Sorry. That should have said "At ISO 100 I got exposures of f/5 for 1/4
power and f/10 for full power." There is 1/2 power on a T32.
Chuck Norcutt
On 9/29/2010 6:15 PM, Chuck Norcutt wrote:
> 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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