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 Post subject: Asking for feedback
PostPosted: Tue Oct 26, 2010 5:27 pm 
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Hi everyone,

I’m very new at this forum and even at gem photography AND unfortunatelly not used in writing in English, so please be lenient. :oops:

Hoping that this is the right topic for my question. I did some gem shots by using a photo cube and a daylight bulb (5400 K) and this is the result. Normally I try to light directly into the table, i.e. at the front face shot, the light source is behind the camera.

Is there anyone who can tell me, where the yellow sparkles at the red stone come from? Imo daylight bulbs provide only white light.

What can I do to improve the quality, (except the dust spots, that’s my inattention) concerning clarity and resplendence.

In the meantime I've read felt like nearly every thread or homepage concerning gem photography :?

Thanx a lot for any hint.
Anja
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Attachment:
R0012201-ganz klein.jpg
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 Post subject: Re: Asking for feedback
PostPosted: Tue Oct 26, 2010 6:56 pm 
Herzlich willkommen Anja!

You will find that everyone here is very kind - even me :)

There are several members in this forum who are expert in macrophotography (such as low magnification photography of jewels), so I expect that excellent advice will follow here shortly.

I admit that your first shot is rather puzzling. I think I can see dusky-pink reflections of what looks like typescript in several places and that is strange indeed. If you can see what I mean, what do these look like if you enlarge the image from your original .jpg file before you reduced its size to upload the image to this site?

The 'yellow' areas I think have to be reflections from pavilion (back) facets rather than the crown (top and facing) facets. This would give some colour change - but how this becomes yellow I can't guess.

In my small experience, it is always better to use flood lighting rather than flash for this sort of photography. It's far more controllable and you can examine and correct carefully the effects you are creating before you ever operate the shutter release. If you must use flash, a useful trick can be to hang a white bed-sheet behind you and to point the flash head at the bedsheet and not at your subject. If you do that and you are using a camera that automatically sets your exposure according to the light it receives from the subject, all is well. However, if you have to - or wish to - set your exposure manually, you should start by adding EV +2.0 to your calculated exposure. Using the 'bed-sheet technique, the exact exposure you require to set manually you must determine by trial and error.

I'm sure that others can help you more than I with this problem but I would be interested to hear (or see) what happens to the 'printing' in your first image if you magnify it to take a closer look.

Anyway, may I say welcome once again.

Owen


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 Post subject: Re: Asking for feedback
PostPosted: Wed Oct 27, 2010 5:00 pm 
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Anja,

the yellow in your images is due to dispersion.

And as an advice to clarity etc... now your shots are somewhat washed out. This is probably cause you are lighting the stone from the front without any diffusing which makes it too easy to overexpose the shot. Try lighting it from the top/back/sides while using a reflector like in this set-up...

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 Post subject: Re: Asking for feedback
PostPosted: Wed Oct 27, 2010 9:13 pm 
Here's another thought for you, Anja. Sometimes, it is not possible or convenient to correct an image in the camera. It's a legitimate alternative to adjust the image when it is stored as a digital file as well as at the point of file creation in the camera. This is no different to a skilled photographer improving an image captured on film with post-camera work in the dark-room. Almost all professionals have always done this.

Here's your image with brightness, contrast, colour hue and colour saturation adjusted a little and with the 'dust' (small chips in the table?) removed. In fact this is low quality work due in part to the low quality of the .jpg that was reduced in size to upload it to GO (that's my excuse anyway :D ). Working with your original image, it should be possible to do better. The work (which took about 5 minutes) was carried out using Photoshop software and working at x3.5 zoom - the maximum possible given the low quality of the image worked on.
Attachment:
R0012200-ganz%20klein(a).jpg
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P.S. The 'type-writing' referred to earlier is probably an artefact created at some point in the original file before storage at GO. It may be a distortion of marks left on the pavilion facets from the cutting. Check the stone with a loupe and strong edge lighting to see if you agree. Look along the length of the pavilion facets and not across them. Compare too with your original image view at x4 - x5 zoom.

I hope this helps.


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 Post subject: Re: Asking for feedback
PostPosted: Thu Oct 28, 2010 5:42 am 
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A bit too much in terms of contrast, to my taste at least.

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 Post subject: Re: Asking for feedback
PostPosted: Thu Oct 28, 2010 7:45 am 
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Hi Gianina

try first to perfect your action the manual way lighting etc. as described by Tim befor you beginn to alter the results digital; otherwise you will never learn it all.
As well with to much contrast usage in the software the stone beginns to look as if it has a lot of extinction. Which your stone actually doesn´t have :D
all the best

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 Post subject: Re: Asking for feedback
PostPosted: Thu Oct 28, 2010 7:57 am 
Conny Forsberg wrote:
A bit too much in terms of contrast, to my taste at least.


Yeah. Seemed to alter a little in the between reproduction here and at GO transmission and I couldn't be bothered to do it again. It serves to illustrate the point - but a work of art it surely is not.... I think it's the first time I've tried 'photoshopping' on such a low pixel count image; very depressing :cry:

Still, it makes it look a bit like an Almandine when it is more likely a Rhodolite.... What *is* the stone Anja?


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 Post subject: Re: Asking for feedback
PostPosted: Thu Oct 28, 2010 3:18 pm 
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My belief is that the first image is at least 1+ stops over-exposed (maybe 1.5 -2 stops), Second, although you are using the correct (or at least a good color temperature light), did you white balance the camera itself? If the camera has a manual white balance then use it with the same lighting and a white card before taking the photos.

Photo #2 is much closer, probably only about 1/2-2/3 stop over exposed.

Next, if you are measuring the exposure by using the whole scene, then expect to correct the image using EV settings (on the camera) as the exposure will be fooled by the large white background. If you are using spot metering, the image will likely still be wrong but not as much (and in the opposite direction), the stone is well below 18% gray which is what the meter will try to reproduce with the spot.

In the first image the over-exposure will wash out the color and likely shift it a bit to the yellow-orange end. Simply because the red will not saturate. (This assumes there is no major lighting shift from the light color itself.) I would guess that the yellowish cast in the high lights is real and from dispersion, but that it is a bit more to the yellow because of the under saturation. Because the image is undersaturated, there is no simply color correction that can be done in photoshop. The gem can be changed, but all parts will be color corrected to fix the yellowish color and thus change the true red of the stone. You need a better exposed image.

By the time I start to get the yellow out of the stone, the color has undergone a huge shift ...
Image
Not too pleasing.

Learn to read the camera histogram if it has one, use this to adjust your exposure. Get the exposure so the image histogram is as wide as possible and has reasonable mass. Don't let either end of the histogram bump into the side walls of the graph. (For a really simple explanation of the histogram try this:http://www.photoxels.com/tutorial_histogram.html Eventually I plan to write up a longer section on the histogram in my general photo write up. (Elsewhere this thread). but the time has not yet come. I do have a potential gemstone setup as the last few pages in the write up, and they are similar to what has been suggested above (use a reflector!)

With Photoshop I tried to fix up the image some, but there is too little original saturation to do much without a fairly large color shift.
Image

Summary of what I would try ...
Color Balance camera first with the light(s)
Re-expose - learn to read the histogram
Use a reflector into the front surface of the stone

hope this helps ...

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 Post subject: Re: Asking for feedback
PostPosted: Tue Nov 02, 2010 3:00 pm 
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At first thank you all for your advices and your engagement! :D

There are some things I already implement, e.g. manual white balancing the camera. But I'm not sure, if the result is proper all the time. It's just a simple compact camera.
I also tried Garys setup before, but my shots weren't as pleasing as I expected (somewhat boring and whithout "glamour"). I turned to the photo cube again because of more flexibility in lighting. Maybe I'll try it again.
And I didn't and don't correct the shots by PS or anything. At least in the beginning. But I have to admit that it looks much better w/o dust chips. :D

You discussed some possible reasons of yellow spots. Could you imagine, that it happened because of energy saving light bulb which alleged has an greenish colour that combined with red results in yellow spots. I'm not sure if this is possible. In this case shouldn't be the whole gem some kind of yellow?

@Kerensky: I didn't find out the typewriting. Can't see it. So sorry. I think, the gem is a Rhodolite, got it from a friend and I know he owns a lot of Rhodolites - but I'll ask...

Now I'm going to experimentalise with exposure and reflectors...
Anja


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 Post subject: Re: Asking for feedback
PostPosted: Tue Nov 02, 2010 4:01 pm 
Gianina wrote:
At first thank you all for your advices and your engagement! :D

There are some things I already implement, e.g. manual white balancing the camera. But I'm not sure, if the result is proper all the time. It's just a simple compact camera.
I also tried Garys setup before, but my shots weren't as pleasing as I expected (somewhat boring and whithout "glamour"). I turned to the photo cube again because of more flexibility in lighting. Maybe I'll try it again.
And I didn't and don't correct the shots by PS or anything. At least in the beginning. But I have to admit that it looks much better w/o dust chips. :D

The less the controls offered by your camera, the more correction or 're-touching' in software may help. Also, the lessons you learn working in software will make your camera-work better. Working with good software, you can see the effect of the changes you make and experiment freely (provided you save safely a copy of the original file your camera delivered). Experimention costs nothing but your time and there is nothing to risk. Learning takes time....and practice.
Quote:
@Kerensky: I didn't find out the typewriting. Can't see it.

OK.... but you can see what I mean in the picture - at least as reproduced on GO? If you can, try looking through the crown with some light behing the pavilion and see if the effect appears then. If it doesn't don't worry. Unless you can re-create fairly exactly the original lighting and angles that you used for illumination when you made the original, the effect may not re-occur.
Quote:
I think, the gem is a Rhodolite, got it from a friend and I know he owns a lot of Rhodolites - but I'll ask...

I thought it might be.... Well, here's another interpretation from me that is just a*little* more like Rhodolite. However, if I try and squeeze more in colour correction (without spending serious time on it) the image deteriorates in otherways :cry: Anyway, its my best shot for you, though I shan't be in the least surprised if you prefer Ron's :D
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R0012200-ganz%20klein(b).jpg
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Quote:
Now I'm going to experimentalise with exposure and reflectors...
Anja

Excellent! Hals und bein bruch!


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