Luna Pro SCB
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In most cases, you can simply use this reading to get a perfectly exposed picture. However, there are a few situations where the readings should be modified.
When measuring a subject that departs significantly from an 18% reflective surface, you may wish to modify your readings. This is because the reading indicated will make the subject appear on the film as if it were 18% reflective.
The Luna-Pro sbc has a measuring angle of 30° when taking a reflected reading. The light from all objects within that 30° measuring range will be averaged to give you the final reading. If you have one or more objects that are significantly lighter or darker than the rest of the scene, the objects will bias the reading away from the average. In cases such as this, the meter should be moved in closer to the main subjects of interest or one of the accessory spot attachments used to eliminate the effect of the light or dark areas. As an alternative, an incident reading can be taken.
 
In certain cases, you may not want the subject being measured to fall into that category. For example, if the indicated reading is set in your camera when measuring a brilliant white bridal gown, the resulting image of the gown on the film will appear with the same density as if it were 18% gray instead of white. Here again, you may wish to use an incident reading or compensate the reflected reading by increasing exposure. The same is true for very dark objects, i.e., a black tuxedo, except the exposure would be decreased.
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  Reflected readings are particularly useful when trying to evaluate the relative range of reflected light from various subjects that may have different reflectivity and may be receiving different amounts of light. Because the reflected reading measures the light reaching the lens, differences in reflectivity and level of illumination are accounted for. Therefore, you can determine the extremes and distribution of light from the scene just the way your film will record it. This technique is covered in sections Scene Brightness Range and Zone Systems.
 
 


  To utilize this function, you must first determine, by testing the limits of exposure change for highlight and shadow areas from average that are acceptable to you with your film. Once this is done, the calibrated reference scale on the meter will automatically indicate if you are within acceptable limits of the film.

       

         
II. i. Scene Brightness Range
     
In order to assure proper exposures for highlight and shadow detail in scenes with a wide range of light intensity and subject reflectivity, the extent of the lighting range must be determined. The Luna-Pro sbc is ideally suited for this type of measurement because of its null meter design. 4www.butkus.org/chinon
 
  For example, if your testing with a particular type of film shows that you could accept an exposure change from average of UNDER (underexposure) 2 to OVER (over exposure) 21/2 EV, your total range would be 41/2 EV. Using reflected measurement, you could then read the light from the most important area of the scene and then null for that reading. Then, without further adjustment of the calculator dial, you could take light readings from highlight and shadow areas and read the EV variance of these areas. If, in this case, the readings fall within the UNDER 2 to OVER 21/2 EV range, your exposures will be good. However, if for example, your readings resulted in UNDER 3 and OVER 1, you would lose shadow detail, even though the total range is still only 4 EV.
           
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. A simple solution would then be to reread the shadow intensity and rotate the computer dial until the meter needle is opposite 2 on the UNDER side which is within the film limits.
 
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Then recheck the highlights which should now read OVER 2. You would then use the new exposure setting indicated on the computer dial. The scene brightness range has not changed, but the meter has adjusted to your exposure so that you are working within the range of the film. To see this graphically in terms of film response see the H & D curves to the right.
 
It is important to note that this exposure adjustment method works best when using negative films because different density levels can be adjusted for in printing. With transparency films, this type of exposure adjustment should be used very carefully because you are viewing the original without the benefit of printing correction.
 
    With transparencies, about 1 EV is the largest practical shift if your main subject is close to 18% reflectance.

 

Situations may arise where the meter shows a range of light intensity that is beyond the total range of film acceptance. In these cases, the use of fill light to lighten shadows or a "gobo" (a device to block or modify light such as a dark card) to soften highlights may be indicated. When the proper corrective action is taken, the scene brightness
range can again be checked to be sure the limits of the film are not exceeded. Modifying the lighting can also be used instead of shifting the exposure as mentioned above if so desired, as in the case of transparency film where the main subject is close to 18% reflectance such as with some skin tones.
  II. j. Color Crossover

 

  The preceeding discussion concentrated on the effects that lighting can have on film, either black and white or color. However, with color, three separate emulsions are on the film each of whose individual response may be different. In normal exposure situations all three layers will track reasonably well, resulting in accurate rendition of color as well as density. However, at the extremes of exposure levels, deviations in the characteristic response of individual color layers of the film can result in a condition called color crossover. This condition results in a color shift in an area of under or over exposure that cannot be corrected without affecting the colors of the properly exposed areas of the scene. It is therefore very important to avoid this condition which shows itself as color shifts in the shadows and highlights.
   
 
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    II. k. Zone Systems
   
 
    There are times when the lighting range cannot be brought within the acceptable limits of the film because of an inability to fill or use "gobos" such as when photographing landscapes. When these situations arise, the exposure. levels can be adjusted so that the most important parts of the scene receive proper exposure. This can be done with either black and white or color film. However, some detail, either in the highlight or shadow areas, will be lost.
     
       


  central zone determines the amount of exposure correction and processing modification, if any, that is needed. With most meters, the zone equivalents must be marked on the face or transferred to another sheet to correlate with changes in light level. However, with the Luna-Pro sbc, the computer dial can be used to adjust the meter needle to null at any light level. Any subject can be nulled for and light variations from that level read directly off the meter face in EV. This means that you can always set null for Zone 5. Or, you may wish to bias the reading in one direction.
When using black and white film, another technique is available to extend the capabilities of the film to record extreme lighting ranges. It is called the zone system. Instead of relying on standard measurement and exposure techniques, the zone system combines special measurement techniques, modified exposures, and altered film processing to expand the range of light values that the film can accept. In doing so, detail can be recorded which would otherwise be lost.
 
  Simply turning the computer dial of the Luna-Pro sbc allows you to put the meter needle anywhere from -3 to +3 EV from a normal value. With a little practice, you will be amazed at the ease with which specialized information can be gotten.
A complete discussion of this technique is far beyond this manual. References are given in the appendix which should help you become familiar with this very useful photographic tool.
 
  II. I. Film Reciprocity Failure
 
  All photographic exposure meters rely on a principle of film exposure called reciprocity, to function properly. Basically, the film integrates or adds up light during exposure to
The Luna-Pro sbc is well suited for use with most zone systems because of its null meter principle of operation. Most systems are based on a central zone, representing a certain lighting level, called Zone 5. From this level, the range of light from highlight to shadow is measured and referred to this central zone. The level of variance from the
 
  produce the latent image. Within certain limits, the same image density is achieved for short exposures of high intensity as with long exposures of low intensity, as long as the product of intensity
   

times time is constant. When the exposure times get very long or very short, however, this reciprocity effect is lost, and an accurate prediction of exposure, and color balance with color films, cannot be determined solely by the meter reading. It is therefore important to check the instructions supplied with the film in use to determine when reciprocity failure can be expected, how severe it will be, and how to correct for it. Here again the Luna-Pro sbc greatly assists in exposure determination because the corrective filters suggested by film manufacturers to adjust color shifts from reciprocity failure have an effect on exposure. These filter factors can be programmed into the Luna-Pro sbc, and the new, corrected f/stop read directly.
       
 
     
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        Your new f/stop is approximately 4.4.
     
               
      II. n. Intermediate Footcandle Values and Exposure Times
   
      Calculation of intermediate values of footcandles and exposure times is basically the same as calculation of intermediate values of f/stops except that the value square root is replaced by 2 in the formula.
   

             
II. m. Intermediate f/stops
           
The Luna-Pro sbc is calibrated in 1/3 f/stop increments with numerical indications at full stops. A table is included below with the actual numerical values of the 1/3 stop increments listed for levels from f/0.7 to f/128. Values not listed can be calculated from the formula that follows.
         
      For example, you have a footcandle level 1/2 stop above 1000 as represented on the chart on the back of the Luna-Pro sbc.
   
   
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New f/stop = (old f/stop) (v2 (f/stop change))
 
For example, if you wish to stop down 1/4 stop from f/4, take the \f2 which equals 1.414 and raise it to the power .25 which is the decimal equivalent of 1/4 stop..
   

Section
         
        When shooting action, you generally need a faster shutter speed to get a sharp photograph. Speeds from 1/125 to 1/1000 are generally used, with the choice depending upon the relative speed and direction of travel of the object. Objects moving toward or away from you can be stopped with a lower shutter speed than those moving across your field. To create a more realistic feeling of motion with objects moving across your field, use a slower shutter speed and pan across the field. When panning, the relative speed between the subject and the camera is decreased while the relative speed between the background and camera is increased. This results in the characteristic action shot with the main subject sharp and the background blurred.
  III
         
               
    Helpful Hints
     
    Ill. a. Choosing Between Action Stopping
Ability and Depth-of-Field
 
    After taking a light reading with your Luna-Pro sbc, you will have a choice of readings to use which may look like this:
 
      For shutter speeds of 1/60 second and longer, the use of a good tripod or other camera support is suggested to avoid camera shake and blurred pictures.
               
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      When subject speed is not a major factor in your pictures, you may wish to choose a longer exposure time and stop down for maximum depth-of-field. This extra depth may be especially important when using long lenses because of their relatively shallow depth-of-field. However, with long lenses, camera shake is accentuated so be careful to use a sturdy support.
    All of them will give good exposures, but, in terms of photographic results, they are all slightly different.
 
   
 
      Conversely, even when subject speed is not a major factor, you may still wish to choose a short shutter speed and a larger lens opening to intentionally limit depth-of-field for selective focus. This is especially useful for eliminating the distraction of cluttered backgrounds. Portraits lend themselves ideally to this technique. 4www.butkus.org/chinon


  III. c. Sunsets
   
  Sunsets can present a problem in light measurement because of brightness range. Sometimes, the sun itself is the most important part of the scene, and at other times, light reflecting from clouds or distant mountains may be more important.
       
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III. b.
   
Snow & Sand
 
When photographing with highly reflective surfaces such as snow and sand, extreme care should be used when using reflected readings. In most cases, an incident reading will produce superior results for normal subject in the scene, although the snow or sand may be overexposed. If reflected readings are desired, the main subject should be metered up close or a spot attachment used to minimize the effect of the reflected light, unless the snow or sand is itself the most important part of the scene. This is an ideal time to use scene brightness range measurements.
 
  You should first determine what part of the scene is most important. Using an incident reading under these conditions will generally give you poor exposures with washed-out colors. Reflected readings are more accurate, but some compensation is still necessary for the sun or sky. When the sun is present and most important, read the sun directly and use that exposure. If the sky and clouds are most important, read these areas, being careful not to read direct sunlight. In all cases, if practical, bracket exposures on both sides of those indicated. You may get some very striking results that are not apparent to the unaided eye.
           


  Generally, in outdoor scenes, the lighting is not as uniform as with daylight. Bright artificial lights can create multiple highlights and shadows, with a tremendously large brightness range. in addition, direct use of the meter readings will result in a picture that appears more like a daylight photo than one taken at night.
  Generally, night exposures get into the area of film reciprocity failure. It is therefore important to know the characteristics of your film before shooting under these conditions.

     

       
III. d. Night Lighting
    After taking film reciprocity effects into account, decrease your indicated exposures by 1/2 to 1 stop to preserve the night appearance in your scenes.
Measurement of illumination levels at night presents several problems to good exposures.
 
       
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  III. e. Backlighting
 
   
  When the main subject of interest is backlit, care should be exercised when taking reflected
9a
           

readings. Light from behind the subject entering directly into the measuring cell of the meter will produce reading errors. To avoid this, take your readings up close to the subject or use one of the spot attachments for more accuracy. An incident reading can also be used, with the meter pointed toward the camera. For the most accurate exposures, measurements should be made as described in the section, Scene Brightness Range. 4www.butkus.org/chinon
  For copy work, the Luna-Pro sbc can be used with the copy attachment for determining exposure and checking evenness of illumination.
 
                 
         
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          Ill. g.
 
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        Excessive Skylight
        When taking reflected readings of scenes where there are large areas of skylight, care should be exercised that the main subject be given the greatest attention either by tilting the meter down taking up-close measurement or by using one of the spot attachments. As an alternative, an incident reading may be used.  4www.butkus.org/chinon
 
Ill. f. Copying
       
Copying places stringent demands on lighting to make sure that the detail and tonal range of the original is recorded on the copy. Lights are usually placed to the sides of the copyboard to eliminate glare from the surface of the copy. Many people prefer to overlight the corners of the copy to compensate for lens falloff. The exact amount of overlighting varies with the individual situation, but 15-20% is common.
   
 
           
 
             
  Ill. h. Bellows [Extension] Factor
     
  When photographs are taken where the focus is a point other than infinity, an exposure correction must be made. At most working distances, the correction factor is so small that it can be ignore
   

However, when working at very close distances, it becomes significant and can result in serious exposure errors if not corrected for. This exposure variance is commonly called extension factor or bellows factor.
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    For example, assume a 210mm lens (approximately 8") is being used with a lens to film plane distance of 14".
 
There are several ways to correct for this effect. Two of the most commonly used take into account the lens focal length and the lens to film plane distance (bellows extension).
     
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The first method gives you an extension factor which can be programmed into the exposure factor ring of the Luna-Pro sbc for direct readout of corrected exposure values. The second method gives a corrected aperture only.
       
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      In this case, set the white index mark of the exposure factor ring opposite the number 3. Note that the exposure factor portion of the ring (numbers in black) should be used, not the EV position. All readings will now be corrected for this extension factor.
 
           
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For example, assume the same conditions as in Example I with an indicated f/stop of f/11
  To calculate the extension factor, measure both the actual object size and the size of the image on the ground glass. These two measurements are used in the formula below
Effective Aperture = (14) (11)
                                           8
     
       
             
 
  = 154
   8
         

                                 2
(EF
=(Image Size +1)
           Object Size

   
    =19.3 or approximately 20       
     
                           
    For example, assume an object size of 2 inches and image size of 4 inches.
In this case, if the lens were set to f/8, the exposure level would be the same as if the lens were set to f/20, although, depth-of-field would remain the same as for f/8. Using this method, each time a different f/stop is chosen, the same amount of correction must be recalculated into the exposure. The first method in conjunction with the exposure factor ring of the Luna-Pro sbc is much quicker and more flexible because once the exposure factor is programmed, all subsequent readings are corrected for with additional calculations and in terms of all values, not just f/stops.
 
           
  Setting 9 in the EF correction ring of the Luna-Pro sbc will give correct exposures for this condition.
  Extension and filter factors can be eliminated from exposure reading by using the accessory fiber optics probe and reading on the camera groundglass. Any changes due to these factors will automatically be sensed and compensated for by the meter.
Another way to determine extension factor is to measure the magnification of the object size at the film plane. This is especially useful when working with large format cameras where measurement of the image on the ground glass is relatively easy.
 
           

Section
Accessories
All of these excellent features are only the beginning of the Luna-Pro sbc story. The wide range of instantly interchangeable accessories set the Luna-Pro sbc distinctly above any other light measuring instrument. And, to make them even more practical, several of them automatically reprogram the meter response for direct reading. With these accessories, you don't have to match special marks or lines to get the right reading. Just attaching the accessory and proceeding with the reading in a normal manner is all that's necessary!

Luna-Sphere Studio Accessory
When working in the studio or with multiple sources of light, many professionals prefer to measure incident light for exposure determination. This can be done with the basic Luna-Pro sbc, but for greater convenience, the Luna-sphere combines its large integrating sphere with a 360° swivel head
plus capability for a flat plane diffuser into one convenient accessory. For photometrically accurate measurements of footcandles or Lux, readings must betaken on a flat diffused plane. The flat diffuser supplied with the Luna-sphere makes these measurements possible, and without affecting calibration of the instrument. Footcandle measurements are preferred by many cinematographers and lighting engineers. Others prefer to use the flat diffuser simply because it is more directional for incident light than diffusing sphere. The Luna Sphere automatically adjusts the meter sensitivity when in use.
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Spot Measuring Attachments
Because of its unique versatility, the Luna-Pro sbc System can readily cope with situations whichb make it desirable to use reflected light measuring angles of less than the meter's standard 30°. These are two accessories which will decrease the measuring angle for "spot" readings.



  have the advantages of a separate 1 ° spot meter for your Luna-Pro sbc, and it automatically adjusts the meter sensitivity when attached.
         
                   
Multibeam Spot Attachment
      Variable Angle Attachment
   
For even greater selectivity, the Multibeam ® Spot Attachment for the Luna-Pro sbc provide not only 15° and 7.5° measuring angles but, in addition, a 1 ° angle for ultra precise exposure measurement. The single lens reflex design permits measuring and viewing through the same lens, eliminating parallax problems which can cause measuring errors with twin lens 1 ° spot meters.
  The modestly priced Vari-Angle Attachment locks instantly onto the Luna-Pro sbc (or regular Luna-Pro) and provides convenient selection of either 15° or 7.5° measuring angles. For reflected light readings, the normal measuring area corresponds to a light acceptance angle of 30°. A
built-in   reflex   viewfinder showing the 15° and 7.5° measuring area permits accurate measurements for exposures with telephoto lenses and selective readings of various parts of the scene or subject when, normal lenses are used.

         
The Multibeam® Attachment focuses from infinity to 1.5 feet for maximum measuring accuracy, and provision is made for eyepiece correction. With this attachment, you    Picture      
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Flash Attachment
Electronic flash has become an extremely important source of controlled lighting in the studio as well as on location. Previously, standard meters designed to measure continuous light could not measure the short, extremely bright bursts of light from such flash units. Now, however, the flash attachment converts your Luna-Pro sbc into a high quality electronic flash meter! Employing many of the engineering concepts of the precision Gossen Mark II electronic flash meter, this accessory can operate either as a cord-connected or cordless meter to measure single or multiple flashes.

After the meter is turned on, any flashes within a two minute period can be measured and stored. Light emitting diodes indicate readiness and activation. The two minute operating cycle can be terminated for individual single flash readings.

When multiple flashes are required to achieve correct exposure at a desired f/stop (e.g. for greatest depth of field in interiors or other still subjects), the readings of successive flashes are automatically accumulated within the two minute cycle to indicate to you how many flashes are necessary for the desired result.

 

Because, with this attachment, the Luna-Pro sbc integrates and measures the total flash - not just the peak intensity - it is accurate with flash units having varying flash durations. Measurements can be made with durations as short as 1/100,000 sec., making the meter suitable for all commercial and amateur flash units, including those with automatic circuits. The attachment automatically adjusts the meter sensitivity.
 

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Microscope Attachment
The Microscope Attachment utilizes the Luna-Pro sbc measuring sensitivity for convenient and reliable exposure measurement when taking photomicrographs.
 
     
 
             
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The Microscope attachment fits the ocular tube of most microscopes for exact exposure determinations, and is useful in measuring light intensity for fluorescent microscopy. Sensitivity adjustment is auto
material to be copied. It can also be reversed for measurements of light transmitted through slides or other translucent material being copied.
         
           
    Enlarging Attachment
 The Enlarging Attachment will help eliminate guesswork in darkroom printing. It determines contrast range and
correct exposure time by measuring the projected image on your enlarger easel. After calibrations for paper speed, direct readings of aperture and exposure times are possible, resulting in savings of time and material.
 

 



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Repro [Copying Attachment]
   
With the Repro Attachment on the Luna-Pro sbc, it is possible to obtain exposure values of flat copy such as paintings, documents, and photographic prints.
 
The illumination on the copy board can be measured for evenness of various points on the
 

 

Fiber Optics Probe Attachment  
With the flexible Fiber Optics Probe Attachment on   
Luna-Pro sbc, measurements can be made in many areas which are usually inaccessible with an exposure meter. It is especially suitable for macrophotography groundglass measurements, density measurements on negatives or transparencies, and for luminous density measurements. Sensitivity adjustment is automatic. These accessories make the Luna-Pro sbc the most versatile and complete systems meter available today. And, because it is a true system meter where the accessories interface with the meter electronics, future advances in light measurement techniques can be accommodated.
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Your Gossen Luna-Pro sbc is your valuable precision instrument, made with great care and accurately calibrated. It deserves your good care!
The battery and zero position tests described on page 5 enable you to check the proper functioning of your Luna-Pro sbc. If meter is to be stored for extended periods of time, remove the battery from the meter.
Measuring comparisons of your Luna-Pro sbc with similar or other types of exposure meters cannot be made properly without special laboratory equipment (optical bench).
Do not attempt to open or repair your Luna-Pro sbc. Service information appears on the following page.

Service  
 
Should your Luna-Pro sbc require service, send the meter (directly or through an authorized dealer), in the original packing if possible, prepaid and insured, to:
    Gossen Service Center
       
    Berkey Marketing Companies
     
    25-20 Brooklyn-Queens Expressway West Woodside, New York 11377
   
    Gossen Service Center Berkey Marketing Companies 1011 Chestnut Street Burbank, California 91506
     

A brief description of the reason for sending the meter should accompany the package.


Specifications
   
         
EV Range   ASA 25 - 6 + 15
Response Time   1/1000 Sec.
Photo Cell   Silicon Blue Cell
Angle of Coverage    30' Reflected 180o Incident
Sensitivity   016 to 32,000 footcandlesin one range
Power Source    9 volt Eveready Battery - or 9 volt Mallory Duracell O Alkaline Battery or equivalent.
 Battery Type #M N1604
Dimensions   43/4x13/4 x23/4
Weight    81/4 oz. with battery
Scale Ranges:
     
Cine Range    4.5to144fps.
Exposure Value Range   -8 to +24
Shutter Speeds    1/4,000 Sec. to 8 hours
Lens Aperture   f/0.7 to f/128 Exposure Factor Scale ... Plus/Minus exposure indicated in EV; Plus exposure indicated in Exposure Factor
ASA Range   0.8 to 100,000

Additional Reference Material
   
                 
Eastman Kodak Co. Kodak Publications
            Stroebel, Leslie; View Camera Technique; Hastings House Publishers, Inc.; New York, New York 10016
Rochester, New York 14650
         
  KODAK Professional Photo Guide R-28
    Zakia, Richard and Todd, Hollis; Photographic Sensitometry; Morgan and Morgan, Inc.; Dobbs Ferry, New York 10522
  KODAK Professional Black and White Films, 2nd Ed. F-5
 
  KODAK Color Films, 6th Ed. E-77
      Sturge, John; Handbook of Photography and Reprography Materials, Processes and Systems; Seventh Edition; Van Nostrand Reinhold Co.; New York, New York 10001
  Sensitometric and Image Structure Data for KODAK Color Films E-78
 
  Basic Photographic Sensitometry Workbook 2-22-FD
 
    Stimson, A.; Photometry and Radiometry for Engineers; John Wiley & Sons, Inc.; New York, New York 10016
  Lens Extension Tables P-300
       
  KODAK Plates and Films for Scientific Photography P-315
 
    Dowdell, J. III and Zakia, R.; Zone Systemizer; Morgan and Morgan, Inc.; Dobbs Ferry, New York 10522

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