I've got a lot of old photographs to digitise. The options are to scan or re-photograph, and a website on the topic suggests that for a lot of photos, re-photographing is quicker, and requiring less re-processing.
A design is given for a small booth. It uses incandescent bulbs - I would prefer to use LED for coolness and lifespan. What light temperature do I go for - cool white or daylight?
Thanks
I'd try asking in rec.photo.digital
My understanding is that a lot of white LEDs have deficiencies in their spectrum that make colour rendering inaccurate. So maybe you have to get special ones made for the purpose. My limited knowledge of colour temperature suggests that it doesn't matter as long as you tell the camera or (usually nowadays) the camera works it out.
(Just my comments to clarify the question while waiting for someone who actually knows to come along.)
Does the camera have white balance adjustment? If so it doesn't matter really.
Id probably go for daylight personally, but I'd suck it and see.
That's exactly what I use. A home-modified bird fatballs box, that holds the slide and the compact camera, and the slide is lit from behind by window daylight through a piece of white perspex. My tripod tips forward so that the perspex is touching the window. Adjust for white balance occasionally, and it works just great. The box was free, and I had the perspex in stock. Cost:£0.00.
Colour temperature isn't much of an issue as the camera or post processing can easily alter that. Colour Rendering Index (CRI) is much more important and the incandescent bulb wins here. CRI is a quantitative measure of the ability of a light source to reveal the colours of various objects faithfully in comparison with an ideal or natural light source. Light sources with a high CRI are desirable in colour-critical applications such as photography.
The sun and an incandescent bulb have a CRI of 100 (the highest possible value), LED about 80 (for good quality LED's, lower for cheap Chinese ones). You can buy high (90) CRI LED's but they will be quite expensive.
Correcting for poor CRI is difficult, far more so than correcting colour temperature. See
CRI isn't a perfect measure and it is possible to get good results from low CRI lights but you might have to buy a lot to find ones that suit your subject. Unfortunately few manufacturers disclose CRI figures for their LED bulbs.
I have had to photograph quite a few documents, mainly so I have a back up copy. I have tried white light balance which does give an improvment but best results came from using daylight near a window.
It has been a friends experience that LEDs do not have a smoothe enough bandwidth. although normal bulbs are biased red, other types of lamps tend to not be like that with holes in some places in the spectrum like we used to get on cfls.
Maybe somebody makes photographic grade ones by now. Brian
Thanks guys - interesting. And I hadn't realised that LED's didn't match e ither the sun or incandescents. So incandescents it will be, though I beli eve I have to get the right ones even there.
For the initial project, LEDs would have done as the pictures are sepia and b & w. A 170 strong collection just found in my parent's house, of 1905 a nd 1912 family photos in two albums. As many of the photos are very nicely set up by someone in the family who knew how to take pictures, I do suspec t that there might well have been albums for the intervening years too, but that would have been a bit too much to sort out!!
It's not so much the colour temperature that matters since that can be adjusted for. It's more the holes and peaks in the light spectrum of ordinary white LEDs. Tungsten is generally far more benign in this respect
- or fluorescent tubes designed for the purpose.
But surely the life of the lamp isn't important for this job? It will hardly be on for long periods?
If you were copying *colour* photographs, I would suggest using daylight or incandescent bulb. Both of these are continuous spectrum so will not have problem with "gaps" in the spectrum, like CFLs and LEDs have.
You'll need to white-balance your camera for whatever light source you use, and I'd suggest if possible doing a manual white balance off a sheet of paper that is illuminated by the light source, rather than choosing a preset for sunlight, shade or incandescent. If you are using incandescent, ordinary
60 W bulbs will be fine (you don't need photographic bulbs) but remember that bulbs get very hot!However...
Since your photos are sepia of black and white, colour rendition is not important. The discontinuous spectrum of CFLs or LEDs won't matter when there's only one colour that you are trying to reproduce. I wonder whether it is better to try to preserve the sepia tone or to convert it black and white. Difficult decision!
If you opt for converting the sepias to B&W, I suggest using any light source that is available, and either set the camera to B&W or else convert the photos to B&W in software such as Photoshop or Paint Shop Pro afterwards. Conversion to B&W is probably better than keeping the photos as colour and striving to make the light as neutral as possible (ie not too red or too blue). May as well map this to neutral grey where R, G and B components are *defined* to be equal.
Whatever light source you use, try to make sure that you minimise any glare off the surface of the photo (eg if it has a glossy finish) as this will lead to localised hot spots or else general sheen that will reduce the contrast and cause you to lose detail in the shadows. Try to angle the light at about 45 degrees to the photo on either side by placing the lights some way to the left and right of the lens, rather than having a light that is very close to the axis of the lens. This is why on-camera flash would be a bad idea.
As an aside, if you are ever in a situation where you want to photograph something reflective and *only* viable light is on-camera flash, photograph it at an angle so the light of the flash doesn't reflect straight back into the lens, and then use the "parallelogram distortion correction" feature of Photoshop or PSP to correct for photographing off-axis. Beware that this will alter the aspect ratio of the photo a bit (ie circles will become oval) so take a straight-on photo (including the flash glare!) as well, for reference, then you can stretch the parallelogram-corrected picture back to its correct shape.
either the sun or incandescents. So incandescents it will be, though I be lieve I have to get the right ones even there.
nd b & w. A 170 strong collection just found in my parent's house, of 1905 and 1912 family photos in two albums. As many of the photos are very nice ly set up by someone in the family who knew how to take pictures, I do susp ect that there might well have been albums for the intervening years too, b ut that would have been a bit too much to sort out!!
Incandescent is a lousy choice. The low blue output of all incandescents ca uses noise in the blue channel. You really need a cool light colour or blue will be noisy. Daylight is free & often convenient, and has the added adva ntage of coming at the subject from a range of angles.
You can correct for tilt and off-axis in post processing, but doing so redu ces effective resolution some. So if you can get them right when snapping, do. Only go off-axis when you need to lose reflections.
Cool CFLs are generally quite good. Some linear fluorescent is, some not. L EDs are rather poorer than CFL. If you go with incandescent, use huge power halogen, like 1kW, to get a cleaner blue channel.
None of this is critical, you can use anything anyhow, but the above will g ive a much better result, and give originals you realistically can make goo d photos from.
NT
Is there any flicker on LEDs? If it's a fairly short exposure, could that cause problems?
I always choose a cloudy bright day and do it in the greenhouse. Set the camera colour balance to daylight and be prepared to tweak the balance in photoshop. Photograph a pure white card when you do the shoot and use it as a balance reference.
Direct sunlight is a no-no. Erect a screen to remove it if necessary.
Uneven light across the print is a big problem. Hence the greenhouse (or conservatory).
Be prepared to use large white pieces of card as reflectors to even up the lighting.
If you're doing a lot it's worth either bracketing the exposures or at least checking the exposure on 'difficult' prints.
Find the optimum focal length for minimum pin cushion/barrel distortion and best resolution, if using a zoom lens. It's likely to be a mid-range focal length.
Each shot should have a generous border which you remove later in Photoshop. Reasons: it allows you to rotate the picture so it is truly upright, and it avoids edge-of-frame lens issues.
Assume that you will spend more time editing in Photoshop and cataloguing than taking the actual shots. Cataloguing is important. Memories and people fade away.
Put some thought into the resolution you need. There's no point in having ten pixels span the lens blur of the original.
Bill
andescents it will be, though I believe I have to get the right ones even there.
rong collection just found in my parent's house, of 1905 and 1912 family photos in two album
s. As many of the photos are very nicely set up by someone in the family who kne
w how to take pictures, I do suspect that there might well have been albums
for the intervening years too, but that would have been a bit too much to sort out!!
These will probably be very high resolution, especially if from plates. You will need to match that resolution.
Bill
Use diffused flash. It will be cool and less prone to shake affecting the pictures.
Odd. That's exactly what was used in colour enlargers.
I doubt this will all be a single session, using the correct preset for the light source will produce consitent results. A manual white balance will vary, perhaps not by much but it will. Essential to use the same sheet of "white" paper (or WHY) for every white balance. Be careful of the exposure of the white as well, any overload/over exposure will confuse the white balance circutry.
For a quick copy of a document yes photographing it is quicker but for archiving photos you want the best possible results you can get. So you'll need very even illumination from a good quality light source and some means of holding things flat that doesn't reflect the light source(s) into the lens or degrade the resolution. They also need to be held dead parallel to the cameras sensor in both dimensions.
A scanner solves all those problems... Also think about the required camera resolution a good quality print could well have a resolution approaching 1000 dpi 6 x 4 print, 6000 x 4000 camera = 24 Mega pixels(ish). It's ages since I looked at scanners but my ancient one can do 1200 dpi. I should imagine modern ones will manage that and be quicker. Another plus for a scanner is overall consitency in results.
If the booth were bigger, I have four 'photo' CFLs free to a good home. IIRC they're 20W spiral cone shape - as they're in the loft and it's literally freezing up there the details will have to wait!
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