Wildlife, long lenses, and sensor format

[jaapv]

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I have disabled it on the GX8 by reversing the LCD closed. The focus point was all over the place when carrying the camera, as any touching of the screen when not using the camera would move the point in an idiotic position. I know some people like controlling the focus point with their left thumb during shooting, but in my case it was my nose doing the same thing.

[willeica]

I have disabled it on the GX8 by reversing the LCD closed. The focus point was all over the place when carrying the camera, as any touching of the screen when not using the camera would move the point in an idiotic position. I know some people like controlling the focus point with their left thumb during shooting, but in my case it was my nose doing the same thing.

 

I am with you 100 % on this. I always lock up touch screens and joysticks as much as possible to avoid this type of thing. Today's electronic devices, including cameras, seem to be designed for those with the manual dexterity of games playing youths. I understand, like you, that some people want this type of thing but camera designers should ensure that those who don't can get their preferred options easily.

 

William

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[jaapv]

It can be practical using LV on a tripod, I suppose.

[Jeff S]

I have disabled it on the GX8 by reversing the LCD closed. The focus point was all over the place when carrying the camera, as any touching of the screen when not using the camera would move the point in an idiotic position. I know some people like controlling the focus point with their left thumb during shooting, but in my case it was my nose doing the same thing.

Can be disabled on SL as well. (I'm still deciding if I want to buy.into the SL system, but that has prompted me to study and test its operation and practical usage.)

 

Jeff

[Steve Spencer]

Yes, the ff crowd is catching up. When will this first camera of the new generation be available? Will Leica implement this technology within the next decade? There will undoubtedly be a next round in this race.

 

But still, the quality-weight and bulk ratio will remain in favour of MFT for simple physical reasons. The FF lenses will remain heavy an unweildy, the bodies larger, the handling differences will remain.

Coming back to one of my earlier posts, as long as I can fit a complete travel/wildlife system into a small bag @ 3 kg with an IQ that approaches FF,  and be able to handle  a 1.5 kg 800 mm handheld,  it is a no-brainer to me.

If I were working for National Geographic and were able to organize a fully staffed expedition, other considerations would come into play. Then a few suitcases of heavy Canikon stuff will go nearly unnoticed and the infrastructure of tripods etc. would be taken care of, or, on the other side of the spectrum, if my travel would consist of a weekend at Disneyland with the family or a ten-day tour to Rome and Paris, then taking the M9/10 with a couple of lenses and an iPhone for the video would be the thing to do.

 

I agree with almost everything you wrote here, but I think Sony and probably Fuji before long will be viable alternative for that 3kg bag and have a quality-weight to bulk ratio that competes with M4/3rds. Right now the Sony A9, 100-400 GM (with the 2X teleconverter), FE 28 f/2 (or 35 f/2.8 if your prefer), the FE 55 f/1.8, and FE 85 f/1.8 would come in at very close to 3kg. That is a lot of quality for the weight bulk tradeoff. At anything shorter than 100mm weight and size is determined more by materials and depth of field capabilities than size of the image circle that needs to be covered. A good example is the FE 35 f/2.8. It is just as small as the Panny Leica 15 f/1.7 and the Only 17 f/1.8 and actually beats those two for depth of field capabilities. After 100mm FF lenses need to be longer and therefore bigger, but and it is an important "but," teleconverters are a great equalizer and depending on the quality of the teleconverter can equalize quality and go a long way to equalizing size. 

 

Fuji with their APSC cameras will likely be pretty competitive soon as well. Their 18 f/2, 35 f/1.4, and 55 f/1.2 are very similar in size and weight to the Panny Leica 15 f/1.7. 25 f/1.4, and 42.5 f/1.2. Their new 100-400 f/4.5-5.6 also holds the promise that with a 1.4 tele extender of being very competitive with the Panny Leica 100-400. I am not sure if the Fuji lens works with a 1.4 tele extender, but if they make a camera that is competitive with the GX8 and that focusses well with a 1.4 teleconverter and their 100-400, then they too could  compete for a very nice 3kg bag.

[jaapv]

Development certainly has not stopped, but FF still needs about twice the bulk of a M4/3rds lens for simple optical reasons (i.e. the energy flow of the light), and APSC is somewhere in between. There is only so much one can do with light-weight materials, Fresnel optics, etc. FF lenses cannot be small and light and high quality at the same time - witness the SL.

There is no overcoming the laws of optics and physics.

As for teleconverters, don't forget that that they will lose you one stop for 1.4x and 2 stops for 2x. Not to mention that one has to close down at least one stop on almost all 1.4x converters, and 1-2 stops on all 2x converters to maintain image quality.  The only acceptable extenders ever built were the Leica APO-R ones, the 1.4 required no stopping down, the 2x APO 1 stop ( the 2x nonAPO 2-3 stops BTW). It will be interesting to see whether anybody will be able to match those with modern technology.t

 So you will be looking at extremely slow lenses that will certainly n ot render your beloved shallow DOF.

Note, btw, that the Sony lens is 50% heavier than the Leica one. And advises to use the converters on APS-C, avoiding the edge and corner problems they might exhibit.

[Steve Spencer]

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Development certainly has not stopped, but FF still needs about twice the bulk of a M4/3rds lens for simple optical reasons (i.e. the energy flow of the light), and APSC is somewhere in between. There is only so much one can do with light-weight materials, Fresnel optics, etc. FF lenses cannot be small and light and high quality at the same time - witness the SL.

There is no overcoming the laws of optics and physics.

As for teleconverters, don't forget that that they will lose you one stop for 1.4x and 2 stops for 2x. Not to mention that one has to close down at least one stop on almost all 1.4x converters, and 1-2 stops on all 2x converters to maintain image quality.  The only acceptable extenders ever built were the Leica APO-R ones, the 1.4 required no stopping down, the 2x APO 1 stop ( the 2x nonAPO 2-3 stops BTW). It will be interesting to see whether anybody will be able to match those with modern technology.t

 So you will be looking at extremely slow lenses that will certainly n ot render your beloved shallow DOF.

Note, btw, that the Sony lens is 50% heavier than the Leica one. And advises to use the converters on APS-C, avoiding the edge and corner problems they might exhibit.

 

FF 35MM lenses shorter than and including 135mm can be small, and light, and high quality at the same time--witness Leica M lenses. Longer than 135mm and it becomes a much bigger challenge, I agree. I also agree that the APO-R teleconverters are the best ones I have encountered, but the third generation Canon ones are quite good, and not surprisingly the MF one built especially for the Zeiss 350 Superacromat is supposed at least rival the Leica APO ones.  A 100-400mm can be about the same size for any format. Getting a wide enough image circle is not difficult at these longer focal lengths. As the focal length gets longer wider image circles become a lot easier. Look at MF and LF lenses and this becomes obvious. The Leica 100-400 is smaller than the Sony 100-400 not because it is so much easier to build a small lens for M4/3rds, but rather because Panasonic and Leica made small size more of a priority including making the max aperture a half of a stop smaller and that half stop smaller does a lot to make the lens smaller. That and some clever use of materials and good engineering is what allows the Panny/Leica to be the size that it is. Even acknowledging that, however, the Sony lens is not that much bigger. Of course that 100-400 on the an M4/3rds camera is a 200-800mm FF 35mm equivalent, but so is the Sony with a 2X equivalent. The real question about which alternative will be better is basically whether cropping using the M4/3rds camera or using the FF 35mm 2X teleconverter gets you better results. That of course could cut either way depending on the quality of the sensor in the M4/3rds camera and the quality of the teleconverter. Right now I don't dispute that with the quality of the modern M4/3rds sensors that option most likely beats the 2X plus the Sony, but it is not inevitably so and as FF 35MM sensors improve and if teleconverters improve, then that advantage could very well diminish and may even reverse.

[jaapv]

Except for, of course, the light loss of converters.

[Steve Spencer]

Except for, of course, the light loss of converters.

 

Well, you are also collecting less light if you are only shining it on a smaller area (i.e., sensor), so in terms of light gathering it is about the same. A 2X teleconverter looses about 2 stops and shining light on a sensor about 1/4 the size is about 2 stops loss of light as well.

[jaapv]

No. The aperture does not change with crop.

[Steve Spencer]

No. The aperture does not change with crop.

 

Yes, the aperture doesn't change, but the amount of light to which the sensor is exposed (as opposed to the brightness of the light) is different. Think of it this way. If I have a flash light (or torch if your prefer and you are British) and I shine that on one square meter, that is a lot less light than if I have a light that is no brighter but I shine it on a whole football field. In fact, there is no way that the light from a flashlight can light a whole football field. It just is not enough light even though in that square meter it can be equally bright to a light covering a whole field. The amount of light to which a sensor is exposed is a function of both how bright the light is and how large the area is that is being lit. Bigger sensors are exposed to more light than smaller sensors at the same aperture, even if the light is equally bright. Aperture determines the brightness of the light, not the amount of light to which the sensor is exposed. The amount of light to which the sensor is exposed is a function of aperture by sensor size, so at the same aperture larger sensors are always exposed to more light. And if we compare M4/3rds to FF 35mm, at the same aperture FF 35mm is always exposed to 4 times the light (two stops more) as M4/3rds.

Edited May 2, 2017 by Steve Spencer

[Steve Spencer]

Further if we extend this to the teleconverter example. The teleconverter dims the light by two stops, but the full frame sensor is four times the size of the M4/3rds sensor, so the same 100-400 at f/5.6 with the 2X teleconverter will expose the FF 35mm sensor to the same amount of light that it would to a M 4/3rds sensor without the teleconverter. The light for the FF 35mm sensor would be 4 times dimmer, but it would expose a four times bigger area, so exactly the same amount of light.

Edited May 2, 2017 by Steve Spencer

[jaapv]

Yes, the aperture doesn't change, but the amount of light to which the sensor is exposed (as opposed to the brightness of the light) is different. Think of it this way. If I have a flash light (or torch if your prefer and you are British) and I shine that on one square meter, that is a lot less light than if I have a light that is no brighter but I shine it on a whole football field. In fact, there is no way that the light from a flashlight can light a whole football field. It just is not enough light even though in that square meter it can be equally bright to a light covering a whole field. The amount of light to which a sensor is exposed is a function of both how bright the light is and how large the area is that is being lit. Bigger sensors are exposed to more light than smaller sensors at the same aperture, even if the light is equally bright. Aperture determines the brightness of the light, not the amount of light to which the sensor is exposed. The amount of light to which the sensor is exposed is a function of aperture by sensor size, so at the same aperture larger sensors are always exposed to more light. And if we compare M4/3rds to FF 35mm, at the same aperture FF 35mm is always exposed to 4 times the light (two stops more) as M4/3rds.

Sorry, you are confusing two things.

If you use a lens of a given aperture on a sensor the amount of light per square unit will always be the same, regardless of sensor/film size or crop.

The exposure will be exactly the same. A 400 mm 4.0 lens on 4/3rds will remain an 4.0/400 lens. The focal length will not change either, just your field of view will turn into an 800 mm equivalent. If you put a 400/4.0 FF lens on a 4/rds sensor there will be no change in the brightness of the light hitting the sensor, the exposure will be identical to the exposure of a FF sensor.

Your flashlight example is neither here nor there. You will have to move it away to attain light coverage, so it will behave like an extender.

 

If you use an extender, the extender will enlarge the central part of the image, effectively doubling the focal length, which in turn will reduce the amount of light per square unit proportionally, thus reducing the effective aperture.

So a 2x tele-extender will reduce the speed of the lens, turning an f 4.0 lens into an f 8.0 lens. In fact, it is even worse, as you will want to stop the lens down one stop for quality reasons, turning it into  an f 11.2 one.

There is no free lunch in the use of extenders.

[Steve Spencer]

Sorry, you are confusing two things.

If you use a lens of a given aperture on a sensor the amount of light per square unit will always be the same, regardless of sensor/film size or crop.

The exposure will be exactly the same. A 400 mm 4.0 lens on 4/3rds will remain an 4.0/400 lens. The focal length will not change either, just your field of view will turn into an 800 mm equivalent. If you put a 400/4.0 FF lens on a 4/rds sensor there will be no change in the brightness of the light hitting the sensor, the exposure will be identical to the exposure of a FF sensor.

Your flashlight example is neither here nor there. You will have to move it away to attain light coverage, so it will behave like an extender.

 

If you use an extender, the extender will enlarge the central part of the image, effectively doubling the focal length, which in turn will reduce the amount of light per square unit proportionally, thus reducing the effective aperture.

So a 2x tele-extender will reduce the speed of the lens, turning an f 4.0 lens into an f 8.0 lens. In fact, it is even worse, as you will want to stop the lens down one stop for quality reasons, turning it into  an f 11.2 one.

There is no free lunch in the use of extenders.

Yes, but you are missing that that in reducing the amount of light per square unit it is still covering a much larger area than the M4/3rds sensor. It is exactly 1/4 as bright of light over 4 times as big of an area and therefore both sensors are exposed to exactly the same amount of light. Yes, an f/4 lens is turned into an f/8 lens, but an f/8 lens exposes a FF 35mm sensor to exactly the same amount of light (although it is dimmer light over a large area) that an f/4 lens exposes a M4/3rds sensor. The formula for amount of light is simple: brightness times area. You are only focussing on the decreased brightness and ignoring that the lens with the teleconverter is exposing that dimmer light across a bigger area. The 100-400 lens without a teleconverter really would expose a M4/3rds sensor to exactly the same amount of light as the lens with a 2X teleconverter would expose a FF 35mm sensor. It is pretty simple physics and math.

 

Said another way, yes the teleconverter reduces the amount of light per square unit, but you are forgetting that the FF 35mm sensor has 4 times as many square units, so even with the 4 times dimmer light when it is spread across 4 times as many units it is still the same amount of light. Amount of light is not amount of light per square unit, but rather amount of light per square unit multiplied by the number of square units.

Edited May 2, 2017 by Steve Spencer

[pop]

.... The formula for amount of light is simple: brightness times area. ....

however, it's not the total amount of light falling on the whole image which determines the exposure. It's the amount of light which falls on each sensor pit. 

[jaapv]

Yes, but you are missing that that in reducing the amount of light per square unit it is still covering a much larger area than the M4/3rds sensor. It is exactly 1/4 as bright of light over 4 times as big of an area and therefore both sensors are exposed to exactly the same amount of light. Yes, an f/4 lens is turned into an f/8 lens, but an f/8 lens exposes a FF 35mm sensor to exactly the same amount of light (although it is dimmer light over a large area) that an f/4 lens exposes a M4/3rds sensor. The formula for amount of light is simple: brightness times area. You are only focussing on the decreased brightness and ignoring that the lens with the teleconverter is exposing that dimmer light across a bigger area. The 100-400 lens without a teleconverter really would expose a M4/3rds sensor to exactly the same amount of light as the lens with a 2X teleconverter would expose a FF 35mm sensor. It is pretty simple physics and math.

 

Said another way, yes the teleconverter reduces the amount of light per square unit, but you are forgetting that the FF 35mm sensor has 4 times as many square units, so even with the 4 times dimmer light when it is spread across 4 times as many units it is still the same amount of light. Amount of light is not amount of light per square unit, but rather amount of light per square unit multiplied by the number of square units.

Sorry, Steve, you are simply wrong, I cannot say it differently. If you use lens with a given aperture on a medium, be it film or sensor, of a given sensitivity, the exposure will remain the same, regardless of the size of that medium. In other words, the aperture stays the same when you go to a smaller format, the focal length stays the same, the shutterspeed needed stays the same, the medium sensitivity stays the same, the only thing that changes is the angle of view. That was true of view cameras versus Leicas, of 6x9 versus 110, and it is still true.

 

If you use an extender you are doing something totally different. You are increasing the focal length of the lens without increasing the size of the entrance pupil, which by simple math will decrease the aperture proportionally resulting in a needed increase in medium sensitivity or a slower shutterspeed to reach the same exposure.

The F- number N, the focal length f and the diameter  of the entrance pupil D.   N=f/D.  So you see that sensor format does not enter into the equation for aperture. An extender changes the focal length and the entrance pupil will remain the same, thus the aperture will change.

 

Forget all that stuff about "amount of light falling through the lens". It has absolutely nothing to do with the extender versus crop situation, and only muddles everything up. See it this way: You have a certain amount of light falling through a window into a room onto a wall. Now does it make a difference to the brightness of the wall whether you take a piece of 1x1 meter or a piece of 10x10 centimeter? Clearly not, the brightness will be exactly the same, despite the small area receiving only a fraction of the light falling through the window.

[Steve Spencer]

however, it's not the total amount of light falling on the whole image which determines the exposure. It's the amount of light which falls on each sensor pit. 

 

Of course and I never said otherwise. I am not talking about exposure. I am talking about the amount of light that is available to convert into an image and that is important in its own right.

[Steve Spencer]

Sorry, Steve, you are simply wrong, I cannot say it differently. If you use lens with a given aperture on a medium, be it film or sensor, of a given sensitivity, the exposure will remain the same, regardless of the size of that medium. In other words, the aperture stays the same when you go to a smaller format, the focal length stays the same, the shutterspeed needed stays the same, the medium sensitivity stays the same, the only thing that changes is the angle of view. That was true of view cameras versus Leicas, of 6x9 versus 110, and it is still true.

 

If you use an extender you are doing something totally different. You are increasing the focal length of the lens without increasing the size of the entrance pupil, which by simple math will decrease the aperture proportionally resulting in a needed increase in medium sensitivity or a slower shutterspeed to reach the same exposure.

The F- number N, the focal length f and the diameter  of the entrance pupil D.   N=f/D.  So you see that sensor format does not enter into the equation for aperture. An extender changes the focal length and the entrance pupil will remain the same, thus the aperture will change.

 

Forget all that stuff about "amount of light falling through the lens". It has absolutely nothing to do with the extender versus crop situation, and only muddles everything up. See it this way: You have a certain amount of light falling through a window into a room onto a wall. Now does it make a difference to the brightness of the wall whether you take a piece of 1x1 meter or a piece of 10x10 centimeter? Clearly not, the brightness will be exactly the same, despite the small area receiving only a fraction of the light falling through the window.

I am not wrong, you just are not listening to what I am saying and instead suggesting that I am saying something that I am not. I am not saying anything about exposure, shutter speed or any of the other things you seem to think I am saying but rather I am making a point about the amount of light that is available to convert into an image. And that point has a lot to do with the crop vs. tele extender argument whether you realize it or not. You are putting words in my mouth that I would never say if you think I am saying the aperture isn't effected by the teleconverter. I know that it is and I said so. Go back and read what I wrote. Again, I am not talking about exposure. I am talking about the amount of light available to convert into an image. So please don't put wrong words in my mouth and then tell me that I am wrong. Please quote anywhere where I mentioned exposure.

Nothing you say above is wrong, but none of it addresses what I said either. And it is true that the same amount of light will be available to be converted into an image in both instances. Now, if you think that point is wrong--as opposed to something you think I said but I did not say--then by all means please tell me how it is wrong, but please don't waste both of our time by telling me how a bunch of things are wrong that I know are wrong and I didn't say.

Edited May 3, 2017 by Steve Spencer

[Exodies]

The amount of light available to be converted into an image is not converted into an image. Only the light falling on a sensor cell is converted into an image and this amount of light is the same regardless of how many cells there are. Bigger cells will have more light falling on them than smaller ones but if they are the same size then whether there are ten or a hundred doesn't change the amount of light falling on each.

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[jaapv]

I'm sorry, I cannot make myself more clear than I did in my previous posts, but you have it wrong if you equate cropping by sensor size to using an extender.

Your argument only explains why a FF lens must be larger than a 4/3rds one.