Re: My lens has a spot on it, is there anything I can do?
 

It doesn't look like aperture ramping, that gets darker as you zoom in, it doesn't get lighter and you don't have variations. As Paul suggests, it's probably the auto exposure system on the camera.

Re: My lens has a spot on it, is there anything I can do?
 

Oh okay, but what auto exposure system would that be, or is there a way to turn that off perhaps? I know it's not the ISO cause I had it locked on 800. Is there a way to turn off that system?

Re: My lens has a spot on it, is there anything I can do?
 

What camera is this again? Are we talking about the Canon EOS Rebel T2i?

Re: My lens has a spot on it, is there anything I can do?
 

Sorry, yes that one. It appeared to have the same problem on the sony a7s II though.

Re: My lens has a spot on it, is there anything I can do?
 

Check your auto exposure settings on both cameras, go through the menu settings to ensure that the exposure is totally on manual. You may need to go through the camera manuals to find the required menus.

Re: My lens has a spot on it, is there anything I can do?
 

Yep its totally on manual. I dont have the sony now but the t2i is. What now though if its on all manual yet it still does that when zooming?

Re: My lens has a spot on it, is there anything I can do?
 

Don't create a problem that may not exist, that's the purpose of the test to prove, If the camera is totally on manual exposure the characteristics of the lens can be seen, rather than the inputs from the camera's exposure system.

The exposure variations match the exposure system making adjustments, either that or the lighting is changing during your shot.

Re: My lens has a spot on it, is there anything I can do?
 

Don't zoom, move the camera. Something is clearly causing it. The lens is changing the iris aperture or the gain of the camera is doing it. Has to be one or the other. You need to find out which it is.

This lens does seem to be a very unfriendly and uncontrolled beastie - all things considered, you need to get something better.

Re: My lens has a spot on it, is there anything I can do?
 

Okay thanks. Well I know it's the lens changing the exposure, cause I just borrowed the Sony A7s II to try it, with a couple of adapters. One of the adapters communicates with the lens, and the other is not electronic and does not.

The one that doesn't communicate the lens with the camera, the aperture is constant throughout the zoom and doesn't change. But with the adapter that does communicate with the camera, the aperture changes, even though it's on the same f stop setting throughout the zoom. So the lens being powered by the camera is causing the exposure changes, cause if you cut off the power between camera and lens, then the aperture is constant.

Re: My lens has a spot on it, is there anything I can do?
 

That sounds a good reason why you should use dumb lenses for drama or other video work where you want total control of the exposure. Cine lenses don't have such auto exposure features (with a couple exceptions for use on the Arri 16 SR film camera - the mechanical control pins could get jammed if you changed the lens mount. It happened to me on a new Zeiss zoom lens, so they were removed by the dealer) .

The alternative is to get a dumb lens adapter, so that the lens doesn't communicate with the camera.

Re: My lens has a spot on it, is there anything I can do?
 

Okay thanks. But the problem with a dumb lens adapter is that you cannot control the aperture, if you want to change it, since the lens does not have an aperture ring.

Are there any adapters, where the power can be switched on and off, so that I or a DP can switch the aperture with the lens, but then turn off the power to the lens after?

Re: My lens has a spot on it, is there anything I can do?
 

That's one reason why people were telling you to buy manual lenses for video work, otherwise you have to fool your camera's auto exposure system to get the stop you want.

ND or neutral density filters are the standard tools for getting the stop you want, since they don't change the shutter speed or the sensitivity in the process.

Re: My lens has a spot on it, is there anything I can do?
 

Indeed, and any lens you cannot control manually is a real limitation. Real video lenses have a manual or auto switch for a very good reason.

Come on Ryan - time to retire that lens and buy something that can do what you need.

Re: My lens has a spot on it, is there anything I can do?
 

Okay sure but i thought it was the camera changing the exposure since the lens does not change it when not attached. Shouldnt i get a new camera tgat doesn't change the lens's exposure as you zoom?

Re: My lens has a spot on it, is there anything I can do?
 

Many people on a budget buy used lenses, some of them prefer the older glass because of the look. Plus you can get lenses with an aperture ring.

Buying from an established dealer reduces the risks and, as I mentioned, will usually have a short warranty.

We were discussing aperture ramping, which is different to what the camera auto exposure does. If you wish to buy a camera that's designed/useful for digital cinema, you'll need lenses with aperture rings.

Re: My lens has a spot on it, is there anything I can do?
 

Oh okay but i thought the camera was telling tge lens to ramp up tge aperture, and therefore, its the camera thats doing it, not the lens.

Re: My lens has a spot on it, is there anything I can do?
 

In your test video the camera's auto exposure system was controlling the aperture. That's nothing to do with what happens with a max aperture f3.5 to f 5.6 zoom lens and avoiding this change called aperture ramping, which was the subject of the discussion.

You should reread the earlier posts which explains it.

Lens with no aperture ring are designed for the camera to control the iris in the lens. This is fine with stills cameras where you can also use the shutter for the exposure etc and each still photograph is complete in it's own right.

With higher end video work you don't want this, you need manual control of the iris so you can set the aperture. If you've lit a scene, you don't want the camera going off and automatically doing it's own thing and hunting the exposure during a shot.

Re: My lens has a spot on it, is there anything I can do?
 

Oh ok i see. But since my t2i is so old and not the greatest camera, i was thinking of upgrading the camera though. So what about getting a camera that does not have an auto exposure system and is all manual control? Would that be good, since i was going to get a new camera anyway?

Re: My lens has a spot on it, is there anything I can do?
 

I suspect you won't be able to get a DSLR without an auto exposure system., however, you may be able to override it in manual mode. How practical it will be for shooting video is another matter, the requirements for stills photography and video, especially high end work like drama are different.

You can get digital cinema cameras without the feature, but you'll need to use lenses which have an aperture ring in order to set the stop. This is a lot faster than setting the aperture using the viewing screen on the back of a DSLR in manual mode, while keeping the same shutter speed.

Alternately, you could use a dumb mount adapter (if required) and fit one of these lenses on your current camera .

Your current camera and changing it was discussed in an earlier message, if you wish to use it for shooting video that's worth considering..

Re: My lens has a spot on it, is there anything I can do?
 

Okay thanks. Well I was going to get another camera soon anyway. The T2i is full manual control, accept for during zooms it seems. Is there a camera out there that has full manual control during the zooms?

I thought about the Panasonic GH5 based on some other recommendations, and I was told it was invented for video in mind as well as stills, and not just primarily stills, if that's true.

But does the GH5 have full manual control when it comes to zooming, even with an adapter that is not 'dumb'?

It's just if I get an old vintage telephoto lens with an aperture ring, I am worried that the look of it, will not match my other lenses, if older lenses have a different look to them. So if I get an older lens, with a ring, does that mean it won't match my other lenses?

Re: My lens has a spot on it, is there anything I can do?
 

The aperture controls are the same for prime and zoom lenses, there's no difference.

Don't get confused with the aperture ramping that you get with many zoom lenses when they're wide open

This is a compromise used by designers to keep the physical size down. As mentioned earlier, this is the outside diameter of the lens acting like a stop aperture at longer focal lengths. F stops are calculated using a formula that has focal length over the diameter so "A 100 mm focal length f/4 lens has an entrance pupil diameter of 25 mm. A 200 mm focal length f/4 lens has an entrance pupil diameter of 50 mm",

If the physical outside diameter of your lens at 200mm is less that 50mm, you wont be at f4, it might be f5.00 for example, so that will affect your exposure, even if the aperture iris is set at f4 and is correct for shorter focal lengths.

However, if you set the lens aperture at f5.00 in this case, the aperture will remain the same throughout the zoom range because the effective diameter is now the same for all focal lengths.

Here's an example of a cine zoom lens that has no ramping: https://www.angenieux.com/collection...-style-25-250/

This is nothing to do with your automatic exposure system changing the exposure as you zoom into lighter or darker areas of the wider shot. That's what these systems will do if you physically changed the lens to a longer focal length instead of zooming in.This won't happen with a manually set exposure.

If you buy the same make of lens it should match pretty well with the newer ones, so if you've currently got Canon lenses buy those..Don't buy a Zeiss lens and use it with a Tamron, the Zeiss lenses have a look of their own. It's better if you can compare the lenses when you buy them. The high quality older lenses will produce better quality than your current 300mm lens.

Re: My lens has a spot on it, is there anything I can do?
 

If your lenses change the light passing through in the same way they look the same, some lenses do add things like colour shifts, but of course they shouldn't. In professional quality lenses, you should be able to mix and match for optical reasons, not age ones! This is why people protect their glass investments because a nice lens that works well and is friendly in how it interacts is worth hanging on to when you change cameras. In broadcast, working with different brands and types of lens is everyday stuff and your concerns would be considered a little strange? It is not only old lenses that have real mechanical control. Vintage glass or modern glass can have proper iris controls. The problem is when the servo control is poorly designed.

Re: My lens has a spot on it, is there anything I can do?
 

Canon 300mm lenses have been pretty standard in the industry for many years and they've been mixed with other makes and age of lenses on a wide range of productions. A used 300mm f4 Canon should do the job without getting into the thousands for a used 300mm F2.8 Canon.

Re: My lens has a spot on it, is there anything I can do?
 

Okay thanks, but I'm confused. What do you mean exactly by this? If you are saying that the aperture should remain the same throughout the zoom at a certain fstop, then why is the camera changing the aperture during the zoom it seems, even though it says the aperture is the same throughout?

If the lens is doing aperture ramping cause of how the lens is built to keep the size down, then why does it do the aperture ramping only when attached to the camera, but not if there is an adapter between the lens and the body? Sorry, there is just something in the concept that I am not understanding, and trying to pinpoint what that is.

If I get a zoom lens with an aperture ring for example, will it be a constant aperture throughout, or does the lens have to be a certain size then? Is it about the ring that keeps the aperture constant, or the size, or both?

Re: My lens has a spot on it, is there anything I can do?
 

Yes indeed. We need to figure out what it is that you're not understanding. I think it would be helpful for you to go back and review the progression of this entire discussion thread. Plus some of your earlier discussion threads as well. It seems to me that you tend to circle back to cover a lot of the same ground over and over again, just as if the previous input didn't even exist, even though it's very plainly documented and very easy to go back and review. You really should consider taking the time to go back through the entire discussions that have been laid down not only here but several other threads as well (specifically the ones that you yourself have started). I think this would be a big help to you.

Not always, no. Some cine zooms that have manual zoom rings are variable aperture, and some are constant aperture. For example, take a look at this: https://www.dvinfo.net/article/buyer....html#cinezoom

The one on the left, which is a wide zoom at 14.5mm to 60mm, is constant aperture.

The one on the right, which is a telephoto zoom at 30mm to 300mm, is variable aperture. Both have manual aperture control rings.

It's the size. The 30-300mm mentioned above is variable aperture, very big, very heavy, and very expensive at $45,000. If it were constant aperture, it would be even more expensive, and prohibitively larger and heavier, too much so for practical cinema work. Therefore it is variable aperture. Does that make sense?

The other advantage of that particular telephoto zoom is that its front diameter matches its counterpart on the left (the wide zoom). Those two lenses are often rented (or bought) in pairs, and the same matte box can be used with either one because they both have the same front diameter. The benefit here is a faster set-up time during lens changes.

Re: My lens has a spot on it, is there anything I can do?
 

It’s amazing this thread started 6 pages ago about a spot of dust. You guys should be commended for limitless patience. I’ve recused myself from all things Ryan to preserve my sanity even though it’s taking all my self will to refrain from giving any advice. May your zoom be long, your aperture be constant and your depth of field always be shallow.

Re: My lens has a spot on it, is there anything I can do?
 

Hear hear Pete!

Re: My lens has a spot on it, is there anything I can do?
 

Speaking of lenses. I pulled out an old macro Nikkor lens to take some closeup photos of a garden spider. Turns out the aperture blades are frozen in the wide open position. Lucky I found a Youtube video detailing the disassembly and repair. Looks like I can fix it myself all I need is some time and patience.

Re: My lens has a spot on it, is there anything I can do?
 

Sorry, what i dont understand is, why is it that people say that in order for a lens to be constant aperture, that the lens has to be larger and heavier, when you can just turn a variable aperture lens into a constant aperture by closing the aperture down?

What's the point of a heavier lens when you can make a variable aperture into constant? Is there a hidden catch or hidden problem to that, that i am missing?

Re: My lens has a spot on it, is there anything I can do?
 

What you're missing is the largest maximum aperture value at full telephoto.

With a constant aperture zoom, you don't have to stop down. That's the advantage.

The trade-offs are size, weight, and cost.

The 30-300 cine zoom that I mentioned earlier has to be variable aperture in order to keep those three factors manageable, because it's *already* big, heavy and expensive.

Your 75-300 is variable for one reason only: to minimize the cost. It is, after all, a very cheap lens.

The Canon 70-200 f/2.8L is constant aperture, and fairly big and heavy for a still-photo lens. If you get it with IS, it's almost $2,200.

The Canon 70-200 f/4L is also constant aperture, but f/4 is as open as it will go. It's also half the size, half the weight, and half the cost of the 70-200 f/2.8L.

The Canon 70-300 f/4-5.6L is a constant f/4 from 70 to 260mm or so and only after that does it stop down to f/5.6.

The Canon 100-400 f/4-5.6L works pretty much the same way as the 70-300 above, but it can be used with extenders (at a cost of one or two stops).

Almost all telephoto zooms above 200mm are variable aperture. It's easier to do constant aperture on wide zooms, such as the Canon 16-35, which can be had two ways, either f/4 with IS, or f/2.8 without IS.

But some wide zooms are variable aperture because they're a lot less expensive that way. Such as the Canon EF-S 10-18, which goes from f/3.5 to f/5.6. But it's a steal for less than $300. I own one and I love it.

All of these lenses though are designed for still photography and were never intended for video production, even though some people use them that way.

It's a lot easier to get larger maximum aperture values (and sometimes constant aperture ranges) on broadcast video lenses since their image circles are smaller than Super 35. For example, the lens in the Canon XF300 is f/1.8 at full wide angle and stops down only to f/2.8 at full telephoto. The equivalent 35mm lens would be 600mm. Canon doesn't even make a 600mm f/2.8 still photo lens. The make a 600mm f/4 and it costs $11,000. The XF 300 has the equivalent of a 600mm f/2.8 and it's half the money of the 600 f/4 still photo lens.

Constant vs. variable aperture zooms are a function of a balance between several factors:

1.) size of image circle (full-frame, Super 35, half-inch, etc.)
2.) maximum focal length: wide zoom vs. telephoto zoom
3.) zoom ratio (widest to longest focal length, could be less than 2x or more than 10x)
4.) application (cinematography, videography or photography)
5.) size and weight
6.) cost

There's no single determiner. Does that help?

Re: My lens has a spot on it, is there anything I can do?
 

Look, both halves of this are true. First:

This is correct. If you could take your current 75-300 and hold it in one hand, and hold the Canon EF 70-200 f/2.8L in your other hand, the difference in size and weight (and cost) might astonish you. The 70-200 f/2.8 is much larger and much heavier (and much more expensive) precisely because it is constant aperture (well, also, it has much better glass, plus a much better AF mechanism).

And:

This is also true. Except... you wouldn't be shooting f/2.8 at 200mm full telephoto. Get it? Some people want that. And they can afford it. And they don't mind the size and weight.

I've been telling you to "just turn a variable aperture lens into a constant aperture by stopping down" because you don't have much of a choice, my friend. There is no such thing as a constant aperture telephoto zoom to 300mm in a Canon EF or EF-S lens mount. The sole exception to this would be the Canon EF 100-400 f/4-5.6L IS, which would give you a constant f/4 from 100mm to 350mm or so. Beyond that it closes down to f/5.6.

I can't speak for Nikon, Sony or anything else in the APS-C / Super 35 image circle size, but I kinda doubt any of them have a constant aperture telephoto zoom that reaches 300mm. Maybe someone else who knows can chime in on that.

Re: My lens has a spot on it, is there anything I can do?
 

There are some 16mm cine zoom lenses, which also display the variable aperture when at maximin aperture, as do ENG zoom lenses and the zooms in video camcorders. The reason is to keep the sizes and weight down..

I saw some constant aperture zooms intended for 2/3" cameras (to be used on dramas) and they were much larger than the usual zooms made by the same manufacturer (with the same focal length) as found on ENG cameras. .

Re: My lens has a spot on it, is there anything I can do?
 

Oh okay that's what I thought. But since being zoomed at 300 mm around has such a shallow deph of field, I didn't think it was possible to shoot an f 2.8 and still have the footage be usable because the depth of field would be way too shallow to fit more than one actor in focus.

so I didn't think I would be using f2.8 anyway therefore, or a wide f-stop at all.

I thought if i shoot under low light I would just get a camera there was good for it like the Sony a7s II or the Panasonic gh5 and then shoot at a deeper depth of field, unless there would be any reason not to?

Well the store was able to replace my lens since it was under warranty and they gave me a new one under store policy. But as far as getting a lens with an aperture ring goes, since I was going to get a new camera anyway, why not just get a camera where I can switch off the servo controls to the lens, rather than by a new lens with an aperture ring?

Re: My lens has a spot on it, is there anything I can do?
 

High end f2.8 300mm lenses have been available since the 1970s and used by sports photographers and film makers ever since.

As for the aperture ring, it really depends on your future plans and if you wish to buy a digital cinema camera, which commonly have an ISO of 800 when shooting RAW and log. If you don't know what these are (and their advantages), please look it up online, since I don't think a thread would be long enough to explain it to you.

If you plan just to shoot with a DSLR and are happy to get a camera that can set the aperture using manual mode (you'll need to check that you can do this with a particular camera) that fine. I don't think this involves switching off the servos controlling the aperture like you can the focus, it involves using the camera menus.

Personally, because it's intended for video rather than stills, I'd buy a f4 Canon 300 with an aperture ring and a range extender, but you seem to make a simple decision complicated.

Re: My lens has a spot on it, is there anything I can do?
 

Oh okay, I've tried shooting at a wide aperture on my lens but feel I need to close it down to around f11 to get a couple of people at least in focus.

What I mean is a camera where you can shut off the auto exposure system, since it was that that was causing the lens to change aperture when zooming, through the servo controls, unless I have that wrong...

I would want a camera where you can have full manual control during the zooming. Or I could get a video camera instead of a DSLR, but I do have projects I want to to do shooting on streets at night, where I can't light the streets, so I would want a good ISO, like the one the Sony A7s II has or something like that, probably.

Re: My lens has a spot on it, is there anything I can do?
 

The aperture setting should be on manual for drama, regardless of if you're zooming. You need to check that the camera can allow you to set that and that also lock the shutter, so that it also won't change.

My argument for the aperture ring is that it's quick to set and you're not fiddling with the camera trying to set the aperture. I lit a video that used a lens with no aperture ring on a GH5 and it involved some playing around and I'm still not sure if everything was under manual control. I wasn't operating the camera, bit there seemed be some compromise going on.

Re: My lens has a spot on it, is there anything I can do?
 

Oh okay, for sure.

On my camera I have full manual controls and have total control on the shutter, aperture, and ISO and it's all locked and won't change. The only thing I don't have manual control over, is the aperture changing while zooming, so I will want a camera where I can lock it while zooming as well.

I've used lenses with the rings while doing projects in a film school course I took. The one dis-advantage of the rings is that the ring was very sensitive to moving and if the lens was bumped or anything, the aperture would move, where as by setting the aperture in camera, it locks, unlike a ring.

But the ring I could probably get more use to. I just figure that since so many zoom lenses out there don't have rings, maybe I should just get the best one, and get a camera where I have manual control of the aperture during zooming, since I was going to get a new camera anyway. If I get a camera that has full manual control during zooming, then I do really need an aperture ring on the lens?

Re: My lens has a spot on it, is there anything I can do?
 

The ring can get know knocked? Well yes, if you are careless, but you just train yourself to do it. I don't think I have ever knocked the iris ring as it's close to the camera - I've done the focus ring lots, because it's at the other end and easier to move when you hold the lens up?

Why are you asking questions, then ignoring the multitude of comments?

You have a lens that is performing poorly from your posts optically, and physically. So when you buy a new one FOR VIDEO - buy one that:
1. Stays in focus when you zoom
2. Stays on exactly the stop you set it to
3. Has sharp focus
4. Is cost effective.

All 4, or nothing - but until you do, don't keep reinventing the problems you currently have.

If you plain just don't wish to hire the right tool, for goodness sake, buy one that will do what you say you need.

You NEED a lens that will allow YOU, or the camera to adjust the iris. It needs to be selectable - give control to the camera or keep it for yourself. Very straightforward.

Loads of lenses have servo control (I just won't use the 'fly by wire' term) and clearly for you these are bad, because it shows they are designed for photography not video. If you want to shoot video, buy video kit. How many photos do you take on your camera? As I have said, nothing would make me shoot video on my DSLR - it's simply awfully designed for moving pictures. Some, I admit can be optimised for this, but so many do video as an 'amateur' add on, and do it pretty poorly - other than maybe picture quality.

Re: My lens has a spot on it, is there anything I can do?
 

Okay thanks. Yes I will get a new lens, just still deciding. As for a new camera, which I also want, since I am not digging the T2i for other reasons anymore, I want a camera like the Sony A 7sII, which is good for shooting on the streets at night, when you can't light a whole street, since it has a high ISO, but I want a camera that a smaller sensor than full frame, like an APS-C sized sensor, cause then the shallow DOF won't be so sensitive, when shooting under low light.

Are there any video cameras, that would have those two features, plus no servo control limitations? :)

Re: My lens has a spot on it, is there anything I can do?
 

Ryan - I know little of the A7, but my colleagues in the Guild of Television Professionals here in the UK have been looking for users with their own recommended setups to solve the camera's noise problem in low light - dealing down to 400 equivalent, and they complain about the screen which is difficult to see in sunlight? No idea if this impacts on you, but thought I'd mention it.