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Post by nomad on Dec 10, 2016 10:10:30 GMT
Many collectors like to photograph their specimens using flash gun attachments, however, museums I visit don't like them but one very kindly provides something much better, a calibrated lightbox, so you see the colours as they are seen by the eye. The reason the museums understandably do not like flashguns is they focus an intense burst of light on the specimen. My question is, those that use flash guns to photograph their specimens, do you worry about colour damage. That damage may not be apparent at the time but do you believe it may quicken fading in your specimens. Any one here like to comment?
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Post by Paul K on Dec 10, 2016 11:22:10 GMT
I don't think that such short time of exposure to flush light would have any visible effect to the specimen in the future. besides how many photos of one specimen one has to take. In my opinion though the flush of camera twists the spectrum of light and change natural colours of the specimen.
Paul
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Post by wollastoni on Dec 10, 2016 11:26:34 GMT
Our specimens aren't often photographed so I don't see the risk.
For rare Museum specimens, there may be a risk, no idea on this. Maybe Xavier Merit knows more about it as he is a colour specialist
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Post by bobw on Dec 10, 2016 12:41:54 GMT
Certainly they won't let you use flash in the library at BMNH to photograph old books as they fear they could be susceptible to damage. I've not heard of it being a problem for specimens there but I would never use flash for specimens as the resultant colour representation is very poor. I remember when they first got some lightboxes in the department about 20 years ago; I was very happy to no longer have to lug my lightbox and copy stand up to South Ken on the train.
Bob
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Post by Paul K on Dec 10, 2016 12:53:22 GMT
Does anyone has picture of this magical lightbox ? I am interested to make one as I am planning to make digital data of my collection in near future.
Paul
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Post by nomad on Dec 10, 2016 12:55:20 GMT
Our specimens aren't often photographed so I don't see the risk. Which is a pity.
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Post by nomad on Dec 10, 2016 13:01:50 GMT
Certainly they won't let you use flash in the library at BMNH to photograph old books as they fear they could be susceptible to damage. I've not heard of it being a problem for specimens there but I would never use flash for specimens as the resultant colour representation is very poor. I remember when they first got some lightboxes in the department about 20 years ago; I was very happy to no longer have to lug my lightbox and copy stand up to South Ken on the train. Bob I agree. Using a light box yesterday, which is much in demand, I put my camera on the screw and took images, while the background was darker, the specimen representation was very good. When I used the normal camera flash with lightbox to see the difference, the background was brighter and so was the specimen and in doing so lost colour detail. I was using my macro lens, which produced good results, especially with smaller specimens such as Microlepidoptera.
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Post by wollastoni on Dec 10, 2016 13:53:32 GMT
Our specimens aren't often photographed so I don't see the risk. Which is a pity. Yes it is. One of the thousand projects I have in mind is to digitalize my Delias collection and to present it in a "Collection" section of the Delias website, along with other interesting private or national collections.
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Post by deliasfanatic on Dec 10, 2016 14:48:57 GMT
There's no risk to personal specimens from using flash once or twice. I can see the museums' point of view, though, in that many visitors could take many flash photos over time, with accumulating damage over the years.
I'd like to see a photo of the "lightbox" referred here. I've experimented quite a bit, and I've found that the best and most natural colour, as well as the least surrounding shadow, is produced with "bounce" flash. Direct flash is typically too harsh, and will create a shadow if the specimen sits above a surface (i.e. pinned, rather than sitting on cotton or such). With bounce flash, I aim the flash toward the ceiling, which illuminates the specimen(s) beautifully with soft light. This works equally well for single specimens or an entire drawer, and is the only method that I use nowadays. It wouldn't be a practical technique in most museums, however; beside the fact that they probably wouldn't allow it, it also wouldn't work well with high ceilings or those that are not white.
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Post by nomad on Dec 10, 2016 17:08:16 GMT
Yesterday at the museum I was experimenting, but I found the best results were without the use of the camera flash, as there were then usually (not always) no shadows. The camera is screwed and tighten to an adjustable arm, which moves the camera up and down to a hole in two sided standing box, containing the calibrated light, where the specimen is placed in. You will have to wait till next Friday to see a version of the magic box. Here is one attempt by me
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Post by Adam Cotton on Dec 10, 2016 18:03:28 GMT
Here's my homemade lightbox: Attachment DeletedYes, it's a cardboard box with a hole in the middle It sits on a sheet of frosted glass, you can see the raised glass scale inside, below the plasticine that holds the specimen in place. The lights are LEDs as you can see in the next photo. Adam.
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Post by Adam Cotton on Dec 10, 2016 18:04:20 GMT
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Post by nomad on Dec 10, 2016 18:09:01 GMT
You will notice a few dirt spots around the specimen image, but I was not to bothered by this, as I wanted a good representation of the specimen with the data. They may be in some instances be amplified dust marks on the plastazote or in some cases minute dust spots on the image sensor. My camera was due for a good sensor clean and I was going to do this after the winter, but now its with a professional, I hate doing this myself.
The moth is the lovely Marbled Green, Nyctobrya muralis. This species is interesting because it shows great variation within its range. Here it is mainly a coastal species of southern England. Unfortunately, the colours in this moth fade badly after death, so this specimen is in quite good condition.
I believe the museum staff have tried various macro lens, but the best results were obtained by a good quality compact zoom, which can reach close to the light box opening with a good depth of field.
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Post by Adam Cotton on Dec 10, 2016 18:16:32 GMT
Here's a sample photo taken with my mobile phone rather than my proper camera, just so you can see the basic idea: Attachment DeletedAdam.
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Post by deliasfanatic on Dec 10, 2016 18:32:10 GMT
I believe the museum staff have tried various macro lens, but the best results were obtained by a good quality compact zoom, which can reach close to the light box opening with a good depth of field. I'd be very surprised if a zoom gave better results than a dedicated macro lens. The latter are highly corrected for close focus and flat field, whereas zooms (even though they may have close focus ability) are generally optimized for "normal" shooting distance and are less sharp at close range. Flat field correction means that focus of a lens is, well, flat...i.e. it will be in best focus on all parts of the flat sensor or film. Most lenses show some field curvature, meaning that their point of focus near the edges and corners will curve away from the intended plane of focus, being sharpest either behind or in front of the main plane. This can be tested by doing the classic "brick wall" photo test. Depth of field is irrelevant to use of a zoom vs macro lens. It depends only on magnification and lens aperture. Therefore, the subject will have exactly the same DOF from a 50mm lens as it does from a 100mm (or other focal length) lens, provided subject magnification and lens aperture are the same. (This doesn't apply in the same way to subjects with a distant background; I won't go into that here as it adds further complications.)
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