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Flash exposure troubles

 
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gyron



Joined: 02 Nov 2009
Posts: 13
Location: Australia

PostPosted: Sat Aug 13, 2011 11:32 pm    Post subject: Flash exposure troubles Reply with quote

I've got a Crown Graphic which is working fine, but I'm now trying to work out how to use it for flash photography. The setup is basically:

  • Crown Graphic with a side-mounted Kalart rangefinder
  • Schneider-Kreuznach Xenar 5.6/150 lens, with a single-post X connector
  • Graflex "No. 2773" 3-cell flash with 5 inch reflector
  • Several #5 bulbs
One end of the flash cable was connected to the single X connector on the lens, and the other goes to the "Shutter" connector on the flash body. The flash body was set to "N". The exposure was 1/125 f8 at 10 feet on ISO 125 film, but the shots came out grossly underexposed (i.e., extremely thin negatives, almost useless).

I wouldn't have thought my exposure was that far wrong, so I suspect either that I'm setting up the gear incorrectly or I haven't got the right combination to make this work. (For example, some things I've read online imply that I need a solenoid which I don't have.)

Flash bulb photography is new to me, I'm used to using electronic flashes but I'd like to learn how to the "old style" flash photos.

I intend to try some more experiments but I don't want to use up too many flash bulbs, I can't source them locally so they work out fairly expensive for me.

Does anyone have any advice for where I'm going wrong?

Thanks.

P.S. I should mention in case it's not clear; yes, I'm certain the flash did fire on each occasion, it's blindingly bright and impossible to miss!


Last edited by gyron on Sun Aug 14, 2011 12:05 am; edited 1 time in total
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bruiser



Joined: 15 Oct 2006
Posts: 259
Location: Northern NSW Australia

PostPosted: Sun Aug 14, 2011 12:04 am    Post subject: Reply with quote

Hi (fellow Aussie) gyron!

Your main problem is that bulbs don't sync with the X connection.

A shutter with 'M' setting is what you need as these fire the bulb a few milliseconds BEFORE the shutter opens. This allows the bulb to achieve peak brightness as the shutter opens.

A shutter with X setting is fine for instantaneous electronic flash but opens too quickly for bulbs, hence the underexposure.

A Graflex Graphex shutter or similar will do the job or any other shutter with M (for normal flashbulbs) or F ( for fast-speed bulbs) settings.

Cheers,
Bruce
http://graflex.coffsbiz.com
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gyron



Joined: 02 Nov 2009
Posts: 13
Location: Australia

PostPosted: Sun Aug 14, 2011 12:08 am    Post subject: Reply with quote

bruiser wrote:
A shutter with X setting is fine for instantaneous electronic flash but opens too quickly for bulbs, hence the underexposure.


I did suspect something along those lines; that the timing of the flash & shutter opening weren't compatible.

Now I suppose I'll need to find a suitable new lens etc. (I've never changed lenses on one of these, I'll do some reading to work out what's involved.)

Thanks for your help.
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bruiser



Joined: 15 Oct 2006
Posts: 259
Location: Northern NSW Australia

PostPosted: Sun Aug 14, 2011 12:29 am    Post subject: Reply with quote

Hi again,

I just sent you a PM with a link to what you need!

Cheers,
Bruce
http://graflex.coffsbiz.com
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45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Sun Aug 14, 2011 2:02 am    Post subject: Reply with quote

This thread may be of some help.
http://graflex.org/helpboard/viewtopic.php?t=6029
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gyron



Joined: 02 Nov 2009
Posts: 13
Location: Australia

PostPosted: Sun Aug 14, 2011 3:04 am    Post subject: Reply with quote

45PSS wrote:
This thread may be of some help.
http://graflex.org/helpboard/viewtopic.php?t=6029

Thanks for the pointer, that thread does have lots of interesting information. It sounds like my lens/shutter can be modified to do what I need but I fear that process would be beyond me.

As bruiser suggests, I'm going to look for a Graphex shutter & lens & lensboard, once I get my head around what's involved. If that fails I'll consider buying a second Crown for flash photography and keep my current one for daylight photography.

Hmm... this kit sounds great, other than the price!
http://www.collectiblecameras.com/product.php?productid=173278&cat=290&page=1
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45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Sun Aug 14, 2011 3:27 am    Post subject: Reply with quote

All you need is one of these:
http://cgi.ebay.com/Graflex-Solenoids-x2-/350467044831?pt=LH_DefaultDomain_0&hash=item519976b5df

http://cgi.ebay.com/ELECTRIC-SHUTTER-RELEASE-SOLENOID-3-GRAFLEX-VIEW-/290597539531?pt=Film_Cameras&hash=item43a8f68ecb
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C. Henry



Joined: 13 Dec 2005
Posts: 357
Location: North East Georgia, USA

PostPosted: Sun Aug 14, 2011 6:05 pm    Post subject: Reply with quote

Suggest you try one exposure at same aperture and distance but with a shutter speed of 1/30 or slower. That should leave the shutter open long enough for the flashbulb to come up to full brightness.

C. Henry
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gyron



Joined: 02 Nov 2009
Posts: 13
Location: Australia

PostPosted: Mon Aug 15, 2011 10:06 am    Post subject: Reply with quote

C. Henry wrote:
Suggest you try one exposure at same aperture and distance but with a shutter speed of 1/30 or slower. That should leave the shutter open long enough for the flashbulb to come up to full brightness.


That's a good idea, I'll try it. If nothing else it'll be interesting to see the different result with some different shutter speeds. And I'm less likely to make a mess of that than I would be trying to fit and calibrate a solenoid
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gyron



Joined: 02 Nov 2009
Posts: 13
Location: Australia

PostPosted: Mon Aug 29, 2011 4:14 am    Post subject: Reply with quote

A belated follow-up. I finally had the opportunity to try C.Henry's suggestion:

gyron wrote:
C. Henry wrote:
Suggest you try one exposure at same aperture and distance but with a shutter speed of 1/30 or slower. That should leave the shutter open long enough for the flashbulb to come up to full brightness.
That's a good idea, I'll try it. If nothing else it'll be interesting to see the different result with some different shutter speeds. And I'm less likely to make a mess of that than I would be trying to fit and calibrate a solenoid


In particular, I ended up testing 1/250, 1/125, 1/60, 1/30, 1/15 and 1/8. All with the original settings, ie f8 on ISO125 at 10 feet, using Number 5 bulbs.

I understand that the root cause of my problems is that the peak of the flash bulb output doesn't match my shutter opening, but I was trying to work around the problem by using a longer shutter speed. I got a good range of results from this experiment;

  • 1/250 was grossly underexposed, virtually no usable information on the negative (extremely thin negative)
  • 1/125 had a recognisable image, but still very thin.
  • 1/60 didn't work due to my brain-fade with the dark slide, oops!
  • 1/30 is a good usable image, but a little underexposed. Quite usable though.
  • 1/15 looks good.
  • 1/8 looks very similar to 1/15, no real noticable difference (at least not one that I can discern without a densitometer)
So for now I'll stick with shooting this camera & flash setup at 1/15 assuming the other parameters, but it'd probably be more practical to use ISO400 film at a shutter speed of 1/60. (I'm using B&W film that I'm developing myself, so I have a fair bit of latitude.)

It's not an ideal solution but at least I can now do some flash photography until I either do a solenoid modification or I change the lens & shutter. Now all I need is to find a source of number 5 bulbs that will ship to me, I've almost run out

Thanks.
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SYNCHROJAMES



Joined: 12 Jun 2007
Posts: 36
Location: SAN DIEGO CA

PostPosted: Thu Sep 01, 2011 10:35 pm    Post subject: Flash bulbs Reply with quote

T don't know how much it will cost to ship, but Pacific Rim Camera in Oregon, USA charges $15.00 U.S. for a box of 12 press 25 or 5 bulbs. Best price I've found. I also picked up a HR solenoid for my CG (GRAPHEX X Contacts) for $15.00 U.S. Overall quite pleased with items purchased, and fast service. I even traded some AG1's for two boxes of 25's.

James
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