Just because I'm curious I did a test with two T32s firing
simultaneously into opposite sides of my office and aimed approximately
at the intersections of ceiling and walls. The room is about 10x13 feet
(approx 3x4 meters) with a white ceiling and light beige walls. Some
light can escape through a large window on one end but the window is
covered by a sheer, white curtain which probably reflects half of the
light. No photos taken but after bouncing off the ceiling and walls I'm
sure the light level must have been pretty even throughout the room.
I tried both flashes set at 1/4 power (1/2 guide number) and full power.
At ISO 100 I got exposures of f/5 for 1/4 power and f/10 for 1/2 power.
Your exact exposures will clearly be different because your room and
diffusers will be different but I was surprised. As you can tell from
my previous posts I was expecting that two flashes in a small area might
produce so much light that the major difficulty would be in controlling
the power of the flash somehow. Now I don't think that will be a
problem at all. If fact, you are likely to need to use the flashes at
full power. But controlling the exposure should be a simple matter of
using the aperture and or perhaps twisting the ISO dial a bit but
probably not over 200.
This is good news and means you're very unlikely to have to resort to
filters or ingenious tricks. Good luck
Chuck Norcutt
On 9/29/2010 3:08 PM, Chuck Norcutt wrote:
> Sorry. Link on point 3) should have been attached to point 2)
>
> Chuck Norcutt
>
>
> On 9/29/2010 11:49 AM, Chuck Norcutt wrote:
>> As it turned out I didn't have to leave yet so I'll continue
>>
>> I'm in agreement with the lightweight wooden frames for your diffusers.
>> They could be shoot-through or might simply be propped against the
>> wall to serve as large reflectors. If shoot-through, an additional
>> layer(s) of cloth or paper can be used to cut the flash intensity if needed.
>>
>> Whether you use only the two T32s or also include the T20 you will not
>> necessarily need the multi-flash connector. T32s have two ports which
>> can be used for daisy-chaining from one flash to the other. But your
>> first problem is connecting from the E-500 (which has no OM TTL
>> connector) to the first T32 in the chain. Options are to:
>> 1) place the first T32 in the hotshoe of the E-510,
>> 2) place the first T32 into a standard hot shoe adapter
>> (just like a T20 TTL autoconnector except that it takes a
>> standard PC cord rather than OM TTL cord).
>> 3) use a TTL auto shoe cord in the hotshoe if you have one. But the
>> coiled, 0.6 meter cord may not be long enough to get to your
>> light stand so you may need the 3 way connector to allow attaching
>> an extension TTL cord. Seen here at far left (also has test button)
>> <http://www.chucknorcutt.com/gear/Homemade%20bracket%20&%20various%20hotshoe%20adapters.jpg>
>>
>> The camera should only be set to manual exposure. Set the ISO to the
>> lowest level (you'll have more than enough light), set the shutter speed
>> to 1/180 (the maximum flash sync speed for the E-500) and adjust the
>> flash exposure with the aperture. If still too much light at the
>> smallest desirable aperture then move the flashes back or add more
>> diffusion/filter material to cut the light. Another option to cut the
>> light (but it will take more experimentation) is to put the T32s into
>> normal auto mode (not TTL) and adjust their output by using the ISO
>> slider on the flash head. But for this to work well you must always
>> maintain the same flash/diffuser setup distances so that the auto mode
>> sensor on the flash always sees the same target at the same distance,
>> presumably the reflector or shoot-through material. Note that the auto
>> mode sensor has about a 20 degree angle of view. Make notes on setup
>> and distances once you've got the exposure correct. Then you'll have a
>> production environment where exposure and color balance are fixed and
>> changing subjects requires nothing other than focusing and pressing the
>> shutter button.
>>
>> Both exposure and white balance setting will only be done once. For
>> exposure *testing* I would use a bright white (same as the shooting
>> setup) background but with no subject in place. The exposure is correct
>> when the white background is near maximum brightness without actually
>> being blown out. Forget the exposure meter, use the histogram on the
>> camera and/or whatever image processing software you have. This
>> exposure testing setup can also serve as the white balance setting
>> environment. One you have the white background exposure under control
>> such that there's no blowout you can use that same exposure for white
>> balance setting using the "setting the one touch white balance"
>> instructions on page 90 of the E-500 manual. But, beyond the exposure
>> and white balance setting, I don't think there's a need to use a bright
>> white background (for even reflection) with all the diffusion and other
>> room reflections you're likely to have. Use whatever color you like
>> best. A medium gray might produce a nicer contrast. Who knows, maybe
>> even red velvet would look nice (although velvet tends to produce
>> reflected hot spots). :-)
>>
>> One other thing I happened to think about is your shooting setup and
>> need for a tripod. I suppose you're probably shooting vertically down
>> on the casings. It occurred to me that you may be able to shoot
>> horizontally with the casing slipped over a nail stuck in a backing
>> board. That way you'd only need something like a cheap table tripod and
>> it might make setup, focusing and shooting easier.
>>
>> Chuck Norcutt
>>
>>
>> On 9/29/2010 9:31 AM, Chuck Norcutt wrote:
>>> I just opened this up and read it very quickly because I have to leave
>>> for a few hours. But it's clear to me that I haven't made myself clear
>>> on a couple of points. First, NO NO NO aperture preferred mode. Fully
>>> manual exposure only. Secondly, I'm not sure you've got this white
>>> balance thing down yet. I'll be back in a few hours for some more detail.
>>>
>>> Chuck Norcutt
>>>
>>>
>>> On 9/29/2010 5:28 AM, Olaf Greve wrote:
>>>> Hi Chuck,
>>>>
>>>> Thanks again for the two additional explicative e-mails: they are
>>>> great and I shall save them for having them as back
>>>> reference. These e-mails make the exact problems, and paths for
>>>> solutions very clear; excellent explanations!
>>>>
>>>> So then, to summarise matters somewhat, I agree that it is more than
>>>> worth a go to use the OM gear I already have; that also gives me a
>>>> very, very good feeling, as it pains me to see it all unused in the
>>>> closet.
>>>>
>>>> It does mean, however, that I need to work on the set-up. I have two
>>>> semi-broken video camera (rather light) tripods which I can use to
>>>> improvise umbrella stands, if I can find the custom made ones again.
>>>> If not, other things could be improvised, such as firing through a bed
>>>> sheet (possibly clumsy due to the size) or through the paper that
>>>> clothes designers use (I don't know the proper English word for it) in
>>>> order to diffuse the flash. I'm leaning towards the idea of giving
>>>> both a go, see what works best, and then create some two wooden frames
>>>> with the material of choice in between, so as to be able to more
>>>> easily put them in place, without having to suspend them from
>>>> something. As a beside, a thing I forgot to mention is that when I did
>>>> some home-studio-experimenting, I used to tape off the windows with
>>>> that type of paper too, so as to prevent outside light coming in
>>>> harshly, and having it diffused.
>>>>
>>>> Indeed a BIG advantage of the digital era is that the exposure can
>>>> directly be previewed for being more or less correct. Actually
>>>> downloading a picture to the computer and checking it full size (as
>>>> the LCD seems to give a brighter display then what I see in the end
>>>> results!) should very quickly give a good indication for good
>>>> settings, distances, etc.
>>>>
>>>> I may choose to not go for three flashes, but rather to just use the
>>>> two T32s, at a 45 degrees angle from both sides of the object in
>>>> question. I think I can then get away with it. I did at one point in
>>>> time experiment a little bit with the T28 directly on the E-500 firing
>>>> t manually. Even when fully stopped down that gave me an almost
>>>> completely white picture. Totally overpowered. This then directly
>>>> makes clear that one or two layers of diffusing material will be
>>>> needed, so the bed sheets or transparant paper might be a better
>>>> alternative than having it bounced in my custom made umbrellas. The
>>>> semi transparent ones you mention sound good though. Particularly if
>>>> they come cheap and complete with stands. A thing I shall be keeping
>>>> my eyes open for.
>>>>
>>>> With that as intended set-up in mind, I can put the T32s in the T20
>>>> autoconnectors for easily mounting them on the tripods. Hooking both
>>>> up with the OM TTL cables (i.e. not the manual cables, which I don't
>>>> have) to the three socket distribution block should then take care of
>>>> the simultaneous firing of the both. I think, and that is, I'm just
>>>> about 99.99% sure that I also have the proper hot-shoe cable to hook
>>>> the distribution block up to the camera (IIRC, when using the 4Ti for
>>>> this, I used to hook it up to the socket on the front, so as to be
>>>> able to use a longer cable for that).
>>>> Then, both T32s could be set to half-power (a thing achieved on the
>>>> back of the flash with the switch panel, IIRC) and the camera should
>>>> then probably be set to force flash usage (which setting is best? you
>>>> mentioned something about the highest sync speed possible... is that
>>>> something like 'lightning x4' or so?). Once configured correctly, the
>>>> set-up could be tested, using a variety of ISO and aperture settings.
>>>> The camera could then possibly be set to aperture preferred mode,
>>>> hence getting a more consistent DOF too.
>>>>
>>>> Then, if the above is correct, a thing I'm still not 100% certain
>>>> about (exposing my noop knowledge of the fine details of digital
>>>> photography ;) ), is the theory behind proper WB setting. My reasons
>>>> for wanting to switch to a white background would be that it tends to
>>>> be more reflective than 18% gray (i.e. on the often round-shaped lying
>>>> down items it helps to light somewhat from below, hopefully preventing
>>>> side shadows (perhaps this is a flawed theory, as shadows shouldn't be
>>>> an issue if the light is diffuse enough) and also to be able to more
>>>> easily do the digital post processing, by having the pictures work
>>>> towards getting a completely white background, as easy visual
>>>> reference. Sounds good or flawed?
>>>>
>>>> Then, as for setting the WB properly... How can I best do that? Does
>>>> this get done once in some custom mode, against a 100% subject (such
>>>> as the intended backdrop?), and can that be locked into the camera for
>>>> all subsequent shots?
>>>>
>>>> Once I have gotten all those techniques mastered, and once I have a
>>>> suitable set-up going (a thing which I may not get around to until at
>>>> the very least this weekend, and then there's TOPE too to finally get
>>>> launched soon...), I will undoubtedly have some follow up questions as
>>>> to how to best use Paint Shop Pro for the digital post processing.
>>>> I've been a long time user of it, and I tend to like it better than
>>>> the de-facto bloated and over-expensive Photoshop. In fact, PSP
>>>> supports plenty more advanced features than I will be likely to ever
>>>> need for the post-processing. All the stuff like tweaking curves,
>>>> brightness, contrast, colour balances are there; possibly a bit less
>>>> flexible than in PS, but it should be possible to get this figured out
>>>> correctly too. IIRC one can also record some macros (or otherwise
>>>> create pre-defined bulk processing options) which would be really
>>>> great: I could then work on defining a standard set of tweaks, which
>>>> can then simply be applied in bulk to possibly hundreds of pictures
>>>> per shoot, after which the only manual work would be to possibly tweak
>>>> rotation, cropping, and actual image selection.
>>>>
>>>> Sounds good -in theory- so far? :P
>>>>
>>>> Cheers,
>>>> Olafo
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