Estimating the distance of an object?

[l2oBiN]

I would like to know how can i accurately estimate the distance of an object I am trying to photograph, or how could I accurately say at what distance is the camera focused on?

[BetterSense]

http://www.bhphotovideo.com/c/product/481597-REG/Bushnell_201916C_Yardage_Pro_Sport_450.html

[Bruce Watson]

How about a laser tape measure (http://www.amazon.com/gp/product/B000BDIRYC?ie=UTF8&tag=wwwgalttechco-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000BDIRYC)? Good down to about 50 cm or so. If you need shorter than that, use a tiny steel tape. You can get both at your local hardware store, or at least your local big-box hardware store.

[domaz]

Or an old accessory (non-coupled) rangefinder like this (http://www.etsy.com/listing/55876778/vintage-hugo-meyer-pocket-range-finder?ref=sr_gallery_3&ga_search_query=rangefinder&ga_search_type=vintage&ga_page=&order=&includes%5B0%5D=tags&includes%5B1%5D=title).

[Vaughn]

35mm or MF camera -- focus and read off the distance.

Try to guess the distance before using the camera/rangefinder or whatever you use -- do it enough and you'll be able to guessimate rather accurately.

[ic-racer]

Calibrate your own intraocular distance an use your eyes and a paper scale as a rangefinder. :
http://photo.net/minox-camera-forum/003HEV

[Brian Ellis]

How far is the object and how precise are you trying to be? I sometimes estimate things up to about 50 yards away by envisioning the 10-yard markers on a football field and counting. More than about 50 yards and I don't bother.

[Steve M Hostetter]

you can always step it off.. each step = 1 yard or 3'-0"

[GPS]

you can always step it off.. each step = 1 yard or 3'-0"

Not at all always! Not on water, not through thorns, not behind a fence... etc.:(

[Vaughn]

I imagine hunters must have several products for determining distance.

Just checked -- can be expensive! But they had one for $120 that was within a yard for up to 400 yards. But there was one for $1000 -- same accuracy but for up to 1500 yards...a bit of an over-kill for photography!

[jnantz]

golfers use a distance scope -
i think they sell for less than 20$ ...

[Caivman]

Golf supply stores carry various "ultrasonic" rangefinders... if you're looking to shoot something a fair distance away.

*see above post*

[Richard K.]

I would like to know how can i accurately estimate the distance of an object I am trying to photograph, or how could I accurately say at what distance is the camera focused on?

Hmm...nobody asked why? So I will. Why?:) I'm assuming not for bellows extension corrections?

[Drew Wiley]

A decent laser distance meter will cost about $150 and be accurate within a millimeter
in a hundred feet. Buy a respectable brand like Leice, Stabila, Spectra, or Bosch. Avoid
like the plague anything that says Stanley on it. Ultrasonic meters are useless for any
kind of real accuracy.

[Richard Mc]

I did the research on this about a year ago.

I found that most of the laser distance measurers for the building industry are useless outdoors in sunlight as it is very difficult to see the laser dot, so you can't tell what you are measuring.

Leica Disto has a couple of models that have a small camera incorporated in the design and show you what you are targeting on the screen with a little crosshair - these models work very well but are not cheap. They have a range of maybe a couple of hundred meters but are very accurate.

If you have some building project at home, maybe one might qualify for a tax deduction.

Then there is the golf/hunting style laser distance meters - these are usually a monocular about the size of a small pair of binoculars. They have a crosshair in the view and aim the scope by looking through it. The best ones can accurately measure distance out to 2km )which is about 1.5 miles) without a special reflective target - anything further than this is likely to be "infinity" as far as any depth of field calculations or dial settings on the lens. I found the best of these was the Laser Technology TruPulse 360.

Here's the website :

http://www.lasertech.com/TruPulse-Laser-Rangefinder.aspx

I won't go over the specs - you can read that on their website.

I bought both a Leica for short distances and the TruPulse for longer distances.

I am very happy with my purchases, though not cheap I have never regretted buying them.

It's not for everyone - some purists may say that it takes away the "art" of guessing distance, but I am a fairly technical person and when setting up a shot I like to use my iPhone to work out exactly where my depth of field limits will be with a particular film format (circle of confusion), focal length, subject distance and aperture.

There are also some manual methods army artillery guys use that are kind of handy - the best one involves measuring your interpupillary distance, then looking at an object in the distance with one eye while holding your index finger upright at arms length in line with the object. You then swap eyes and estimate the distance on the ground at the target between the two "images" of your finger. This might require there to be some size reference close to the target (such as a person, light pole, house, car etc.). Then a simple arithmetic calculation will give you the distance to the target. You can calibrate this method to your metrics (interpupillary distance) with a laser distance meter and get results within about 10%... if you google it there is plenty of info.

Hope that helps.

[aduncanson]

OP, You do not exactly say, but you seem to want this capability for focusing the camera. Have you considered what your accuracy requirements are based on depth of field equations?

At f/16 the hyperfocal distance for a 210mm lens is something like 101 feet or 31 meters. In focusing there is not a lot of value gained by measuring the distance to a subject at the hyperfocal distance more accurately than 10%, and at greater distances the accuracy becomes even less critical. Accuracy at close distances is far more critical. Of course, if you intend to be shooting at larger apertures, your requirement for accuracy at large distances becomes more stringent, but they still fall off quickly as the distance increases. The accuracy requirement can be estimated by looking at the change in subject distance that corresponds to a change in image distance equal to 1/20 of the focus spread (http://www.largeformatphotography.info/fstop.html).

My point is that systems like laser rangefinders that are engineered to provide accuracy to a fraction of a meter at distances of hundreds of meters may be the wrong solution for your purposes. Good old parallax rangefinders are at their best at close distances and have served photographers well for something like 100 years.

[l2oBiN]

Thank you all for your input. As many of you have guess I am interested in marrying the hyperfocal distance and focusing the camera to accurate measurements of the distances. I was initially thinking of the digital rangefinder but now, an interest in a reflex based rangefinder arises. I have not heard of these. How do they work? Is there a good model to look out for?

[BetterSense]

They work through optical parallax. There are some sold for archery and some sold for golfing. You can make a reasonable parallax rangefinder out of cardstock with peep-holes in it, as someone has already mentioned.

[aduncanson]

Looks like the Fotoman rangefinder (http://www.fotomancamera.com/Specials.asp)is still available.

[l2oBiN]

Do they only come in feet? I would like one in meters

[aduncanson]

Do they only come in feet? I would like one in meters

The illustration is in feet but originally they came both ways. I interpreted the page to say that this was the version in meters since it said "Auxiliary Rangefinder (Meters)" and "(ARF-M) 1 meter to infinity".

Contact Fotoman for any necessary clarification.

[Richard Mc]

If you are into the idea of a completely battery free, optical only, and reasonably accurate method of rangefinding, you could always look at what the army did before laser rangefinders became commonplace.

Have a look at Wikipedia under :

coincidence rangefinding

and

stadiametric rangefinding

The Fotoman rangefinders use the coincidence method but the small size limits accuracy. Coincidence rangefinders used by the army are about 3 feet long (there is a picture of one on the Wikipedia page) and have far greater accuracy but sacrifice some portability, but they are pretty cool if you like that sort of thing.

Stadiametic rangefinders require some object of known size (eg. person, car, power pole etc.) to be in the field of view at the target distance. Most sniper rifle sights have a mil-dot reticle used for this purpose. So one of these gun sights might make a relatively portable and battery free rangefinder for photography but in the US you might get a call from Homeland Security if you try to buy one ;-).

[Leonard Evens]

I finally got myself a laser measuring device, which I use only for very special purposes. But for most purposes, you don't need to know the distance of a subject very accurately. Everything you need to know is present in the camera. For example, depth of field can be determined entirely by looking carefully at what you see on the ground glass or by making relatively simple calculations based on bellows extensions when focused on near and far objects.

For what purposes do you need to know subject distances?

[l2oBiN]

Fir judging focus planes and hyperfocal distance.