overexposed over overdeveloped?

[vicmortelmans]

Hi,

I'm starting to practice my new workflow: develop b&w film at home and scan using filmscanner. This to reduce (expensive) round-trips to the lab, while first usage of pictures is digital anyway and only some will be printed (which I want to do digitally).

I've developed an Ilford HP5plus (ISO400) in Rodinal 1+25 for 10minutes. The negatives look very dense, but (being no expert in judging negative quality) to the eye these negatives look better than most of the lab-developed negatives that seem very transparant and hold almost no *real* density, even not in bright highlights.

Nevertheless, my filmscanner has sever trouble scanning this film. It's like it doesn't 'get through' the density, because all the highlights come out bad (visible scanner artifacts, stripes typically).

The scanner documentation says it's capable of a 3.6 density range. Thought that was already quite a bit?

I'm now wondering: did I overexpose (my Canonet QL17's meter may be wrong,or maybe I forgot to set the ISO to 400?), or did I overdevelop? Also: is a dense negative always bad? How would it react when being printed on paper?

Is there a way to tell if you overexposed or overdeveloped?

Note: I also developed some other films (APX100 in Rodinal 1+25 for 8 minutes and Ilford FP4+ in Rodinal 1+25 for 10 minutes, all at 20degCelcius and nominal ISO). These films gave less trouble for the scanner...

Groeten,

Vic

PS: I intend to stick to Ilford film in the future. What developer agent do you recommend, since Rodinal will be harder to get (still have stock for a dozen of films, I guess)? Of course I'll have to straighten out the HP5+ development practice first...

 

[kaiyen]

It could be both, to be honest.

Scanners prefer thinner negatives. 3.6 isn't bad, but even the best scanners (4.0+) in terms of dmax still prefer thinner negatives.

You have to learn how to read the negatives.

How is your shadow detail? Look at an area that represents shadow. Is there more density there than you'd like? Did you mean it to be almost but not quite black, in which case that area should be almost but not quite clear? Or is it actually got a decent amount of silver?

If it's denser than you wanted, then you overexposed. If you develop normally, you will get extra density in the highlights, too, since overall exposure was increased but development was not decreased proportionally.

But let's assume you like your shadows. If you're still seeing that much density in the highlights, then you overdeveloped. Based on what you're seeing, you overdeveloped by a lot. I'd cut by at least 30% next time and see how it goes. Bear in mind that, unless you're using a spot meter, it might be hard to dial in an exact EI and development time, so you'll need to fudge a bit. For instanc,e when I use a spot meter I rate TXT @ 320. But when I'm using any kind of averaging meter or even a center-weighted one I shoot at 250, which will increase grain a bit if the meter happens to be right but will also help shadow detail if the meter is influenced by a contrasty scene.

allan

 

[peterc]

I've developed an Ilford HP5plus (ISO400) in Rodinal 1+25 for 10minutes.

This is a bit much development for HP5+ in 1+25 Rodinal. I'd suggest 6 minutes maximum, or 11 minutes at 1+50.

Peter

 

[bmattock]

Here's a nice example of different types of development:

http://www.ephotozine.com/techniques/viewtechnique.cfm?recid=119

Best Regards,

Bill Mattocks

 

[vicmortelmans]

Thanks Bill and the others, got me some more understanding.

To understand better what happens during development of b&w negative film, I've tried to visualize it. Maybe you want to get a look at it and give some feedback.

http://users.pandora.be/vicmortelmans/fts/development/index.html

Also included is a representation of what's happening when pushing film and what it means to 'expose for the shadows and develop for the highlights'...(but I may be completely wrong as well... It's all quite confusing)

Groeten,

Vic

 

[jano]

Isn't it funny how the negative scans usualy look really good, but once inverted they look terrible? Pffft!

 

[vicmortelmans]

Isn't it funny how the negative scans usualy look really good, but once inverted they look terrible? Pffft!

What kind of invert do you apply? Most programs just subtract the negative value from 255. A proper 'invert' of a scanned negative should also apply a gamma correction. This is necessary to compensate for the fact that the densities on the negative are also related to the captured light intensities via a gamma correction. And on top of that, the actual pixels stored in an image file are assumed to be pre-gamma-corrected to anticipate the gamma of the CRT monitor on which you'll be viewing.

Most film scanners can autotically convert negative scans to positive images, but I've never seen a proper specification of the conversions they make automatically. That would be a nice thing to understand better what is done to your picture!

I'm doing a bit of investigation on how to convert a raw negative scan to a positive image that --when viewed-- gives a valid representation of the original scene, but it's a hard exercise if you want control over everything! I'm not expecting better results than the automated scanner functions, but it will help me to evaluate my metering and developing techniques better.

Groeten,

Vic

 

[ed1k]

Vic, I use black end (leader) to judge development accuracy. If you look throug it at an electrical bulb aproximately 40W from a distance 5 meters you will see:
1) just a lamp thread - significantly overdeveloped;
2) lamp thread, bulb shape and some surroundings - normal;
3) you can easily see surrounding the lamp details - underdeveloped;
I know it's not scientific and very subjective... at least I'm not sure about wattage of my bulb and distance, I just gave my best estimate as a reference point. Also it depends on kind of developer you use (some will never give you densities for point 1) After you examinated the leader, you may examinate exposure of each negative by looking at shadows details (less dense parts of negative).
For scanning you need slightly underdeveloped negatives. Often you just can't scan what you can easily print using traditional method on grade 2 or 1 paper, even adjusting exposure control of your scanner. And good for scanning negatives will require grade 4 or 5 paper for traditional printing. I mean scan with a good quality without excessive noise.
IMHO, overdevelopment increase grain more significantly than overexposure.
Regards,
Eduard