Advice regarding exposure

fabulousrice

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I shot an event this weekend and for two of the automatic (autofocus, auto exposure/speed and Flash) cameras that I used, I thought it would be a good idea to tape a small piece of white paper towel over the flash to diffuse it.
My reasoning was that there were lots of pictures of people - and I didn't want the flash to make people's foreheads look shiny, or faces be overexposed, big shadows behind people, etc.

I have tried that trick in the past and it worked well - but it was a long time ago, and after coming back from the event I started second-guessing myself whether or not I might have underexposed the photos by doing that.

I mostly took photos of people standing indoors on a bright although overcast day, near large bay windows.
The Fuji GA645 was loaded with Kodak Gold 200 (shot two rolls), and the Pentax ZX-60 was loaded with ProImage 100 (2 rolls as well). Everything shot at box speed and the flash fired for all the shots.
(I also have shots from a Minolta and a Bronica for which no flash was used, hand metered).

Since this is a project for which I want to limit risks of delivering bad pictures, I was gonna have the photos scanned and processed by the lab. It's also faster.
To be on the safe side, should I tell the lab that I shot these at iso 100 (for the Gold) and iso 50 (for the ProImage) so that they push it and make the photos brighter?
Or would that be more of a risk versus getting them processed normally?

I could reproduce the conditions and load a new roll in the cameras and shoot with the paper towel over the flash and process them to make up my mind before I do anything to the clients' pictures - but if someone has recent experience of a similar situation, I would be grateful to hear it.
 

koraks

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There's no way to make up for underexposure. Push processing will increase gamma, but if you scan the negatives, it won't make much of a difference. Light that wasn't captured is never going to appear in the photograph.

The degree to which you've underexposed depends on whether the flash and/or camera did any auto-exposure (TTL etc.). If so, they should have compensated for the additional filtration of the flash light. If not, and you relied on the guide number, you will have underexposed these (at least the flash component) significantly as a piece of paper towel will easily eat up 2 stops or so.

Personally, I'd just drop off these rolls and have them developed normally. If the scans aren't to your liking, inspect the negatives and see if the image information you need is actually there. If so, invest (time, effort, money) in getting new/better scans made.

Scanners are generally good at extracting shadow detail from underexposed negatives. You've got that going for you.

Good luck; I hope it all pans out and the results are still acceptable!
 

Don_ih

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fabulousrice said:
To be on the safe side, should I tell the lab that I shot these at iso 100 (for the Gold) and iso 50 (for the ProImage) so that they push it and make the photos brighter?
Click to expand...

Definitely don't tell them that, since that would require pull processing if anything (but I'm sure the lab would just process normally if you say you overexposed one stop).

I think how much light the paper towel ate depends on the size of the flash. A tiny flash in a point and shoot would be drastically reduced by it. A large flash in a hot shoe might be impacted less.

You could ask for bleach bypass, which could add to the contrast if you're worried about underexposure.
 

grain elevator

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Tissue paper taped right in front if the on-board flash? I can't imagine this will help much except darken the flash. It's still pretty much a point light source. Effective diffusion would need to increase the area the light is emitted from. I'd suggest you work with an external flash or two, or, as you're working with window light, a reflector. OTOH if it's worked for you in the past, maybe the attenuation is what you need.
 

Chan Tran

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As long as your flash has enough power the automatic would compensate for the tissue. However, if the flash doesn't have enough power it would underexpose your shot. Most auto flash would have a confirmation ight to confirm that it has received sufficient light coming back from the subject. I tend to agree with Grain Elevator that tissue paper over the flash wouldn't do much to soften the light nor reducing the brightness different with near and far subjects.
 

Hassasin

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I'm perplexed by the stated formula to start. There are proven ways to use flash and not have a harsh results.

And I don't believe there is anything post shooting here that can be advised.
 

Chan Tran

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Correct me if I am wrong. You used the same flash with several different cameras for the event correct? If so you could put the flash on a digital camera to test and see.
 
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Hassasin

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I suggest round / domed flash head like Godox V1 or similarly configured / not as evenly lit / at multiple the cost - Profoto A1x.

Standard flash units have accessories like bounce or soft boxes to be applied over the head, all meant to work as intended. The difference is that all these things were designed and factory tested to work with predictable results.
 

Sirius Glass

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I either use bounce flash or a plastic diffuser that came with my flash. Either of those will cut the unwanted harshness from the closest people without impacting the exposure as I use the flash's sensor for exposure control.
 

MattKing

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Sirius Glass said:
I either use bounce flash or a plastic diffuser that came with my flash. Either of those will cut the unwanted harshness from the closest people without impacting the exposure as I use the flash's sensor for exposure control.
Click to expand...

Assuming:
1) that exposure control isn't based entirely on subject to camera distance; and
2) that your flash has enough power to make up for the effects of using bounce or a diffuser.
 

Hassasin

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There are also a number of items available at Victoria's Secret that would nicely diffuse light, but may otherwise cause unwanted reactions.
 

wiltw

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Color neg has wide enough exposure latitude that 'normally' processed rolls will provide excellent quality prints, and scans...both will be normalized to the same level of brightness in the conversion of negative to positive image. There is virtually no need for push-pull processing of the film when +- 'deviation' is within one EV of the rated film speed.
Color neg has long been characterized as having about 5 stops of latitude, from -2EV to +3EV, but underexposure tends to result in what is termed 'muddy color' in the shadow areas of a scene, so my personal preference is to lean to the 'over'exposure side by +1EV so that shots that are accidentally 'under' do not end up with muddy colors as much. This applies to shots with flash, too, since areas of low ambient light do not end up looking muddy to much.

As @grain_elevator sated, "Effective diffusion would need to increase the area the light is emitted from." Overall SIZE is what matters, not the fact that 10 or 20 sq.in. of tissue 'diffusion' was used.
Proof that SIZE MATTERS...
Shot with 5" x 7" softbox at distance of 20'


Shot with 16" x 20" softbox at distance of 20'


...note the degree to which shadowing is apparent, and the 'softness' of the shadow edges in the two shots.
(comment: the difference in warmth of photos is due to the yellowing of the 30 year old 16x20 softbox material, which I made no attempt to neutralize in postprocessing)

For 'shadow fill' uses, this composite compares 'no fill' vs. 'fill with normal flashhead' vs. 'fill with 5" x 7" softbox on-camera flashead" with a flash unit positioned to the right of lens axis

note little effect on the shadow edge due to the flash (indicated by red arrow)...although the softbox presence did reduce the amount of fill-in of shadows of the sun falling on the pole.
 
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fabulousrice

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Chan Tran said:
Correct me if I am wrong. You used the same flash with several different cameras for the event correct? If so you could put the flash on a digital camera to test and see.
Click to expand...

No, the Pentax ZX-60 and FujiGA645 have a pop-up flash integrated to the camera body
 
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fabulousrice

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I'd have a very hard time knowing how to properly use these with an all automatic camera without manual settings for aperture such as the fuji ga 645
 

pentaxuser

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From these quotes and questions it appears the OP, having set out his circumstances to us, is asking only one question of us, namely the question in the first quote in bold. He goes on to ask in the second para in bold if anyone who has recently has a similar experience would share their experience

Surely all he wants is pertinent answers to that question and subsequent request. Anything else may be irrelevant to his current situation

He may want to extend the discussion of course but isn't that better left to his initiative? I really wonder how much help any other answers are to him right now

pentaxuser
 

Hassasin

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Sure, any question is a fair question, even if public perception on the matter continues to evolve. But "paper towel over flash head" brings up several things to mind, but hardly any direct experience.
 

Chan Tran

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To use such a flash you have to use it in manual with film cameras. Wouldn't be an easy thing covering an event.
 
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