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OTT light degradation in Digital Photography of Coins (a bit long)

Every once in a while I go through one of my boxes of pieces and upgrade my images from scans to digipics. I have noticed that the first few pictures always look nice and accurate with respect to color, but then as time goes on and I shoot more pictures, the images get harsher and harsher.

I finally decided to design a simple experiment. Since the camera and the OTT light both stay on during the time period that I am shooting pictures, I looked at both camera electronics and light "power-on" time as factors. The idea was to isolate which factor was causing the problem, or to determine if it was some combination of both.

I decided to choose a full red example of a George V halfpenny as the subject. This coin was photographed four times on obverse and four on obverse and the best image for each side selected for each setting.

The settings were selected thus:

* Turn on camera and light and shoot pictures of the subject immediately. C = 0, L = 0
* Turn on camera, shoot some pictures periodically. Turn on light after 15 minutes and shoot pictures of the subject immediately. C = 15, L = 0
* Turn on light and let it stay on. Turn on camera 15 minutes later and shoot pictures of the subject immediately. C = 0, L = 15
* Turn on light and camera, shoot dummy pictures periodically. Wait 15 minutes and shoot pictures of the subject. C = 15, L = 15

Other potential sources of variation were controlled as carefully as possible, given my rather slipshod setup. image

Here are the results:

C = 0, L = 0; This is a pretty accurate image!

image

C = 30, L = 0; This is a pretty good image too! But...I left the camera on a bit long. image

image

C = 0, L = 15; The image has yellowed considerably.

image

C = 15, L = 15; The image has yellowed considerably.

image


Conclusion: time that my OTT light is on is a major factor in the quality of my coin photography. The camera electronics plays a small role, but is insignificant in comparison.
Former owner, Cambridge Gate collection.

Comments

  • AuldFartteAuldFartte Posts: 4,597 ✭✭✭✭
    Now, that is bizarre! I see virtually no difference between the first and second images, but the yellow really jumps up in the third and fourth sets. Was there any difference in external light during this experiment, like light coming in through a window? (I know you said you controlled other light - not questioning your ability, just curious) It seems a bit odd that this would happen because of the light degradation due to the time the light was left on.
    image

    My OmniCoin Collection
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    Tom, formerly in Albuquerque, NM.
  • coinpicturescoinpictures Posts: 5,345 ✭✭✭
    Great experiment! DPOTD material IMO.

    So it appears to be better to photograph coins in several small batches as opposed to long sessions.

    The question then becomes "How long does the Ott Light have to be turned off before returning to its initial lighting capability/characteristics?"
  • Very interesting post!!!! Thanks for the info.
    Shep
    image
  • All bulbs change color as they warm up. They also change color as they age.

    I have no specific information about OTT lights, but there is information about their CRI or Color Rendering Index that runs from 85 to 95. The higher the number, the better the bulb for accurate color photographic images, 94 to 96 is considered very good. There is also the color temperature which should be between 5,000 and 5,500 degrees Kelvin, which approximately simulates daylight.

    I know that may seem very technical, but those are the things that will affect the color of the images that you shoot. Yes bulbs will change as they warm up. As for the camera, I don’t think that it should change as it warms up, but I have never made any tests for that.

    Your tests seem to have a larger color difference than I would have expected, you might want to shoot something every 5 minutes for about 30 minutes to see where the change takes place or stabilizes. Then in the future leave your lights on for that long before you start.

    Bob
    I like Ikes!! But I especially like Viking Ships, Swedish Plate Money, and all coins Scandinavian.
    imageimageimageimageimage
  • laurentyvanlaurentyvan Posts: 4,243 ✭✭✭
    Outstanding post Wybrit-answers some questions...image
    One of the penalties for refusing to participate in politics
    is that you end up being governed by inferiors. – Plato
  • very nice info - I'll have to remember to turn off my lights between photo sessions (and make the sessions much shorter).
    Cecil
    Total Copper Nutcase - African, British Ships, Channel Islands!!!
    'Do not meddle in the affairs of dragons, for you are crunchy and taste good with ketchup'
  • lordmarcovanlordmarcovan Posts: 43,194 ✭✭✭✭✭
    Y'know what? I think this site needs a whole Coin Photography Forum.

    I'm not suggesting this didn't belong here- far from it! I just wish that threads like this were in one central place where it would be easier to access them for reference, don'tcha think?

    Nice work, Wybrit. I am still struggling up the learning curve. In exasperation, I find myself going back to my scanner sometimes.

    Explore collections of lordmarcovan on CollecOnline, management, safe-keeping, sharing and valuation solution for art piece and collectibles.
  • wybritwybrit Posts: 6,952 ✭✭✭
    All bulbs change color as they warm up. They also change color as they age.

    I have no specific information about OTT lights, but there is information about their CRI or Color Rendering Index that runs from 85 to 95. The higher the number, the better the bulb for accurate color photographic images, 94 to 96 is considered very good. There is also the color temperature which should be between 5,000 and 5,500 degrees Kelvin, which approximately simulates daylight.

    I know that may seem very technical, but those are the things that will affect the color of the images that you shoot. Yes bulbs will change as they warm up. As for the camera, I don’t think that it should change as it warms up, but I have never made any tests for that.

    Your tests seem to have a larger color difference than I would have expected, you might want to shoot something every 5 minutes for about 30 minutes to see where the change takes place or stabilizes. Then in the future leave your lights on for that long before you start.

    Bob


    In a past career I studied this at length. Indeed the characteristics of bulbs change through their lifetime and they also experience a transient as they power up, which is why mercury arc lamps, for example, must warm up for some time before they are put to technical use. What I was disappointed to find is that the best quality pictures for me happen in about the first 5 minutes of the "power-on" instead of after the time when the transients die down. image

    I have two of these lights and so for the next experiment I will probably study the two lights and the transient time effect, now that I have ruled out camera electronic transients as a possible second cause.

    Where do you find the specifications for the lamps that you mention?
    Former owner, Cambridge Gate collection.
  • wybritwybrit Posts: 6,952 ✭✭✭
    How long does the Ott Light have to be turned off before returning to its initial lighting capability/characteristics?

    Good question. It is probably a matter of lamp temperature, so it might be able to be estimated with a thermocouple (if only I had one at home...).
    Former owner, Cambridge Gate collection.
  • wybritwybrit Posts: 6,952 ✭✭✭
    I'll have to remember to turn off my lights between photo sessions

    It might not have that effect for you. My experiment really only holds for my system. Your light may actually work better after the transient state dies away. I guess the underlying message here is to check your light source.
    Former owner, Cambridge Gate collection.
  • Actually this summer will mark my 50th year working in Professional Photography. Some of you know that I am involved with photography, but not how much. Most of my career has been with the very technical side of things, both Shooting, and Processing of images.

    The CRI information as well as the color temperature information came from an internet search of the OTT lamps. The lower numbers came from competitors comparisons, so they may be a little suspect. CRI numbers are very important for judging the color of prints, and you really do need a number above 92. It simulates sunlight very well, and makes a good light for shooting. Since they are fluorescent type, the light will be soft, and give shadows that are less harsh. I prefer the Reveal bulbs with 45 degree glass.

    This type of bulb is the most stable after a few minutes on. I would suggest adjusting things so that you shoot after the lamps are on for a few minutes. I don’t know if it would be 3 , 5, or 8 minutes.

    I travel quite a lot, so there are times that I can not answer questions. When I am around, I will gladly help anyone. 10 days ago I was working with one of the large Labs in Manhattan, and sometime next week, I will be working in Hollywood. No, travel is not fun especially the overseas trips.

    I am not a big fan of manipulating images in Photoshop or what ever program you use. I much prefer to make the first image right, and only crop a little, or change the size.

    Photography of coins is not really that hard. Use a good Macro lens, use good lights, and record how you do it, and then you can repeat it later and know what results to expect. A good photographer knows what will be on the film, or in the computer before he pushes the shutter button.

    Sorry for such a long response, but shooting coins does not need to be as hard as some people make it.

    Good Luck,
    Bob
    I like Ikes!! But I especially like Viking Ships, Swedish Plate Money, and all coins Scandinavian.
    imageimageimageimageimage
  • MacCrimmonMacCrimmon Posts: 7,051 ✭✭✭
    Nice thread! Let me guess; you must be an engineer.image

    It would be nice to see the two lamp differentials. Most of my set-up are 'one-offs' or different metals/toning combos so I've never seen this phenomenon, but it is quite apparent.

    BTW, is that one of the 1917 1/ds from that bag you have?image
  • YQQYQQ Posts: 3,264 ✭✭✭✭✭
    edited June 11, 2017 8:24AM

    this is about the most ( and ever soooo little) I have learned in years photographing coins ( ditched the scanner years ago).

    I have use certain OTT lights and thought I had success, just to find out a while later everything had changed.
    I know that the on-off frequency plays a reasonable role in their life span and quality and accuracy of their out put.
    Based on all your inputs and experiences, it looks like I need to take a complete new approach. But, can you really teach an old dog new tricks?
    when results changed, I blamed it on the WB setting and simply used Auto setting. New experiments coming up.

    Bob,
    No, travel is not fun especially the overseas trips.
    Know exactly what you mean. not just OS trips. TransCons can be even worse. I had the big awakening years ago when I walked into the AC lounge at YYZ. the girls on the counter looked at me and one said: Where were you, we have not seen you for 10 days?
    sitting comfortable on the plane to FRA 90 minutes later, glass of wine in hand, the bell went off.....
    when I returned from this trip, I called my team for a meeting and told them I wish to retire and they can buy the co.
    they did. I retired and now i have very little desire to smell the inside of an aircraft, unless it is on the way to a white sandy beach.

    Today is the first day of the rest of my life
  • brg5658brg5658 Posts: 2,384 ✭✭✭✭✭

    Wow, really? Bumping an 11 year old thread? :confused:

    -Brandon
    -~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
    My sets: [280+ horse coins] :: [France Sowers] :: [Colorful world copper] :: [Beautiful world coins]
    -~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-

  • YQQYQQ Posts: 3,264 ✭✭✭✭✭

    Nothing wrong with that. Some different members, some different experiences, New ideas to do better.
    waiting for Airplanennut to chime in on the photographic issue. How about it Jamie? your experience is valued! :)

    Today is the first day of the rest of my life
  • brg5658brg5658 Posts: 2,384 ✭✭✭✭✭

    @YQQ said:
    Nothing wrong with that. Some different members, some different experiences, New ideas to do better.
    waiting for Airplanennut to chime in on the photographic issue. How about it Jamie? your experience is valued! :)

    ... @airplanenut 's name is Jeremy, not Jamie... :confused:

    -Brandon
    -~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
    My sets: [280+ horse coins] :: [France Sowers] :: [Colorful world copper] :: [Beautiful world coins]
    -~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-

  • airplanenutairplanenut Posts: 21,881 ✭✭✭✭✭

    Quick reply: If you have good white balance, then some amount of color in a bulb won't matter. That said, I prefer to avoid the soft light of Ott and CFL bulbs and shoot with halogen floods. The light strength improves the quality of the photo in my opinion.

    JK Coin Photography - eBay Consignments | High Quality Photos | LOW Prices | 20% of Consignment Proceeds Go to Pancreatic Cancer Research
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