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 Post subject: Grainy pictures
PostPosted: Tue Nov 26, 2013 1:31 pm 
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I have a problem that I cannot figure out. Basically, my pictures are not clear or in focus to the level of detail that I've seen on this forum.

Here is my equipment. Nikon D5200 with AF-S Nikkor 35mm 1:1.8G DX lens. I use a light box I made from white materials and one lamp positioned over the top (and have tried sliding back to dim the light); I have the reflective white board positioned over the lens (the single best trick I've learned to date). All ambient lights off. I use a tripod, timer and leave the camera in the auto-focus mode. I've moved the camera back from two feet up to really close. I use Aperture priority, different f stops, I've used the "close up" mode, manual mode, changing the ISO, Shutter speed, etc. I use the camera with the JPeg Fine (15 MB). I have not used RAW.

The pictures come out grainy like the camera was moving. Any suggestions?


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 Post subject: Re: Grainy pictures
PostPosted: Tue Nov 26, 2013 3:31 pm 
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Ok, I'm still playing around. I changed to 18-55 lens and zoomed in to about 45. Got as close to the ring as it would focus and backed off just a hair. Turned on all overhead florescent lights and the light on the lightbox. Did not use the reflector because my lightbox diffusers may be blocking out too much light, hence the darker picture the first time. This is what I got:


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 Post subject: Re: Grainy pictures
PostPosted: Tue Nov 26, 2013 3:32 pm 
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I'm no expert on gem photography but in my opinion there are a few measures that always needs to be taken.
1. Use lowest possible ISO
2. Make sure light is adequate
3. Use tripod and
4. preferably wireless shutter control
5. A proper macro lens would also be beneficial
6. Proper white balance

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 Post subject: Re: Grainy pictures
PostPosted: Tue Nov 26, 2013 5:00 pm 
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The photos look pretty dark. As Conny said in 2), you might want to get some more light in there. Most digital cameras have a bad time in lower light conditions.

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 Post subject: Re: Grainy pictures
PostPosted: Tue Nov 26, 2013 5:11 pm 
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Does this image look more like reality? If so it's probably your white balance setting. There are some exposure and focus problems too.


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 Post subject: Re: Grainy pictures
PostPosted: Tue Nov 26, 2013 5:41 pm 
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Thank you all so far for your comments. Lighting is a problem. I took another stone with a different background. Lowered the ISO and installed the wireless app on my phone to take the picture. This one is looking better. I didn't cut this stone, but it's a 1.55 ct Lilac Amethyst.


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 Post subject: Re: Grainy pictures
PostPosted: Wed Nov 27, 2013 1:31 am 
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Hi Steve - try getting an 18% grey card and use that to set your exposure. When shooting in automatic mode, you can hold the shutter button half-way down and the camera will set the exposure. Hit the Exposure Lock button and then release the shutter button. Move the grey card out, put your stone in and take your shot.

You may have to change your camera settings so the exposure lock is long enough for you to switch out the card, place your piece and take the shot.

As the others have said above - LOTS of light. If you're using a light tent, you're going to need at least 2 light sources with 23W CF or 100W incandescent bulbs in order to provide enough light inside so the camera can get a decent exposure.

I use a light box and 2 or 3 23W CF bulbs in lamp heads touching the light box (Ikea student lamps). I have a D7000 with either my kit 18-108mm lens, or 105mm macro mounted on a tripod. I trigger the shots with a remote to prevent camera shake, or use ControlMyNikon to take the shot using my PC. I manually set the aperture to no smaller than f/11.

Good luck!

-Allan

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 Post subject: Re: Grainy pictures
PostPosted: Wed Nov 27, 2013 8:19 am 
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Allan,

Thank you for your suggestions. I will do what you suggest. I had a lot of light initially, but the picture was coming out yellow. I've changed bulbs and think this is corrected. I'll need to add more though. Also, I assumed my prime macro lens was the ticket for taking good close ups, hence the grainy problem when I cropped it close. A zoom lens has shown me that this is what I need to use.

Where can I get an 18 percent grey card? B&H or similar? I'll look around.

Steve


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 Post subject: Re: Grainy pictures
PostPosted: Wed Nov 27, 2013 12:20 pm 
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Steve - you can get a grey card ad most photo shops. They're not expensive, and they will also get rid of the colour-cast you're talking about from the lights. It basically allows the camera to properly set the white point of the photo.

When you're shooting, all that bright white background confuses the camera which is expecting a scene to have an average colour value of 18% grey (hence the 18% cards). If you set your colour balance using the grey card or a white paper in the light tent your camera will compensate for any colours in the light and give you a more accurate rendition of colour.

Hope this helps

-Allan

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 Post subject: Re: Grainy pictures
PostPosted: Wed Nov 27, 2013 12:45 pm 
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That's good information. Thanks for your help.

I have a great camera and do well with landscapes, HDR, etc., but this close up stuff is new to me.

Steve


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 Post subject: Re: Grainy pictures
PostPosted: Mon Nov 07, 2016 10:22 pm 
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SteveH wrote:
Thank you all so far for your comments. Lighting is a problem. I took another stone with a different background. Lowered the ISO and installed the wireless app on my phone to take the picture. This one is looking better. I didn't cut this stone, but it's a 1.55 ct Lilac Amethyst.

It looks like you might still have a focus issue. If you look you can see the texture in the material the stone is sitting on is sharp and in focus from the middle of the stone and back towards the cullet but out of focus near the front of the stone. If your camera has a setting to choose center spot focus try using that and focus on the front of the stone.


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 Post subject: Re: Grainy pictures
PostPosted: Mon Nov 14, 2016 2:40 pm 
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Personally I would recommend turning off all the auto functions and adjusting everything manually. The problem with using auto settings is that one does not know what the camera is thinking, or even whether those thoughts are appropriate for close up gem photos (as opposed to photos of the beach).


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 Post subject: Re: Grainy pictures
PostPosted: Mon Nov 14, 2016 10:02 pm 
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I recently picked up a used telephoto lense at the local thrift store and reverse mounted it. Total investment for the reverse mount ring and lense $15.00.

It is a decent setup, but like most macro work, the depth of field (the portion of the picture that is in focus) is very small.


I am looking into some of the free stacking software, that allows you to take several pictures at different focuses and it merges them together. There is a lot of this used in the thread on inclusions.

I think that this approach will give good results. It is a little more work, but should help.


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 Post subject: Re: Grainy pictures
PostPosted: Sat Nov 19, 2016 9:51 am 
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Try shooting in the M (Manual mode), and use a small aperture, something like f18 or f22 to give you better depth of field. Focus at the girdle of the stone and with the small aperture you should be able to get the entire stone in focus. Use ISO 200, shoot in RAW and you can always color correct afterward in your software.

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