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DTTL and wiring problems


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#1 Alex_Mustard

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Posted 09 March 2003 - 10:28 AM

When I bought my SB80DX I got my Subal D100 housing rewired (with all 5 wires connected in the flash circuitry so I could use DTTL). I can now shoot this gun in DTTL and Manual without problems.

However with all 5 wires connected in the housing I am unable to fire older strobes (e.g. YS30).

The only solution I can think of is to leave one flash socket wired for DTTL. And connect a second flash shoe adaptor to the other flash socket on the housing, with just two wires connected, to let me use my older non DTTL guns in manual.

Does anyone have any other suggestions/experience with this problem?

Does anyone know if strobes like the YS90DX and the DS-125 will work when all 5 wires are connected?

While writing this post I have got an email suggesting blocking the offending contacts on the hot shoe. Anyone know which ones?

Alex

Why couldn't Nikon have got the D100 to work with standard Nikon TTL (like the increasingly attractive S2) rather than just with DTTL?

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#2 donauw

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Posted 09 March 2003 - 11:38 AM

Alex -

Taken from Stephen Frink's SeaCam site:

But if you are in the field and don't have the right cord, a simple piece of electrician's tape over the contact as in the diagram below will do the trick. NOTE THAT THESE ARE ISSUES OF CAMERA AND STROBE COMPATIBILITY AND HAVE NOTHING TO DO WITH THE HOUSING.

Posted Image

#3 Marc Furth

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Posted 09 March 2003 - 04:26 PM

I removed my post temporarily.

Marc
Nikon D3, 16mm Nikkor,14-24 Nikkor,24-70 Nikkor, Sigma 15 mm New DIY housing,Nikon D2x, DIY housing, Ikelite Strobe 400's, twin iTTL housed Sb 800's, Sigma 14 mm, Tamron 90 mm, Nikkor 80-400 VR, Nikkor 18-200 VR, Tamron 180 mm macro, Epson Pro 4800 printer.

#4 Alex_Mustard

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Posted 10 March 2003 - 02:45 AM

Thanks for the tip Don.

Problem solved.

It is worth noting that when the flash circuitry is disabled in this way the camera no longer knows it has a flash attached - although the flash is triggered when the shutter is released.

As a result we have to watch our flash synch speeds (only 1/180th) when shooting on Aperture Priority Auto - because the camera will not complain/stop us if we exceed them.

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#5 davephdv

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Posted 10 March 2003 - 06:50 PM

This information agrees with what Subal told me. That if you have the TTL wire connected you won't be able to use other strobes in Manual. This is the reason the housings ship with the TTL wire not connected. Does that taping of the connector pin work well ?

If you use Ike's manual controller, do NOT have the TTL wire attached. Even though you put the strobe in TTL you are not using TTL you must not have this wire attached. Like mentioned above, with the Ike manual controller you will not get the strobe confirmation light inside the camera to light.
Dave Burroughs, Nikon D300, D2X, Subal housing, DS160 strobes

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#6 ikelite

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Posted 10 March 2003 - 07:22 PM

The Manual Controller only connects the two sync terminals so housing wiring could actually be either way. The strobe MUST be in TTL position to respond to the predetermined quench signal sent by the Controller.

#7 Alex_Mustard

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Posted 11 March 2003 - 01:19 AM

My Subal has been rewired for DTTL and I have found this works very well.

On the page below there are a set of test shots I took in the pool with the D100, Sigma f2.8 28-70 @ 44mm. Exposures were all at 1/160th @ apertures: f32, f22, f16, f11, f8, f5.6, f4 & f2.8. DTTL has controlled these flash dominated exposures (of the orange fish) very well at all apertures apart from f2.8 where the camera was not able to quench the light quickly enough. I am very impressed that DTTL works relaibly over 6 stops.

My D100 test page

I am using insulation tape to block the contacts in the hotshoe. Which I have found is very easy to do, reliable and simple to reverse. I am now happy again because I am able to shoot both DTTL and manual guns!

After trials I am happiest using manual strobes with all three small contacts in the hot shoe blocked (see diagram on webpage linked above). Although as stated by Don (from Stephen Frink) they will work with only the top contact blocked. The solution I am using leaves only the trigger and ground connected - all that is needed to fire a manual flash. I prefer this because I know I have stopped all unwanted communication between the camera and strobe.

Alex

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#8 james

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Posted 11 March 2003 - 05:48 AM

Very good test page Alex!!! I was hoping to see something like this! Does your flashgun go to sleep in the flash housing? Have you disabled the flash head zooming? Do you use the additional "lightbox" on the flash head?

Did you know that you can "hotlink" to photos in your posts?

I'm going to use your test photo as an example. If you want me to remove it, just ask:

Posted Image

All I did was click on IMG above and enter the url of the test photo. It will display the image from your site in the post.

Again, if you want me to "unlink" it just ask.

Cheers
James
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#9 Alex_Mustard

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Posted 11 March 2003 - 06:48 AM

No problem with the image, James, I only put things on the web that I want to share.

I'll try the IMG button next time.

I used to use a housed SB26 a few years ago with my film system. But never really got on with it. I did keep the housing - its just a tube with no controls for the strobe. It does have a dome port to maintain the flash coverage.

Anyway the same tube fits the SB80DX and it works very well indeed. I leave the flash on DTTL mode and let the head zoom with the lens. The lightbox, however, doesn't fit in the flash housing. You can turn off the sleep - but I don't think I bothered - because it wakes up again when you half press the shutter.

Alex

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Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#10 PauP

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Posted 11 March 2003 - 12:09 PM

Alex,

I guess the SB80DX still fires monitor preflashes when flat (bounce position) in the housing?
...... still in D-TTL auto flash mode.

If you wished to use two flash guns with D-TTL, would the second gun need to ignore the preflash?

PauP

#11 Alex_Mustard

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Posted 11 March 2003 - 11:38 PM

The SB80DX does do pre-flashes while flat. DTTL, unlike standard Nikon TTL (with a Nikon land speedlight), does all flash metering with preflashes. Yes, that's right - once the shutter is open DTTL cannot react to any changes!

The use of two guns is a real minefield. Standard guns (on slave) will fire at the same time as the DTTL preflash and therefore will not light the picture. A pair of SB80DXs might work - but there is some stuff in the SB80DX instruction manual about this and I can't remember what it says.

I have been considering using a reflector as an alternative to a second strobe for macro - but am not progresssing much with this idea.

For cost, plus the risk of bring additional complexity and problems, I will be sticking with a single SB80DX for macro and standard lenses then going over to a pair of manual Subtronics (that I normally use with my F100 35mm camera) for wide angle.

Alex

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#12 james

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Posted 12 March 2003 - 05:58 AM

From what I understand, D-TTL has big problems when used with two flashes. The software logic for D-TTL assumes that you are using one flash and that it is in the plane of the CCD. D-TTL measures and takes into consideration the distance from the flash to the subject. When one flash is closer than another the preflashes do not return to the camera at the same time and "confuse" it.

HTH
James
Canon 1DsMkIII - Seacam Housing
Dual Ikelite Strobes
Photo site - www.reefpix.org