Photo lighting

[dougsmit]

The lighting is more even with the DSLR which is a big improvement.  A bit of reflected light from the bottom sometimes helps with high relief coins but it is easy to overdo.  That is what I accomplish with my small paper ring around the coin. 


Canon cameras come packed with free software called Digital Photo Professional that allows use of RAW mode and a lot of controls for image processing but NOT cropping and combining images so you still need something else.  While this is only somewhat useful for coins it makes a lot of difference on some images where you have less control over the lighting circumstances like nature and kids.  I recommend learning it. Other manufacturers sell similar software but that is an extra $100 while Canon is free.  It was on a disk packed with the camera.

[peterpil19]

Hi Doug,

I have updated my post to show the reverse of the coin tool as taken with the DSLR. I am pleased with the initial results.

1. I have tried the paper ring technique with my compact camera in the past but I could never get it to work. I would end up with strange looking results. I will try it again with the DSLR and post the results here.

2. Is there much of an advantage to shooting in RAW vs. JPEG? I have never used the RAW format. Do you find the differences noticeable enough that they are worth the effort of additional post processing? I did some reading and was surprised to learn that with JPEG the camera does quite a bit of processing (including sharpening) so am now curious to understand what the difference would be if I shot in RAW. I have no knowledge yet about how to process RAW photos.  Do you happen to have any examples you could share?

Peter

[dougsmit]

All of my photos from recent years have been RAW.  For coins, it makes less difference if you are careful to get everything just right before you shoot.  I still do coins RAW since I am comfortable with the concept. 

The big advantage of RAW is that you do not make decisions about an image that are not reversible like you do with JPG.  When you shoot JPG, the camera takes the RAW image and processes it sight unseen based on settings you made before the shot was made.  The RAW image is then deleted with no chance of review.  When you shoot RAW, you make those same decisions and save the result as a JPG image but not until you have viewed what the result will be in terms of color balance, tonal range and to a limited degree exposure.  The really big difference is you can opt to retain more than 8 bits of each color so making a low contrast image more snappy will not leave gaps in the tonal curve that would result if you added contrast postprocessing an 8 bit by definition JPG.  If no changes are made, there will be no difference but it leaves open a chance to correct things without gaps in the tones of the image.

I suppose this is like asking a tone deaf person like me to appreciate the difference between a Stradivarius and a Wal-Mart violin???

[peterpil19]

Hi Doug,

Thank you for pointing out that Canon software!

Not only does it allow processing in RAW, it allows me to remotely and wirelessly control my camera via my computer and see my photos (in full resolution) immediately after each shoot!

Wow!

I never realised how laborious the process I took for granted of transferring the SD card back and forth between camera and computer was by comparison!

I sent you a PM but on reflection I think my questions may be of interest to others and is still within the subject / theme of this thread.

1. The Canon software has preset processing (e.g. sharpening) which it applies to each RAW image and which can be undone and modified. Do you start off with that preset processing and then make adjustments, or do you turn that preset processing off and start from the raw RAW image?

2. On the subject of lighting, is there any difference for a given aperture in having more lighting and faster shutter speed, vs. less lighting and slower shutter speed? My reading on this says that exposure is theoretically the same (I am using aperture priority mode) but that a faster shutter speed is preferable for sharper images. I am using a copy stand and would like to know because I can get more time from my battery operated light if I use less brightness. Also I would like to know in case there are any noticeable differences in image quality. I have not noticed any.

Thanks,

Peter

[dougsmit]

1. Sharpening is best applied last after cropping and all other postprocessing so I don't use it in the RAW conversion step but only at the end.

2.  Smaller apertures (larger f/ numbers like f/16) give more depth of field than wider ones (like f/8) which can be good shooting high relief coins BUT they increase an aberration called diffraction so there is a place in the middle that gives best results.  This differs according to sensor size and amount you will be enlarging the image.  With my full frame DSLR, I shoot at f/9 or f/11 but suspect your crop camera might be better at f/8 or f/9.  Many point and shoot cameras are diffraction limited at full aperture because of their tiny sensors.  The differences here are gradual and may not show up much unless you make huge prints.  There is always the fact that most of our coins add their own unsharpness so we might not see differences on coins lacking fine detail.  All this assumes your tripod/copy stand is rock solid and you are using a remote release or self timer to take the shot.  Vibrations are worse than diffraction.  At some point you may be tempted to have a 20x30" print made of a super sharp coin just to prove you can but for selling coins online, all this is moot.

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm
The above will tell more than most people want to know.  It has a utility where you input the variables and it calculates whether you are diffraction limited for a specific camera and aperture.  Your camera is a 1.6x crop model and should match other Canons of that group.   

I will be in and out a lot this week and next so may be very slow at replying to questions.

[peterpil19]

Hi Doug,

Thanks again for the information - you are a wealth of knowledge. The article was particularly useful and did a great job in explaining diffraction as I never really understood what was causing it. I would encourage others to read it too.

When initially testing aperture, I found f/11 to be optimum but achieved a better depth of field at f/13 for the particularly convex / concave Philip II coins I am photographing (around 30 more to go!) without noticeable  effects of diffraction (though I am sure it would be noticeable to your experienced eyes!).

My question on lighting was assuming a constant aperture (e.g. f/11), is there any difference between having the same theoretical exposure with a faster shutter speed and more brightness from the light source vs. less brightness from the light source and a slower shutter speed. Reading I have done suggests go for an increase in brightness and get a faster shutter speed to reduce effects of vibration etc. but I was wondering if you had noticed any difference on quality in doing so.

Peter