Hi Suzanne.
I'm such a barbarian. Use a diffuser beneath the lens ( don't remove the negative ).
A styrofoam coffee cup works well. If you have some Rosco Tough Rolux on hand ( and you should ! ) that works better. Any old thing. White paper.
Pre-flash.
The HP-5 & DD-X, though, suggests there may be plenty of data in the negative that you can retrieve.
Have you ever used 2 bath development ?
If not, it's easy. LPD, Dektol, and most of the rest, are pretty contrasty developers. Dilution doesn't change that. Selectol-Soft is lower contrast. Mix Selectol-Soft, use it in the first bath, and expose until you get the detail & tone in the sky you like.
It will probably have shadows that are too soft, possibly even muddy. To deepen the blacks, simply place the print into LPD / DEKTOL ( AT A HIGHER THAN NORMAL DILUTION ) until the blacks perk up.
Ansel talks about this in The Print.
So, you have 3 very different techniques: pre-flash, split filter, and 2 bath. Because the film and developer make a VERY long scale, I bet two bath will give you a better print. Had you used a combination that either has an early shoulder, or a steep contrast, pre-flash and filtration are necessary for putting tone into the print from an empty negative.
There is a fourth way, that often does the trick: a simple water bath.
Adjust the contrast until the midtones are a little to contrasty. Then, determine the exposure to print in the sky as you like, developing in normal developer, for your normal time ( say, 2 - 3 minutes ).
Then make an exposure at that time, and put the paper into the developer for thirty seconds, drain for ten, then slip it into the tray of water for a minute. Let it drain, then back into the developer for another 30 seconds. It's pretty intuitive. 2 or three cycles usually do the trick. Fine tuning follows a good, dry proof. Good luck !
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