At the outset, I was very skeptical of the value of this exercise. Man was I wrong! This is very helpful information. Thanks!

Another interesting much needed understanding part of using the Harman Direct Positive Paper very fascinating

You can speed this process up if you have a view camera by taking step wedge photos.  For example, set up for a 2 second shot at your target ISO, say 2.  Pull out the dark slide a third of the way and take two one-second shots.  Then pull the dark slide out by another third and take a one second shot.  Remove the dark slide and take another one second shot. Now you have shots at 4, 2 and 1 seconds on the same photo, covering ISOs 1 (4 seconds), 2 (2 seconds) and 4 (1 second).   You can then develop and compare 3 ISOs on the same shot.

Great videos Joe, thanks so much. An in depth video like this discussing potential issues with pinhole cameras and Ilford Harman DP paper would be great!

Thanks Joe, wonderful insights!!

great video, very useful

Great series,learned allot. Now i know why my exposures keep changing....Thanks.

Great videos, Joe, thank you.  Your point about UV and spectral sensitivity is illuminating, (no pun intended) as is your advice to be consistent in exposure and processing.  I shoot mostly in my studio, and I also have my darkroom there so I can shoot and process one at a time very easily.  I will do a video on still life photography using this paper and hope it is as helpful as your videos are.

Joe, I think there is one way out of this iso/asa cunundrum, an old trick for metering, esp. tungsten light, put a gelatin filter (UV/IR)- in this case, in front of the meters' bulb/sensor, this allows through ONLY the frequencies you want to meter.

Try adding clean marbles to the container to take up the space and lift the developer to remove the air. I keep 5 lbs of the marbles for this purpose. I also wonder if a blue filter might give give a more accurate reading. I have several  used for printing photos.

Nice videos Joe.  Regarding the metering of faces (particularly with this paper), I wonder if it would be helpful to close the diffuser bulb and read toward the camera? Thoughts? (incident reading- isn't that what it's called?)

hey joe - what if any reciprocity factor have you experienced with very long exposures? thanks again - great series on this paper - amazing resource!

Hi ,Sir,  how much studio flash power  need to expose a portrait on Hermon direct positive paper. Recommended f number ? 😊

I wonder -- if the paper only responds to blue & UV light, would you get a more consistent year-round metering by spot metering through a blue filter?
EDIT: Just realised someone else has already suggested that idea :P

Joe, This is my first try at paper negatives. I am a pinholer. Pretty good at exposing film. With this paper I am only getting blown out whites but borders seem exposed well. I have been working all weekend trying to get an exposure and I am not even close. My pinole is F176 and I am calculating with reprocity effect as I would with film. Guessing I am over exposing? Meter reading is like 1/8 at 5.6 ISO 6? HELP

Could you filter the light meter to match the light the paper is sensitive to?

I feel like this is obvious, but when you say to change ISO and keep everything else, you mean to change the whole exposure based on that ISO change, right? Meaning, if you were at ISO 6, Shutter 1/4th, and aperture 5.6, if that's underexposed, you'd "change" the ISO to 3, which would bump shutter to 1/2, and keep aperture the same, right? Just making sure I understand what you're saying, it seems like a standard exposure calculation, but I'm just making sure.

Please help!

I loaded Harman DP with glossy side facing lens/facing out. I developed in super monobath and nothing came out. The paper was completely white after bath and wash.

I even put the paper both sides under my cellphone light just to get anything to come up and nothing.

I redeveloped and re-washed at 80 degrees which was 5 degrees more than recommended. Still no image.

I saw some black residue that was easily rubbed off with my thumbs. I’m assuming they’re from my previous bnw developments.

Can you tell me anything about what I’m doing wrong here?

Late as usual, but what if using an UV filter on the lens?

Thank you for the very instructive video.

I was aware of this paper some years ago, but had forgotten about it.

I am thinking of using it with the cyanotype process. Scan the 4x5" DP print, enlarge to 8x10 digital negative, then direct print the cyanotype to watercolour paper.

Do you have any thoughts on this, or would it be too much trouble vs exposing regular 4x5 film?