RH Designs Paper Flasher

jstraw · Apr 21, 2007

First, allow me to get in my brief gloat over having just placed my order for a StopClock Professional, Zonemaster II and Paper Flasher. Thanks for the tax refund check, Uncle Sam.

Now 2 questions about the paper flasher.

Is it important to flash paper from a consistant height?

Assuming so, how have paper flasher owners solved that? I want my flashing to be consistant, regardless of where the enlarger head is for any given print. I don't want to be moving the head once I've composed a print on the easel. So I'm envisioning some mechanism for positioning the flasher at the same height all the time, independent of the enlarger head's position. I don't have the luxury of a separate enlarger or copy stand for this purpose. I'm thinking about a wall mounted swing arm.

ann · Apr 21, 2007

use a piece of velco. a piece on the flasher and a piece on the lens board.

then the equipment will be at the same height of the orginal exposure and youi wouldn't have to move the head.

jstraw · Apr 21, 2007

ann said:
use a piece of velco. a piece on the flasher and a piece on the lens board.

then the equipment will be at the same height of the orginal exposure and youi wouldn't have to move the head.

Allow me to clarify. That would mean that the position of the flasher is tied to the position of the enlarger's head. If the head is higher, the paper isn't going to recieve as much flashing exposure as it would when the head is lower. A given paper emulsion needs the same amount of light to overcome the silver's inertia each and every time, yes?

Hence my desire to decouple flasher height from enlarger head height.

Am I not thinking of this correctly?

Leon · Apr 21, 2007

Jstraw - I do as Ann does, then carry out a quick test strip to work out the flash/ fog exposure. I guess that if you do fix it somewhere that it will stay constant, then you will only have to do the test strip once for each paper, then use this value everytime, but my darkroom is too small to have a fixed flashing area, it really only takes a few extra seconds each time.

Mark Layne · Apr 21, 2007

jstraw said:
First, allow me to get in my brief gloat over having just placed my order for a StopClock Professional, Zonemaster II and Paper Flasher. Thanks for the tax refund check, Uncle Sam.

Now 2 questions about the paper flasher.

Is it important to flash paper from a consistant height?

Assuming so, how have paper flasher owners solved that? I want my flashing to be consistant, regardless of where the enlarger head is for any given print. I don't want to be moving the head once I've composed a print on the easel. So I'm envisioning some mechanism for positioning the flasher at the same height all the time, independent of the enlarger head's position. I don't have the luxury of a separate enlarger or copy stand for this purpose. I'm thinking about a wall mounted swing arm.

I stuck a piece of board onto the back of mine so that it slides in and out of my Multigrade filter holder
Mark

jstraw · Apr 21, 2007

Leon said:
Jstraw - I do as Ann does, then carry out a quick test strip to work out the flash/ fog exposure. I guess that if you do fix it somewhere that it will stay constant, then you will only have to do the test strip once for each paper, then use this value everytime, but my darkroom is too small to have a fixed flashing area, it really only takes a few extra seconds each time.

The extra time doesn't bother me but the extra paper does. I have a very small darkroom as well but I'm determined to come up with a solution.

ann · Apr 21, 2007

with pre-flashing the old fashion way, yes you maintain a constant distance.

with this toy , many use if for post flashing which is a different animal.

also, you could use some smaller strips
of paper to be used only in the area that you want flashed with will help control the cost

not knowing what your darkroom space looks like it is hard to determine exactly what would be most helpful; however, you could also attach the flasher along side of the enlarger at a given height , perhaps on a wall which will aid with the consistency of time regards of enlarger head height.

it has a foot switch which will allow you to place the flasher at a varity of places and few up your hands and arm length as well.

jstraw · Apr 21, 2007

Sounds like I need to do some research. While I have a rudimentary understanding of pre-flash. I'm ignorant about post-flashing.

The reason I'm thinking about some sort of armature is that the inverse square rule is unforgiving and surface mounting it on a wall perpendicular to the surface the paper is on means that the light will not be even across the paper.

jeroldharter · Apr 21, 2007

I use Blue Tack and attach the flasher to the lens board.

That requires a test strip every time you flash.

What I have been meaning to do is mount the flasher to a swinging arm that is mounted on the wall. I would place it so that it would swing below the lens when the enlarger is focused at the smallest print size (the unit casts a wide beam) and then I could standardize the flashing time to each paper type with test strips and be more efficient. An alternative would be to mount the flasher to a pedestal, sort of like a goose neck desk lamp, so that the flasher is portable but always at the same height.

lee · Apr 21, 2007

I also use Blue Tack and it is attached to the lens board. make sure the unit is off because it does use up 9volt batteries. and congrats on the purchase.

lee\c

gainer · Apr 21, 2007

I have an easel densitometer-exposure meter with which I set exposure for printing. I built my own flasher which is tied to the enlarger head by velcro and which is on when the enlarger lamp is on and the flasher switch is on. The flasher has a simple diaghram to control light. I set the enlarger for the shadow exposure with the flasher turned off. Then I turn on the flasher and adjust it for the highlight to give the total amount of exposure that will give Zone 7 or 8. It is neither pre- nor post-flashing, but while-flashing.

In order to work properly, the color temperature of the flashing lamp must be the same as that of the enlarger lamp. That is why I use a diaphram instead of a rheostat to control the intensity of the flashing light. This diaghram is simply two pieces of matte board with v-shaped cutouts. You can visualize how this works, I'm sure. You may need some neutral density filtration to cut down the light from the flasher. It need not be of optical quality and can be made from film.

jstraw · Apr 21, 2007

Hmmm...I wonder if the Zonemaster II print meter could be used to determine adjustments in the duration of the flashing exposure so that they can be consistant with the flasher at any height.

I can determing a flashing exposure for a given paper at a given height. If I can meter that output so that the Zonemaster II indicates that this produces a given zone on it's scale, if I raise or lower the head, I'd just need to determine the changed flashing exposure duration to achieve the same zone from that new position.

Does that make sense?

It might also be possible, if the lattitude involved is sufficient, to just do tests for flashing exposure for each paper I use, at one or two inch increments and make a chart. Then I could just flash for the nearest charted height to the actual height.

Mark Fisher · Apr 21, 2007

I took a piece of plexiglas and added some legs about a foot long (maybe 18 in....not home right now) that fold up. It is big enough to fit over my easel. The flasher is them placed on the plex. I made the legs as short as I could and still get even illumination. For awhile I just used the rights sized cardboard box and cut a hole in it...that worked fine too.

I did it mostly because I am lazy and don't want to figure out flash times......btw, I am only pre-flashing, but I don't see how that would make a difference except in the time used.

Mark

jstraw · Apr 21, 2007

Mark Fisher said:
I took a piece of plexiglas and added some legs about a foot long (maybe 18 in....not home right now) that fold up. It is big enough to fit over my easel. The flasher is them placed on the plex. I made the legs as short as I could and still get even illumination. For awhile I just used the rights sized cardboard box and cut a hole in it...that worked fine too.

I did it mostly because I am lazy and don't want to figure out flash times......btw, I am only pre-flashing, but I don't see how that would make a difference except in the time used.

Mark

I like that approach!

timbo10ca · Apr 21, 2007

This may be a dumb question, but if people are mounting this device to the lensboard region (which varies each time a print is made) and having to test strip each print, why bother using the device at all? Why would you not just use the enlarger to flash the paper, especially when it is mentioned by gainer that you'd want the same color temp in the light sources?

Tim

patrickjames · Apr 22, 2007

This thread caught my attention and I have been thinking about it all day trying to figure out if it is worth making or buying the flashing device. Right now I am simply using frosted mylar in the red filter holder under the lens (after taking the filter out of course). It has worked well for me for the most part as I use a general percentage of the exposure to set my flashing time. I thought this procedure would make the most sense since one is exposing with the same light temperature as the exposure for the print, so the appropriate layer in the paper is being exposed.

I don't see how attaching the device to the lens board or enlarger head would be that overly complicated. After all most of us make prints about the same size most of the time. My enlarger (Saunders) has markings on the column, so it would be simple to just run some tests and take notes. Seems pretty easy to me. Setting the device the same distance from the paper would be the simplest way, as long as you could achieve even illumination. I am sure you will find a way that is best for you.

Good luck

Patrick

Solarize · Apr 22, 2007

timbo10ca said:
This may be a dumb question, but if people are mounting this device to the lensboard region (which varies each time a print is made) and having to test strip each print, why bother using the device at all? Why would you not just use the enlarger to flash the paper, especially when it is mentioned by gainer that you'd want the same color temp in the light sources?

Tim

I think its partly an issue of convenience and accuracy. I dont use a dedicated flasher but plan on buying one; my current apprach of flashing without the neg in the carrier is tiresome and has led to mistakes. I've knocked the focus and misaligned the carrier so the composition goes amiss when making the proper exposure.
I could post-flash but if I want to make several copies of one print (which is often the case) or if I dont get the first one right (which nearly always happens) then resetting the negative, refoccusing etc becomes annoying. Also, my archaic analogue timer doesnt have the same accuracy or control that a dedicated flasher would. And as I dont print with the same enlarger head height or f.stop on each print, a test strip is mandatory on each new print.

Jstraw - I like the idea of a wall mounted swinging arm.

jstraw · Apr 22, 2007

I don't understand the importance of having the flashing exposure's color temperature match the enlarger's light source. Gainer, can you elaborate?

Andrew4x5 · Apr 22, 2007

I have my flasher mounted at a fixed height. It is about 300 mm (1 foot) to the side of the enlarger, so that the enlarger never shades the paper. In practice, I place the paper immediately under the flasher to flash it, before moving it to the easel.

gainer · Apr 22, 2007

jstraw said:
Hmmm...I wonder if the Zonemaster II print meter could be used to determine adjustments in the duration of the flashing exposure so that they can be consistant with the flasher at any height.

I can determing a flashing exposure for a given paper at a given height. If I can meter that output so that the Zonemaster II indicates that this produces a given zone on it's scale, if I raise or lower the head, I'd just need to determine the changed flashing exposure duration to achieve the same zone from that new position.

Does that make sense?

It might also be possible, if the lattitude involved is sufficient, to just do tests for flashing exposure for each paper I use, at one or two inch increments and make a chart. Then I could just flash for the nearest charted height to the actual height.

If your flasher has variable intensity, you can use the Zonemaster just as I do with my home made apparatus. Leave the flasher on at minimum intensity while using the Zonemaster meter to adjust Zone 1 or 2 using the enlarging lens and exposure time as you would were you not using flashing. Use the flasher intensity to adjust Zone 7 or 8 to suit the Zonemaster. Now check the shadow. You will see that the Zonemaster reading has not changed significantly. All you need is a switched outlet into which you plug both the flasher and the enlarger so that both are either on or off together.

The best you can do by flashing is to add enough light so that the places where you want Zone 7 0r 8 are exposed just slightly more than the threshold of the printing material. Adding a certain amount of overall light will not add the same density increment to both high and low because of the logarithmic function involved. The log of 1 + 1 is 0.3 while the log of 10 + 1 is 1.04. This reasoning assumes that you want to add the minimum light to bring some detail into the highlights. If you just want to darken a certain area, you are netter off with dodging/burning.

jstraw · Apr 23, 2007

gainer said:
If your flasher has variable intensity, you can use the Zonemaster just as I do with my home made apparatus. Leave the flasher on at minimum intensity while using the Zonemaster meter to adjust Zone 1 or 2 using the enlarging lens and exposure time as you would were you not using flashing. Use the flasher intensity to adjust Zone 7 or 8 to suit the Zonemaster. Now check the shadow. You will see that the Zonemaster reading has not changed significantly. All you need is a switched outlet into which you plug both the flasher and the enlarger so that both are either on or off together.

The best you can do by flashing is to add enough light so that the places where you want Zone 7 0r 8 are exposed just slightly more than the threshold of the printing material. Adding a certain amount of overall light will not add the same density increment to both high and low because of the logarithmic function involved. The log of 1 + 1 is 0.3 while the log of 10 + 1 is 1.04. This reasoning assumes that you want to add the minimum light to bring some detail into the highlights. If you just want to darken a certain area, you are netter off with dodging/burning.

Right, my interest in flashing is just about getting the highlight areas over the threshold. I assume that flashing the whole sheet does no harm. I don't know if the flasher has variable output. I don't think that it does.

I'm going to refer back to your post when I have the flasher and zonemaster in hand. Thanks.

gainer · Apr 23, 2007

The idea still works. You just have to implement it differently if the flasher has fixed light output. It is probably easiest to contrive a way to control the light from the flasher, either by a simple iris or by neutral density filters, which need not be accurate but must cover a range of densities. I have not seen the flasher in question. I made my own, and if I were the manufacture, the ones I sold would be like mine.

Do not use a variable resister or light dimmer switch to control the flasher. These devices will change the color of the light, thereby adding another variable.

lee · Apr 24, 2007

I use the flasher as a paper fogger. after the print is made and there is still a highlight that is still too bright I will burn in the area with a hard filter and then fog the area with the flasher. I do have to make a test print but that is not hard to do.

lee\c

Dave Krueger · Apr 24, 2007

gainer said:
It is neither pre- nor post-flashing, but while-flashing.

You never cease to amaze.

keffs · Apr 25, 2007

How about the ceiling?

Steve

RH Designs Paper Flasher

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