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Author Topic: digital camera as light meter  (Read 2959 times)

Dark Reality

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digital camera as light meter
« on: December 11, 2012, 01:12:29 PM »
Hopefully a simple question. Can I use my camera as a advanced light meter for a medium format film camera?  I could just get a light meter, but if I could see in advance exactly ( or very close ) what the image will look like, I would prefer that.
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digital camera as light meter
« on: December 11, 2012, 01:12:29 PM »

rj79in

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Re: digital camera as light meter
« Reply #1 on: December 11, 2012, 01:25:59 PM »
Good question as I've always wondered whether using a light meter would have any benefits as opposed to the camera. Never used a light meter though ... Just curious!

Dark Reality

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Re: digital camera as light meter
« Reply #2 on: December 11, 2012, 01:32:40 PM »
The main reason I would prefer a camera used just for metering, is I sometimes go against what my in-camera meter says, to get my desired result.

If this way works, it would literally be as easy as replacing camera A, with camera B. And saving a lot of film too. 

Also, what is the crop factor for say, a full frame vs mf.   (like 1.6x , is for crop and full frame)
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rj79in

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Re: digital camera as light meter
« Reply #3 on: December 11, 2012, 01:43:16 PM »
Never shot with a MF but I understand that a 80mm lens on a MF gives a FOV equivalent to 50mm on the FF hence a 1.6 factor again, only on the flip side.

Drizzt321

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Re: digital camera as light meter
« Reply #4 on: December 11, 2012, 01:50:55 PM »
Are you looking for an incident reading or reflected reading? Incident is you put the meter between the subject and the light source(s), reflected is you point the meter are your subject. So your normal camera with a light meter built in is generally going to be reading the reflected light, however it's also calibrated more specifically for that sensor/electronics. If you want an incident reading, you probably should get a dedicated light meter.
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Dark Reality

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Re: digital camera as light meter
« Reply #5 on: December 11, 2012, 02:17:06 PM »
Are you looking for an incident reading or reflected reading? Incident is you put the meter between the subject and the light source(s), reflected is you point the meter are your subject. So your normal camera with a light meter built in is generally going to be reading the reflected light, however it's also calibrated more specifically for that sensor/electronics. If you want an incident reading, you probably should get a dedicated light meter.

Neither, I WANT a digital MF camera.  But that's not going to happen. But if the image on my lcd of my digital camera can be reproduced with the MF film camera with the same settings, I see no need for a light meter, which can only tell you what IT thinks is correct. ( I understand some differences will be there, depth of field, FOV, etc..  )
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Drizzt321

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Re: digital camera as light meter
« Reply #6 on: December 11, 2012, 02:38:44 PM »
Are you looking for an incident reading or reflected reading? Incident is you put the meter between the subject and the light source(s), reflected is you point the meter are your subject. So your normal camera with a light meter built in is generally going to be reading the reflected light, however it's also calibrated more specifically for that sensor/electronics. If you want an incident reading, you probably should get a dedicated light meter.

Neither, I WANT a digital MF camera.  But that's not going to happen. But if the image on my lcd of my digital camera can be reproduced with the MF film camera with the same settings, I see no need for a light meter, which can only tell you what IT thinks is correct. ( I understand some differences will be there, depth of field, FOV, etc..  )

I think the biggest thing would be the ISO, since actual effective digital ISO levels actually vary a bit from the stated ISO levels often. So the shutter/aperture listed will likely be in the ballpark, but not necessarily exactly what your MF camera would need to be set to. If it's not too expensive, you can try doing a series of +/-Ev on your DSLR and compare against the actual exposure for that subject on your MF film. Plus you have the different metering modes. Spot, center-weighted average, partial, evaluative. So, you may need to experiment some to find the one you like best, or just simply use spot to get the most specific metering mode on a very specific part of the image.

So, my guess it'd take a bit of experimentation to get exactly what you want, but it certainly can be done. Just make sure you record everything until you figure out the exposure correction factory (e.g. if your DSLR shows f/5.6 @1/500 ISO 400, by experience you've found you need either 1/1000, or f/5.0 to get a correct exposure on your MF film with film of ISO 400).
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Re: digital camera as light meter
« Reply #6 on: December 11, 2012, 02:38:44 PM »

RLPhoto

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Re: digital camera as light meter
« Reply #7 on: December 11, 2012, 03:11:32 PM »
Yes, you can use a digital camera to meter your scene for Film. Just be sure to use equivalent F-stops from MF to 35mm to get the DOF you need. It works quite well.

PVS

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Re: digital camera as light meter
« Reply #8 on: December 12, 2012, 05:30:25 AM »
I use 5dc all the time for metering, when I shoot slide film I keep the EVs about the same and when I shoot C41 I usually add 0.5-1EV compared to 5dc shot. I mostly shoot with Bronica SQA cameras but also with M645 and RB67 gear.

AUGS

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Re: digital camera as light meter
« Reply #9 on: December 12, 2012, 06:22:16 AM »
The main reason I would prefer a camera used just for metering, is I sometimes go against what my in-camera meter says, to get my desired result.
If this way works, it would literally be as easy as replacing camera A, with camera B. And saving a lot of film too. 

Yes, you can use the digital camera as a light meter and I've heard people using it for just that purpose. In fact, a friend uses his 5D2 to meter for his medium format 617 film camera.  It may be a bit more trial and error at first adjusting for the appropriate film characteristics to get the exposure you are looking for.  He was using Velvia 50 & 100, which can be a bit more sensitive.  Also remember the reciprocity failure of film for long exposures, which the digital camera does not allow for.

Also, what is the crop factor for say, a full frame vs mf.   (like 1.6x , is for crop and full frame)
This depends on your camera.  Medium format cameras for film come in many form factors, eg 6x4.5, 6x7, etc.
I found this reference useful a while ago:  www.viewcamera.com/images/focalchart.gif
It gives the corresponding 35mm (or full frame) focal length equivalent for different medium and large format cameras, and you can determine the "crop" factor from that.

TexPhoto

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Re: digital camera as light meter
« Reply #10 on: December 12, 2012, 08:03:50 AM »
Yes, you can use your DSLR as a light meter, transferring settings from one camera to another.  I own a Widelux 1500 medium format panoramic camera, and do this all the time with great results.  My exposures on Fuji Velvia are dead on are dead on.  When i first started i thought there would be some adjustment factor, but I had no issues.

I did this because I did not want to carry a separate meter, or pay for it, and I was going to have a DSLR with me anyway.  Now that I think about this, I started with film doing this with a Nikon D90 about 15 years ago.  The Widelux does not get much action as of late, but I still like to use it from time to time.

Obviously flash exposures are not gong to work this way.

Dark Reality

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Re: digital camera as light meter
« Reply #11 on: December 12, 2012, 08:15:07 AM »
Thanks so much everyone. I'm so looking forward to trying this. 
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M.ST

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Re: digital camera as light meter
« Reply #12 on: December 12, 2012, 09:32:41 AM »
You can use a digital camera for metering, but if you want the best results (professional use) I recommend the Sekonic L-758DR instead.
« Last Edit: December 12, 2012, 09:34:34 AM by M.ST »

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Re: digital camera as light meter
« Reply #12 on: December 12, 2012, 09:32:41 AM »

bycostello

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Re: digital camera as light meter
« Reply #13 on: December 13, 2012, 12:07:03 AM »
i think you'd be better buying a light meter, they are quite cheap...

Drizzt321

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Re: digital camera as light meter
« Reply #14 on: December 13, 2012, 11:44:38 AM »
i think you'd be better buying a light meter, they are quite cheap...

I think the OP is also looking to use the DSLR as both lightmeter, and simulated captured image, kinda like how they used to use Polaroids to get the right shot before actual exposure.
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Re: digital camera as light meter
« Reply #14 on: December 13, 2012, 11:44:38 AM »