Long exposure considerations...?

[hoakin1981]

I am thinking of shooting some long exposures with TMAX 100. Since It will be the 1st time of doing so I would like to make sure I have the basics covered so please confirm my below understandings and provide any useful extra info. if necessary.

1. For a correct exposure. The films reciprocity failure must be taken into account and this means that, If I plan on using a 10-Stop ND filter, I would:

• Meter for the scene as I normally would for the shadows
• Calculate the respective exposure with the 10-Stop ND in place
• Increase the "new" exposure value according to the reciprocity failure of the film

So as an example, if normal exposure is 1/8 sec, then with the ND filter the same is 2 min and with the reciprocity failure in mind it would be 4 min. Is this correct?

2. Can anyone point to the direction of a good/reliable reciprocity failure chart for TMAX 100 and perhaps other films as well?

3. One last question, what are the available options to keep the shutter open for minutes using the cable release?

Many thanks in advance!

 

[fotch]

#3 Use a cable release that has a locking screw on the plunger.

 

[jp80874]

If the shutter has a "T" setting, using a cable release, press once to open, once again to close the shutter.

Use a tripod

Be aware of any vibrations that might show on the film. Example a truck driving by will make the ground vibrate and cause wind that would disturb a bellows if your camera has a bellows. Walking on an old poorly supported floor will cause movement on the film. I found this out after a 26 minute exposure in an old building at below freezing temperature.

Wind can vibrate a camera.

John Powers

 

[Alex Muir]

Try online for the Kodak data sheet for this film. It will give details of reciprocity corrections. I recall when using it some time ago that the correction was less than I would have thought.
Alex

 

[Jim Jones]

I rely on the booklet Kodak Professional Black-and-White Films for reciprocity failure and other technical information. The data sheet for T-Max films can also be downloaded from http://www.kodak.com/global/en/professional/support/techPubs/f4016/f4016.pdf. This contains much of the information in the booklet.

 

[MattKing]

You may find that you need less ND correction with Tri-X 400 than with T-Max 100, due to the reciprocity failure characteristics of the films.

Or if you have some, with Plus-X.

 

[ataim]

On my Iphone I use the app Reciprocity Timer 2.0 its has always been SPOT ON. I use Ilford HP5+, Delta 100 and FP4. I had a 15 minute exposure (adjusted for reciprocity) and it was lovely. Tons of goodies in the app, bellow factors, filters and such.