Tmax-400 @ 1600 continuous agitation develop time using D-76?

Until yesterday have never used my Bressler motor base to continuously agitate, while doing B&W film developing, and loved it.
Kodak states that you can use the same developing timing for Tmax 400 sheet film pushed to 800 if using rotary. (see below) but nothing is listed for developing Tmax 400 pushed to 1600. So wondering if its not listed because the rotary processing would cause more variance in its developing?

What we would like to do is use stock D-76 @68* for MF sheet film, in a small tank.
(Normal developing timing for pushed 1600 is listed as 9,25 minutes on Massive Dev Chart and on the Kodak site).

Note: No increase in development time is required for a 1-stop push. https://imaging.kodakalaris.com/sites/default/files/files/resources/f4043_TMax_400.pdf

Unless your scene was a very low contrast one and you want that for LF sheets only, D-76 stock with continuous agitation for 1600 is far from optimal, as you know.
Kodak's (800) recommendation is aimed at a system (exposure + development) in which it's preferable to avoid any longer development time, so you can yet print your sunny scenes with decent highlights, and keep grain and image structure as they were designed to work the best possible way.
So at 1600 your soft light scenes will have normal tone with some shadow loss that's not too relevant because there are no real shadows in a soft scene, but your sunny scenes, because of the high contrast 1600 development, will ask you to cut exposure a lot, so highlights don't get blocked, and that means you'll get very dark shadows, a la slide film on a sunny day: again, if nothing matters in the shadows, then it can work for some scenes, but in general, that poor shadow detail is not very appealing.
At 1600, a speed increasing developer like Microphen will do wonders for you:
It will care about your highlights (D-76 won't), it will give you better shadow detail, and although it makes grain grow a bit more than the standard D-76 development at 400, it won't grow as much as with a D-76 stock development for 1600 with constant agitation.
Happy weekend !

@peter k. A baseline starting point is to be found on the top right of pg.9 of the data sheet. A 2-stop push is usually somewhere between a 0.7 and 0.8 aim Contrast Index depending on various factors.

Furthermore, if you look at the chart on the left of pg. 6, you will find where the massive development chart lifted their numbers from, and that Kodak are aiming for a 0.75-ish CI at EI1600 when used with D-76 in rotary tube processing.

Are you aiming for the aesthetics of underexposed & push-processed film, or to expand the contrast range to fit a particular process/ material?

Try the D-76 datasheet instead: https://125px.com/docs/techpubs/kodak/j78-2017.pdf

Jaun... thank you very much for your explanation. We rarely push or pull film but the image we were trying to capture, without tripod is the one below.



We shot it at 1600 and processed it normally, and it seemed to come out quite well. The sun is hitting the Santa's seat and the candle. We cropped the image where the sun highlighted the floor area to bright. . So as you stated: "So at 1600 your soft light scenes will have normal tone with some shadow loss .."

Lachlan Young said:

Furthermore, if you look at the chart on the left of pg. 6,

Click to expand...

Oh there it is, thank you we missed it, and the rotary time is the same as normal developing.

MattKing said:

Try the D-76 datasheet instead:

Click to expand...

Ah a newer data sheet then the one we were referring to, will have to read that one, thank you.

peter k. said:

We shot it at 1600 and processed it normally, and it seemed to come out quite well. The sun is hitting the Santa's seat and the candle. We cropped the image where the sun highlighted the floor area to bright. . So as you stated: "So at 1600 your soft light scenes will have normal tone with some shadow loss ..".

Click to expand...

Looks pretty good to me and if there is shadow loss here I can't see it other than what seems normal for shadows in such a scene

pentaxuser

Your scenes are close to perfect. Have you seen what you get printing them in the darkroom? That's the real game... Scanning is a virtual adventure.