Tips for Mastering In-Camera,Double Exposure Portraits
 

On Tue, 15 Jan 2019 19:24:01 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

Double exposure in film, I can understand.

But a digital camera would just add the pixel values from two files,
thus being no different from postprocessing on the computer.

To be valid, the sensor would have to be exposed, and then, without
reading it, exposing it again. Are they really doing it?

Nikon, Canon, and Fujifilm (and probably others) have a multi-exposure
feature/mode which allows for two separate exposures, on two frames,
which
are blended into a single file. It is a bit of a novelty and nothing
that
cannot be done in post.

Ok, so they do two frames, then merge or blend them into a single file.
That's postprocessing, not really "double exposure" in my book. It
simply emulates it, but it is not it.

are you channeling eric?

He is being precise. You are not.

nope. he's trying to come up with a distinction when there isn't one.

two clicks. one photo. double exposure.

one uses chemicals and the other uses electronics.

One makes two separate images to create a third. The other makes a
single image in two stages.
--

Regards,

Eric Stevens

Tips for Mastering In-Camera,Double Exposure Portraits
 

On Jan 16, 2019, Carlos E.R. wrote
(in article ):

On 16/01/2019 22.44, Ken Hart wrote:
On 1/16/19 6:42 AM, Whisky-dave wrote:
On Tuesday, 15 January 2019 18:22:08 UTC, nospam wrote:
In ,
Whisky-dave wrote:

and
it's a lot easier to do it in camera than later.

Only with digital not with film, as you run the risk of the film
moving.

push the little button and the transport is disengaged.

It can still move slightly, ideally it shouldn't.

Depends on the design of the camera. In the manual for the Canon FX
(1964-1969), you first use the rewind crank to get the film taut, then
while holding the rewind crank with one hand, you press the rewind
clutch button on the bottom of the camera with the other hand, and with
the third hand, you operate the film advance lever while holding in the
rewind clutch with the second hand and keeping tension on the rewind
crank so the film doesn't move. Operating the film advance lever
disengages the rewind clutch, so you have to hold it in.

Not being familiar with every camera ever made, I assume there are
cameras where the method is simpler.

My Minolta was the same. I don't remember reading about the method in
the manual, though, I think they said nothing. I just found it by
experimenting.

There was some risk of the film actually moving a bit backwards. But the
rewind had to be a bit taut, or the clutch would not disengage and the
film could move a bit forwards.

Tricky.

I can remember some view cameras in the past which had the shutter, and
shutter release on the lens with a cable release (before that they used a
squeeze bulb). In that case the shutter had to be set in much the same way as
the hammer on a single action firearm. With those deliberate, double, or
multi exposures on a single plate, or sheet of film would be possible without
worry of moving film out of frame register.

--
Regards,
Savageduck

Tips for Mastering In-Camera,Double Exposure Portraits
 

On 17/01/2019 11.17, Whisky-dave wrote:
On Wednesday, 16 January 2019 15:55:48 UTC, nospam wrote:
In article ,
Whisky-dave wrote:

It is two separate exposures on the same frame. Which is what a digital
camera does not do, so it is not double exposure.

it's two separate exposures in the same memory, before it's written to
a raw or jpeg image, thereby making it a double exposure by any
definition.

No it wouldn't, as it would be in the same 'memory' as that would require
complety overwriting the information from the previous exposure.

no.

yes, you obviously dont know much about electronics down to that level.
Itls digital remmeber either a 1 or a 0 unlike film.

That's correct. Each memory position, corresponding to a pixel, has to
be read, its value added to the new value from the sensor or other
memory map, then written back to the memory, or to another memory map.
The CPU has to intervene.

That's not much different from adding to images on file on the card, and
thus not much different from doing it on the home computer.

And of course, it can be added or any other more complex operation the
programmer puts there.


Very different from exposing the sensor twice before reading it, which
would be similar to what is done on film. I don't know if that is
doable, the sensor could lose the information in the interval. And
anyway, pointless, except for the sake of saying "I did it!". Better
use digital cameras in new digital era methods.


--
Cheers, Carlos.

Tips for Mastering In-Camera,Double Exposure Portraits
 

On 17/01/2019 15.23, Savageduck wrote:
On Jan 16, 2019, Carlos E.R. wrote
(in article ):

On 16/01/2019 22.44, Ken Hart wrote:
On 1/16/19 6:42 AM, Whisky-dave wrote:
On Tuesday, 15 January 2019 18:22:08 UTC, nospam wrote:
In ,
Whisky-dave wrote:

and
it's a lot easier to do it in camera than later.

Only with digital not with film, as you run the risk of the film
moving.

push the little button and the transport is disengaged.

It can still move slightly, ideally it shouldn't.

Depends on the design of the camera. In the manual for the Canon FX
(1964-1969), you first use the rewind crank to get the film taut, then
while holding the rewind crank with one hand, you press the rewind
clutch button on the bottom of the camera with the other hand, and with
the third hand, you operate the film advance lever while holding in the
rewind clutch with the second hand and keeping tension on the rewind
crank so the film doesn't move. Operating the film advance lever
disengages the rewind clutch, so you have to hold it in.

Not being familiar with every camera ever made, I assume there are
cameras where the method is simpler.

My Minolta was the same. I don't remember reading about the method in
the manual, though, I think they said nothing. I just found it by
experimenting.

There was some risk of the film actually moving a bit backwards. But the
rewind had to be a bit taut, or the clutch would not disengage and the
film could move a bit forwards.

Tricky.

I can remember some view cameras in the past which had the shutter, and
shutter release on the lens with a cable release (before that they used a
squeeze bulb). In that case the shutter had to be set in much the same way as
the hammer on a single action firearm. With those deliberate, double, or
multi exposures on a single plate, or sheet of film would be possible without
worry of moving film out of frame register.

Yes, I have some old cameras in which the shutter "arming" is not linked
to the film movement. Double exposures were a risk, by accident, when we
forgot to wind them. So we had to train ourselves in the routine of
winding the film just after shooting. And not arming the shutter till
needed, so to avoid storing the camera with springs tensioned.

--
Cheers, Carlos.

Tips for Mastering In-Camera,Double Exposure Portraits
 

In article , Carlos E.R.
wrote:

yes, you obviously dont know much about electronics down to that level.
Itls digital remmeber either a 1 or a 0 unlike film.

That's correct.

actually, it isn't correct. silver halide crystals on film are 0 or 1.
sensors in cameras are not.

Each memory position, corresponding to a pixel, has to
be read, its value added to the new value from the sensor or other
memory map, then written back to the memory, or to another memory map.
The CPU has to intervene.

and with film, the addition is done when light hits it a second time.

Tips for Mastering In-Camera,Double Exposure Portraits
 

In article ,
Whisky-dave wrote:

It is two separate exposures on the same frame. Which is what a
digital camera does not do, so it is not double exposure.

it's two separate exposures in the same memory, before it's written to
a raw or jpeg image, thereby making it a double exposure by any
definition.

No it wouldn't, as it would be in the same 'memory' as that would require
complety overwriting the information from the previous exposure.

no.

yes, you obviously dont know much about electronics down to that level.

actually, i do.

Itls digital remmeber either a 1 or a 0 unlike film.

a silver halide crystal on film is 1 or 0, depending if light hit it or
not.

a sensor in a digital camera is an analog device whose output voltage
varies on how much light hits it. not 1 or 0.

the values stored in memory are as much as 48 bits per pixel, much,
much more than 1 or 0.

Tips for Mastering In-Camera,Double Exposure Portraits
 

In article , Eric Stevens
wrote:

But a digital camera would just add the pixel values from two files,
thus being no different from postprocessing on the computer.

it's different in that it doesn't require a computer.

Not even the one in the camera.

more of your semantic bull**** arguments. you know quite well what is
meant by computer, and it's *not* camera.

"in the camera" I said.

that doesn't matter.

if you think otherwise, then explain how one can connect a keyboard,
mouse to the 'computer' in the camera, how to connect it to the
internet to download photoshop and then install it, and how to process
images on its tiny little 3" display.

Not even you are silly enough to think that's what I meant.

a bit extreme, but it makes the point.

As for
your idea that a computer needs a keyboard or a mouse to make it a
computer,

missing the point, as usual.

what are you going to make of an iPad, let alone the flight
systems in an Airbus?

ipads use touch instead of a mouse and there is a built in keyboard as
well as the ability to connect external keyboards.

but the real kicker is i remember you arguing several years back that
an ipad wasn't a computer. now you say it is.

Tips for Mastering In-Camera,Double Exposure Portraits
 

In article , Eric Stevens
wrote:


at the end of the day, it's two clicks resulting in one image, just as
it's done with a film camera.

No it's not.

it is.

In a film camera, which is where the expression originated, a double
exposure is one exposure made on top of a prior exposure. It is not
the later combination of two separate exposures.

it definitely is. one exposure is taken later than the other, combined
on one piece of film.

as i said, it's two clicks resulting in one image.

Tips for Mastering In-Camera,Double Exposure Portraits
 

In article , Eric Stevens
wrote:


One makes two separate images to create a third. The other makes a
single image in two stages.

nope. both are two images combined into one.

Tips for Mastering In-Camera,Double Exposure Portraits
 

In article ,
Whisky-dave wrote:


Itls digital remmeber either a 1 or a 0 unlike film.

a silver halide crystal on film is 1 or 0, depending if light hit it or
not.

No it is not it has levels the individual molecules do.

it's exposed or it's not. 1 or 0.

a sensor in a digital camera is an analog device whose output voltage
varies on how much light hits it. not 1 or 0.

In yuor dreams perhaps.

nope. that's how they work.

If the sensor is analogue then why is it a digital camera.

because the rest of the camera is digital.

the values stored in memory are as much as 48 bits per pixel, much,
much more than 1 or 0.

Irrelivant

nope. it's exactly on point.