Printing - change from test strips to 8x10 enlargement

[simon_rodan]

Here's my problem: After making a number of test strips, I finalised the exposure for the print I am working on (20 secsonds @ f11). Then I take a sheet of 8x10 and without altering anything (enlarger height, aperture, focus), I make the exposeure and develop the print EXACTLY as I have the test strip, (2 minutes constant agitation, 4 times the image appearance time). However, the shadows which were a nice rich Zone I on the test strip appear as Zone II or III on the 8x10. <p>I then make a repeat test strip to cehck that I have not done something silly and again the blacks fall on Zone I - then I make another 8x10 and again they rise to Zone III. <P>This, as you might imagine, is rather frutating. Does anyone have a suggestion as to what is going on.

<p>Many thanks<p>Simon

[pat_krentz]

Are you doing your test strips on a sheet of 8x10 paper also? There

is a variable in there somewhere. Has the temp of your developer

changed in the time it takes for you to finish your test strips? Pat

[pat_krentz]

Developer temp, that is! Pat

[duane_kucheran]

Are you using a densitometer to check the exposure, comparing the

strips and prints side by side or just eyeballing the 8*10? If the

latter, I would bet that viewing the strips by themselves or against

a light background will cause them to appear darker. The eye is not

too good at absolute measurements and is better at differential

comparisons. An example of this is a television screen. If there is

a high contrast image displayed the blacks look very black but notice

how grey the screen looks when the TV is off. If you think about it,

that grey is made to look black only by the brighter parts of the

image.

 

<p>

 

I have a wild idea about reflected light from your easel getting back

into the optics and changing the exposure. The only way I could

imagine this affecting the image is if you had an enlarger head with

a light source that had some sort of feedback that actually monitored

the light emitted and/or reflected. You don't have one of these

fancy high tech head gizmos with an electronic controller perhaps?

 

<p>

 

Cheers,

 

<p>

 

Duane

[david vickery]

Hello,

When you place the strip on top of the full sheet do the tones

really look different?

Maybe your aggitation is more efficient with a small strip of paper

than it is with a full sheet?

Many times it is difficult to get an acceptable print when testing

for the lower zones, it may be easier to first test for the proper

highlight densities and then control the shadows areas with paper

grade/filter.

[brian_ellis3]

Are you literally using a narrow strip of paper for your test strips?

If so, there's quite a difference in the developer between developing

one little strip and developing an 8x10 print. Obviously, with a

little strip there's much more developer per square inch than there

is with the print so the rate of exhaustion is greater with the

strip. This would be particularly true if you have only a small

amount of developer in the tray. If you are using just a small strip

of paper (not a very good practice anyhow, IMHO, because it's so hard

to tell much from just a small segment of the print), try making your

test "strip" on a sheet of 8x10 paper and then comparing the results.

Also, as someone else has suggested, the brightness of the area

surrounding the shadows will have a big effect on how they look to

you. In his Expressive Black and White Print workshop, John Sexton

does a demonstration in which he makes a highlight of a print look

brighter even though in fact it is more gray, by making the shadows

around it darker.

[david richhart]

Simon...Michael Smith has a great article that explaines how he

prints, and determines printing exposures. It might change your

methods completely! The website is at www.michaelandpaula.com <p>

Best wishes -Dave

[david richhart]

I have several emails from people wanting the specific URL of the

Michael Smith address, so here it is... <p>

www.michaelandpaula.com/index_skip.html <p>

All of the articles are well worth reading... but the one I refer to

in this case is the one on printing difficult negatives. <p>

While I am here I would like to take a moment to thank Michael Smith

for his time in sharing his craft...-Dave Richhart

[john_sarsgard1]

I second the suggestion to read Michael Smith's approach, but you

might be more comfortable with test strips until you've got a bit more

experience. FWIW, make sure the strips are from the same batch of the

same paper as the full sheets. Paper varies from one box to the next

a little (sometimes more than a little). As another poster mentioned,

it's sometimes hard to judge a strip compared to a full sheet. David

Vestal, who wrote an excellent book on B&W enlarging, and writes

monthly in Photo Techniques, says he always gives the full sheet a

little more exposure than the strips, but never understood why.

Personally, I always use a full sheet, because judging density and

contrast is just a lot easier for me looking at the complete image,

even if it receives five different exposures. I can compare them side

by side. You can also more easily judge how much the problem areas

might need to be dodged/burned, because you have a variety of

exposures all together. Run the strips vertically or horizontally or

diagonally or whatever and try to get both highlights and shadows in

each "band".

[kcrisp]

Simon: Strange as it seems, I have sometimes found that 10X2 does

not equal 20. In other words, a test strip which looks great at 10

exposures of 2 seconds each will sometimes look significantly

different than giving the same material 20 continous seconds of

exposure. The agitation comments above make some sense. Developer

warming up in the tray makes sense, since the test strips tend to be

earlier on in the printing session and the final print at the end.

[r.l.__mac__mcdonald]

Simon,

 

<p>

 

All of the above should be checked and let me throw another one into

the mystery. If you are doing your test strips as most schools teach.

The problem may be the heating and cooling of your light sorce. If

you have a compensated light then you do not need to worry about this

problem. If not,then you may want to think about how you do your

testing. Before I had compensated lights, I had take this into

consideration. So if I made my all of my test strips one right after

the other(by 1 x set time, 2 x set time, 3 x set time and so on) my

light would be warming up as I made the different test strips. And

thenI would develope as normal(so thats some cooling time) and then I

spend some time looking at the fine test strips to pick the best time

(thats some more cooling time). So if I go back to make the full size

Print,the darn light is cooled down. And if I choose a 15 sec exposure

the light may have had 30 seconds of warm-up to produce the 15 second

test strip! Just a thought.. Best of LUCK.. And do not forget to

check out and follow thru on the recomendations in the above posts.

Just try to do them one at a time to see where the problem for

you,may be.

 

<p>

 

MAC

[simon_rodan]

I would like to thank everyone who posted an answer for their great

thoughts and advice. I now have a variety of tests to carry out this

weekend. Thanks again.

Simon