Metering with filters

[Sweep]

Hi Guys,

I am looking for some guidance, or links to videos, as to the best technique when using Lee 100 filters with my 10x8.
I have red and orange for b&w, Autumn and Landscape sets for colour, and ND hard grads and polariser which are good for both.
Using the red, orange and polariser individually seems pretty easy as I measure EV through the filter to establish what exposure correction I need and then make my adjustment to time or aperture.
Using the ND grads is not that problematic either. I spot meter the lightest part of a scene and compare that, usually, to the sky which then determines which grad to use (1, 2 or 3 stop) to hold back the sky.
I have also used the Autumn set to warm up a scene as the grad line is 90mm so I can use those to cover the whole lens. No problem.
My worries, however, are when I want to use, for example, one of the Autumn set, lets say Coral 6 which has 1.5stop effect, to lift the foreground and a ND Grad to hold back the sky.
Should I meter the difference between the foreground highlights and the sky, lets say that's 2 stops, add the Coral 6 (1.5stop) to the foreground, and then add the two numbers together to arrive at what ND grad is actually required for the sky; that being 2+1.5=3.5stops?
I suppose I should then ignore this number and adjust by 1.5stops for the whole scene to take into account the Coral 6. Right?
If, however, I was also want to use a polariser (let's say that is also 1.5stop), then do I adjust by a total of 1.5 (Coral)+1.5(Polz)=3 stops?
My final question is regarding the transition line on any of my 100x150mm filters which is really difficult to see on the 10x8 ground glass. I have cut out a piece of thin cardboard which replicates the position of the grad line but does anyone have any better ideas?
Using my 645 is easy as it has TTL metering but as I am starting to shoot 10x8 Provia I can't afford to make too many mistakes without breaking the bank.

thanks ...Sweep

[Pere Casals]

For slides first you have to do is acquiring a shutter tester (under $100) and checking real speeds vs marked speeds. Exposing slides requires precision, and you may remember a burnt provia 8x10 for decades with great pain. Remember the bellow compensation and LIRF instructions. https://kenrockwell.com/tech/exposure-large-format.htm

IMHO metering for LF slides require spot metering, this is the procedure I used to adjust my slide exposures.

1) Take a lightweight nikon F65 and load it with 35mm provia

2) Decide a suitable exposure for a typical scene, anotate with that exposure what metering has the interesting spots of the scene: Sky, clous, trees, water, faces.

3) Make a bracketing from -3 to +3.

4) Judge how it looks each anotated spot with the exposures, for example if sky was at +2 in the base exposure then you will know how sky looks form -1 to +5.

With that information when you spot meter an scene you will know how sky, clouds or water will be by recalling the test exposures.

This is important because metering is color sensitive. The sky can be blue and meter may be less sensitive to blue, so the overexposure may be greater than what meter says, for this reason it's important you test how over/under exposure works with different subjects. The faster way you will get that information is by testing on real subjects, anotating well the spot metering of each spot of interest and making the bracketing.

Congratulations for engaging 810 slide shooting, IMHO this is by far the best still image system in the world.

[Sweep]

Hi Pere,

Many thanks for your guidance.
The next time I go out I will take my Contax 645. Normally I would just rely on the TTL but I will take my spot meter and simulate how I would meter a scene with my 10x8. I suppose it makes sense to just work with shutter times no shorter than 1/125 as this corresponds to the Copal 3. The Contax will also make assessing things easier as it prints the exposure data between frames. I might even be able to build a nice HDR image with all the over and under exposures!

As far as shutter timings are concerned, there is a guy selling a detector that fits to a Windows PC for very little money so might give it a go. There are a few more expensive, and I presume easier to use, devices but I suspect it wont get used more than once per year so I may as well spend as little as possible. Any thoughts? https://www.ebay.co.uk/itm/Camera-sh...EWxR:rk:9:pf:0

I appreciate your reply focuses on understanding the fundamentals of how different exposures will effect the image captured, and establishing the actual shutter speeds that each lens will provide, but I would still appreciate guidance on my original question about metering with filters. What technique do you use when using filters that do not cover the whole scene or when multiple filters are required?

Thanks ...Sweep

[Pere Casals]

Contax 645.

hmmm, this is world class top gear... very best wedding photography is made with that, and this is 2018 !! Villa and friends...

https://www.ebay.co.uk/itm/Camera-sh...EWxR:rk:9:pf:0

This is perfect, I use a similiar one, but I use a usb oscilloscope instead audacity, (to me it's more convenient). A standalone one is also useful, but the one you point shows the open/close flanges and this also helps for diagnostics.

The important thing is checking that the speed is repetitive, then knowing the actual speeds you can manage to get a correct exposure. Think that those shutters are not electronic and were sold with +/- 30% tolerance, so 1/30 can be 1/20 or 1/40 !

What technique do you use when using filters that do not cover the whole scene or when multiple filters are required?

Use the same technique: bracket Provia with the filters on the lens. That bracketing will cost you one or two rolls, but it willl deliver you surgical capability in using your filters on your subjets. for those bracketings 35mm are more efficient because you make 36 exposures per roll... You know, measure twice cut once... Making those test bracketings with precission will ensure you nail your precious 8x10" slides.

[Sweep]

Thanks again Pere,

I am a sucker for good quality kit which, I guess, the Contax easily qualifies. I keep toying with the idea of swapping the Contax for a RZ67 because it's 645, not 6x7, and I do like a big neg. The other thing is that the Contax is mint, and very expensive, and I am terrified of marking it. Such is the curse of the amateur!
Not wanting to labour the original question but, once I have done all that you have suggested, and I will, what are practical steps you follow when taking your shot with single or multiple graduated filters; things like being able to see the grad line on the 10x8 ground glass etc.? I can't even see the grad line clearly even with hard grads.

...Sweep

[Pere Casals]

Contax -- RZ67 because it's 645

The Contax is agile compared to the RZ. The Contax is also valued because it mounts that CZ 2.0, but Rz also has absolutely wondeful glasses, with great performance because of "unit focus". I'm using a RB67 and a borrowed Pentax 67II. The 67II is also an amazing choice, but its price has sky rocketed in an incredibe way...

things like being able to see the grad line on the 10x8 ground glass etc.? I can't even see the grad line clearly even with hard grads.

There are metering probes fot the back:



This is an smart way because you meter the light that will arrive to the film...

There are other tricks I've improvised. One is placing a black strip on the grad line to see better where it has an effect on the GG. Also another thing I did is mounting a SLR (or DSLR) in the back to use it as a TTL spot meter, with shift rise we can explore the scene.

For a 4x5 monorail this is straight, just attaching a macro extension ring (with the bayonet) to a lensboard we just place the lensboard in the back, for 8x10 it requires a DIY plating that can be taken in place of the spring back.

IMHO it's not the everyday way, but IMHO it's quite useful the understand how the things are going and to have a sort of calibration.

[Sweep]

Taking a prompt from you about the metering probe, I had a look in my Sekonic L-508 manual and they actually do what they call a Booster which they describe as being "For light measuring on camera ground glass, focusing screens, SLR eyepieces, microscope eyepiece. • When the Booster is used without any accessory attachments, it can measure reflected light over approximately a 60 degree angle of field."
Anybody used one?

[Sweep]

...or could I just use my spot meter directly onto the ground glass? I suppose I would make a correction for loss of transmission through the glass but after that was done I could quite accurately measure any part of the scene.
Just trying to get my head around how I meter through the lens with it wide open at f5.6 as I feel I will end up compounding my measurements.
Or am I overcomplicating things as ive never noticed anyone else using this technique?

[Bob Salomon]

...or could I just use my spot meter directly onto the ground glass? I suppose I would make a correction for loss of transmission through the glass but after that was done I could quite accurately measure any part of the scene.
Just trying to get my head around how I meter through the lens with it wide open at f5.6 as I feel I will end up compounding my measurements.
Or am I overcomplicating things as ive never noticed anyone else using this technique?

For decades people just used the filter factor and, if necessary from experience, made their own adjustment. Not difficult.

[Pere Casals]

For decades people just used the filter factor and, if necessary from experience, made their own adjustment. Not difficult.

Bob, yes... film has latitude, but exposing 8x10 slides requires extreme care. A cooked Provia is like being stabbed, priority is not overexposing, but if we have an underexposed Provia shot we may need 8x10 drum service at $150 to $280 per sheet at 2000dpi only, so one remembers an underexposed holder like a car crash.