How to evaluate an image (BD)

[Javi]

Dear Daguis,

 

ten days after timeless efforts (you all know that bit, right?), I finally got an image. Though satisfied, I realize it is just a starting point. Could anyone help me in assessing the image and give their input in various questions?

 

My data (for this particular image) and doubts are the following:

 

1. REUSING THE PLATE. It was the 10th time I reused this plate. I read that a up to 3 times is reccommended. However, I want to know what is the max. you have tried and still got a decent image?

 

2. HAND-BUFFING. I hand-buff for about 10 minutes on each buff but I got the impression (by visual inspection) I don’t erase hardly any imperfection. Is buffing suppose to eliminate also stains or only mild scratches?

 

3. SENSITIZING. I go to first cycle yellow-green. It takes 1’15” at 18ºC.

 

4. EXPOSURE. I took two exposures of 1’30” and 3′. By viewing the plate, I am still puzzled to what is the best exposure. Any clues in evaluating exposure? The EV was 14@100ASA. 12:00PM. Also, I use f8 (max. aperture, what a pity!) but the image seems out of focus.

 

5. DEVELOPMENT. After relative failure using red plastic, I got hold of Rubylith and works perfect. I developed the image for 1 hour in direct sunlight and 9 hours more inside with a 150W Halogen Lamp. Does development work well in the shade? Or should I stick with the Halogen Lamp?

 

6. FIXING. My question is: is sodium sulfite also necessary in the formula? Or only the sodium thiosulfite solution will do?

Needless to say, I didn’t gild the image.

 

I don’t have a scanner, so I just took a picture of the plate (damn family of angles!).

 

Thank you so much for your help, I hope one day I can answer all these questions…

 

Greetings from Japan,

 

Javi

 

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[photolytic]

Javi,

Thanks for the update. Your dag stll looks slightly dark but the tones are good.

The center image looks to be the 3min exposure. Is that correct? Over exposure can block the highlights, making them look out of focus.

Ten times is about max for a plate with 13microns (.0005in)of initial silver plate.

For a 25micron silver plate you can get about 20 images before it wears out.

All this depends upon how agressive your polishing technique is.

If your polishing is sufficient and you have enough silver left on the plate, you should have no stains or scratches on the plate. The stains may be a sign that you have buffed through to the copper. Those dark wavy lines around the edges of your plate indicate the copper is closer to the surface. The plate can still be used for experimenting.

I would suggest you try a more agressive polishing technique such as randon orbital buffing, or hand buffing with a courser buffing compound to get rid of all scratches and stains.

What are you using now?

A first cycle magenta fuming may be more sensitive.

Developing in weak shade light takes too long, allowing the latent image to fade. Better to stick with the brighter halogen light if the sun is not available.

The sodium sulfite is added to prevent the oxygen in the air from oxidizing the thiosufate.

If your hypo is fresh (no sulfur odor) and you make up fresh fixer for every plate you can get by without the sulfite.

[Javi]

Thank you so much for your wise input.

I will try and shorten the exposure time a little bit and try to get an overall image less dark. Another doubt I have is how much exposure changes between camera-to-subject distance (and hence, focus). I have tested other plates to more close-up objects (all out in the sun) and having a hard time determining a good exposure.

About buffing, I use Red Rouge (first buff) and then nothing (second buff). I use a song by Queen as a time and pressure pattern (no joking!). I play it once and then turn 90º the plate and keep on buffing, turn again 90º and so on). Maybe I should try other compounds just in case and be more careful not to scratch the surface of the plate.

I prefer making up new fixer every day for consistency’s sake. Do you recommend a final bath in distilled or pure water (even if not gilding)?

Thank you again!

Javi

[photolytic]

Javi,

As you know, the intensity of light from a lens diminishes as the square of the distance from lens or in other words the area covered by the image it casts. Hence your exposure should be proportional to the square of the ratio of the (close-up) lens to plate distance divided by the normal focal length of the lens at infinity.

EX: for a 100mm lens extended to 150mm, the exposure time should be extended by 150mm/100mm squared or 2.25 (a full stop).

Brian May of Queen, a Daguerreotype collector himself, would be amused to learn that he has become part of the process itself.

Wash the plate in flowing tap water, being careful not to place the plate itself under the spout to avoid damaging the delicate image. Then, holding the plate at an angle, flood the upper edge with a stream of distilled water so that it flows off the opposite edge. Do this several times(3)until all the tap water has been washed off. At this point the water should be repelled by the surface of the plate and flow off completely when chased by a stream of hot air from a hair dryer.

Happy Daging, John

[Javi]

John,

 

thank you so much for your help. I decided to spend a few days focusing only on exposure. I ended up with two “better” exposures at 1′ and 1’30” at 11:00AM and EV14.5. I am getting more comfortable with exposure times but still need more & more & more & even more practice. I decided to “start” again with the whole process learning, devoting a few days (or more) to each step (buffing, sensitizing, exposure & fixing/gilding).

 

About buffing, could an orbital sander be a substitute for the hand buffs? Not that I enjoy buffing but after a while my arm becomes numb (as a positive side at least I do exercise!). I also get exasperated to see how much the cotton-velvet hand buffs “attract” dust when I’m buffing.

 

As a last question, I am considering switching my current (oldie but goodie) 5×7 camera for a 4×5. Any suggestions of models and lenses to avoid/obtain? Unfortunately, price does matter and I doubt the 5×7 is worth much (Eastman 33A) to trade it.

 

Thanks again!

 

Javi

 

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[photolytic]

Javi,

Nice images,

Yes a random orbital buffer can be used at low speed in place of hand buffing.

You need more sponge applicator pads though. One for rouge, a second for lampblack, and a series of clean pads to remove the reside from the plate after steps 1&2.

Last minute buffing of the inverted plate (face down)on a clean hand buffing pad can be used to remove any dust or velvet lint just before fuming. Keep your buffing pads in sealed plastic bags when not in use to prevent dust contamination. Warm the pads with a hair dryer before use to remove traces of moisture.

Crown Graphic cameras are nice and relativly cheap ($300USD on EBay).

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