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Using electronic flash with LF cameras
The distance between the lens front and film plane can be noticeably greater with LF cameras than with 35mm cameras.
Therefore is it necessary to take into account this extra distance when using a standard electronic flash on a LF camera?
To clarify, with 35mm the flash's GN = aperture x distance; where distance can be direct or bounced.
Therefore, with LF does the GN = aperture x (flash to object distance (bounced or direct] + distance from lens front to film plane)????
Or conversely is there a correction factor for the light loss due to increased optical path in LF versus 35mm camera????
regards
Tony
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Re: Using eletronic flash with LF cameras
No it doesn't and there isn't.
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Re: Using eletronic flash with LF cameras
Look up bellows factor for this topic. The light source doesn't matter
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Re: Using eletronic flash with LF cameras
Do the arithmetic... in many cases any “additional distance” between the lens and film planes will be rather insignificant (in practical terms) in the GN formula.
What is your photographic scenario... normal “average “ pictures, close-up portraits, or strobe-illuminated extreme macro work?
The metric for when bellows extension might be worth considering is deviation from “normal infinity” bellows draw, not the difference based on camera format.
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Re: Using eletronic flash with LF cameras
1) Unless there is smoke or other optically dense gas in the camera, light rays will not diminish in intensity along their path through any camera.
2) The flash-to-subject distance equation for exposure does not have a "camera position" component in it.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
BrianShaw
Do the arithmetic... in many cases any “additional distance” between the lens and film planes will be rather insignificant (in practical terms) in the GN formula..
Quote:
Originally Posted by
ic-racer
Unless there is smoke or other optically dense gas in the camera, light rays will not diminish in intensity along their path through any camera..
Agreed with both of you. But I'm trying to understand why my electronic flash guns do not expose paper negatives in my LF camera.
The flash guns have GNs of 30 & 46 (metric @ ISO100) I've corrected those values to suit ISO6 and have checked and tripled checked lens speed, aperture, pc-cable, lens filter [not being red], distance to object, dark slide out, lens cocked etc etc but all I get is unexposed sheets irrespective of which flash gun I use.
regards
Tony
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
Agreed with both of you. But I'm trying to understand why my electronic flash guns do not expose paper negatives in my LF camera.
The flash guns have GNs of 30 & 46 (metric @ ISO100) I've corrected those values to suit ISO6 and have checked and tripled checked lens speed, aperture, pc-cable, lens filter [not being red], distance to object, dark slide out, lens cocked etc etc but all I get is unexposed sheets irrespective of which flash gun I use.
regards
Tony
That sounds like a sync issue. Which kind of shutter do you use ?
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Re: Using eletronic flash with LF cameras
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
Agreed with both of you. But I'm trying to understand why my electronic flash guns do not expose paper negatives in my LF camera.
The flash guns have GNs of 30 & 46 (metric @ ISO100) I've corrected those values to suit ISO6 and have checked and tripled checked lens speed, aperture, pc-cable, lens filter [not being red], distance to object, dark slide out, lens cocked etc etc but all I get is unexposed sheets irrespective of which flash gun I use.
regards
Tony
Plug in your flash, remove the camera’s gg. Point the flash and the camera at a wall. Look through the back and fire the shutter. You should see a full circle of bright light in the shutter when the flash fires. Do you? Then your shutter is properly synched for your flash. If you don’t make sure if your shutter has an M/X lever it is set at X and try again. If not the you need an X synch shutter or your shutter needs service!
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Re: Using eletronic flash with LF cameras
What would a typical flash to subject distance be? and at what f stop would you shoot please?
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
cowanw
What would a typical flash to subject distance be? and at what f stop would you shoot please?
The corrected GNs are 7.5 and 11.5 so the distances for the aperture son my lens are between 0.86m and 2.45m - see below
6ISO GN7.5=f4.7@1.60m or GN11.5 = f4.7@2.45m.
6ISO GN7.5=f5.6@1.34m or GN11.5 = f5.6@2.05m.
6ISO GN7.5=f8@1.00m or GN11.5 = f8@1.44m.
6ISO GN7.5=f11@0.68m or GN11.5 = f11@1.05m.
regards
Tony
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Bob Salomon
If you don’t make sure if your shutter has an M/X lever it is set at X and try again. If not the you need an X synch shutter or your shutter needs service!
MXV shutter recently serviced 'x' contact is synch'd - Shutter set at 'x' by default.
regards
Tony
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Re: Using eletronic flash with LF cameras
In my modest experience paper does not respond the same to electronic flash as film does. I look forward to someone smarter who me can correct my opinion.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
The corrected GNs are 7.5 and 11.5 so the distances for the aperture son my lens are between 0.86m and 2.45m - see below
6ISO GN7.5=f4.7@1.60m or GN11.5 = f4.7@2.45m.
6ISO GN7.5=f5.6@1.34m or GN11.5 = f5.6@2.05m.
6ISO GN7.5=f8@1.00m or GN11.5 = f8@1.44m.
6ISO GN7.5=f11@0.68m or GN11.5 = f11@1.05m.
regards
Tony
Just the way you said that; that is .86 m to 2.45 m flash to subject, not subject to aperture, right?
Bounce can take up an extra stop depending on the ceiling.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
cowanw
Just the way you said that; that is .86 m to 2.45 m flash to subject, not subject to aperture, right?
Bounce can take up an extra stop depending on the ceiling.
Aperture is given in the 'table' from f4.7 to f11. The distance range is from f11 with a [corrected] GN of 7.5 to f4.7 with a [corrected] GN of 11.5
Direct no bounce
regards
Tony
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Jac@stafford.net
In my modest experience paper does not respond the same to electronic flash as film does. I look forward to someone smarter who me can correct my opinion.
Agreed - my flash guns and LF camera work with film (Fomapan 100) without problem.
Also electronic flash is used by others to 'pre-flash' paper negatives.
This is why I'm trying to determine the factors that [might/are/could] preclude my use of electronic flash with paper negatives
regards
Tony
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
GN = aperture x (flash to object distance (bounced or direct] + distance from lens front to film plane)????
Tony, here you have conceptual issue.
With flashes and GN, the distance from camera to subject is always irrelevant, what is used in de calculation is the distance from flash to the subject, both in 35mm and in LF. In 35mm flash can be not in the camera...
So to apply GN always use flash to subject distance, adding the bounce in the ceiling if it's the case.
What is different in LF is that you have to use the bellows compensation factor, exactly the same factor has to be applied for flash exposure or for (no flash) outdoor shots, for close subjects.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Jac@stafford.net
In my modest experience paper does not respond the same to electronic flash as film does. I look forward to someone smarter who me can correct my opinion.
Jac perhaps (speculating) there is a reciprocity failure factor. LIRF may be present both for long exposures but also for extremly short exposures, and a flash can be 1/30,000 , for example.
"Reciprocity also breaks down at extremely high levels of illumination with very short exposures" https://en.wikipedia.org/wiki/Recipr...rocity_failure
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Pere Casals
Tony, here you have conceptual issue.
With flashes and GN, the distance from camera to subject is always irrelevant, what is used in de calculation is the distance from flash to the subject, both in 35mm and in LF. In 35mm flash can be not in the camera...
So to apply GN always use flash to subject distance, adding the bounce in the ceiling if it's the case.
What is different in LF is that you have to use the bellows compensation factor, exactly the same factor has to be applied for flash exposure or for (no flash) outdoor shots, for close subjects.
QUOTE=Pere Casals;1483086]Jac perhaps (speculating) there is a reciprocity failure factor. LIRF may be present both for long exposures but also for extremly short exposures, and a flash can be 1/30,000 , for example.
"Reciprocity also breaks down at extremely high levels of illumination with very short exposures" https://en.wikipedia.org/wiki/Recipr...rocity_failure[/QUOTE]
Pere, thanks for comments.
However, though the flash duration is short its intensity is large
Using a 135mm lens at circa 2m [lens/flash to subject] the bellows extension is well below 1.5x focal length
So, I should be able to get some 'exposure' on the paper negative BUT I'm getting absolutely nothing.
Hence my posting and persistent questioning.
regards
Tony
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Re: Using eletronic flash with LF cameras
Can you be putting the paper in the dark slide backwards?
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
QUOTE=Pere Casals;1483086] So, I should be able to get some 'exposure' on the paper negative BUT I'm getting absolutely nothing.
hmmm.... perhaps the synchronization is wrong. If you set the "M" position then the flash fires 20ms before the shutters opens. Use X position. M position was for antique gear needing to ignite the flash 20ms before exposure to allow the light source to reach peak power before the shutter openned, if not the the light was weak, but in M position a modern flash throws all its power sin (say) 1ms, then shutters delays its aperture 19 milliseconds, and then the shutter opens capturing darkness. So check you have set X position.
Also do this, use darkroom safe lights, always open. Close lights "white" lights in the darkroom, now you see with the safe light...
Open shutter like if you were focusing, fire manually the flash, close shutter, and open lights. In this way you don't relly in sinchronization, so you will have a diagnostic.
I guess you are used to make paper negatives without flash, if not ensure you get good exposures with contiunous light before. Compare the images taken with a DSLR with flash vs continuous to stablish flash exposure.
Tony, this is about making key tests to have a diagnostic about what happens...
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
cowanw
Can you be putting the paper in the dark slide backwards?
Bill,
Possibly once but not several times - even so should get some 'impression'.
Quote:
Originally Posted by
Pere Casals
hmmm.... perhaps the synchronization is wrong. Also do this, use darkroom safe lights, always open. Close lights "white" lights in the darkroom, now you see with the safe light... I guess you are used to make paper negatives without flash,...
Pere,
Sunch checked when shutter cla'd last year. Set on 'x' as default.
Have used the flash with 'B' setting and firing via the 'Test' button whilst the shutter was open in a very dark room [I assumed Test means full power]. All to no avail.
Paper negatives exposed in 'daylight' without flash all turned out okay - except when I inadvertently used a red filter!!!!
Both flash guns work okay with film.
All flash exposures done on the 'x' setting - the computer controlled exposure never chosen
Diagnostics infer electronic flash is not compatible with paper negatives in my setup.
Yet in a private message Emil Schildt states "This [paper negative portrait] is actually with the use of flash - with soft box attached - it works really well"
????????????
regards
Tony
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
????????????
Shot the flash to the paper and develop to see....
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Re: Using eletronic flash with LF cameras
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2 Attachment(s)
Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
Agreed with both of you. But I'm trying to understand why my electronic flash guns do not expose paper negatives in my LF camera.
The flash guns have GNs of 30 & 46 (metric @ ISO100) I've corrected those values to suit ISO6 and have checked and tripled checked lens speed, aperture, pc-cable, lens filter [not being red], distance to object, dark slide out, lens cocked etc etc but all I get is unexposed sheets irrespective of which flash gun I use.
regards
Tony
I would think you need a lot more flash power, at a minimum 4000WS out of a 5" reflector (150,000 BCPS), giving a guide number of about 350 with that slow emulsion. This is line with what photographers I know are using to expose wet plate with electronic flash. If you want light modifiers, even more power is needed. Your flash guns may not even be reaching the paper's threshold exposure. Try multiple pops and see if you can bring up some tone. See Norman chart below.[Attachment 187564
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Pere Casals
Shot the flash to the paper and develop to see....
Excellent fundamental requisite. I look forward to the outcome.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Pere Casals
Shot the flash to the paper and develop to see....
And do that at different distances from the paper - you will have your answer about the necessary flash power right away.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Pfsor
And do that at different distances from the paper - you will have your answer about the necessary flash power right away.
...or with a stouffer wedge on the paper...
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Pere Casals
...or with a stouffer wedge on the paper...
He could even use just a flash exposure meter, even quicker than meddling with the paper processing.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Neal Chaves
I would think you need a lot more flash power, at a minimum 4000WS out of a 5" reflector (150,000 BCPS), giving a guide number of about 350 with that slow emulsion. Try multiple pops and see if you can bring up some tone.]
Going from your/the nonograph I don't see 150,000 BCPS - more likely a tenth or less than that. However I agree with your prognosis
Quote:
Originally Posted by
Pfsor
He could even use just a flash exposure meter, even quicker than meddling with the paper processing.
Unfortunately I do not have a flash exposure meter
I guess I need to do some trials
regards
Tony
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Re: Using electronic flash with LF cameras
I have been using paper negs in an old passport camera. In the studio I use 3 x 500w flash heads on full power with softbox diffusor screens removed pointing at a subject at a distance of about 1.5 m. It looks about right at f/16. Scaling that back to your scenario I would say that you need lots more light.
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
Phil Hudson
I have been using paper negs in an old passport camera. In the studio I use 3 x 500w flash heads on full power with softbox diffusor screens removed pointing at a subject at a distance of about 1.5 m. It looks about right at f/16. Scaling that back to your scenario I would say that you need lots more light.
I’ve found a reference that states: As a rough rule of thumb, multiplying the square root of the (wattsecond) Ws number by 4 gives a indicator of the metric GN at ISO 100.
Therefore assuming your shutter is set at 1/60th second and your studio lights give 1500w power
We get 1500 x 0.017 = 25Ws
Therefore GN = SQRT(Ws) x 4 = 20
Both of my flash guns have a higher GN at 100 ISO
However, as stated above this is a rough rule of thumb.
regards
Tony
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
I’ve found a reference that states: As a rough rule of thumb, multiplying the square root of the (wattsecond) Ws number by 4 gives a indicator of the metric GN at ISO 100.
Therefore assuming your shutter is set at 1/60th second and your studio lights give 1500w power
We get 1500 x 0.017 = 25Ws
Therefore GN = SQRT(Ws) x 4 = 20
Both of my flash guns have a higher GN at 100 ISO
However, as stated above this is a rough rule of thumb.
regards
Tony
It has to be very rough as watt seconds is not a rating of output.
At any given WS the output will change with reflector size, reflector shape, length of the connecting cable, etc.
Base output on BCPS or ECPS.
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Re: Using electronic flash with LF cameras
... but the paper may be ISO 5 or less, so you may need x20 more flash power in the flash than with TMX.
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
Bob Salomon
It has to be very rough as watt seconds is not a rating of output.
At any given WS the output will change with reflector size, reflector shape, length of the connecting cable, etc.Base output on BCPS or ECPS.
Agreed, but it surely is some form of indicator even if it is out 10 fold
Quote:
Originally Posted by
Pere Casals
... but the paper may be ISO 5 or less, so you may need x20 more flash power in the flash than with TMX.
Post #31 refers to 1500w when using paper negatives [ie low ISO] therefore I've assumed apples v apples
regards
Tony
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
Post #31 refers to 1500w when using paper negatives [ie low ISO] therefore I've assumed apples v apples
yes...
...but I'd take your own exposure working well for ISO 100 film, and I'd multiply x20 the light, around 4 or 5 stops in aperture or light power.
Or easier, use a DSLR, adjust for a good digital shot at ISO 100 and give 5 stops more light.
A DSLR is a perfect flash meter for LF, we only need to understand the relationship in the look. Also I manage to shot the DSLR at the same time than the Norma, so I preview face expresion and if eyes are open.
Not that weird, Hollywood's cinematographers still using film also record video to know if the have the scene. Digital is amazing.
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Re: Using electronic flash with LF cameras
[QUOTE=tonyowen;1483480]Agreed, but it surely is some form of indicator even if it is out 10 fold
It is no indicator of output at all. It is an indicator of input. And the most efficient flash units are only able to discharge about 80% of their input!
And, since output changes with reflectors, umbrellas, soft boxes, cable length, efficiency of the flash tube, number of connections, etc. watt seconds are the last thing you want to rely on.
Just think, a given unit with say 500 watt seconds will have different outputs with a polished reflector, a matte reflector, an elliptical reflector, an umbrella reflector a snoot, a background reflector or when used bare bulb. But all were 500 WS. How can that WS rating relate to a consistent f stop?
There is no formula to convert a watt second into a f stop without knowing the loading of the capacitors, and no flash manufacturer includes that specification.
On the other hand there are easily found formulas that are accurate that convert a BCPS or an ECPS rating directly into a guide number or f stop.
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1 Attachment(s)
Re: Using electronic flash with LF cameras
Now here's an electronic flash worthy of LF photography
The K-17 was, IIRC 9.5" x 9.5
Attachment 187646
http://invention.si.edu/seeing-dark-...naissance-wwii
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Re: Using electronic flash with LF cameras
Very interesting and I love the quote,
“If you don’t wake up at three o’clock in the morning and want to do something,” Edgerton quipped, “why, you’re wasting time.”
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Re: Using electronic flash with LF cameras
I ran my tests again and ended up with essentially an unexposed paper negatives.
I’ve listed below what I know and what I DO NOT know.
I know the shutter [cla’d November 2017] was set to 1/60th sec and f4.7. Also the ‘X’ setting chosen
I know the flash [Cobra D650] was set to ‘manual’ with the hood set at 85 degrees to give a GN 46.
I DO NOT know the exact/current GN of the 30+ year old flash.
I positioned the flash and camera about a metre from the subject and the flash fired when the cable release was pressed.
I use a one shot developer [Ilford PQ Universal] in a Jobo 2509 reel.
I DO NOT know how viable/potent the undiluted developer is.
I used Ilford Multigrade paper but DO NOT know the quality of the sheet used.
So back to square one!
Regards
Tony
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
I ran my tests again and ended up with essentially an unexposed paper negatives.
I’ve listed below what I know and what I DO NOT know.
I know the shutter [cla’d November 2017] was set to 1/60th sec and f4.7. Also the ‘X’ setting chosen
I know the flash [Cobra D650] was set to ‘manual’ with the hood set at 85 degrees to give a GN 46.
I DO NOT know the exact/current GN of the 30+ year old flash.
I positioned the flash and camera about a metre from the subject and the flash fired when the cable release was pressed.
I use a one shot developer [Ilford PQ Universal] in a Jobo 2509 reel.
I DO NOT know how viable/potent the undiluted developer is.
I used Ilford Multigrade paper but DO NOT know the quality of the sheet used.
So back to square one!
Regards
Tony
GN is easy. What does it say at 3 meters? That’s the GN for whatever ISO you chose.
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Re: Using electronic flash with LF cameras
Tony, if not specified otherwise the GN is in feet for ISO 100. At three feet -- for this exercise, close enough to 1 m -- with ISO 100 film, the correct aperture if the flash makes its rated output is 46/12 = f/4. Again, close enough to the true value.
Little flashes like the Cobra D650 typically have actual GNs one stop slower than claimed. The only way to be sure is to measure, by shooting a test strip or with a known good flash meter.
Until your flash is proven to make its rated GN, the likely correct aperture with ISO 100 at 1 m is probably f/8. Your paper is approximately six stops slower than ISO 100. Of course you're getting no exposure.
Also, have you verified that on X sync your flash is in fact open when it fires the flash? It should be, but this has to be checked anyway. Remember the strong version of Murphy's law. What can go wrong will go wrong. What can't go wrong will go wrong too.
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
Dan Fromm
Tony, if not specified otherwise the GN is in feet for ISO 100. At three feet -- for this exercise, close enough to 1 m -- with ISO 100 film, the correct aperture if the flash makes its rated output is 46/12 = f/4. Again, close enough to the true value.
Little flashes like the Cobra D650 typically have actual GNs one stop slower than claimed. The only way to be sure is to measure, by shooting a test strip or with a known good flash meter.
Until your flash is proven to make its rated GN, the likely correct aperture with ISO 100 at 1 m is probably f/8. Your paper is approximately six stops slower than ISO 100. Of course you're getting no exposure.
Also, have you verified that on X sync your flash is in fact open when it fires the flash? It should be, but this has to be checked anyway. Remember the strong version of Murphy's law. What can go wrong will go wrong. What can't go wrong will go wrong too.
You also want to know the coverage angle of your flash as these small, cheap units are usually rated in the center of the beam and you may be using more then that.
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Re: Using electronic flash with LF cameras
Hey Bob, I looked Tony's flash up. If I got it right it is a potato masher and I might have been mistaken in treating its GN as feet, ISO 100. Tony stated a meters GN for it in an early post in this discussion. All that said, what he's getting reeks of massive underexposure.
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
Dan Fromm
Hey Bob, I looked Tony's flash up. If I got it right it is a potato masher and I might have been mistaken in treating its GN as feet, ISO 100. Tony stated a meters GN for it in an early post in this discussion. All that said, what he's getting reeks of massive underexposure.
Dan,
Potato masher is the correct reference. It is large and [according to the specs] powerful - not quite the big Metz units but getting there.
For information, the GM (metric) is 32 at the 35mm zoom position and 46 at the 85mm zoom position. I calculate the imperial GNs would be 105 & 151 respectively
You refer to a 'good flash meter' but Murphy's Law guarantees the one I get will be 'wrong in some way and how does one prove that the meter is accurate, reliable and consistent!!!
regards
Tony
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Re: Using electronic flash with LF cameras
I have proved to myself my flash bulbs, studio flash and modern Nikon flash with DSLR and film.
It all makes sense, then I forget to write it down.
Doing it again soon. :)
I have a Sekonic 758 and it agrees exactly with my Paul C Buff Cyber Commander.
This time it gets printed in large font in seal a meal, actually the heat plastic stuff whatever that's called
and nailed to the studio wall
Quote:
Originally Posted by
tonyowen
Dan,
Potato masher is the correct reference. It is large and [according to the specs] powerful - not quite the big Metz units but getting there.
For information, the GM (metric) is 32 at the 35mm zoom position and 46 at the 85mm zoom position. I calculate the imperial GNs would be 105 & 151 respectively
You refer to a 'good flash meter' but Murphy's Law guarantees the one I get will be 'wrong in some way and how does one prove that the meter is accurate, reliable and consistent!!!
regards
Tony
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Re: Using electronic flash with LF cameras
Quote:
Originally Posted by
tonyowen
I ran my tests again and ended up with essentially an unexposed paper negatives.
I’ve listed below what I know and what I DO NOT know.
I know the shutter [cla’d November 2017] was set to 1/60th sec and f4.7. Also the ‘X’ setting chosen
I know the flash [Cobra D650] was set to ‘manual’ with the hood set at 85 degrees to give a GN 46.
I DO NOT know the exact/current GN of the 30+ year old flash.
I positioned the flash and camera about a metre from the subject and the flash fired when the cable release was pressed.
I use a one shot developer [Ilford PQ Universal] in a Jobo 2509 reel.
I DO NOT know how viable/potent the undiluted developer is.
I used Ilford Multigrade paper but DO NOT know the quality of the sheet used.
So back to square one!
Regards
Tony
If you tried different flash distances from a very close one you would know what the ballpark you're in is. Like this it seems you want to work on this simple problem for months.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Jac@stafford.net
In my modest experience paper does not respond the same to electronic flash as film does. I look forward to someone smarter who me can correct my opinion.
I know that reciprocity failure occurs with extremely short exposure times, electronic flash being the most common source. With paper designed for seconds and minutes exposure timnes, that may be the case.
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Re: Using eletronic flash with LF cameras
Quote:
Originally Posted by
Randy Moe
I have proved to myself my flash bulbs, studio flash and modern Nikon flash with DSLR and film.
It all makes sense, then I forget to write it down. Doing it again soon. :) I have a Sekonic 758 and it agrees exactly with my Paul C Buff Cyber Commander.
This time it gets printed in large font in seal a meal, actually the heat plastic stuff whatever that's called and nailed to the studio wall
Quote:
Originally Posted by
Pfsor
If you tried different flash distances from a very close one you would know what the ballpark you're in is. Like this it seems you want to work on this simple problem for months.
Quote:
Originally Posted by
David Lobato
I know that reciprocity failure occurs with extremely short exposure times, electronic flash being the most common source. With paper designed for seconds and minutes exposure times, that may be the case.
Randy - mine works with film but not paper. [see bottom response]
Pisor - have tried many distances but all (with paper) fail [see above and below}
David - I've come across that before and it matches my experiences. The quoted flash time for the Cobra's 'manual setting' is 1/1000th sec
regard to all
Tony
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Re: Using eletronic flash with LF cameras
Tony,
Noted, I only shot 2 paper negs with solar pinhole long ago. I tried Harman Positive with strobes but never liked any result.
I will revisit paper negs soon as I do have a project in mind.
Thanks for the tip!