New to strobes, film ended up blank

[Gary L. Quay]

Hi all,
I was working with a model a couple weeks ago. I had originally intended to use my old movie floods, but my friendly salesman at Citizen's Photo asked my if I had an oven thermometer handy to see when she'd be cooked. So, I bought a strobe unit. I've always used natural light, but since I was using slower film indoors, I needed lots of light. I bought a Speedotron 2401 with two 102 heads. I bounced them off of umbrellas. I metered at the subject. The previous night I used a two boxes ofPolaroid B&W (3000 asa) on my hasselblad getting the exposure right, and did the division to arrive at the exposure for each of my films: Efke R25, Efke R50, Efke R100, Bergger 200, Tmax 400, and for 4x5: Arista 100, Ilford 125, and Efke PL50. The reason I used so many films is I'm trying to recreate the look of 1920's glamour photography, and I wanted to see which one had the best look for the job. All of the 4x5 was blank, even after pushing two stops. I got usable images out of the Tmax, and the Bergger after pushing. I got nothing useful out of the Efke roll film, even after pushing. I even calculated bellows factor for the 4x5.

A few things come to mind. 1) my math sucks. 2)My meter, a Polaris, has always metered properly for my Vivitar flashes, but I've never used it with strobes units. 3)I've used flash mostly with color films, not B&W. Assuming that the meter will read it at 18% gray, I have to adjust, but I thought I had worked it out with the Polaroid.

Any help would be greatly appreciated.

Thanks!
--Gary

[JW Dewdney]

IT seems to me that it could be any of a dozen (or more) things, Gary. If you're able to get successful results NOW - it's probably not your shutter or cable. But I can think of any number of scenarios that would do this (not pulling darkslides, having residual fixer in your dev tank, problem with the speedo, etc etc etc...). You'll have to do a little bit of detective work, unfortunately. If you can tell any of us exactly what you've proven DOES function properly, we can try to narrow it down... but without knowing specifics... well, it's kinda hard.

Jonathan

[Ole Tjugen]

Could the shutter sync be off?

You haven't put the little switch to "M", by any chance?

If not that, you could try a "manual sync": Open shutter, trigger strobes, close shutter. My first LF lens had no flash contact (broken off the shutter), but I still managed this:http://www.bruraholo.no/bilder/Truls.jpg

[Helen Bach]

What exposure did you arrive at for the Polaroid, and what did you calculate for the various films?

Best,
Helen

[steve simmons]

Too many variables and not enough info as JW said but here are some suggestions.

Use a Polaroid film with a speed of 100. It will make the math easier.

Narrow your choices of films/

The films in the 20s may have been primarily orthochromatic in color response in which case nothing you used would match


steve simmons

[Nick_3536]

If the film is totally blank I'd lean away from math/metering issues and towards some other failure. Flash sync or you processed the wrong film?

[Helen Bach]

Were you using the roll film in a roll film back on the 4x5, or in your Hasselblad - ie did the failure happen with two different cameras, one of which had already worked with your setup?

Best,
Helen

[Mike Davis]

Do you remember the exposures that you used for the 25, 50, and 100 speed films? What is the power rating of the flash units?

One thing to remember with flash units is that you can't just keep decreasing(increasing) the shutter speed in a linear fashion to improve exposure. The flash is only there for a short time. In other words going from 1/125 to 1/60 won't get you another stop.

[Robert Oliver]

I would bet on the flash sync switch first (it should be on X, not M).

but then again, I would think it would be difficult to arrive at a correct exposure using a 3000 iso polaroid film to try to figure out exposure for 25 iso film. your dealing with a test film that is 7 stops different than one of the films you are using. I've never tried it, but I would guess you would have to power the strobe down as much as possible and still shoot at f90 to come anywhere near the correct exposure for iso 3000 film. depending on how far away your strobes are, you might even after to use ND filters to reduce output from your lights. the speedo packs are extremely efficient and powerful. (and fun to carry long distances) . If your at f90 with the 3000 iso, then your exposure for 25 iso should have been f8. you would want your polaroid film to match your intended film so you could also check your depth of field.

Get 100 speed polaroid and shoot 100 speed film. You have too many variables going on at once for even the most experienced studio shooter. remember the KISS rule. Keep it simple stupid (not that i'm calling you stupid, it's what my high school photo teacher taught us). with a flash meter that's anywhere near accurate, you shouldn't have to push film at all.

was the film blank or completely over exposed. if it's clear check the switch on the lens.

you could also test your flash meter by using manual guide number calcualations. The problem is coming up with accurate guide numbers for a given powerpack/head/box combination.

[Nick_3536]

What is the power rating of the flash units?
.


He mentioned a 2401 with two 102 heads. So depending on how he plugged in the heads it's either 200ws or 1200ws per head. So some combination in between. Even at 200ws he should have gotten some exposure.

[Mike Davis]

He mentioned a 2401 with two 102 heads. So depending on how he plugged in the heads it's either 200ws or 1200ws per head. So some combination in between. Even at 200ws he should have gotten some exposure.

OK 200ws with a bounce umbrella and 25iso. Depending on aperature he well could have wound up with nothing. Now at 1200ws per head I would agree that there should be something on the film and there was with the pushed Berger and Tmax.

[Vick Vickery]

If its not the sync setting (some lenses have to be set for "X", others are there all the time, others just aren't synced with electronic flash at all), did you pull out the dark slide on the holder after putting it on the camera???? We've ALL done that before! :o

[gregstidham]

If the Bergger and TMax show an exposure after some pushing, I'd suggest rechecking your math for the slower films and opening up your aperture or increase your strobe output.

What was your aperture setting for the Polaroids and what did you use for the slower films?

[Nick_3536]

OK 200ws with a bounce umbrella and 25iso. Depending on aperature he well could have wound up with nothing.

But he also used faster film. Sounds like he got nothing on everything for the 4x5.

Actually looking at things I wonder if he didn't flash the strobes at all but just used the modeling lights? :confused:

Would explain why the faster 120 film came out some what and the slower 4x5 did nothing.

[Donald Qualls]

I'm with Nick -- something faint after pushing on the faster films, nothing at all on the slow sounds very much like a synch issue (unlikely, since the 'Blad was good with the Polaroids) or some failure that kept the strobes from flashing at all (which would be easy to miss with your eye screwed to an SLR finder, but seems unlikely to go unnoticed with the large format).

Maybe both -- M synch on the LF shutter, and no flash at all on the Hasselblad at the actual shoot?

[RDKirk]

The setup worked fine in the tests with the Hasselblad. With pushing, there were images on the faster films.

It does look like a sync issue to me. I believe that the images finally seen on the faster films were created by the modeling lights.

I'd check this quickly by pulling off the groundglass and looking through the camera while releasing the shutter. You should see the flash, and you should see it as a perfectly round aperture--you should not see any blades.

[Peter Mounier]

I wonder if you might have had the film in the holders upside down?

Peter

[Gary L. Quay]

Do you remember the exposures that you used for the 25, 50, and 100 speed films? What is the power rating of the flash units?

One thing to remember with flash units is that you can't just keep decreasing(increasing) the shutter speed in a linear fashion to improve exposure. The flash is only there for a short time. In other words going from 1/125 to 1/60 won't get you another stop.

I kept the exposures on a sheet of paper, which I'm unable to find at the moment, but I think I had the R25 at F11 and 1/30th sec. The main strobe was set at the 800W setting, and was 6 feet away. The hair light was at 400W.

Strangely enough, I noticed that my meter didn't seem to function like I thought it should by changing shutter speed. So, in other words, if my strobe has a 1/125th sec flash, I'm stuck with that, and I have to adjust exposure with f-stop? I have two books on studio lighting, and numerous articles in magazines, and none of them mentioned this.

I checked my cameras, and they were both on X. After I got the first batch of blank negs, I verified that the lenses were, in fact, working. The strobes flashed for every exposure. Dark slides were pulled, and replaced.

I would like to thank everyone for their input. It seems that it was a math error coupled with misunderstanding the nature of the length of the flash / f-stop issue. I wanted to keep a tight aperture to have good depth of field, because I built a 5' deep set, and I wanted it all in focus. I calculated my exposure by manipulating shutter speed. Oops. So, if I want to meter correctly, I should pick a shutter speed that corresponds with the length of the flash, and use the given f-stop? For B&W, do I need to increase exposure to adjust the 18% gray reading given by the meter? Say, if my subject is a person with pale skin... Of course, I'm going to test this vigorously before I hire another model.

Someone suggested that I use a 100 speed polaroid. In the future, I will. The faster stuff was all I had the night before the shoot, when I remembered that I needed to test exposure. The shoot happened on a Sunday, so getting a slower film was impossible.

Thanks!
--Gary

[Donald Qualls]

Your strobe most likely has a maximum exposure time of 1/1000 second (a few very high power strobes might run as long as 1/500), and if set at reduced power will have corresponding shorter flash (some thyristor flashes run short enough that the 1/10,000 lower reciprocity limit for most films becomes an issue); any shutter speed slower than that will encompass the entire flash duration. If you see 1/125, it might be a synch speed, typically an issue only on focal plane shutters (and that's a typical one for modern high-speed focal plane shutters).

So, if your flash meter doesn't record any change with different shutter speed, that's as it should be. You could change shutter speed to vary exposure (by cutting off part of the light output) with magnesium bulbs, but while I use those occasionally (and have a couple hundred of them on hand), I'd bet you don't.

You'd make the same corrections (for pale or dark skin, say) with flash that you'd make in hot lights or natural light -- if metering from the skin, open up 1 1/2 stops for average Caucasian skin, more for very pale, less for darker (you may even need to close down as much as a stop with very dark African skin). But you must make all corrections with aperture or by adjusting the flash power setting.

[Gary L. Quay]

There's 5 12-packs of magnesium bulbs in a junk store across town. I've considering buying them. I have the equipment to use them.

--Gary

[Mike Davis]

Gary,

I've made the same type of Math error. My saving grace was shooting the same speed polaroid as sheet film. So I was able to see my error in my initial test shots the day of the shoot. It sounds like you have a good set of strobes.


Good luck,

Mike Davis

[Nick_3536]

The only time you worry about shutter speed with flashes/strobes is when you want to balance existing light. But if you are only using the strobes then you basically set the shutter speed fast enough and ignore it.

Unless you increased the shutter speed past the speed of the strobes you should have gotten something. The thing is no LF lens has a shutter so fast it can't handle your lights.

On the Speedotron website you can download the current manual.

800ws is pretty power full at six feet.

You can gel the lights to lower power. You can move them further away. So you don't need to change either F/stop or shutter speed.

[Ron Bose]

I have a feeling that this is a metering issue.

As your 'blad and your large-format lenses are leaf shutters, we don't need to worry about shutter speed.

You also don't need to worry about flash duration, it's fine, it takes care of itself. It will always be faster than your fastest shutter speed on a leaf shutter.

With a flash meter that shows lighting ratio (ambient -v- flash) it's easy to see what the break point shutter speed is. That is the point at where you start to drag the shutter and allow ambient light to start illuminating your background. Usually speeds slower than 1/60th will allow ambient light to have an affect.

So I would re-read the manual on your Polaris and understand how it behaves. This weekend I was helping my gf on a baby shoot. I set up my power pack to give out enough juice to correctly expose at 100iso, f8 at 1/125th (as metered by my trusty Minolta V).

Once you figured out the metering and maybe always stick to one film, you'll be good.

[Gary L. Quay]

The metering could be a part of it. I've been searching for the manual for a week. It's somewhere...

[gregstidham]

I don't have my strobes with me to test, but 800ws, direct with no diffusion, at 6 feet should be pretty close to f11 on ISO 25 film. Maybe 1 stop under, but should have exposed something if shutter was fired correctly and the dark slide was pulled. :)

[Nick_3536]

Ya I'm having the same problem. I can't imagine a metering problem that would lead to totally blank film. Over exposed maybe.

If you metered the modeling lights instead of the strobe then you would have over exposed most likely.

[Mike Davis]

I don't have my strobes with me to test, but 800ws, direct with no diffusion, at 6 feet should be pretty close to f11 on ISO 25 film. Maybe 1 stop under, but should have exposed something if shutter was fired correctly and the dark slide was pulled. :)

He said it was 800ws of bounced light at 6 feet.

[Mike Davis]

Ya I'm having the same problem. I can't imagine a metering problem that would lead to totally blank film. Over exposed maybe.

If you metered the modeling lights instead of the strobe then you would have over exposed most likely.


There is no way that 800ws of bounce at 6ft would overexpose PL25 at f11.

[Nick_3536]

No I was thinking of the other films that also ended up blank. How did they all end up blank?

[Mike Davis]

No I was thinking of the other films that also ended up blank. How did they all end up blank?

Well, we know that the 200 and the 400 had images when pushed. This makes me think that everything else was under exposed. I don't know by how much. But I do know that if you start trying to use shutter speed to control lighting with the flash, you are going to have trouble.

That can be a tricky realization sometimes. Those of us who shoot mostly natural or hot lights are used to using a combination of shutter speed and aperture to control the lighting and dof. With the flash, a slower shutter won't double the amount of light as it would with hot lights.

Mike

[gregstidham]

He said it was 800ws of bounced light at 6 feet.
Oh, thanks

[Robb_Scharetg]

Gary

Shooting with strobe, unless you're in a room with fairly strong ambient light, 100 ASA film won't register that light at over 1/60 @ 5.6ish, and usually if you want that aperture you're shutter speed will be lower. 3000 ASA is another matter entirely in ambient light. However, that should not matter as it's all a matter of ratios and if you use your meter correctly and your strobes are firing your film should match the polaroid no matter the speeds of each medium. If you're metering 3000 ASA film with ambient light only I'd think you'd be at 1/500@f11 (5 stops difference), again ambient light only.

It should not matter what speed your polaroid is, go by the meter unless you want to do the math in your head, which is certainly fine too. Assuming the strobes fired and your modeling lights were off the only way you'd end up with blank film is that your math is/was off. And as others have said it could be due to the fact that you can't factor shutter speed into the equation above 1/60 +/- unless you're 'dragging' the shutter to allow in ambient light.

If you'd metered @ ASA 3000 and kept the shutter speed CONSTANT and then re-metered at each respective film speed, keeping the shutter speed constant you're apeture should have gone more and more open- i.e. from say f90 to f 11 to maintain the same lighting ratio (I'm not factoring in any changes in strobe output as made by the operator).

If you were to balance or blend the strobe with the ambient (which I do a lot) you'd meter the ambient light (shutter speed AND aperture deciding on depth of field wanted) and then match the shown STROBE aperture to the ambient aperture. Strobe stays more or less constant. I usually have a ratio of strobe over ambient by 3/4 to 1 stop, i.e. ambient's at 1/30 @ f4 so I power the packs to read at 5.6 and then shoot at 5.6. It's perfect every time, based on the meter. I usually 'polameter' just to be sure it's all good, it is.

I'll be curious to hear how it pans out. Another thing to consider if you want, shoot Fuji FPC 100 proofing film (color's better and speeds more accurate) and chrome film as a test. Chrome is a LOT less forgiving in terms of latitude. Once you've nailed the chrome, B&W neg will be a walk in the park.

Good Luck

Robb Scharetg
www.scharetgpictures.com

[Gary L. Quay]

Interesting. I'm going to give the FPC a try. I like the idea of learning with a difficult medium. It makes everything else seem easier.

Also I like the idea of using more ambient light. The trouble was that my studio was my livingroom, which is nearby one of the most heavily traveled streets on Portland, OR. I should have put a rice paper, or some other thin paper, over the windows and left the blinds open, but as it was , I had to close the blinds.

Thanks!

--Gary

[Gary L. Quay]

Well, we know that the 200 and the 400 had images when pushed. This makes me think that everything else was under exposed. I don't know by how much. But I do know that if you start trying to use shutter speed to control lighting with the flash, you are going to have trouble.

That can be a tricky realization sometimes. Those of us who shoot mostly natural or hot lights are used to using a combination of shutter speed and aperture to control the lighting and dof. With the flash, a slower shutter won't double the amount of light as it would with hot lights.

Mike

Yes. This seems to be the case.

The Efke roll films had very thin images on them after pushing. All of the 4x5 was blank.

I'm making another go at it this weekend. I'll let you know the results.

--Gary