ASA400 to ASA 800 - double development time?

[ryanmills]

Flog me as needed but if I shoot ASA400 film at ASA800, its a good starting point to just double my development time. I have read so many dev charts and I dream about numbers and ratios, brain is slightly fried...

[tigger_six]

Try to multiply by 1.5 instead of doubling.

[Richard Rankin]

Try here for your film/dev combo and probably get it right the first time:

http://www.digitaltruth.com/devchart.php

Richard

[ryanmills]

Yea I have an odd ratio im toying with now, wanted to try it pushed and just wanted a rough idea where to start for time.

[Terry Christian]

1.25 x the original development time is usually a good start for a one-stop push. See the manufacturer's spec sheet on your film, as it might give you further information.

[Peter Mounier]

Tigger_six and Terry Christian are right in the ballpark. I used to increase dev. time 1.4x for 1 stop push with T-max. If the scene is contrasty to begin with try 1.25x, if the scene is flat, try 1.4x or 1.5x

[polyglot]

The 1.4x rule of thumb is good for traditional films. T-grain films seem more sensitive to development time changes, so (for example) I add only 20% to TMY2 when going from 400 to 800.