With what Telephoto Lens might One Achieve such a Photo...?

[comicsdecoder]

Okay, here goes my first bizarre question on a forum where my membership will undoubtably not produce a multitude of conventional queries....

I'm working on an experimental, Ballardesque (read strange) short story that focusses heavily on voyeurism and the like, and—in a bid to maintain some degree of accuracy and realism—I was wondering if someone could tell me what sort of telephoto lens (i.e., magnification-wise and otherwise) would be required for a closeup of a person's facial profile in a flat/apartment—i.e., through the flat's window pane—at a distance of 40 to 50 meters, and at night. With my luck, such a photo isn't even possible at this point in photographic history! The equipment in question might be of the digital persuasion or of the more traditional nature.

Any takers...?

Anyway, regardless of what responses I might or might not inspire, this is a rather attractive little website—enticing but not overwhelming. Glad I came across it.

[Colin Southern]

From 50 meters I suspect you'd probably need one of these for a closeup, probably with a Teleconverter as well!

[Shadowman]

At that distance his subject will still be able to see the white lens.

From 50 meters I suspect you'd probably need one of these for a closeup, probably with a Teleconverter as well!

[arith]

Cor; I would have thought a 200mm good enough. Maybe http://www.canon.co.uk/For_Home/Prod...0mm_f2.8L_USM/ and add this little thing http://www.photosolution.co.uk/canon...ter-p-286.html for 400mm at f5.6 max.

For only $3500 you get a decent lens but not too good for low light unless you have a Canon 7D with superior noise control and very high iso. So we must be up to $6000 now.

However you want to look through windows so you need a good polariser and...
http://www.hoyafilter.com/products/hoya/pro1d-04.html

Only a few hundred dollars so you now have your image but to get the best out of it you will need something like Neat Image and Photoshop. I believe it is possible.

[William W]

in a bid to maintain some degree of accuracy and realism—I was wondering if someone could tell me what sort of telephoto lens (i.e., magnification-wise and otherwise) would be required for a closeup of a person's facial profile in a flat/apartment—i.e., through the flat's window pane—at a distance of 40 to 50 meters, and at night. Any takers...?

It being at night, or not does not affect the FL required.

It being at night actually does not affect anything, really, because scene lighting / and or / post production could make it appear at night anyway – the point is if you are framing the scene that tight you can light the room such that it appears only the inside of the room lights make the scene appear "at night".

The rest is just simple Mathematics.

With a 1200mm lens, using an APS-C or DX camera at 50m Subject Distance you will get a FoV (Field of View) of just over 500mm high in Horizontal format.

Considering you want an image “that [focuses] heavily on voyeurism” I expect you will shoot horizontal format – as most voyeurism images follow the traditional movie format.

If you used a 135 format camera, like a 5D or Nikon D700, you would need that 1200 lens and a x1.4 tele-converter.

Another option would be a 600mm lens and the x2.0 tele-converter for an APS-C body, or the same 600mm lens with both tele-converters stacked together for a 5D / D700 format camera.

Speaking Canon specifically - considering the EF1200L is custom made to order, if you only want to pull a few shots with it - renting one would be a good idea - (if you can find a person to rent you one).

Also the EF600L is a little more than pocket book money, so renting it might be a good idea too, the two tele-converters could be picked up for about $US650 I guess – if you are buying second hand make sure you get the MkII versions.

A realistic option might be using a telescope and suitable camera adapter . . .

In any event your Subject will need to be quite adept at keeping still, I expect, because even at ISO6400, you will have slowish Tv.

WW

[Colin Southern]

If you used a 135 format camera, like a 5D or Nikon D700, you would need that 1200 lens and a x1.4 tele-converter.

So my educated guess was pretty close eh?

[William W]

So my educated guess was pretty close eh?

OH! Crikey! egg all over my face Colin . . .

I scanned the replies and didn't even see yours! ! !

If I had I would have opened the link.

I opened the link “arith” provided and I knew that the 70 to 200 would be way too short (no offense intended) so I made my comments -
]
Sorry that I skimmed over the answer which was already provided –

I need more Scotch

Best to you,

Bill

[arith]

I'm going to have more Scotch after seeing the price of that lens.

[Colin Southern]

OH! Crikey! egg all over my face Colin . . .

Hi Bill,

No no no - I wasn't "lining you up in my sights", so no egg or apologies necessary - I just took an educated guess, which you kindly "validated" for me

I often use 200mm for portraiture, and I know that I only need to stand a few meters away - so I just did a bit of quick "doubling" in my head to get out to 50m and thought that the EF1200 would probably be close with a little help from a TC.

Sadly, it's one lens I'll probably never own (I only buy new! )

[comicsdecoder]

Wow! I'm impressed! Keep in mind that my question simply evolved out of my desire to keep things a tad bit accurate in a short work of fiction--I have no intention of taking up high-tech voyeurism anytime soon! (Gave that up around 11 or 12, after we were caught spying on the girls' changing room!) I had a feeling I had come to the right place when I stumbled upon this site and did a bit of subsequent probing. I'm going to take a closer look through your suggestions above and then make additions/modifications to my notes. Thanks, fellas.

One thing's for certain: If my occasional camera usage ever develops into a full-time hobby or obsession, I'll know where to post queries!

(Scotch is pretty much a good idea for just about any occasion, I'd wager. I always preferred Black & White (haven't seen it on the market here in Canada for years), with Grant's coming in a close second. Never too fond of Bells', though....)

[Colin Southern]

No worries Robert

I'd be careful about using an EF1200 for illegal voyerism ... there's rumoured to be only about 20 of them in the world, and I'm sure it wouldn't be too hard to track an offender seen using one of them down!.

PS: Prefer Bacardi Rum to Scotch myself

[William W]

Hi Bill,

No no no - I wasn't "lining you up in my sights", so no egg or apologies necessary - I just took an educated guess, which you kindly "validated" for me

Chill Partner.

I never thought that - this is the CiC forum - not that "other" place - we are friendly and have a joke here just as a matter of course

***

They brought out the 1200 for the Rowing here in 2000 - there were three of them . . . I saw a glimpses on the TV coverage - quite impressive - never got to see one in person - as Rowing does not "float my boat" like swimming does - I have used the 500 once - but 400 is all we need inside at the pool - actually I prefer the 300 . . . it is lighter and shorter and I am older.

WW

[William W]

I'm going to take a closer look through your suggestions above and then make additions/modifications to my notes.

One point to consider is, how much you need to be technically correct to convey the vision – I would suggest that the “average viewer” could not tell the difference if the shot was taken with a 1200 + x1.4MkII or a very small section of the 70 to 200 + x2.0MkII . . .

As an absurd example . . . The white building (Top Right) is 1800m away the “window” (Bottom Left) is about 1500m away. This Image, “Moonset”, was taken using 70 to 200 + 2.0MkII and a 5D

Tech: F/8 @ 1/500s @ ISO400, HHeld, Spot M (three readings computed), ExComp = O, AWB, Manual, Single Shot.



For your gig, I suggest that you could get what you want using a 200mm lens with a x2.0MkII with a window about 15m to 20m distance from you, crop the image, and the punters would never know the difference.

WW

[comicsdecoder]

So the bottom image is a blowup of the cropped area in the top image? Interesting. Actually, I was considering having the protagonist of the story crop his photos for maximum enlargement. You've given me something to think about. Cheers.

[rick55]

I think the "at night" part might be a bigger problem than the magnification.

A 400mm lens on a full frame camera will have a field of view of 4.5m x 3m, so you'll certainly be able to zoom in on your subject.

But in a room that isn't too brightly lighted, at ISO 1600 you're going to shoot f/2.8, 1/30 or 1/60, right there in the room. I'd expect available light at a lens to follow an inverse square law. So if inside the room is 5 or 6 meters, the available light at 50m will be at 3 doublings of distance, which is then 6 stops less light. You might do better to use a 100mm f/2.0, and crop, as Bill suggested above. Otherwise, you'll probably have to assume a well-lighted room, ISO 6400, and 1/15 shutter speed. That adds 3-5 stops, and then you just expect it to be a couple of stops under-exposed.

Cheers,
Rick

[Dave Humphries]

I think the "at night" part might be a bigger problem than the magnification.

and hope they don't draw the curtains

[William W]

I think the "at night" part might be a bigger problem than the magnification. . . But in a room that isn't too brightly lighted, at ISO 1600 you're going to shoot f/2.8, 1/30 or 1/60, right there in the room. I'd expect available light at a lens to follow an inverse square law. So if inside the room is 5 or 6 meters, the available light at 50m will be at 3 doublings of distance, which is then 6 stops less light.

Gidday Rick.

Sorry I didn’t get to replying to this earlier, when I noted it pop up on my email alert.

I think you are thinking incorrectly about this and drawing a wrong conclusion as a result.

Certainly a the LIGHT EMITTED FROM A SOURCE follows the inverse square law, but what we would be photographing is the SUBJECT (inside the room) which is ILLUMINATED BY THE LIGHT (inside the room).

Sure the room light (i.e. the LIGHT BULB) is going to throw very little illumination to allow me read by it, if I am over the other side of the street – but the SUBJECT IN THE ROOM WILL APPEAR JUST AS BRIGHT "in the room" or at 50 mtrs from it.

Think of it this way – in daylight – you are at the goal line of a football field and I am standing next to you and you take a photo of my face – you shoot for correct exposure on my skin tones and pull F/8 @ 1/200s at ISO200 (a light/cloud day).

Now you move to the 50 yard line and you whack on a 400mm lens and you pull F/8 @ 1/200s @ ISO200 - my skin tone is still perfectly / properly exposed.

My guess is you would not ever think of pulling six stops over (F/8 @ 1/200 @ ISO 12800) simply because you moved back 50 yards and you were thinking to allow for my skin tone (the SUBJECT's EXPOSURE) falling off, because of the inverse square law?

Does that example make sense?

WW

[carregwen]

Robert

This sounds less Ballard and more Hitchcock. Have you seen 'Rear Window'? http://uk.imdb.com/title/tt0047396/ And I still want to know who posted this shot using my username. Let's get undressed and watch the boys...

But... if you are serious about this, then forget the EF1200 (that's for amateurs) and get yourself this little(?) beauty for $55,000! http://soldierllk.multiply.com/journ...200mm_f14_lens

EDIT: Sorry, mate, forgot to add the

[rick55]

Gidday Rick.

Sorry I didn’t get to replying to this earlier, when I noted it pop up on my email alert.

I think you are thinking incorrectly about this and drawing a wrong conclusion as a result.

Certainly a the LIGHT EMITTED FROM A SOURCE follows the inverse square law, but what we would be photographing is the SUBJECT (inside the room) which is ILLUMINATED BY THE LIGHT (inside the room).

Sure the room light (i.e. the LIGHT BULB) is going to throw very little illumination to allow me read by it, if I am over the other side of the street – but the SUBJECT IN THE ROOM WILL APPEAR JUST AS BRIGHT "in the room" or at 50 mtrs from it.

Think of it this way – in daylight – you are at the goal line of a football field and I am standing next to you and you take a photo of my face – you shoot for correct exposure on my skin tones and pull F/8 @ 1/200s at ISO200 (a light/cloud day).

Now you move to the 50 yard line and you whack on a 400mm lens and you pull F/8 @ 1/200s @ ISO200 - my skin tone is still perfectly / properly exposed.

My guess is you would not ever think of pulling six stops over (F/8 @ 1/200 @ ISO 12800) simply because you moved back 50 yards and you were thinking to allow for my skin tone (the SUBJECT's EXPOSURE) falling off, because of the inverse square law?

Does that example make sense?

WW

Hi, Bill;

Your example makes intuitive sense, but I'm not sure it actually behaves that way. It's an unusual example in real life, I think, where I'm at 6m, then move out to 50m and frame the shot the same way. Or vice versa.

Here was the way I figured it, and I could certainly be wrong.

The inverse square law applies to any point light source, in theory, not just a primary. Consider a tiny point on the subject's face, the ambient light reflected by that point is collected by the lens, obviously, and in my current frame, it completely fills one pixel of a camera sensor. The light from that point is available to any lens that's placed around a sphere around the point. I can fill the sphere with cameras (ignoring the fact that lenses are circles, and I can't pack them), and each camera gets the same light on pixel X, Y of the sensor. This fits with the fact that (minus specular reflections) a face looks the same from most any angle. Of course, in the case of a point on a face, it may only be available to half a sphere, but that really doesn't change anything.

The key is that if you now move out twice as far, you can now fit 4 times as many lenses on that surface (half a sphere or sphere), so the same amount of light that was hitting the sensors of N cameras is now hitting the sensors of 4N cameras. So each camera now has one fourth the light coming to the X, Y location of the sensor.

The only way I can see that you can move back and still have the same light is to have a physically bigger lens to collect the light. I may certainly be missing something, but it seems fundamental physics that the photons reflected from each infinitesimal point of the scene will occupy four times the surface area at each doubling of distance from the scene. So a lens of a fixed light-gathering framed on exactly the same scene will experience one quarter the light at twice the distance.

Cheers,
Rick

[William W]

Your example makes intuitive sense, but I'm not sure it actually behaves that way.

Gidday again,

I had to run when I wrote that previous, but I have more time now as I just got home from my shoot.

***

Frankly, I am (and was previously) confident about the theory and also how it works in the field.

***

I have my kit with me, so let's look at these three shots out of a 5D I will shoot now . . . (PAUSE whilst I take photos) . . .

Back again! . . .

These all are JPEGS straight out of the box the only manipulation is the last frame, where I have enlarged it nine times.

It's bloody dark here so I'll switch on just one room light, I am inside - this is ET sitting on the Piano, you can see the one light above him – the window is on the right, ET is facing the Window, 50mm, F5.6 @ 1/30s @ ISO1600 (Set K = 2800):



***
Now I have moved outside, still have the 50mm lens and I am shooting through the window and I am 2 yards away - metered on the grey card and shot: F/5.6 @ 1/30s @ ISO1600:



***
Now I have moved across the road and up the street a little - I am about 40 yards away I have a 400mm lens loaded and I will still shoot F/5.6 @ 1/30s @ ISO1600:



***
Now I have taken the JPEG from the 400mm shot and enlarged it nine times - there a bushes in front of the window - but I think the point is proven both on ET's skin tone and the grey card - and also it proves that I am tired and can't hold the lens still even on a monopod:



***
It is the same whether it is day-time or night-time the SUBJECT is ILLUMINATED it is NOT the ILLUMINATING SOURCE.

If this were not so, we would be constantly changing our exposures for a long shot of the football player as he ran toward us right up until he was 6ft away – and that is NOT the case – in constant ILLUMINATION the Exposure Settings do NOT change as the Player runs towards us.

This is a conversation I have with students, every year . . . truely . . . maybe the best way to satisfy yourself is to shoot the JPEGS for yourself, that's what I say to them.

Cheers,

WW

PS: they really are JPEGS straight out of the box the EXIF is attached for you to interrogate – and you will see, if you look at the date and time I did just get home from my very late Saturday night shoot – and it is early Sunday morning ... and I am quite mad.