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  1. #1

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    Fresnel, some light questions. (Strand Arri etc.)

    Just bought 2, very old but fine working, 2000W Strand-quartzcolor castor Fresnels and some things puzzle me.

    Is there much difference in lens quality between brands?

    1) The beam of a 650W Arri gives much harder shadows than the beam of the Strand. (Both focussed in spot) Is this just the size of the fresnel, 122mm versus 250mm or is the lens in the Arri simply better?

    I figured the Strand would give a bigger parallel beam because of the bigger diameter lens, if you like the fresnel type of light this should give even better results. For example Arri made an ST version of their T series with a bigger diameter lens. But is this more of the good per se?

    2) The Strand has a matt black inside! (Arri is silver/grey) Would it produce noticeable more light after putting aluminium foil on the inside or might this overheat the lamp?

    Any knowledge on these great lights is more than welcome!

    Thanks,
    Quinten

  2. #2
    cscurrier's Avatar
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    There should not be much of a difference between the lens qualities. The size of the fresnel lens is definitely what would be affecting the light qualities. Is the opaqueness of either fresnels equal? Or is the Strand more diffused than the Arri?

    I wouldn't bother lining the inside with foil on the Strand. I don't think it would make a noticeable difference, and on a 2000w light, it could definitely burn the foil or raise the temp inside the house enough to continuously burn out your bulbs. I've seen foil lined 1000w soft boxes burn off the foil... not too much fun.
    "If it can be written or thought, it can be filmed." - Stanley Kubrick

  3. #3
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    The size of the lenses would make a difference to quality of light but most fresnel lenses made for Arri and Strand come from the same glassworks and should have the same manufacturing quality when the lamps were originally sold as new. That said I have seen, over the years, some lenses with a slight translucent quality to them (as mentioned by Cscurrier). Mostly these were replacement fresnels. Apart from the size issue, the other difference might be the reflector attached to the lamp carriage – my Arri's have a polished mirror-like finish alloy reflector while the Strand's that I have are brushed matte-like alloy. Don't forget to check the optical path that may be out of alignment i.e. filament and reflector both centred on each other AND on the middle of the fres. Oh and one last thing which I think might be way too obvious....dust on the inside of the fres. The internal surface bits of the lamp housing would not make anything more than a negligible difference. If you had ultra sensitive foot-candle meter you might see the diff but over all I doubt it. In my opinion though if you are talking about the quality of "hardness" of the light beam you should be observing it at the flood setting rather than the spot. Hope that this helps....p.s. do not forget to lubricate the carriage rails and mech, from time to time with a mixture of kerosine and graphite (the kero will evaporate quickly leaving the graphite in situ). Cheers, Sam
    Last edited by samcomet; 01-11-2013 at 07:29 PM. Click to view previous post history. Reason: spelling

  4. #4
    AgX
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    Quote Originally Posted by Quinten View Post
    I figured the Strand would give a bigger parallel beam because of the bigger diameter lens,...
    Of course a bigger focusing lens is needed to achieve a bigger parallel beam, but typically parrallelity is not the issue with spot lights, but the eveness of lighting and the variability of beam angle.

  5. #5
    cscurrier's Avatar
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    Great maintenance tips, Sam!
    "If it can be written or thought, it can be filmed." - Stanley Kubrick

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    Thanks for the replies! The foil sounds potentially messy, not to think of the glue! Thanks for stopping me from doing that And the about the dust, it might sound obvious but I didn't think of it, those lamps have been hanging under a studio roof for years so little cleaning won't hurt them.

    Do you guys use the fresnels for lighting scenes? ASA 400 seems about the lowest you can shoot with a 2000W key. Wonder what lights guys like Vincent Peters use, he shoots kodak portra 160, but maybe those HMI lights are a different ball game.

  7. #7
    cscurrier's Avatar
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    At work, for commercial/video work, we typically use a 1200w HMI along with some smaller lights for fill/specialty lighting. Sometimes we bring along an additional 1200w or 2000w HMI depending on the scene but still try to bring the exposure down(mainly by either bouncing light, scrimming, or silking the light) so we can shoot f1.8 on our lenses.

    For my own personal analog photography, I like to work with natural light as much as possible. So I guess in other words... I don't shoot with studio lighting much. But on the few occasions I have, I'll just throw up our 1200w HMI(to sort of edge light) and put a silk diffusion in front of it, maybe a half or quarter scrim to cut down on the light a bit, and I'll be shooting between f1.7-f4ish with 400 speed film in my ME Super.

    I don't know if what I just blurted out really helps at all, but I figured I'd share my common uses for studio lights, atleast. Fresnels are great because they are much easier to focus. I would recommend getting some sort of flags/filters/gel set if you don't have some already. Fresnels can be harsh and it's nice to soften them up a bit.
    "If it can be written or thought, it can be filmed." - Stanley Kubrick

  8. #8
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    For what it is worth, in APUG's world, I am a street photographer so I use ambient light when shooting. I am also however a Gaffer/Chief Lighting Technician on motion pictures (35 years now) and use the whole gamut so to speak. I concur with Csurrier having a selection of light modification devices on hand to trim the shapes and/or to soften the output of fresnels. Examples of cutters/flags/nets/kookuloris/wires/bounces/ diffusions are available in images all over the net and can be home-made very inexpensively. Gels for accents or colour temp modification is usually a purchasable item but can he had at film production houses. Gels also last "forever" depending on how they are treated. I notice that you are from A'dam and I have used Het Licht once or twice so they may have some off cuts that they can throw your way instead of throwing in the rubbish bin. Because I am a very "old fart" I have aesthetic tendencies leaning towards bare fresnel lighting....this IS somewhat old fashioned by todays standards but I have noticed that a "retro" look is now coming back into portraiture. There are many picture folios of the old style "noir" lighting looks from Hollywood films and portraitists of yesterday available at the usual internet book places.Just my humble opinion but it's not the light source that is an issue (HMI v. tungsten v. flash) in portraiture but the last thing that affects the light before it hits the subject (be it a naked fres or a frame of diffusion or a bounce board – in pecking order from hard to soft). HMI's produce an extraordinary amount of light for the given current pulled from the electricity source. They are daylight balanced (5500 - 6000º K) and have a CRI (Colour Rendition Index - i.e. the ability to make a red apple appear the proper red) of 95+ (100 being perfect). They are great if you have the $$ (hire or purchase) and the ability to colour balance either the lamp or the camera or the film stock to daylight. I do think that the important concept here though is the placement of the key (lamp height and azimuth) to the sitter. Next decision should be various other lamps to accent – fill, kicker, back, set and other lights as deemed necessary. One last thought though and this again may sound superfluous but many time in my life it was NOT how much light you used to illuminate a subject BUT rather how much you took away with judicious cutting ........ I have seen incredible lighting with just one source but cut up in such a way as to make a breath taking picture. Anyway sorry to all posters and readers fro rambling on like this - can't help being old. I am not sure (like Csurrier) whether I have answered your question or if in fact helped you at all but hey, there ya go! Good luck and cheers for now, Sam

  9. #9
    cscurrier's Avatar
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    Seems continuous lighting is getting more and more popular for still photography lately. I'm happy we have Sam here as a good resource! I've always told young filmmakers that when they find a good gaffer... stick with them!

    I may have to PM you Sam sometime in the future if I have any questions with studio lights!

    Cameron
    "If it can be written or thought, it can be filmed." - Stanley Kubrick

  10. #10
    samcomet's Avatar
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    Cameron,
    It would be more than a pleasure to be of any assistance whatsoever mate!!!! Please feel free, if only for a chat.
    Cheers once again,
    Sam

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