FAQ like Info about 35mm lenses

[mvansomeren]

.....
I just am confused about the lens aspects and their apertures when it comes to 35mm adapters.

In simple terms, the "F" stop is a measurement of how much light the lens loses. The smaller the number, the less light it will lose. Another way to look at it is that a lower number lets in more light. Either way, its imporant, not so much to the focus, but to the brightness of the image. The 35mm adapter loses some light...usually from .5 to 2 stops depending upon the adapters. Add to that the amount of light the lens loses and suddenly, you might have a problem seeing the image.

In the paragraph that you quoted, many telephoto lenses lose more light the more you zoom in. So, it may have a begining apeture of f3.5 when it's set to wide angle, and go all the way to f5.6 when fully zoomed in. Constant apeture zoom lenses are able to maintain one f stop through the entire range of zooming.

When you're outdoors in sunlight, this won't cause you much grief, but when it's getting dark or you're inside, you'll need to add lights to get a good shot.

For this reason, people try to get lenses that have small f stops. A 50mm lens, for example, may come with maximum apetures of: f1.4, f1.8, f2. The f1.4 is the better choice, in general. And, the lower fstops usually means more expensive, as well.

 

[MitchLewis]

35mm lenses (Nikon for example) are either a "prime" lens, which means you can zoom with it, it's just a fixed lens (ex: 28mm, 50mm, 85mm, etc...).

35mm lenses also come in a variety of apertures. For example an expensive 50mm "prime" lens may be available with an f-stop that opens as wide as f/1.2, but the cheaper ones may only open to f/1.8.

35mm lenses are also available as zoom lenses. This means you might be able change the focal length from say 80mm to 200mm. KEY POINT: But on the cheaper zoom lenses the f-stop will change when you zoom in. It might go from f/3.5 at 80mm to f/5.5 at 200mm....or something like that. Where as Nikon makse an expensive 80-200mm lens where you can use f/2.8 no matter if your at 80mm or 200mm. Because the low f/2.8 can be used at both 80mm and 200mm (and everywhere in between) it makes the lens much "brighter" for shooting in dark situations.

 

[MitchLewis]

mvansomeren beat me to it!

 

[mvansomeren]

I type fast:2vrolijk_08:

 

[luke e]

In simple terms, the "F" stop is a measurement of how much light the lens loses. The smaller the number, the less light it will lose. Another way to look at it is that a lower number lets in more light. Either way, its imporant, not so much to the focus, but to the brightness of the image. The 35mm adapter loses some light...usually from .5 to 2 stops depending upon the adapters. Add to that the amount of light the lens loses and suddenly, you might have a problem seeing the image.

In the paragraph that you quoted, many telephoto lenses lose more light the more you zoom in. So, it may have a begining apeture of f3.5 when it's set to wide angle, and go all the way to f5.6 when fully zoomed in. Constant apeture zoom lenses are able to maintain one f stop through the entire range of zooming.

When you're outdoors in sunlight, this won't cause you much grief, but when it's getting dark or you're inside, you'll need to add lights to get a good shot.

For this reason, people try to get lenses that have small f stops. A 50mm lens, for example, may come with maximum apetures of: f1.4, f1.8, f2. The f1.4 is the better choice, in general. And, the lower fstops usually means more expensive, as well.

I understand what aperture is and how it effects the image. I just don't understand what it means when you say the maximum aperture is f1.4. Like does that mean the lens won't focus if you open up the aperture any more?

This sentence confuses me: "So, it may have a begining apeture of f3.5 when it's set to wide angle, and go all the way to f5.6 when fully zoomed in."

What is the beginning aperture? are you saying that when it's fully wide angled, zoomed all the way out, you have a maximum aperture of 3.5? How does the aperture change automatically when it zooms in? This is what I don't understand? Are you just saying that it will have to open it up to f5.6 when you zoom in because it loses that much light from the aperture that is needed with the lens zoomed all the way out?

edit:

KEY POINT: But on the cheaper zoom lenses the f-stop will change when you zoom in. It might go from f/3.5 at 80mm to f/5.5 at 200mm....or something like that.

what do you mean it will change? I am thinking about this as someone who has shot only digital video[no adapters]. like is there an aperture on the lens along with the aperture in my dvx? That is what I don't understand.

 

[davide]

I understand what aperture is and how it effects the image. I just don't understand what it means when you say the maximum aperture is f1.4. Like does that mean the lens won't focus if you open up the aperture any more?

This sentence confuses me: "So, it may have a begining apeture of f3.5 when it's set to wide angle, and go all the way to f5.6 when fully zoomed in."

What is the beginning aperture? are you saying that when it's fully wide angled, zoomed all the way out, you have a maximum aperture of 3.5? How does the aperture change automatically when it zooms in? This is what I don't understand? Are you just saying that it will have to open it up to f5.6 when you zoom in because it loses that much light from the aperture that is needed with the lens zoomed all the way out?

edit:



what do you mean it will change? I am thinking about this as someone who has shot only digital video[no adapters]. like is there an aperture on the lens along with the aperture in my dvx? That is what I don't understand.

Hi Luke,

Maximum aperture means that you can't physically open up the aperture anymore, that's as wide as it is going to get. Minimum aperture is when you can't physically make the aperture any smaller. At 1:25 of this video you can see the host opening and closing the aperture of the lens: http://www.youtube.com/watch?v=u8myC4-bhAY.

For some zoom (probably most) lenses the maximum aperture changes as you zoom in from wide to telephoto. I am not physically sure of why this is. It may have something to do with the fact that f-stop is a result of aperture and focal length so as the focal length changes the f-stop goes down for a given aperture width. The important thing to know is that it does happen. So if you're on a zoom lens at its widest setting and its widest aperture and you zoom in the picture is going to get darker.

What digital camera do you have because this happens on most digital cameras as well. On the DVX100 the maximum aperture is about 1.7, but if you zoom in to the full telephoto you'll lose about a stop of light. Try setting up your digital camera by zooming out and opening up the aperture all the way. Then, with an eye on the LCD screen, zoom in to the max telephoto. If the image gets any darker then your zoom lens ramps aperture as it zooms in to telephoto.

davide

 

[MitchLewis]

Dang! Beat me to it again!

 

[TimurCivan]

ok...lets start with what apeture is.

Its the ratio of the focal length to the width of the elements in the glass.

For example. a 50mm lens with a focal length of 50mm. Its internal build is a piece of glass that 50mm across. thats a F1.0 ( theoretically)

45mm and its something like a F1.2... 40mm F1.4..... Thats its maximum apeture. ITs the widest the glass can physically be. ( now its not that simple, and there are other factors, but this is the easiest way to understand it...) Esentially every time the apeture drops a stop, the area of its maximum opening is reduced by half.

Now imagine a lens thats a 200mm ... Imagine a lens thats 200 mm wide... thats HUGE. hence why most 200mm lenses are usually a F2.8 or about 50mm wide. They do make F2.0 200mm lenses but they cost 2500$.....

Now why a Zoom lens loses "stop" when ou zoom in is that the realtive maximum apeture of it at wide angle, lets say 35mm-105 Zoom. At 35mm the opening in proportion to its widest peice of glass is 20mm. Thats like a 2.8 for arguments sake. But when the Focal length becomes 105mm when you extend the lens out to zoom in, that same 20mm opening is proportionally a F5.6 to a 105mm lens.

get it?

 

[mvansomeren]

In addition to what davide said...

I understand what aperture is and how it effects the image. I just don't understand what it means when you say the maximum aperture is f1.4. Like does that mean the lens won't focus if you open up the aperture any more?

I think you may be associating apeture with focus. It's true that if you open a lens up to the lowest f stop (maxium), let's assume it happens to be f1.4 on a particular lens, the image will tend to be a little "soft". And, as you stop-down the lens (close down the apeture) to say f4, the image will be slightly sharper. That said, it's important that you understand that apeture is directly related to the brightness of an image, not focus.

Are you just saying that it will have to open it up to f5.6 when you zoom in because it loses that much light from the aperture that is needed with the lens zoomed all the way out?

Actually, when you move from f3.5 to f5.6 you are closing the lens down, not opening it up.

Regardless of how it happens (nice explanation, Timur), look at it this way. If you have a zoom lens and set it's apeture to maxium, let's say on this lens it's f3.5 and the lens is set to the widest angle.... if you look through the lens, the image will be a certain brightness. As you start to zoom in, the image will get darker. so when you're fully zoomed in, even though your apeture is physically set to f3.5, the brightness of the picture will be as if it was set to f5.6. Since you are already set to the maxium apeture of f3.5, the only way you can compensate is to add more lights.

You can purchase zoom lenes that have constant apeture. These lenses keep the image the same brightness throughout the entire zoom range.

Oh, by the way, if you want to try this on your camera as davide suggested, make sure you set your camera to manual mode so the camera doesn't automatically compensate and try to keep the picture a certain brightness.

 

[Dionisio]

Thanks a lot Tim,

Very appreciated info.
Saludos,

 

[luke e]

ok, I may be thinking about things completely wrong. let us see..

I'm going to simply state what I understand and what is confusing me.

"It's true that if you open a lens up to the lowest f stop (maxium), let's assume it happens to be f1.4 on a particular lens, the image will tend to be a little "soft". And, as you stop-down the lens (close down the apeture) to say f4, the image will be slightly sharper. That said, it's important that you understand that apeture is directly related to the brightness of an image, not focus. "

I understand this completely. the whole concept and effect of aperture seems to be clear to me, I understand what it means and what it does to the image.

what i dont understand is the difference of aperture[same as exposure correct?] of my digital camcorder or of a 35mm adapter rig..

"Maximum aperture means that you can't physically open up the aperture anymore, that's as wide as it is going to get. Minimum aperture is when you can't physically make the aperture any smaller."

This makes complete sense to me, I understand what max and min aperture mean. the thing is, I think about this things from a standpoint of someone who has no experience with anything but digital. The thing I don't understand is pertaining to the 35mm options of video. So:

I have used a dvx and I know my way around the camera fairly well.
when you attach a 35mm adapter to the front of it, and you are setting up to shoot, how are you setting the aperture? Is there a dial on the 35mm lens that effects it's brightness? Because what I would think is that you set the aperture via exposure dial on the dvx. Now I know that could be the completely wrong thing to do but I'm trying to explain my standpoint. when you are opening the aperture on the lens like shown in that youtube video, what exactly will happen if the lens is attached to a 35mm adapter on a dvx100? will it affect the brightness of the image? Or do you change the exposure on the dvx?

so in a nutshell here is what I don't understand:

I don't understand exactly how you set the focus AND aperture of a 35mm lens when on my little experience of my d70, you change the aperture in camera and all that I am changing with my lens is the focus.

So it would be great if someone could explain to me step by step how they get the settings right if they are using a 35mm adapter rig with say a 50mm lens. Do you set exposure in camera or on the lens? PHYSICALLY SPEAKING, how is the focus different than aperture[i know how each of them effect the image]

I am really confused guys so thanks a bunch for talking me through this stuff. :dankk2:

 

[TimurCivan]

well the beauty of the 35 adapter system is this. the 35mm lens, controls what the Video camera sees. if you are out doors and the amount of light is no worry, you can set the exposur with either the 35mm lens, or the HVX.

I prefer to stop down the 35mm lens first, then the HVX.

 

[Shooter]

I am real curious Tim...why do it that way?

Surely one needs to set the HVX aperture to minimise the risk of focussing the adapter screen grain and to optimise the sensitivity of the sensor chip first.

Then treat the 35mm lens as one would if there were no other devices in the light path. ie 35mm lens directly mounted to the camera sans DOF Adapter.

 

[TimurCivan]

you get better optical performance out of a stopped down 35mm lens. so long as you are not underexposing what the HVX can recieve at wide open on the HVX iris.... Stop down the 35mm glass to get the best performance there.

SGpro's are less sensitive to GG grain than letus adapter, or brevis adapters. though the light penalty is higher in exchance.

Stropping down up front has never been a problem for me.

 

[bluesgeek]

For narrower DOF, decrease exposure in the camera while keeping the SLR lens more open (but stop the lens down just a bit because lenses are not as sharp when wide open). For wider DOF, keep the camera exposure open and stop down the lens more. Yes?

Here's a good DOF tutorial.

 

[Kit_L]

some additional info on Nikon and Zeiss 35mm lenses

some additional info on Nikon and Zeiss 35mm lenses

Timur, great thread, but no one has mentioned that the latest Nikkor "G" lenses cannot be used as you describe, because they do not have an iris ring (on DSLRs, controlled electronically).

As well, stopping down a 35mm lens has limits, too; depending on the lens, stopping down more than ƒ11 can render the final image soft. Best if you can use the sweet spot of the lens and keep the aperture there in bright light by using an ND filter.

Dan, you wrote:

50mm 1.4 AIS - I scored one in really good condition on Ebay for $185.00
85mm 1.4 AIS or D - these are expensive, around $600.00 to $1,000.00 usually, that's why I went for the 85mm 1.8 AIS - mint used for $185.00
105mm 2.8 D Micro - When they come on the market, they are around $500.00 to $600.00
180mm 2.8D - $659.00
200mm 2.0D - $3,789.00

If I can just add a few remarks (also with ~35 year's shooting stills with pretty much all maker's glass!):

The Nikon 50/1.4 is just one of the great lenses, and great value for money. I also have the Zeiss ZF (Nikon mount version) of the 50/2 Makro-Planar; this is razor sharp wide open, and sharper at ƒ2 than the Nikon is at the same aperture, as well as having an absolutely flat field. The long throw of the focussing helicoid is a great blessing here too in some circumstances, too, but much more expensive, of course.

The 85/1.8 Nikkor is similarly outstanding value, and is sharp wide open. I have had two copies of the ƒ1,4 version, and each time sell them to buy the ƒ1.8 version. DOF is so thin at ƒ1.4 that missing the precise point of focus is easy. As an example, if making a head and shoulders image front on, at ƒ2.8 the top of the ears will be very soft---my preference at this distance is to shoot at ƒ4. The point? The ƒ1.8 version, at half the weight and similar sharpness, is the better lens for most people, and will be so in the context of the adapter/video camera application being discussed here.

The 105/2.8 Nikkor is a great lens; the Zeiss 100/2 Makro-Planar is a *legend* of a lens, and is the best 35mm lens I have ever owned. The Out Of Focus (OOF, or 'bokeh') areas on this lens are truly painterly, but if you have the 85, you may not need it.

I would add just two lenses to your list: the humble Nikkor 35/2 (again, a good copy is sharp wide open, sharper at ƒ2,8 and very very sharp at ƒ4), and the Zeiss 28/2 Distagon---IMHO, better than any Nikkor 28 made, so far.

Re. zooms: a good copy of the 37-70/2.8 Nikkor is very sharp at ƒ4---this can be enough in some circumstances. The 80-200/2.8 I have shot wide open for brochure shots for John Deere many times, so will be fine on the adapter, IMHO. Similarly good copies of the 28-105/3.5-4.5 and a spectacular copy of the 24-85/3.5-4.5, but might be considered too slow by many here, but the 28-85 lives on my D700.

I agree, though, that a good prime usually looks better than the same focal length in a zoom---*except* for the 14-24/2.8: that is in a league of its own. Pity it's a G mount. Cheers, kl

As I work out how I am going to pay for a 35mm adapter for my HMC150, I am glad I still have most of my best lenses! Cheers all

 

[ChrisHurn]

I'm very new to this, thanks for the posts, but just to clarify something. I'm looking at the Letus35 extreme and I notice there are different kinds of mounts, say I was to get a Nikkon AI mount, does this mean I can only use Nikkon Lenses? And what does the AI mean? Cheers. I apologize for the noob question, but I want to be double sure since the lens mounts are about $100 each.

 

[MitchLewis]

http://www.kenrockwell.com/nikon/compatibility-lens.htm

 

[Luis_]

All in all, a proper 35adapter setup can cost you almost $4,500. Thats nearly as much as an HVX200!

I think people need to be aware of the "hidden" costs associated with the 35 system. Suddenly, film starts seeming cheaper and cheaper........



All my best hope this was helpfull!

-Timur

I'm not planning to make movies any time soon but I will shoot music videos and odds and ends like weddings and stuff like that. ​

I have the HVX200A.
I have a budget of $2,000 right now.
Can I get any kind of decent setup with that?
or am I going to have to shoot a few more sweet sixteens to get there?

 

[USLatin]

Is there anyone in the Northern Minnesota area with a 35mm rig? If so please PM me!
I hope you guys don't mind me hacking a post here, and I apologize for it, but we need to find a few pieces we are missing to make a production happen at the end of the month and I would love to find someone out of the people posting on this thread. Maybe we get lucky and shoot on a Blade

BTW, I just saw Leo's rig on the show-off thread and man... what a sexy rig... rogar-Love(DBG):

I hope the footy will be rolling in soon. hint hint