30D & Grip & Copy Stand & x-rays

[pigtailpat]

I need to digitilize dental x-rays. I have done copy stand work in the past, but not with a 30D and grip.

I have 2 lenses, the 24-105 L f/4 and the 70-200 L F/2.8 (the tank will probably not fit on the copy stand but I shall try). This is a limited project, and otherwise will not do any copy work with the 30D and have no interest in investing in a prime or macro at this point. I'm done with purchases for this year. (hey but after the holidays is another story........)

On the base of the copy stand will be a lightbox (viewbox) that is illuminated and on topy of that will be the x-rays. The copy stand I have does have lights on the side - which will not be used - because for x-rays it needs to be illuminated from behind. This is like a poor man's version of the Kaiser stand that you can see at http://www.bhphotovideo.com/product/168161/KACSCE/REG/711

the viewbox is a very slim 3/4" thick profile and it is 5000 degrees kelvin so it'll be a white, white light.

My questions:

(1) should the shot be taken in surrounding darkness with only the viewbox and the x-rays illuminated??

(2) Assuming the 70-200 can fit - which is doubtful - if I need to shoot in surrounding darkness with no flash - would it be better to have a 2.8 lens do it rather than the f/4 24-105?

(3) should the shot be done in complete manual mode to fully open the aperture and set the ISO and shutter? For the conditions I'm describing - what would be an appropriate shutter speed and ISO (bump up high because of surrounding darkness?)

(4) dental x-rays have certain highlights and shadow detail that need to be preserved - unfortunately a dental x-ray scanner is not within financial reach - this is why this process is being done - any other suggestions to preserve the highlight and shadow detail found in x-rays would be welcome -

(5) should I take the grip off before mounting to a copy stand, or is it OK with the grip on (if I need to use the 24-105 - I probably have to remove the grip for the tank on the 70-200 - no way I think I will fit all that)

I'm supposed to get the viewbox next week - so I would be starting then. This is not going to be a mass project - only a few here and there.

Thanks!

[xray]

I take digital shots of hard copy xrays/CT/MRI/US nearly every day. I hang the film on a light box and kill all the other light in the room. I use my kit lens and shoot hand held. I typically have the camera at ISO 400, shutter speed 200 and lens wide open. This seems to work well. I shoot in RAW and then can crop in DPP. The xrays turn out pretty well. Sometimes I have to adjust a little for better bone detail depending on the original films exposure.

You could put your camera on a tripod and use a cable release if you needed even sharper pics. Make sure you mask the extraneous light from the light box out. No flash (all you'd see is reflection off the film). I've never tried capturing a dental film, but this technique works for all other radiographic images (including bone films and chest xrays which have quite a few lines/inch).

Good luck!

[StewartR]

@ xray: Wouldn't it be better to use the 'sweet spot' of your lens, i.e. stopped down about 1-2 stops from wide open? I'd have thought that would be preferable, in order to get a sharp an image as possible. (But I've never photographed X-rays, so take this with a suitable pinch of salt...)

@ pigtailpat: This might be a stupid question, but if you're concerned about preserving detail in the shadows and highlights, is there anything that says you have to achieve that in the same photo? Given that you're using digital and it costs nothing, is there any reason why you can't bracket your exposures all over the place and then pick the one(s) that give you what you need?

[pigtailpat]

@ pigtailpat: This might be a stupid question, but if you're concerned about preserving detail in the shadows and highlights, is there anything that says you have to achieve that in the same photo? Given that you're using digital and it costs nothing, is there any reason why you can't bracket your exposures all over the place and then pick the one(s) that give you what you need?[/quote]

Yes I could bracket and try different exposures - I just never tried copy stand work with a 30 D before - - with your other question - regarding why at wide - because using only the light illuminated from the view box (x-ray above answered my thought to kill all the other light in the room - I was thinking along those lines) - you need the widest aperture available for the lens to let in the most amount of light in that environment - I know this makes for a shallow depth of field - but on a copy stand, I'm going to be pretty close anyway (very close if I can fit the 70-200 on the stand) and hopefully this can still work.

[StewartR]

regarding why at wide - because using only the light illuminated from the view box (x-ray above answered my thought to kill all the other light in the room - I was thinking along those lines) - you need the widest aperture available for the lens to let in the most amount of light in that environment - I know this makes for a shallow depth of field - but on a copy stand, I'm going to be pretty close anyway (very close if I can fit the 70-200 on the stand) and hopefully this can still work.I think you might be getting confused about a couple of things.

Depth of field is irrelevant because your subject is completely flat. It sounds like the focus distance could be an issue if you don't have much space to work in, but the minimum focussing distance for the lens is not affected by the aperture.

And since the camera is on a stand, you don't need a fast shutter speed either.

[PhotosGuy]

And since the camera is on a stand, you don't need a fast shutter speed either. Mirror slap? I think the stand doesn't have a strobe, & I wouldn't want to copy slides without one. My solution to your problem: Do you Cobble? (http://photography-on-the.net/forum/showthread.php?t=58609) (3) should the shot be done in complete manual mode I do. (4) dental x-rays have certain highlights and shadow detail that need to be preserved Raw, & maybe blend the high/low conversions together. "Contrast Control" Tutorial (http://photography-on-the.net/forum/showthread.php?t=39702)

[pigtailpat]

>> Raw, & maybe blend the high/low conversions together.<<

I was hoping to avoid shooting in RAW right now, but if I have to, I'll try it for the x-ray project.

Regarding shutter - I was figuring on a slower shutter speed in any event - but didn't know exactly what values to try.

Thanks.

[xray]

StewartR is correct. The DOF is not a factor because your photographing a 2D subject. As to why I don't stop down, mostly because I'm taking pictures as cases roll across my alternator. Basically, I have a certain number of cases I need to read in a short amount of time. I can't stop and set up a tripod due mainly to time factors. The wide open kit lens allows me to shoot at a reasonable ISO (800 and 1600 are too grainy for a good radiographic reproduction) and a fairly fast shutter speed. If I stop down and then have to change my shutter speed I tend to get motion blur.

That all being said, I should probably stop down a little and take the time to set up a tripod. For me, most of my images are CTs/MRIs/US which are very low res (256-512 matrix) compared to plain film. If all I was shooting was plain film (such as a small dental xray) and I was really concerned with detail I'd agree that wide open is probably not the best choice.

If you're having to digitize a lot of these and it is a work related/required thing, they do make scanners which can scan xray film. They're pretty expensive, but a local hospital/medical school may have one they're willing to let you use if it is for educational purposes. I've used them in the past and they great. The last option is to use a scanner with a backlit panel. I used to have an HP which could scan 35mm slides, you might be able to fit the small dental xrays into something like that. You can also build a pyramid out of foam core and place it over the film on a regular flat bed scanner and that will work as a backlight also. I've done this with 35mm slides of photographs of xrays to some success (which after that many reproductions is somewhat limited).

[xray]

One other thing about RAW vs. JPEG. I shoot entirely in RAW, but that's just how I leave my camera set up. When I photograph radiographs I usually just batch process them right into JPEGs without any alteration.

I've got to go into work on Thursday. I'll try and take a few representative shots of an xray with different set ups and post the results so you can judge for yourself what would be best.

[pigtailpat]

If all I was shooting was plain film (such as a small dental xray) and I was really concerned with detail I'd agree that wide open is probably not the best choice.

Yes, the detail in small dental x-rays is very important. I was under the impression that if I'm shooting in overall no light - the only illumination would be from the viewbox - wouldn't I have to a wider aperture to let in the most amount of light into the lens?? I know you sacrifice some sharpness, but the other way, closing down the aperture to let in less light - wouldn't I run the risk of being underexposed and a dark shot? How do I figure on the happy medium?? I guess this is the point where I am the most confused, and basically because of what I am shooting (x-rays).

If you're having to digitize a lot of these and it is a work related/required thing, they do make scanners which can scan xray film. They're pretty expensive, but a local hospital/medical school may have one they're willing to let you use if it is for educational purposes. I've used them in the past and they great. The last option is to use a scanner with a backlit panel. I used to have an HP which could scan 35mm slides, you might be able to fit the small dental xrays into something like that. You can also build a pyramid out of foam core and place it over the film on a regular flat bed scanner and that will work as a backlight also. I've done this with 35mm slides of photographs of xrays to some success (which after that many reproductions is somewhat limited).

I won't have to do alot, this is not a mass thing, but it pops up every now and then. An xray scanner - for the volume we do - is just too expensive and not a reality.

Thanks for any further tips.