A relatively easy way of doing this on your blank piece of paper is to flash whilst you burn in at the same time, then you can see what you are doing. This is why I have 2 flashing set ups. One sits at the back of the darkroom and 'looks' up to the ceiling. The result is an omni directional low level flashing light which flashes, or even fogs if I wish, whilst making an exposure or burn in, but is not bright enough to make the projected image difficult to see. It is linked into the timer.
Originally Posted by Brook Hill
(the other flasher is another adjacent enlarger for direct flashing)
Tim, what flashing system do you use, and how does it link into your StopClock?
Apart from Dave, no one has answered your question yet, so here is my 2p worth.
I would like to start by saying that I am a fan of RH Designs, I use their pro stop clock and I often demonstate it on B&W workshops and everyone immediately wants one! I don't use their paper flasher because I have 2 alternative set ups that I prefer.
I have tested it and I did find that for my use there were drawbacks - not major, but it didn't offer me an advantage to what I use. This was mostly due to siting of the unit. If flashing the paper in the easel the flash light source needs to be in the lens axis otherwise 'shadow' artefacts may occur. A light shadow may appear next to the edge of a masking frame or blade, or a reflection may be thrown onto the paper from an edge of a 2 blade frame. the 1st will give a light 'shadow' (unflashed), the 2nd a dark shadow. These are more apparent with some masking frames than others (I have quite a few, generally 4 bladers are better)
I also didn't find a really happy place for it. My ceiling was too high and anyway the unit had to be significantly off axis to avoid a shadow of the enlarger head. Applying it to the lens mounts with blue tac or similar tended to all too easily give alignment discrepancies from pressing it into place, which I am slightly paranoid about.
I run 2 different flashing systems, both from my stop clock, which are very reliable for different purposes, and give me everything I want, so I don't use it.
However, I also know that many people use the unit and love it - so hopefully some will now chip in and counter my views
Hope this helps.
I'll answer Henry's question and at the same time comment on Tim's response.
Henry, I have used the RH Designs Flasher since before Richard Ross actually started to produce it commercially largely because the first flasher was made for me by RH Designs based on an idea that I had. I attach the light source to my enlarger, initially using blue tac, but now with velcro and have never encountered the problems suggested by Tim, namely enlarger alignment discrepancies or shadow effects. I do admit to using an enlarger alignment tool every time I make prints in my own darkroom but have attached the Flasher to all manner of enlargers when doing workshops and teaching in colleges throughout the country and have never encountered the above problems.
I find the flasher an invaluable tool when having to deal with small highlight areas of the print that require selective burning in either to subdue the brightness or enhance highlight texture. Both operations being quite tricky to deal with by using a paper grade and image forming light. Tim has already stated that the Flasher is an excellent tool but prefers to use his own methods which do work, which I can testify to for I have seen him do it.
Last edited by Les McLean; 12-10-2007 at 07:41 AM. Click to view previous post history.
Reason: finger trouble, hit the post button before I'd finished?
Why do you flash the paper? What is the effect on the image? Thanks!
in a nutshell it has the effect of bending/lifting the toe of the paper towards or onto the the light sensitivity threshold of the paper.
Therefore it only affects the hightlights of the area flashed. The result is that it can bring back into the print, some subtle highlight details that would otherwise be burnt out without having to adjust the contrast of the rest of the print.
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not to hijack this trhead, but what about the Daux Lite selective flasher tool? Anyone used it as there is one for sale on the APUG classifieds.
It's very simple. Instead of plugging my enlarger into the enlarger socket on the timer, I plug in a multi gang switchable extension cable (cut down to about 12 inches for tidiness). My enlargers and my distant 'omni flash/fogger' light are all plugged into the multi gang. Each one is switchable so when I hit the foot pedal any combination that is switched to 'on' will come on under the control of the timer.
Originally Posted by ITD
I use a low wattage night light bulb in a flexible small desk lamp on a shelf at the back of the darkroom. The hood faces the wall/ceiling, thus dimming it further to allow quite long flash or fog times to use whilst burning in impossible areas. (i can move it easily to give a brighter light but then need a new flash strip, so mostly I don't, as i have it adjusted as I like it). This is some 12 feet behind me and the glow is omni directional by the time it gets to the paper. this is incredibly useful for flashing or fogging whilst burning in. I improvised this system almost 20 years ago and haven't improved on it. If you have my 1st printing book you can see an example of burning+fogging on page 83. it's an eye-opener what this can do.
I use also an enlarger adjacent to the one I am printing on for simple quick max-flash exposures through the second channel of the stop clock. This is hugely convenient as again I can switch enlargers on/of and switch channels in a moment.
I find this works so well for me that I have no need for the RH flasher, but I know many people like it and I don't want to give the impression that I have anything against it - I am a declared RH fan. For me though, having a flasher on the enlarger head would be a nuicance as I would have to re-calculate the flash exposure every time I move the head up/down.
I have one and use it often. Great for toning down those bright areas. My use is not very accurate as far as exposure goes. I just use a best guess to start with and work from there. You can also get some variation between prints if you don't get the distance the same each time. This is usually not noticable unless you compared two prints side by side. The object is to get distracting hot spots toned down. I usually also do some burning in the area.
Originally Posted by Andrew Moxom
The Duax Lite exposure is normally done during the print exposure so you can easily see the area being exposed. If not you have to guess at the right location.
For flashing a full sheet or large areas using a mask I use an enlarger and timer. You can use an old print to cut a rough mask that allows only a certain area to be flashed. Move the mask during exposure like in dodging. You could setup a holder for the Daux Lite and use it to flash the larger areas but turning it on and off is a problem. Would need to uncover and cover the print by hand to do the timing.
The light is really an advancement of the old penlight used for years by people for small area flashing. You could easily build something out of a penlight to try. The big advantage of the Duax Lite is the easily adjustable intensity and various spot sizes.
Ah, this brings back memories that I had long forgotten.
Originally Posted by ChuckP
Gene Nocon showed me threshold flashing back in about 1980 (ish). I had not heard of the concept 'til then. But I had previously devised my own system for small hot spots, which started with a penlight and black paper funnel and then got adapted to a fibre optic 'wire' (or whatever it's called) taped onto a penlight with black tape and used as one would a dodger but to burn or fog small areas accurately.
Back in the 60's and 70's it was common practice to slightly overdevelop film. Since I improved my negative processing from the late 80's on I don't get such hot spots and my printing is more interpreation than rescue I'm glad to say.
This is the into para on one of my printing workshop handouts Janet. I can send you more info if you want.
Originally Posted by jgcull
Printing paper has an ‘inertia’ when first exposed to light. It requires a surprising amount of light exposure before it will register any tone at all on development.
‘Pre Flashing’ is a technique of exposing paper to a carefully controlled and measured amount of uniform ‘white’ light up to, but not exceeding, the paper’s inertia threshold.
The effects of pre-flashing are:
- To shift the overall image-forming exposure away from the toe of the paper’s sensitivity curve.
- Altering (lowering) contrast – useful for in-between grades with graded paper
- Extending tonal range– graded & VC papers
- Improving detail or tone in highlights – graded & VC papers
- Making subsequent highlight burning-in easier, with less risk of ‘dark haloes’– graded & VC papers.
NOT all prints require or benefit from flashing.