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05-29-2016, 11:00 PM - 2 Likes   #1
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Shutter open indicator for long auto exposure

I have been conducting extremely long aperture priority auto exposures with the Pentax LX - some lasting minutes to hours, as shown in some examples below.

Using Kodak Gold 100 for about 15minutes


Using Kodak Ektar 100 > 40 minutes.


Using Kodak Gold 100. Fired the shutter about 9pm and found it had closed after 4am


The Pentax LX is the only camera ever - by any brand or make, that can aperture priority auto expose a scene for as long as it takes - or batteries dies, all the while checking the scene lighting for changes and adjusting exposure time accordingly. Unfortunately, there is no indicator when the LX has completed it's exposure so I have to occassionally check by looking into the viewfinder to see if the mirror has come back down. I posed the question before if there was an accessory that would help with this and someone here recommended to check the X-sync terminal but I cannot find that thread to give proper credit. Thanks to you, I finally got around to doing this and the solution works!

The X sync terminal provides a normally open connector and closes when the shutter is fired for the duration of the exposure. I simply needed an X sync connector, an indicator - in this case I used an LED, and a battery in series that provides power to the LED when the shutter is fired and opens once the exposure is done. Below is what I put together very quickly to try it out. Top picture shows the LED off as the shutter hasn't fired yet and the bottom shows the LED is on as the shutter has fired. BTW, my solder skills are up to NASA standards and this is just very fast and loose prototype . . .


Larger version -> Shutter open indicator

I tested it using the manual exposure times as well as in aperture priority mode for >30 minutes successfully.
I've also tested it on some of my other bodies and they work accordingly but probably not needed unless it is capable of the very long auto exposures.
I suppose I could use a piezo electric buzzer for audio queue but this battery LED can last an exposure a couple of days long so it maybe a match for the LX.

05-30-2016, 12:13 AM   #2
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I want one. Nice work!
05-30-2016, 03:47 AM   #3
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Great work but as I already told you the K2DMD (and I supposed the K2) has the same long exposure capability of the LX, which is not surprising as I assume the LX lightmeter is the development of the K2DMD one.
05-30-2016, 08:39 AM   #4
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Thanks guys. My first revision is to use a battery holder instead of soldering directly to it.

QuoteOriginally posted by Cuthbert Quote
Great work but as I already told you the K2DMD (and I supposed the K2) has the same long exposure capability of the LX, which is not surprising as I assume the LX lightmeter is the development of the K2DMD one.
From your previous posted results testing the K2DMD, you did say that that it can aperture priority auto expose a scene for very long times. However, I stated further, all the while checking the scene lighting for changes and adjusting exposure time accordingly. This is of course only possible because of it's unique Integrated Direct Metering (IDM or off-the-film).

05-30-2016, 11:08 AM   #5
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QuoteOriginally posted by LesDMess Quote
From your previous posted results testing the K2DMD, you did say that that it can aperture priority auto expose a scene for very long times. However, I stated further, all the while checking the scene lighting for changes and adjusting exposure time accordingly. This is of course only possible because of it's unique Integrated Direct Metering (IDM or off-the-film).
I need to repeat the experiment, but if I remember correctly the lightmeter of the K2DMD reacted to changes of light.
05-30-2016, 11:28 AM   #6
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QuoteOriginally posted by Cuthbert Quote
I need to repeat the experiment, but if I remember correctly the lightmeter of the K2DMD reacted to changes of light.
I only have the K2 and it's meter is in the viewfinder and hence the need for a viewfinder blind. The manual I have for the K2 DMD looks like a subset as it only identifies what's different to the K2 so I cannot verify that this is in fact the same in the K2 DMD. If this is the case, then the K2 DMD is blind to changes in light when the mirror is up.
07-07-2016, 08:47 PM - 2 Likes   #7
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I revised the setup by using a button cel battery holder just so I can readily change the battery.



So I took my setup out to the boardwalk at night to do some long exposures on Kodak Ektar 100. It works really well as it is very visible in the dark settings that I was shooting in. I had quite a few folks giving me a curious look . . .







I took a pic of this setup while it was exposing that last pic above just as a reference on how dark it was. You can see the LED over the shoulder of the LX to the right. But of course the Moto can only achieve this as that was about a 20 minute exposure on the LX.



I might attach a buzzer - along with the LED, so that I can hear it when it is done.
07-07-2016, 10:48 PM   #8
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QuoteOriginally posted by LesDMess Quote
I revised the setup by using a button cel battery holder just so I can readily change the battery.



So I took my setup out to the boardwalk at night to do some long exposures on Kodak Ektar 100. It works really well as it is very visible in the dark settings that I was shooting in. I had quite a few folks giving me a curious look . . .







I took a pic of this setup while it was exposing that last pic above just as a reference on how dark it was. You can see the LED over the shoulder of the LX to the right. But of course the Moto can only achieve this as that was about a 20 minute exposure on the LX.



I might attach a buzzer - along with the LED, so that I can hear it when it is done.
Nice work!

Phil.

07-08-2016, 05:16 AM   #9
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I think you should sell it to LX users.
07-08-2016, 11:28 PM   #10
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How nice, indeed!
I will copy your work...
07-09-2016, 08:31 AM - 1 Like   #11
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Thanks Phil. Cuthbert, parts and labor probably cost less than shipping. vrolok, feel free to do so. You can definitely get all the parts - cel battery holder, pc sync cord, battery & LED, from the auction site for cheap.
07-09-2016, 09:48 AM   #12
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Seriously awesome. That solves the single downside to long exposure with the LX in auto.

I took several long shots on EliteChrome at the coast a few nights ago, between 5 and 30 minutes, pointed at the fishing/crabbing boats on the horizon, and catching the strong phosphorescence activity in the foreground waves. My LX is still with Eric though, so I had to do some extreme exposure guessing on the MX. Hoping they turn out - I think they will as I took two test shots with my GR digital which looked pretty dang good. Cant' wait to see the slide roll.

Here's one of the digital tests. It was black... and I mean black except for slight glow in the clouds from the boats' light, and the glow of the strong phosphorescent waves as they broke. My LX, with your signal setup was what I kept wishing for in the back of my mind, but it was still fun with what I had, and this digi allowed me to check my exposure times afterward.


Last edited by chickentender; 07-09-2016 at 10:03 AM.
07-09-2016, 12:18 PM   #13
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Thanks Kevin. I hope your long exposure shots turn out and look forward to seeing them.
03-04-2017, 09:06 AM - 1 Like   #14
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Finally, I have managed to make my "shutter open indicator".



I am using a buzzer (very noisy btw) and AAA batteries (have plenty of rechargeable ones).

I hope to start using it "in the field" in the next few days...
03-04-2017, 10:13 AM   #15
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QuoteOriginally posted by vrolok Quote
Finally, I have managed to make my "shutter open indicator".



I am using a buzzer (very noisy btw) and AAA batteries (have plenty of rechargeable ones).

I hope to start using it "in the field" in the next few days...
Well done!

Phil.
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