Ilford Delta 400 is a tabular grain black and white negative, belonging to the Ilford Delta film series which also consists of Delta 100 and Delta 3200. Like its counterpart, the Kodak T-Max 400, it aims for giving high resolution while maintaining film speed. Unlike the Ilford HP5+, Delta 400 requires more attention on processing as it is not as forgiving on errors. The Ilford website has detailed information on processing which should be pretty helpful. Personally, I prefer using DD-X.
The contact sheet above shows the differences in exposing the film at ISO 200, 250, 320, 400, and 800 (frames 17A to 21A). All exposures were given by the generic 5-zones matrix meter of my Nikon F-801 with no compensation and variations were done by simply adjusting film speed. For black and white emulsions, many would over-expose the film in order to capture more shadow details. For example, I usually expose HP5+ at ISO250 rather than the rated speed of ISO400. However, after some tests, it seems that the Delta 400 is able to retain the same amount of shadow details at its rate speed of ISO400 as compared to over-expose it one stop at ISO200. This can be demonstrated by the two sets of images below:
As for resolution, the Delta 400 is very capable in capturing fine details, retaining the reputation of being a tabular grain film. I almost exclusively shoot all my 6×4.5 medium format works in Delta 400 as its high resolution can compensate the relatively smaller frame size when compared to 6×6 and 6×7 (which I would use HP5+ handheld). Being able to expose at the rated speed of ISO400 (instead of ISO250 for the HP5+) also allows me to use a smaller aperture since medium formats give narrower depth-of-field than 35mm at the same aperture value for the same equivalent focal length. The sample image on the left below was taken with 120 format Delta 400 and on its right is a 100% crop of a 2400 dpi film scan of the same frame.
Finally, Delta 400 has a not well-known advantage of being able to be pushed to extreme speeds. Even in 35mm, the results can be amazing when using the right developer with the right processing time. Shown below is an image shot with 35mm Delta 400, exposed at ISO3200, and push +3 development in DD-X. On its right is its 100% crop, again from a 2400 dpi film scan of the frame.
The next sample image shows the result of the pushing the emulsion to ISO3200 when shooting in 120 format under a twilight environment. The details being captured is surprisingly rich as shown in the buildings in the background and the concrete floors on the foreground. However, it is worth noted that with the speed being pushed to extreme, the capability in retaining shadow details diminishes very quickly as a result. This property is well demonstrated in the two 100% crops below the the full frame image.
This is it, my experience so far with Delta 400, another amazing black and white emulsion from Ilford.