Efke 25 Long Time Exposure- Reciprocity Failure?

[markus_muller]

<p>I want to do a night shot with efke 25. I meter about 5 min. How long would you expose (reciprocity failure)?<br>

The efke website says @100 Sec x 1.5. But what about times around 5 min. ? Any experiences?</p>

[Mike Gammill]

<p>This really is a "shot in the dark" (no pun intended). I would bracket generously. Even if I had precise reciprocity data for a specific time I would still bracket. I haven't tried Efke 25 for long exposures, but my experiences with Ilford Pan F+ (ISO 50) and Panatomic-X (ISO 32) indicate that bracketing is really a good idea. Also, the area that you are metering will make a difference. Averaging metering really won't be of much use if there are huge extremes between the brightest and darkest areas in the picture. But, if I were trying this with the Efke film, I would use 1.5X the indicated exposure as a starting point and go from there.</p>

[vinny_walsh]

<p>I've shot quite a bit of this film in 120, 4x5, and 8x10 in the last few years. For exposures that long, I double it.</p>

[Fotohuis RoVo]

<p>I would go for x 1,5 (@ 100 S) and from there bracketing to the longer time. The reciprocity data is not always very accurate.</p>

<p> </p>

[jim_gupta_carlson]

<p>for a 4 miute exposure my data says 16 mins.</p>

<p>I'd say expose for 20 minutes and you should be safe</p>