marnel

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I did a search up on here and couldn't find anything so I thought i'd pass on this cool little trick i learned last night from a buddy of mine who has used them outside of brewing.

Have you ever been trying to get a reading and the contrast line was all blurry and fuzzy making you have to guess at the reading or try another sample. All you have to do is take your hand and raise it above the sample window and between your light source and move it around until the contrast line becomes sharp. I know this will make some readings less aggravating for me

starsailor

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Chalk this one up to stupid pet tricks with optics.

Actually, what's happening here is you have multiple light sources, either light bulbs inside or near by bright reflections outside, that are hitting the input sample prism at different input angles causing slight refraction aberations. By using your hand above the sample window to block some light, you're eliminting some of the off angle light sources thereby eliminating some or most of the aberation, hence a sharper image. A single light source directly overhead would give the sharpest result.

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marnel

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That makes sense, since i only have 1 light source in my brew room and my reading during mash and boil are always perfectly sharp, then i take my OG readings usually at my bar with has many lights, i just always attributed that to all the coldbreak particles that might have been in my sample. Thanks for the insight.

KevinP

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What then is the correct angle for the single light source?

ClaudiusB

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Just turn the refractometer, sample window down and the image will be sharp.
No hand required to block the light.


Cheers,
ClaudiusB

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manoaction

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I'm surprised that they don't make a shade to make sure you've only got one light source coming in at the correct angle. That seems like it should be standard.

samc

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I've found that just lifting the plastic lid and re-seating it does the trick. In my case it has nothing to do with the light source.

rcrabb22

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That could be a bubble in the sample window. Happens to me all the time.

ReefkprZ

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90 degrees from the sample pane, so above and just forward of the refractometer. which is why natural light (the sun) works best, first it contains the full spectrum of light so the light has the most predictable refraction index if you stand and point your refractometer in the direction the sun is while holding it level (in most cases) the angle of light will be roughly 90 degrees from the plane of the sample pane. using another type of light source will only skew the results by an amount smaller than you can probably discern. so dont worry if you can't use the sun. but using a single light source such as an incandescent bulb is better than trying to use a 6 foot long flourescent since the light is then sourced from many angles at once blurring your results.

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