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Unihedron Sky Quality Meter with Lens - Narrow Field of View

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#1 arshadwm

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Posted 22 May 2022 - 09:53 AM

Please advise about 

 

Unihedron Sky Quality Meter with Lens - Narrow Field of View

this is a sky quality meter. Is it worth buying this ? 

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#2 AstroBrett

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Posted 22 May 2022 - 10:19 AM

I use mine extensively. It is one of my most important tools for determining sky brightness. I consider it one of the best investments I have made.

 

Brett


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#3 havasman

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Posted 22 May 2022 - 10:30 AM

Yes, that is the one you want. + everything Brett said.



#4 B 26354

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Posted 22 May 2022 - 10:38 AM

Totally agree with Brett & havasman. I use mine every time I'm out.



#5 Rich V.

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Posted 22 May 2022 - 10:47 AM

I'm glad I have one; it's a useful tool.

 

While two different SQM-L units used side by side may give slightly different readings, they're close enough for my purposes.  My eyes can see that conditions change by the hour over the course of the night, but it's nice to be able to verify and quantify what I'm seeing.

 

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#6 Jon Isaacs

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Posted 22 May 2022 - 10:47 AM

That is the SQM-L 

 

Is it new or used?  I'd be reluctant to purchase a used SQM-L, they're a calibrated instrument and factory new is best. 

 

I bought the SQM-L first, about 5 years ago. My thinking was I could measure regions of the sky and add them up. And I can. But the SQM-L varies depending on exactly where it's pointed and takes time to settle down. And it's not so easy to compare reading with other amateurs.

 

I bought a SQM a couple of years ago and I use it for my site readings. It's a one shot reading, it's settles more quickly and it's easier to compare with others. I mostly use the SQM-L to get an idea of the sky in the local region. I'll hold the meter against the upper cage of a Dob so the SQM-L is pointed where the scope is pointed.

 

Jon



#7 arshadwm

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Posted 22 May 2022 - 07:19 PM

Thank You all. Should I buy narrow or wide angle ?

#8 Jon Isaacs

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Posted 22 May 2022 - 08:20 PM

Thank You all. Should I buy narrow or wide angle ?

 

I personally prefer the Wide Angle as I wrote above.

 

Jon



#9 treadmarks

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Posted 22 May 2022 - 08:53 PM

Thank You all. Should I buy narrow or wide angle ?

The advice I've heard on this is that if you're planning to use this in areas with lots of lights, get the SQM-L. The wide angle version could pick up those lights and distort its readings whereas the SQM-L will do more like a spot reading of what you're pointing at, preferably the sky.



#10 Ihtegla Sar

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Posted 22 May 2022 - 10:17 PM

SQM v SQML? It depends on what you want it for. To compare overall brightness of a site with your online friends or just to get an average reading for a site in one shot, get the regular version SQM. If you want to check how dark it is in a particular area of the sky you are working, get the SQML.

I chose the latter, since I can always take a number of readings in different directions if I want to get an idea what the average darkness is across the sky but more often I like to know how dark it is in the specific area I am pointing my telescope, which is something the SQM cannot do.
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#11 arshadwm

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Posted 26 May 2022 - 05:13 PM

Thank You all. They have three model and I want narrow band. Which one should I buy

nihedron catalog

Sky Quality Meter
$138.00
Sky Quality Meter-L
$155.00
Sky Quality Meter-LU
$218.00

#12 Ihtegla Sar

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Posted 26 May 2022 - 06:13 PM

Thank You all. They have three model and I want narrow band. Which one should I buy

nihedron catalog

Sky Quality Meter
$138.00
Sky Quality Meter-L
$155.00
Sky Quality Meter-LU
$218.00


This one (commonly referred to as SQML) is the version with the narrow field of view:

Sky Quality Meter-L
$155.00

The one that costs $218 has a USB connection, so only get that one if you want to set it up to interface with a computer for automated use, at an observatory or something like that.

#13 phototech

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Posted 29 May 2022 - 01:39 AM

I have the LU and log SQM every 15minutes to a file. I’ve been able to look back over time to see if it’s getting lighter

Also, imaging programs can be told to add the current SQM if you’re are constantly reading it say every 15minutes, to the file name. That will give you an idea of images taken at the darkest time.

The LU doesn’t have a display so you need a computer to read the value

All unihedrin devices are supposed to be calibrated

#14 airbleeder

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Posted 29 May 2022 - 08:21 AM

  I've had a SQML for 3 or 4 years but used it maybe 5 times, less than 10 for sure.  My eyesight has deteriorated but not enough that I can't see when the sky is brighter.




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