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Could someone please explain this?



 
 
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  #1  
Old August 5th 06, 05:51 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
joe mama
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Posts: 105
Default Could someone please explain this?

Two cameras...both with the same film, from the same lot numbers. developed
at the same time in the same tank with the same chemicals. the difference
is, one came out fine, the othe came out as if way underexposed.

the scenario:

one camera was a nikon fe-2 with a 105mm 2.5 lens. these are the pics that
came out fine. the other camera was an older pentax spotmatic with a 55mm
1.8 lens. this camera yielded the softer results. now, these were also done
with a studio lighting setup, so there was no difference in lighting
conditions.

now that i am typing this, i can only think of one thing. the spotmatic had
two pc connections on it. i used the top one. i don't have an old manual for
this camera, so maybe it was synced differently or something. i still don't
know how that would explain the overall underexposed look. the lens also has
a manual/auto slider that may have been in auto, instead of manual. would
that have mattered?

the lens looks fine. it is very clear. i doubt that it is the problem. the
flash sync speed was only 1/60 of a second on it, but i don't know how a
slower sync speed could account for underexposure. you'd think the opposite.

any help would be great.....


  #2  
Old August 5th 06, 05:56 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
joe mama
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Posts: 105
Default Could someone please explain this?


"joe mama" wrote in message
...
Two cameras...both with the same film, from the same lot numbers.
developed at the same time in the same tank with the same chemicals. the
difference is, one came out fine, the othe came out as if way
underexposed.


okay, i just happened to find an online manual that says the flash sync i
used wa a p sync, and the other one was the x sync. what would have made
these underexpose?


  #3  
Old August 5th 06, 06:26 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
wsrphoto
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Posts: 19
Default Could someone please explain this?


joe mama wrote:
"joe mama" wrote in message
...
Two cameras...both with the same film, from the same lot numbers.
developed at the same time in the same tank with the same chemicals. the
difference is, one came out fine, the othe came out as if way
underexposed.


okay, i just happened to find an online manual that says the flash sync i
used wa a p sync, and the other one was the x sync. what would have made
these underexpose?


The manual should have said what each sync does with the exposure. You
didn't say what shutter speed setting you used and what mode (manual,
program, etc) you set the flash, because the timing of the flash with
the shutter is the difference. I'm not familar with Nikon, only
relating my experience with Minolta, but try it again with identical
settings, or without flashes, and you should be the same and equal
results. Good luck.

  #4  
Old August 5th 06, 07:12 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
Bandicoot
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Posts: 470
Default Could someone please explain this?

"joe mama" wrote in message
...
Two cameras...both with the same film, from the same lot numbers.

developed
at the same time in the same tank with the same chemicals. the difference
is, one came out fine, the othe came out as if way underexposed.

the scenario:

one camera was a nikon fe-2 with a 105mm 2.5 lens. these are the pics that
came out fine. the other camera was an older pentax spotmatic with a 55mm
1.8 lens. this camera yielded the softer results. now, these were also

done
with a studio lighting setup, so there was no difference in lighting
conditions.

now that i am typing this, i can only think of one thing. the spotmatic

had
two pc connections on it. i used the top one. i don't have an old manual

for
this camera, so maybe it was synced differently or something. i still

don't
know how that would explain the overall underexposed look.


If your lighting is electronic flash, you you need to use the X sync.
socket. If it's flash bulb, you need to use the B sync. socket (there's
also an FP type, but we won't go into that now, especially as it isn't
relevant to the two sockets on the Spotmatic anyway.)

Electronic flash fires almost immediately it is triggered - a delay of
microseconds. Flash bulbs take longer - a few milliseconds - to reach full
brightness after they are fired. So there are two sorts of flash
synchronisation provided: X, for electronic flash, fires the flash as the
shutter is wide open; B, for bulbs, fires the flash a fraction nefore the
shutter is open to give the light time to reach full intensity before the
shutter opens.

So: if you used the B sync. socket with electronic flash, the flash will
have fired and been finished fractionally _before_ the shutter opens. Hence
your grossly underexposed pictures.

the lens also has a manual/auto slider that may have been in auto, instead

of
manual. would that have mattered?


No, that just sets whether the aperture is kept wide open until you press
the shutter release, then stopping down to the set aperture for the exposure
and opening again after (auto) or stays stopped down at the set aperture the
whole time (manual). Won't alter what the aperture is _at the moment of
exposure_, only what you see through the viewfinder.


the lens looks fine. it is very clear. i doubt that it is the problem.

the
flash sync speed was only 1/60 of a second on it, but i don't know how a
slower sync speed could account for underexposure. you'd think the

opposite.

In this case, since using the B sync. with electronic flash means that the
flash fires before the shutter opens, using a slower shutter speed makes no
difference at all.

If things are the other way round - using X sync. with flashbulbs - then a
longer shutter speed does mean that the bulb has time to reach full
intensity: you may even get a little more light as you are getting the lead
in and tail of the flash that normally are cut off. But as the Spotmatic's
top sync. speed is 1/60, you'd need to be at 1/30 or less to use bulb flash
with the X sync.


any help would be great.....


Hope that made some sense,



Peter


  #5  
Old August 5th 06, 08:40 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
j
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Posts: 77
Default Could someone please explain this?

The top terminal is the "FP" synch intended for "FP" Flash BULBs (which
synch up to 1/1000th of a second on the Spotmatic.)

Play it safe. Use the X terminal (bottom one).

The Auto setting on the Pentax lens is irrelevant. It simply allows you to
focus wide open, and the aperture closes when the shutter is tripped.


  #6  
Old August 5th 06, 08:44 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
j
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Posts: 77
Default Could someone please explain this?

"Bandicoot" wrote
[...] If it's flash bulb, you need to use the B sync. socket (there's
also an FP type, but we won't go into that now, especially as it isn't
relevant to the two sockets on the Spotmatic anyway.)


It would seem to be relevant to the Pentax Spotmatic. The top socket is
explicitly labeled an FP synch on that camera. At least mine was. However,
at 1/60th of a second mine synched to either the FP or electronic flash
socket. (Not to M bulbs, however.) So, maybe Pentax got it wrong?


  #7  
Old August 5th 06, 09:34 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
Richard Knoppow
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Posts: 751
Default Could someone please explain this?


"j" wrote in message
...
"Bandicoot" wrote
[...] If it's flash bulb, you need to use the B sync.
socket (there's
also an FP type, but we won't go into that now,
especially as it isn't
relevant to the two sockets on the Spotmatic anyway.)


It would seem to be relevant to the Pentax Spotmatic. The
top socket is explicitly labeled an FP synch on that
camera. At least mine was. However, at 1/60th of a second
mine synched to either the FP or electronic flash socket.
(Not to M bulbs, however.) So, maybe Pentax got it wrong?

Class FP flash bulbs are intended for Focal Plane
shutters. The bulb is designed so that the flash duration is
extended for long enough, and the output over that time
uniform enough, for use with focal plane shutters provided
the shutter is operating within certain limits. Most Class
FP bulbs require the same delay as a Class M bulb; 20
milliseconds. Because the total travel time for the shutter
on a miniature camera is fairly short FP bulbs offer the use
of flash over most of the shutter's speed range (varies with
the camera). Since all flash bulbs require some time to come
up to full brightness synchronizers fire them before the
shutter is tripped.
Class X synch is for strobe flash. The flash is triggered
when the shutter just reaches fully open. For a focal plane
shutter the speeds are limited to those where the shutter
aperture exposes the entire frame. For older 35mm cameras
this is typically 1/60th second. At higher speeds the
shutter exposes only a slit of varying width so only a part
of the frame will be exposed by the strobe.
When bulb synch is used with a strobe the flash is set
off well before the shutter opens regardless of the shutter
speed. When strobe synch is used with bulbs the bulb will be
fired late so there will be reduced or no exposure depending
on shutter speed unless a very slow speed is used.
FWIW, there are several classes of flash synch:
Class F (Fast), 5 milliseconds (miniature and gass filled
bulbs). These could be used in simple cameras with long
shutter speeds and simple, non-delayed synch.
Class M (Medium), 20 milliseconds (most older bulbs)
Class FP (Focal Plane), 20 millisecond delay but long
duration for focal plane shutters
Class S (Slow), more than 20 millisecond delay. These were
very large bulbs meant to be used open flash (wihtout a
synchronizer) in studio reflectors.


--
---
Richard Knoppow
Los Angeles, CA, USA

There are also other bulb types, flash cubes, etc.


  #8  
Old August 5th 06, 10:29 PM posted to rec.photo.darkroom,rec.photo.equipment.35mm
David Nebenzahl
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Posts: 1,353
Default Could someone please explain this?

Richard Knoppow spake thus:

FWIW, there are several classes of flash synch:
Class F (Fast), 5 milliseconds (miniature and gass filled
bulbs). These could be used in simple cameras with long
shutter speeds and simple, non-delayed synch.
Class M (Medium), 20 milliseconds (most older bulbs)
Class FP (Focal Plane), 20 millisecond delay but long
duration for focal plane shutters
Class S (Slow), more than 20 millisecond delay. These were
very large bulbs meant to be used open flash (wihtout a
synchronizer) in studio reflectors.


So what kind of synch was used for flash pans? (You youngsters may know
them only from old movies.)


--
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solve the problem: negotiations and peace with the Palestinians,
the Lebanese, the Syrians. And: with Hamas and Hizbullah.

Because it's only with enemies that one makes peace.

- Uri Avnery, Israeli writer and peace activist with Gush Shalom.
(http://counterpunch.org/avnery08032006.html)
  #9  
Old August 6th 06, 12:02 AM posted to rec.photo.darkroom,rec.photo.equipment.35mm
William Graham
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Posts: 4,361
Default Could someone please explain this?


"David Nebenzahl" wrote in message
.com...
So what kind of synch was used for flash pans? (You youngsters may know
them only from old movies.)


You mean your new digital SLR doesn't have a, "gunpowder synch" setting?


  #10  
Old August 6th 06, 12:09 AM posted to rec.photo.darkroom,rec.photo.equipment.35mm
John
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Posts: 212
Default Could someone please explain this?


You mean your new digital SLR doesn't have a, "gunpowder synch" setting?


No but it can be connected to the George Foreman USB grill !!

{;)


==
John S. Douglas
Photographer & Webmaster
Legacy-photo.com - Xs750.net
 




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