Long exposure device for Bulb setting?

[rjsphd]

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Did anyone ever make a mechanical timer to use with the Bulb setting to get accurate long exposures?  I am using my iPhone timer in one hand and a shutter release cable in the other on my M6 and my Rolleiflex, but there has to be a better way.

I see lots of old self-timers for sale, but that is not what I am looking for.

Thanks in advance,

Rob

[Guest]

What’s the issue with the phone timer and cable release? What is it you’re looking for?

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[rjsphd]

Better accuracy

[ianman]

Bteer accuracy is not really required for long exposures. 

[rjsphd]

Thanks

[Guest]

6 minutes ago, rjsphd said:

Better accuracy

How accurate do you need? My iPhone goes as accurate as 1/100th Of a second, are you looking for 1/1000th, or less?

What I’m not understanding is the statement “Better accuracy”. 

Using bulb means you need more than 1 second, your phone can do that with the stopwatch. 

[a.noctilux]

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Ian is right.

 

When I fancied using long exposure on film, I used my wristwatch (chronograph type of everyday 😜),

having a locking shutter release can help for longer than 10 seconds.

...

Accuracy math : 10 s more or less 1s that is 10%, film can easily hold that.

 

Think also for reprocity things, I never remember how much, but safe side is more exposure, in my experience.

[rjsphd]

Its not the phone accuracy, its the accuracy of my reaction time.  I had a shot for which I needed a 4-second exposure.  I shot several.  I am sure the exposure error was +/- 1/3 second.  Not a cost issue so much for 35mm film--you just take several shots and hope for the best.

It is a more expensive proposition on the Rolleiflex.

Anyway, I will get the rolls back from the developer and see how well I did.

Thanks for chiming in.

 

[ianman]

3 minutes ago, rjsphd said:

Its not the phone accuracy, its the accuracy of my reaction time.  I had a shot for which I needed a 4-second exposure.  I shot several.  I am sure the exposure error was +/- 1/3 second.  Not a cost issue so much for 35mm film--you just take several shots and hope for the best.

Factoring in reciprocity compensation is way more important than your reaction being a fraction of a second too slow.

[rjsphd]

Thank you a.noctilux and ianman for enlightening me on reciprocity.  I had never heard of it!

Now I am really glad I posted.  I will have to play with the formula and my Ilford film to see how it comes out.

Best,

R

[a.noctilux]

Let's take FP4 Plus as example, my 10s "metered" time needing exposure of 20s,

https://www.ilfordphoto.com/amfile/file/download/file/1919/product/690/?___store=ilford_brochure&___from_store=ilford_uk

MAKING LONG EXPOSURES
For exposures between ½ and 1/10 000 second, no
adjustments are needed for reciprocity law failure.
When exposures longer than ½ second are given, FP4
Plus, along with other films, needs to be given more
exposure than indicated by a meter. Use the graph to
calculate the increased exposure time which should be
given once the metered time is known.
The graph is based on the formulae Ta = Tm1.26

Ta = Adjusted Time
Tm = Metered Time

 

[Guest]

20 minutes ago, rjsphd said:

Its not the phone accuracy, its the accuracy of my reaction time.  I had a shot for which I needed a 4-second exposure.  I shot several.  I am sure the exposure error was +/- 1/3 second.  Not a cost issue so much for 35mm film--you just take several shots and hope for the best.

It is a more expensive proposition on the Rolleiflex.

Anyway, I will get the rolls back from the developer and see how well I did.

Thanks for chiming in.

 

Ah I get you now. You accuracy is the issue. I wouldn’t worry too much about it.

As @ianman and @a.noctilux says over 1 second (HP5+ film) reciprocity comes into play. So in your case 4 seconds will be 6 a 1/10th or 1/2 second delay won’t hurt much in the grand scheme of things. if you feel it does click the shutter just before the required time.

Keep us posted on how the shots came out. 

[Guest]

FYI most film manufactures have technical information documents, you might want to look up for reciprocity failure.

In my case ILFORD: https://www.ilfordphoto.com/wp/wp-content/uploads/2017/06/Reciprocity-Failure-Compensation.pdf

 

[a.noctilux]

One of the things I appreciate with Fuji Acros 100 (very good all round film) is the only film I used that "reprocity compensation" is not required untill 120 seconds.

data from this .pdf file (link to .pdf )

 Reciprocity Characteristics
No exposure compensation is required for exposures at
shutter speeds of less than 120 seconds. However, for ex-
posures of 120 seconds or longer, provide the compensation
indicated below.
Exposure Time (sec.) 120 - 1000
Exposure Corrections* +1/2
* A “+” followed by a number indicates the required increase in lens opening

[rjsphd]

Thank you.  I will check out the Fuji film.  So much to learn!

[ianman]

6 minutes ago, a.noctilux said:

One of the things I appreciate with Fuji Acros 100 (very good all round film) is the only film I used that "reprocity compensation" is not required untill 120 seconds.

I agree, Acros really is a beauty. Is the “no need to worry about reciprocity failure” still valid for the new version. I still have plenty of the old one left so have never tried the new one.

[Guest]

7 minutes ago, rjsphd said:

So much to learn!

You and me both.

[ianman]

There must be an “app” for this sort of thing.

[Guest]

59 minutes ago, ianman said:

There must be an “app” for this sort of thing.

There is it’s called a calculator 😉

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[Guest]

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<cough> <cough> For iOS anyway: https://apps.apple.com/gb/app/film-reciprocity/id1605389719