Polarisation Filter

[neildw]

Hi all,

I'm at the beginning of starting a new series which shall involve cars.
And I want to reduce the reflections as much as possible.

I'll be working with a 150 mm lens on a 4x5.

Any tips on what I should be looking at? What kind of pola filter?
Any tips on working with them on LF?

[BrianShaw]

Which 150mm lens? That would help of figure out which size polarizer filter to get. Only other suggestion would be also to use a lens hood.

[Drew Wiley]

Polarization is relative to the position of the light, where the sun is in the sky. And if you're using color film, too much polarization can make the colors look questionable. In a studio, you can predictably cross polarize floodlamps, along with a pola filter over the lens. But again, over-doing it will look paste-like and unrealistic. Most pola filters and polarized lighting "gels" have a slight greenish bias. Only the very best and most expensive doesn't.

[Alan Klein]

Don't assume you need to turn the polarizer to full impact, Because a car has a lot of bends and turns, the polarizing effect will shift and change the way it works on the various surfaces of the car as you turn it. So view it before you put it on the lens. Get the right position and note it. Then match that position when you mount it on the lens. Good luck.

[Pieter]

Polarization is relative to the position of the light, where the sun is in the sky. And if you're using color film, too much polarization can make the colors look questionable. In a studio, you can predictably cross polarize floodlamps, along with a pola filter over the lens. But again, over-doing it will look paste-like and unrealistic. Most pola filters and polarized lighting "gels" have a slight greenish bias. Only the very best and most expensive doesn't.

Also, most car shooters have a set of "shark fins"--large white foamcore cut in a wavy shape, sometimes like a shark fin, to reflect into the windows and polished surfaces, giving interesting reflections that are indistinct and not distracting. It may not be your style (very clean studio shots), but you might want to check the work of Michael Furman. http://www.michaelfurman.com

[r.e.]

Any tips on what I should be looking at? What kind of pola filter?

There are linear polarisers and circular polarisers. In this case, "circular" is a technical term and doesn't mean "round". There are square and round versions of both linear polarisers and circular polarisers.

Photographers stopped using linear polarisers with the advent of digital cameras. If you're interested, there's lots on the internet about the reasons. These days, a linear polariser should work just as well on a digital camera as a circular polariser, but the main filter makers don't make them anymore (apart from quite large, extremely expensive ones for high-end filmmaking) and nobody wants them. If you come across one, it is likely to be very cheap, and it will work just as well.

Recently we've seen the introduction of filters that combine a polariser with variable neutral density. There is quite a lot of information about these on the internet, as well as a fair number of YouTube videos about them. Personally, I'm not keen on variable ND and I have no experience with these new filters. That said, if you need neutral density, a variable ND filter is a lot cheaper than buying individual filters and can be a real timesaver, especially for video. These filters have become very popular for good reasons.

[Doremus Scudder]

Unless you have through-the-lens metering on your LF camera, :rolleyes: you can use a linear polarizer. You can often find them used and cheaper than circular polarizers. Get a good-quality coated one for best results. B+W, Heliopan, and Hoya coated filters are all good. Get a filter for the largest lens you plan on using and step-up your others to fit; then you can use one filter for all of them.

Reducing all reflections isn't always the best solution, as mentioned above. If outdoors, overcast days are often your friend.

Best,

Doremus

[Bob Salomon]

Unless you have through-the-lens metering on your LF camera, :rolleyes: you can use a linear polarizer. You can often find them used and cheaper than circular polarizers. Get a good-quality coated one for best results. B+W, Heliopan, and Hoya coated filters are all good. Get a filter for the largest lens you plan on using and step-up your others to fit; then you can use one filter for all of them.

Reducing all reflections isn't always the best solution, as mentioned above. If outdoors, overcast days are often your friend.

Best,

Doremus

Through the lens metering doesn’t necessarily mean you need a circular polarizer. Nikon, Canon, Minolta, Pentax, Rollei, Hasselblads all did TTL metering with no problem with a linear polarizer.
You need a circular pol if your camera uses a beam splitter for auto focus and/or metering.

[pdmoylan]

Several techniques I used to manage proper exposure:

1. I employed use of a 35mm film or digital camera as a meter, placing a Pola filter on that camera.
2. Since exposure loss with pola filters changes markedly to the extent you change amount of polarization, you will have to set the filter to where you see the changes you want in the scene and meter accordingly.
3. Place a comparable pola filter on the LF lens and adjust the amount of polarization to how you set it with the 35mm.
4. Experiment prior to calibrate exposure readings with the LF results. I had a 90mm f8 Nikkor which was always .5 stops darker than the exposure determined with the 35mm. My other lenses needed no adjustment.
5 so this process a. Eliminates having to exposure compensate for the pola filter but you will have to adjust exposure for any calibration differences.
6. Even with the best pola filters, I found color issues when using them in very low light, but this is particularly true with modern day digital cameras.
7. I found old tiffen linears to be somewhat neutral whereas Nikons tended towards blue (cooler) and calumet towards green.
8. Set your pola filter to neutral setting at first and watch change as you turn it. You may find that the slight polar effect at neutral position is sufficient. There is a marked difference between unfiltered clvs neutral position.
9. As Drew mentioned, using pola filters on artificial lighting in addition to on the lens may give you a denser look, something to experiment with.
10. I expect there are other methods of determining exposure compensation for pola filters, but they are not all the same regarding amount of light loss, particularly with the HR thin filters being made now.
11. The range of light loss I found to be between 2/3 and 1.5 stops depending on how much you turn that filter.

[Bob Salomon]

Several techniques I used to manage proper exposure:

1. I employed use of a 35mm film or digital camera as a meter, placing a Pola filter on that camera.
2. Since exposure loss with pola filters changes markedly to the extent you change amount of polarization, you will have to set the filter to where you see the changes you want in the scene and meter accordingly.
3. Place a comparable pola filter on the LF lens and adjust the amount of polarization to how you set it with the 35mm.
4. Experiment prior to calibrate exposure readings with the LF results. I had a 90mm f8 Nikkor which was always .5 stops darker than the exposure determined with the 35mm. My other lenses needed no adjustment.
5 so this process a. Eliminates having to exposure compensate for the pola filter but you will have to adjust exposure for any calibration differences.
6. Even with the best pola filters, I found color issues when using them in very low light, but this is particularly true with modern day digital cameras.
7. I found old tiffen linears to be somewhat neutral whereas Nikons tended towards blue (cooler) and calumet towards green.
8. Set your pola filter to neutral setting at first and watch change as you turn it. You may find that the slight polar effect at neutral position is sufficient. There is a marked difference between unfiltered clvs neutral position.
9. As Drew mentioned, using pola filters on artificial lighting in addition to on the lens may give you a denser look, something to experiment with.
10. I expect there are other methods of determining exposure compensation for pola filters, but they are not all the same regarding amount of light loss, particularly with the HR thin filters being made now.
11. The range of light loss I found to be between 2/3 and 1.5 stops depending on how much you turn that filter.

The density of a single polarizer, circular or linear, does not change as you rotate it. It always passes the same amount of light, regardless of its rotation.

[pdmoylan]

The density of a single polarizer, circular or linear, does not change as you rotate it. It always passes the same amount of light, regardless of its rotation.

Perhaps in theory, but not my experience. Max polarization = greatest light loss. Try it with any camera.

[Alan Klein]

The density of a single polarizer, circular or linear, does not change as you rotate it. It always passes the same amount of light, regardless of its rotation.

So if the polarizer filter mfr recommends 1 1/2 stops loss, just use that amount regardless?

[Bob Salomon]

So if the polarizer filter mfr recommends 1 1/2 stops loss, just use that amount regardless?

Good place to start. Do a test.

[LabRat]

Some things I learned on many pro car shoots I have worked on is that car designers actually design body surfaces to reflect light to give surfaces "body" and form... That light is a key ingredient to the design and surfaces... Designers have very complex software that simulates light from a multitude of angles so overall appearance is even from many as possible viewing angles... Without the light, areas tend to look "naked" and surface volume changes, even to the point where raised areas can look depressed or unfinished... So, for body work, usually all surfaces will be lit, or at least some reflector card etc will be reflecting some light energy off subject and back to camera...

Polarization can cut one area, but not another plane in the shot, so not usually used, and can form unwanted patterns in polarized areas (esp glass), and bring out usually invisible surface issues... And highlights/reflections (like on glass) can look weird...

So, I'm mentioning that the solutions involve adding more even light until balances are achieved... Usually, this involves even light from tenting, and strategically placed lighter and darker large fill cards to apply broad illumination...

One cheat that's applied often is shooting very early or late in the day where the sky before sunrise/after sunset is used to light the side of a vehicle, camera is low, so top is not seen clearly, slightly darker, and blue skylight flows off top with a deeper blue color (think Jeep on a mountaintop look ads)...

Cars can be tough, but if you follow a plan to apply broad, even light, can be quite manageable...

Good luck!!!!

Steve K

[Bernice Loui]

One of the prime aspects of car styling/design has much to do with reflections, shadows, textures and more coupled with how light interacts with these sculptured shapes. Car Fotos should enhance or capture the car stylist intent of visual expression. Applying a polarizer to cut/reduce these reflections could be counterproductive to the original styling of the car as the car's stylist-designer intended. Typically, a VERY large diffused light source is used combined with reflectors (white, off-white, silver, gold or _) where needed or negative fill (black often velvet material) is applies where reflective light control is needed.

Back in the color transparency with 4x5 sheet film car images like these demanded phenomenal strobe power often in the five digits of watt/seconds distributed evenly across the diffuser "light bank" due to the large area being lighted and diffusion. Found an example on the web:
https://macbethstudio.com/blog-home/building-a-giant-overhead-light-bank

Not only did the diffused light bank have phenomenal strobe power, color temperature of the lighting MUST be correct for the color transparency film used, E6 processing and every aspect of the image making system involved to reveal accurate and precise color rendition of the car being imaged. Exposure/film density is a precise given.

One alternative is to exploit outdoor light near sunrise or sunset. When the weather and sun conditions are correct, the effective lighting can work as an effective light source that enhances the reflective surface shapes designed into the car body. Found this example done some time in the late 1980's _ early1990's of a Saab 9000T once owned. Using a 5x7 Sinar C, 8 1/2" Commercial Ektar @ f16 (camera movements as needed), Kodak Ektachrome film, E6 processing at The New Lab in San Francisco. Note the colors of the sunset is reflected to the imaging system over powering the metallic blue of the Saab 9000T and how the reflections from the car body's shape interacts with the ligting.

223033

https://lh3.googleusercontent.com/Y2LC2nS-e51--jpOa0iuAfH6dDCC6ho56dLK-pcXT-9oqkDxcYk7qGE-P4gIgEz18bcI_EJxYsTHDTjaurfaKCxTmL6WuBl9Ehq3eAJ-iw77rKmKhuWLuOV7Li0u_Q-99ugOb4EaDC8qaQ44bF-veTW1mndrWabvG6fD454LSZAbEw33IbYt-D-3KVAfWk58hni5BCFzpLVRIFfsdBsmipeZaEtzOHUfFT20kajDIp7wKgAN06i8vNeKnrKLsfWL4aP5jKTy0IL8LYJhTmZ6kx8xXQSqXm587xOv5lIyloGfEe7sLcXuYrUzpowXWLenpOpnnt4GM5kz0t53m1zSJOUWta-l1j-8kt5Nu4mWae5nhjO4hsjJQtLPwiHhHhzCivg-uL-AxFE1stpJJFNLiC23Rrz5KZnNnNvVMorhVG0zymUYI-qOvGGoZQSvU6zEPaK44qoLd1YAyJF5gloBdhAXCBM0_qWRP-W3SbuGqTxyuHuVaIju-NFvp6T78c4cwibK5mzMJbsmGVVQ3JYN_yHAlxHlX06H4DjAqcRBA7Nqh8bMwb3V8yPRnN4eRrYGAuK_Jpm_67dXDPswudVkS0pY_NJgoUvEUAw84Zu9qr4H4yz6W0wUPSUOEtAFv8yOAtuA8s2t3owq65UyMQ4fAHkRNtGoQGt_Bdrqs7AgaC2RFlClspJ6reI77VA2yN71qobW-U_iMOn40FcIHYpTLMHP=w1830-h1270-no?authuser=0


Lighting often makes enough difference to put lens, camera, film, post processing and .. secondary.

Bernice






Some things I learned on many pro car shoots I have worked on is that car designers actually design body surfaces to reflect light to give surfaces "body" and form... That light is a key ingredient to the design and surfaces... Designers have very complex software that simulates light from a multitude of angles so overall appearance is even from many as possible viewing angles... Without the light, areas tend to look "naked" and surface volume changes, even to the point where raised areas can look depressed or unfinished... So, for body work, usually all surfaces will be lit, or at least some reflector card etc will be reflecting some light energy off subject and back to camera...

Polarization can cut one area, but not another plane in the shot, so not usually used, and can form unwanted patterns in polarized areas (esp glass), and bring out usually invisible surface issues... And highlights/reflections (like on glass) can look weird...

So, I'm mentioning that the solutions involve adding more even light until balances are achieved... Usually, this involves even light from tenting, and strategically placed lighter and darker large fill cards to apply broad illumination...

One cheat that's applied often is shooting very early or late in the day where the sky before sunrise/after sunset is used to light the side of a vehicle, camera is low, so top is not seen clearly, slightly darker, and blue skylight flows off top with a deeper blue color (think Jeep on a mountaintop look ads)...

Cars can be tough, but if you follow a plan to apply broad, even light, can be quite manageable...

Good luck!!!!

Steve K

[xkaes]

Good place to start. Do a test.

I agree with Bob. Much depends on how you meter -- incident vs reflectance. If you use a TTL meter you will see a change in the exposure as the PL is rotated. If there is a lot in the scene impacted by polarized light it will make a BIG difference and vice versa. Do you want the elimination of polarized glare to change your exposure? If you do, you're probably not metering the subject correctly. When I meter a scene, I want to meter it without the glare -- that's one of the reasons I use incident metering.

[r.e.]

How to photograph an Aston Martin without CGI, substance from 07:00. Finished photographs at https://www.andreiduman.com/Automotive/thumbs.

Camera: medium format with a PhaseOne back.


https://www.youtube.com/watch?v=mk67nifSI70

[r.e.]

This is a short BTS video for the above Eizo webinar:



https://www.youtube.com/watch?v=LJG52h6aN4Q

[Doremus Scudder]

Several techniques I used to manage proper exposure:

1. I employed use of a 35mm film or digital camera as a meter, placing a Pola filter on that camera.
2. Since exposure loss with pola filters changes markedly to the extent you change amount of polarization, you will have to set the filter to where you see the changes you want in the scene and meter accordingly.
3. Place a comparable pola filter on the LF lens and adjust the amount of polarization to how you set it with the 35mm.
4. Experiment prior to calibrate exposure readings with the LF results. I had a 90mm f8 Nikkor which was always .5 stops darker than the exposure determined with the 35mm. My other lenses needed no adjustment.
5 so this process a. Eliminates having to exposure compensate for the pola filter but you will have to adjust exposure for any calibration differences.
6. Even with the best pola filters, I found color issues when using them in very low light, but this is particularly true with modern day digital cameras.
7. I found old tiffen linears to be somewhat neutral whereas Nikons tended towards blue (cooler) and calumet towards green.
8. Set your pola filter to neutral setting at first and watch change as you turn it. You may find that the slight polar effect at neutral position is sufficient. There is a marked difference between unfiltered clvs neutral position.
9. As Drew mentioned, using pola filters on artificial lighting in addition to on the lens may give you a denser look, something to experiment with.
10. I expect there are other methods of determining exposure compensation for pola filters, but they are not all the same regarding amount of light loss, particularly with the HR thin filters being made now.
11. The range of light loss I found to be between 2/3 and 1.5 stops depending on how much you turn that filter.

I see no reason to go to such complicated lengths to expose through a polarizer.

Just meter through it with your trusty spot meter with the filter oriented to give you the amount of polarization you desire. No need for using a 35mm camera as a meter...

If there is a discrepancy between the meter reading through the polarizer and the actual results, this will be made abundantly clear from your careful field notes. If it is consistent, add an exposure factor to your through-the-filter reading.

Polarizing filters don't change the colors in the scene enough to not simply meter through the filter.

If you shoot color transparency materials, you need to invest in a high-quality polarizer that has little color cast and/or add the appropriate CC filtering when using it.

And, it's easy to determine how a polarizer will render a scene; simply look through it... EZPZ.

Best,

Doremus

[Peter De Smidt]

My experience matches Steve's. We did a lot of the photo work for Pierce fire trucks, Oshkosh Truck, ..... Back in the film days, they were mostly photographed in a large cyclorama, where the entire ceiling was a controllable light source.....These days, they are often photographed in a parking lot using many exposures, all pieced together in post, just like interiors for Gulfstream planes.

[r.e.]

And, it's easy to determine how a polarizer will render a scene; simply look through it... EZPZ.

This is why I'm not complaining about the 112mm (4.4") polariser that I recently purchased for use with Schneider's Centre Filter IVa, or about my 100mm (4") square polariser. When it comes to holding up a polariser to a scene to work out rotation, big is good :)

[cowanw]

The density of a single polarizer, circular or linear, does not change as you rotate it. It always passes the same amount of light, regardless of its rotation.

I have read this before and I have been thinking about this recently and wonder how that can be so if the filter blocks light whose waves are in one or other plane.

[Pieter]

B+W states their polarizing filter factor as 2 to 3 (1 to 1.5 stops), not as a single factor. They also suggest not using a focal length less than 28mm in FF 35mm format, for an even effect.

[LabRat]

B+W states their polarizing filter factor as 2 to 3 (1 to 1.5 stops), not as a single factor. They also suggest not using a focal length less than 28mm in FF 35mm format, for an effect.

Unless you want a big, dark "kidney bean" in the blue sky... ;-)

Steve K

[pdmoylan]

B+W states their polarizing filter factor as 2 to 3 (1 to 1.5 stops), not as a single factor. They also suggest not using a focal length less than 28mm in FF 35mm format, for an even effect.

Exactly.

My method though supercilious gave me precision with color transparency film where even being off by 1/3 stop produces a “throw out”. Those who shoot Velvia know.

[xkaes]

B+W ... suggest not using a focal length less than 28mm in FF 35mm format, for an even effect.

That's a very arbitrary focal length to choose, and only applies to a few subject, like some clear blue skies -- some of the time. I've used polarizers with fisheye lenses, with perfect results, thank you very much!

[Greg]

The density of a single polarizer, circular or linear, does not change as you rotate it. It always passes the same amount of light, regardless of its rotation.

I do agree with Bob that the polarizer always passes the same amount of light, but it has been my experience that areas of the image may change by several Zones (usually becoming darker) and this affects how one takes their meter readings and determines one's final exposure. When I was shooting 4x5 Chromes, the only way that I had gotten accurate exposures was to use my Sinar Six meter with the polarizer rotated in its final position. For B&W I just always used the same loss of 1 1/2 stops.

[Alan Klein]

Exactly.

My method though supercilious gave me precision with color transparency film where even being off by 1/3 stop produces a “throw out”. Those who shoot Velvia know.

So how do you meter with a polarizer like B+W that recommends adjustments from 1 to 1 1/2 stops?

[Pieter]

So how do you meter with a polarizer like B+W that recommends adjustments from 1 to 1 1/2 stops?

Through the filter with a reflected light meter. Or with the meter attached to a camera with a TTL meter.

[Pieter]

That's a very arbitrary focal length to choose, and only applies to a few subject, like some clear blue skies -- some of the time. I've used polarizers with fisheye lenses, with perfect results, thank you very much!

How do you use a polarizer to any predictable effect with a fisheye lens? I assume the filter has to go behind the lens. The unevenness of the effect is because the actual sky light is unevenly polarized and becomes more apparent with ultra-wide angle lenses.

[pdmoylan]

Through the filter with a reflected light meter. Or with the meter attached to a camera with a TTL meter.

Alan,

Having never used a light meter (sacrilege) other than through 35 cameras to meter LF film (and rarely having exposure issues), I am not familiar with other methods. Call me lazy.

I found myself taking a 35mm camera with a 50-55mm lens to use for closeup work not practical with LF.

So I started using it as a meter (calibrating each lens as mentioned above), and added a PL to the process when needed. Mostly matrix meter mode worked out best, spot etc if you prefer.

[xkaes]

The unevenness of the effect is because the actual sky light is unevenly polarized and becomes more apparent with ultra-wide angle lenses.

Call me lucky, I just haven't run into that many instances where I've wanted to have large portions of a color picture being nothing but clear, blue sky that I want to polarize -- and I've spent a lot of time in the desert.

[Martin Aislabie]

Going back to the OP.

Buy a good Polarising filter (B+W or similar)

I find it is best to have the polariser set to something close to mid-point in its effects.

Minimum = almost no effects and maximum = weird, rather dead looking effects.

I find it pays to take a long time viewing the subject through the polariser off camera to find the effect you like and then lining up the filter on camera to the same position.

Other things to look out for :-

Find a suitable uniform dry surface to stand the car on - tarmac or concrete are good - I once shot some cars on gravel and they looked like they had acne.

Almost every car photograph uses some level of matting spray to manage reflections - unless you already have a matt effect car paint.

Don't shoot on bright sunny days - overcast can be good as can the time just before sunrise or just after sunset.

As ever - watch your background - you want to photograph the car not a distracting background - unless you are in to the lifestyle type of photograph/car advert.

Make sure the car you are photographing is scrupulously clean - photographs somehow amplify any dirt or imperfections.

Most external car shots are made from the height of the wheel hub (middle of the wheel) - unless for a specific purpose.

Cars in car adverts have lots of weight inside them to weigh them down to reduce the ride height and the gap between the top of the tyre and the bottom of the wheel arch - otherwise they can look a bit dorky as they seem to be standing on tip toe.

Other than that - take your time and enjoy yourself.

I hope this helps

Martin

[xkaes]

The LAST thing you want to think about is how to get the exposure correct!!!

[pdmoylan]

The LAST thing you want to think about is how to get the exposure correct!!!

Indeed. You've worked so hard to get to the point of taking a nice photo, why mess it up with an exposure mishap. Better to eliminate risk of at least one variable.

[Doremus Scudder]

pdmoylan,

If you carry your 35mm camera with you anyway, then it can function as your meter too, eliminating the need to carry a separate one. Using TTL metering with the camera and the polarizer mounted (along with your "fudge factors*") is a good method to get exposure spot-on. My earlier post may have been a bit hasty; I thought you carried the 35mm camera just for the purpose of using it with the filter, and your lengthy description seemed a bit convoluted.

If you're just using the camera with polarizer mounted as I would reading the scene with my meter through the polarizer, then we're really doing essentially the same thing.

*Still, I'm surprised that you see the need to compensate exposure for this or that lens. The whole point of having f-stops is to be able to have the same setting regardless of focal length, etc. If you find one lens really transmits half a stop less light than others, something is likely wrong somewhere...

Best,

Doremus

[xkaes]

pdmoylan,

If you carry your 35mm camera with you anyway, then it can function as your meter too, eliminating the need to carry a separate one.

Best,

Doremus


Carry a 35mm camera and lens, along with all my 4x5 gear -- instead of a meter. I'll have to weigh that idea -- literally.

[Pieter]

Going back to the OP.

Buy a good Polarising filter (B+W or similar)

I find it is best to have the polariser set to something close to mid-point in its effects.

Minimum = almost no effects and maximum = weird, rather dead looking effects.

I find it pays to take a long time viewing the subject through the polariser off camera to find the effect you like and then lining up the filter on camera to the same position.

Other things to look out for :-

Find a suitable uniform dry surface to stand the car on - tarmac or concrete are good - I once shot some cars on gravel and they looked like they had acne.

Almost every car photograph uses some level of matting spray to manage reflections - unless you already have a matt effect car paint.

Don't shoot on bright sunny days - overcast can be good as can the time just before sunrise or just after sunset.

As ever - watch your background - you want to photograph the car not a distracting background - unless you are in to the lifestyle type of photograph/car advert.

Make sure the car you are photographing is scrupulously clean - photographs somehow amplify any dirt or imperfections.

Most external car shots are made from the height of the wheel hub (middle of the wheel) - unless for a specific purpose.

Cars in car adverts have lots of weight inside them to weigh them down to reduce the ride height and the gap between the top of the tyre and the bottom of the wheel arch - otherwise they can look a bit dorky as they seem to be standing on tip toe.

Other than that - take your time and enjoy yourself.

I hope this helps

Martin

Most car shooters will wet down the road before shooting--it looks much better than dry, and the bit of reflection of the car is nice. Position the camera so the road does not reflect back onto the car, though. I have never shot with a car photographer who used dulling spray--you really want it to look shiny if that is what the surface is. It takes careful camera placement and even lighting (usually from an enormous light box suspended over the car) plus reflectors and flags to do a proper job. And skip the polarizer, you really don't need it. As a side note when car designers make a clay mock-up, they will cover it with the equivalent of a silver metallic paint finish. That has enough reflective qualities for them to evaluate the lines of the car. Dark colors or white don't really work well for that purpose.

[Alan Klein]

Carry a 35mm camera and lens, along with all my 4x5 gear -- instead of a meter. I'll have to weigh that idea -- literally.

I carry an Olympus E-PL1 micro 4/3 which I use for metering, framing, visualization, etc. It's about the same size as my Minolta IIIF Autometer, which I also keep in the camera case.

[pdmoylan]

pdmoylan,

If you carry your 35mm camera with you anyway, then it can function as your meter too, eliminating the need to carry a separate one. Using TTL metering with the camera and the polarizer mounted (along with your "fudge factors*") is a good method to get exposure spot-on. My earlier post may have been a bit hasty; I thought you carried the 35mm camera just for the purpose of using it with the filter, and your lengthy description seemed a bit convoluted.

If you're just using the camera with polarizer mounted as I would reading the scene with my meter through the polarizer, then we're really doing essentially the same thing.

*Still, I'm surprised that you see the need to compensate exposure for this or that lens. The whole point of having f-stops is to be able to have the same setting regardless of focal length, etc. If you find one lens really transmits half a stop less light than others, something is likely wrong somewhere...

Best,

Doremus


Doremus,

The only thing I can attribute the difference to in exposure with the 90 f8 is lower transmission. The lens if I recall is an 8 element biogon design vs the almost symmetrical 6 element plasmats of my other 3 lenses. 1/2 stop add exposure required no matter the shutter speed vs my other lenses.

Used the 90 f8 for maybe 75% of my shots with the 300mm next eventually.

I don’t tend to analyze the whys, just find a solution and stick with it, of course unless someone provides something better.

“Convoluted”, well ok, will edit posts more carefully.

[Drew Wiley]

I have some nice polarizing filters, but other than for cross-polarization of high gloss prints in copy-stand mode, don't use them whatsoever. I live for reflections, even when shooting cars. But I suppose every studio at least needs that option laying around somewhere, just in case.

[Pieter]

I use polarizing filters on lights in combination with a polarizer on the camera for copying paintings. Just need to watch out for color shifts due to the polarizer.

[LabRat]

I tend to just treat a polarizer filter as a 1 stop ND filter, as the extra cut is usually used for suppressing highlights, and usually just partially polarize outdoor stuff, then maybe allow an extra 1/3 stop depending if shadow areas even darken at all...

Used to use cross-polarization in the studio sometimes, which could cut reflections on tough stuff like shooting a plastic bag full of vegetables, but at the cost of subject looking green, maybe covered with spectra, and "dead" looking...

Avoided it for art repo as paintings tended to look "dead" and color shifted... Usually there was a lighting set-up for excessively textured works that could be used instead (like using 2 soft boxes for cross lighting etc)...

Could be useful for copying foto prints with excessive old surfaces, like the surface with concentric rings often on wedding prints...

Polarization could be the disease, not the cure... :-0

Steve K

[Bob Salomon]

Doremus,

The only thing I can attribute the difference to in exposure with the 90 f8 is lower transmission. The lens if I recall is an 8 element biogon design vs the almost symmetrical 6 element plasmats of my other 3 lenses. 1/2 stop add exposure required no matter the shutter speed vs my other lenses.

Used the 90 f8 for maybe 75% of my shots with the 300mm next eventually.

I don’t tend to analyze the whys, just find a solution and stick with it, of course unless someone provides something better.

“Convoluted”, well ok, will edit posts more carefully.

Have you had the shutter speeds on that lens professionally checked?

[Drew Wiley]

It's hard to reproduce paintings well due to the variables of gloss & reflection, impasto, and inevitable hue shifts under polarization; likewise, high gloss prints like Cibachrome, especially when large. When I was involved with paintings at the copy stand, it was mainly forensic anyway, sleuthing this or that art-fakery. Now there are far fancier ways of doing that. With antique photo restoration via re-printing, a polarizer could help by removing the sheen of "bronzing" due to under-fixing or even fire stain.

[LabRat]

Other filters were useful for B/W also... A studio exec from Capitol Records had a stack of badly fading/stained publicity 8X10's all signed by their recording artists to her, but prints were nearly history... I copied them 35mm Pan-X with a stack of 29 red + polarizer, then printed higher contrast to even densities out... She was shocked, said they looked like new!!! ;-)

Steve K

[Drew Wiley]

Yeah, I always had a 29 red filter around the copystand. But my favorite forensic film was TechPan, deliberately engineered for "tech" purposes. For restoration copy work, I generally shot TMax or FP4 in sheet version. My then copy rig could accommodate a Sinar monorail setup. My current setup is way more deluxe, but designed for just SLR's, whether P67 MF or 35mm film Nikon or DLSR. Hope to catalog my personal print collection with it, once I have enough Pepto Bismol on hand to even tolerate working with digital files. Not my cup of tea, though I've done it before, but only web-related, never for original shots per se. Have no interest going there. I built a nice darkroom space for a reason.

[Doremus Scudder]

Doremus,

The only thing I can attribute the difference to in exposure with the 90 f8 is lower transmission. The lens if I recall is an 8 element biogon design vs the almost symmetrical 6 element plasmats of my other 3 lenses. 1/2 stop add exposure required no matter the shutter speed vs my other lenses.

Used the 90 f8 for maybe 75% of my shots with the 300mm next eventually.

I don’t tend to analyze the whys, just find a solution and stick with it, of course unless someone provides something better.

“Convoluted”, well ok, will edit posts more carefully.

I've got the Nikkor 90mm f/8 as well and have never noticed any difference in transmission from my other lenses. It does have a fair amount of falloff, just like other 90s, and I'm in the habit of giving a bit more exposure than indicated when things at the edges are important (I don't use a center filter, but do "center burn" a lot when printing to compensate for the falloff). I might have the lens' shutter speeds checked if I were you. Slower speeds are pretty easy to check by ear.

And go ahead and be convoluted :) There's too much simplification and lack of detail out there these days!

Best,

Doremus

[Alan Klein]

I've got the Nikkor 90mm f/8 as well and have never noticed any difference in transmission from my other lenses. It does have a fair amount of falloff, just like other 90s, and I'm in the habit of giving a bit more exposure than indicated when things at the edges are important (I don't use a center filter, but do "center burn" a lot when printing to compensate for the falloff). I might have the lens' shutter speeds checked if I were you. Slower speeds are pretty easy to check by ear.

And go ahead and be convoluted :) There's too much simplification and lack of detail out there these days!

Best,

Doremus

I use my cellphone to check shutter speeds. I just record the sound and measure the signal using Audacity, a free app. https://www.audacityteam.org/

Here's what the signals look like on a 90mm lens at 1/4, 1/8, 1/15 and 1/2, top to bottom. I've selected 1/8 shutter test the second from the top and highlighted the signal begin and end. The time appears in milliseconds at the bottom 0.124ms which when converted to a fraction is almost exactly 1/8 of a second. (1/8=0.125) The time indicated in the circle is changed to a fraction to check the actual speed. It's good up to about 1/60th. It gets a little flaky above to measure easily. But most of your shots will be at low speeds which are fairly easy and accurate to check.
223205

[Alan Klein]

I was wondering whether this sample picture and recommendation for checking shutter speeds with Audacity should be placed in a permanent section of the forum for others to reference?

[Doremus Scudder]

I use my cellphone to check shutter speeds. I just record the sound and measure the signal using Audacity, a free app. https://www.audacityteam.org/

Here's what the signals look like on a 90mm lens at 1/4, 1/8, 1/15 and 1/2, top to bottom. I've selected 1/8 shutter test the second from the top and highlighted the signal begin and end. The time appears in milliseconds at the bottom 0.124ms which when converted to a fraction is almost exactly 1/8 of a second. (1/8=0.125) The time indicated in the circle is changed to a fraction to check the actual speed. It's good up to about 1/60th. It gets a little flaky above to measure easily. But most of your shots will be at low speeds which are fairly easy and accurate to check.
223205

Yep, I use a similar method, the Shutter Speed app. I have Audacity, so maybe I'll use it as you describe next time and see how the two methods stack up.

Plus, when I have my lenses CLAd, I make sure the tech tests the shutter speeds optically at f/22, a few times at each speed setting, and then sends me the average for each speed in ms. I'll then make a sticker for the lensboard if there are significant discrepancies. I like to round off to the nearest 1/3 stop; that's way close enough for B&W.

I like to have my shutters tested at my average taking aperture because the effective speed changes with aperture, being faster for wide apertures and slower for smaller ones.

Best,

Doremus

[Alan Klein]

I'm sorry you told me that. Now I have to retest all my lenses. I have no idea what aperture I used during testing. :confused:

[Rod Klukas]

And, though someone may have mentioned it, a warning that you should always focus through your filter. If you do not when the filter is introduced, the focus at the film plane will move 1/3 the thickness of the introduced filter. This is a problem which increases as the focal length shortens.

Unfortunately Polarizers are thicker than a UV or even a light colored, same brand filter. When using a Red 25 or 29, for instance, I often focus through a UV of the same brand and model line, filter. Then switch to the darker filter to make the shot. The filters need to match though, for best sharpest results.

Rod

[Doremus Scudder]

And, though someone may have mentioned it, a warning that you should always focus through your filter. If you do not when the filter is introduced, the focus at the film plane will move 1/3 the thickness of the introduced filter. This is a problem which increases as the focal length shortens.

Unfortunately Polarizers are thicker than a UV or even a light colored, same brand filter. When using a Red 25 or 29, for instance, I often focus through a UV of the same brand and model line, filter. Then switch to the darker filter to make the shot. The filters need to match though, for best sharpest results.

Rod

This has been discussed in another thread recently. I learned quite a bit from the discussion.

The upshot seems to be that focusing with the filter in place is not usually necessary when the filter is in front of the lens (i.e., between lens and subject) at "normal" working distances since the focus shift is usually tiny compared to the lens-to-subject distance. Depth of field and depth of focus are usually more than enough to handle the slight shift (which is usually less than normal focusing tolerance when focusing by eye).

However, when working close up, the focus shift introduced by a filter might be significant (depending on magnification), so focusing with the filter in place is a good idea in that situation.

Of course, focusing through the filter if possible, would be the wisest option and reduce the possibility of compounded errors. Using a weaker filter as ersatz for a denser one, even if not quite the same thickness/refractive index, would certainly reduce the error some (if not mostly).

It's all a question of tolerances anyway, especially when we're maximizing the depth of field.

Best,

Doremus

[Drew Wiley]

Amen. Habits which many find perfectly adequate for their own purposes, I happen to find abominable with respect to the significantly greater degrees of magnification in larger prints which often potentially accompany my own needs.

[r.e.]

And, though someone may have mentioned it, a warning that you should always focus through your filter. If you do not when the filter is introduced, the focus at the film plane will move 1/3 the thickness of the introduced filter. This is a problem which increases as the focal length shortens.

Unfortunately Polarizers are thicker than a UV or even a light colored, same brand filter. When using a Red 25 or 29, for instance, I often focus through a UV of the same brand and model line, filter. Then switch to the darker filter to make the shot. The filters need to match though, for best sharpest results.

Rod

As Doremus says two posts up, focus shift is discussed in this recent thread, especially in relation to filters mounted on a rear element: https://www.largeformatphotography.info/forum/showthread.php?166701-Using-a-Neutral-Density-Filter-on-a-Rear-Lens-Element

A lot of filmmaking, including most professional filmmaking, is done without autofocus. I use my Blackmagic camera only with manual lenses. As you suggest in your post, focusing manually through a filter is frequently impractical. Neutral density filters, used constantly with video, are an obvious example. I've never heard anyone, in a video context, suggest that one should focus through a UV or clear filter before adding an ND or any other filter. I also don't recall that advice in the context of large format photography. It's hard to imagine users of Lee Filters and similar systems adopting that procedure.

That said, I don't question that what you are saying has an historical foundation. I'm just curious what it is.

[LabRat]

Add focusing after stopping down with filter on, and things get dimmer...

And for those who like shooting very old lenses, often colors focus differently in those under corrected optics...

Steve K

[Alan Klein]

This has been discussed in another thread recently. I learned quite a bit from the discussion.

The upshot seems to be that focusing with the filter in place is not usually necessary when the filter is in front of the lens (i.e., between lens and subject) at "normal" working distances since the focus shift is usually tiny compared to the lens-to-subject distance. Depth of field and depth of focus are usually more than enough to handle the slight shift (which is usually less than normal focusing tolerance when focusing by eye).

However, when working close up, the focus shift introduced by a filter might be significant (depending on magnification), so focusing with the filter in place is a good idea in that situation.

Of course, focusing through the filter if possible, would be the wisest option and reduce the possibility of compounded errors. Using a weaker filter as ersatz for a denser one, even if not quite the same thickness/refractive index, would certainly reduce the error some (if not mostly).

It's all a question of tolerances anyway, especially when we're maximizing the depth of field.

Best,

Doremus
Do you have to re-tilt as well as refocus?