Binoculars with rangefinder - Are they any good and how do they work?

Bilge Rat

Bilge Rat

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Hi,

Wife of Bilge Rat here........... looking for some quality advice from the many forum experts.

I am going to purchase a new pair of binoculars for Bilge Rat (a birthday approaches) and have been looking at the models with rangefinders and compass included. It is obvious how the compass works but can anyone please explain how the rangefinder feature works and also how accurate any result may be.

For the model I am looking at I have a horizontal scale visible through the viewfinder and a vertical scale that intersects this at the half way point. I had a sneaky look at the instructions but they were of no help at all.

Thanks
 
You need to know the height of the object you are looking at to determine the range.Not very useful in practice and the vertical scale is little annoying. It's a feature I would try to avoid if I was buying.

Had a play with a laser rangefinder recently that another boat had. I could measure the front of out boat was 87 m away. The rocks near the back were 56m away etc. could be quite useful on a boat, but not cheap.
 
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My bins (same as http://www.ebay.co.uk/itm/Tasco-Off...Monoculars&hash=item20bcef6422#ht_1525wt_1110) have this (if you mean what I think you do!)
You can work out the distance of an object if you know the size of it, or the size of it if you know the distance. You read from the graticule then convert it on a scale on the body of the bins - you can see the scale round one of the objective lens mounts in the pic on ebay. It's not an active rangefinder like a camera has. (Tasco do not call it a rangefinder, in fairness to them.)
Not a lot of use IMO.
The compass is useful though, again IMO, some opinions differ.
 
Most graticules on binoculars are at 10 mils, or numbered parts thereof.


One mil is one metre height or width at a distance of one thousand metres. If you know the distance, you can calculate the height or width; if you know the width or height, you can calculate the distance.


They are quite useful in finding if you are forereaching on a boat ahead, or whether you are getting closer to a vessel on a fairly constant bearing.


Recommended.
 
Thanks for the feedback

Thinking honestly about using the binoculars on the boat there is a huge variable in how still I can stand and therefore how accurately I can read of the scale initially.

Based on your advice I agree it's something to play with when bored but not something that I would neccessarily use to make navigation decisions unless all else failed.

I like the compass feature and the fact that they are both waterproof and floating but shan't worry too much about the range finder

Wife of Bilge Rat
 
Bilge Rat said:
Thanks for the feedback

Thinking honestly about using the binoculars on the boat there is a huge variable in how still I can stand and therefore how accurately I can read of the scale initially.

Based on your advice I agree it's something to play with when bored but not something that I would neccessarily use to make navigation decisions unless all else failed.

I like the compass feature and the fact that they are both waterproof and floating but shan't worry too much about the range finder

Wife of Bilge Rat
Click to expand...

One word of warning on Compasses. I have a set of Bushnell with a analogue compass (as opposed to digital). They are so undamped as to be useless except at anchor. I have returned them - but they get sent back - no fault found. They do a digital compass as well, but I have not tested that because it did not have a light for night time use. This was their Marine range of Bino's!

I did use a pair of auto damping bins the other day and they were absolutely brilliant - well worth looking at if a bit more in price. But then Bilge Rat may be worth the extra???
 
noelex said:
You need to know the height of the object you are looking at to determine the range.Not very useful in practice and the vertical scale is little annoying. It's a feature I would try to avoid if I was buying.

Had a play with a laser rangefinder recently that another boat had. I could measure the front of out boat was 87 m away. The rocks near the back were 56m away etc. could be quite useful on a boat, but not cheap.
Click to expand...

If you need a laser rangefinder to determine that the rocks are 56m away & your bow is 87m, I think you should reconsider sailing as your chosen recreation!
You should be able to smell the seaweed at that distance & most likely your to F'ing close for comfort! :D
 
I have found it difficult to use the ranging graticule or the compass on mine in anything but very benign conditions as holding a pair of 7x50 still enough is almost impossible. They were a cheap pair though and the compass not damped enough. I think a normal hand bearing compass is as good as anything. If you want to do ranging I think there is something that uses two superimposed images which when aligned gives the range.

On the binos for ranging as everyone has said you need to know the height of the object so headlands, lighthouses, towers etc. where heights are given in almanacs or charts.
 
One way to look at this (pi:)) is as an "aid to navigation" meaning you need to have this feature to determine your location when coastal cruising. Even before Loran and GPS I have found many, many other resources to be able to do so without ever needing this feature in a pair of binoculars. Suggest you spend the money you would for this on a better pair of glasses (i.e., better prism and lenses).

Happy birthday. :cool:
 
alant said:
And the engraved scale does what?
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If you hold a ruler out at fixed distance you can estimate the distance an object is from you providing you know the height or length of an object and measure this height or length on the ruler. Simple geomety. The engraved scale on the binoculars does the same thing, but the added magnification helps make the measurement a bit more accurate.

alant said:
Thats what I said, its simple triangulation, knowing the height of the target.
So, what is different about a laser one?
Click to expand...


The laser rangefinders do not work like this and the size of the object is not needed. They measure the time taken for the laser pulse to travel the distance and give an instant readout. Very impressive in my simple test.
 
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alan said:
Only when you have a flag with a known height, to triangulate with.
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No I think you are mistaken, you can buy smaller version from B&Q that are used for up to 15 metres and Golf ones that cost between £ 100 - £200 that measure directly to target and back.
I do not know the maximum range. Think about 400 meters which would be handy in mooring stern to, knowing how much chain to flake out /drop.
 
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