontinued the adapter a couple of years ago so you are unlikely to find even a used one. And if you can find a used one, they sell today for more than when they were new.

Yeah, that was a pisser when they stopped making the adapters, although the fact that they even gave us a cheaper alternative to SxS cards that worked completely was very un-Sony like, so I guess we should just be happy that it lasted as long as it did. I guess someone at Sony finally did the math and figured out how much money they were leaving on the table by not forcing users to have to use SxS cards in cameras like the F55/F5. I know I probably saved well over $10K-$15K. I have about ~15 adapters and I've been using the adapters with XQD cards in my F55 since I got it. They were about $35 each, new, and I have seen them going for upwards of $300 EACH on the used market, now. My adapters are now literally worth more than most of the actual memory cards I have in them.