finding distance to object: I had a search already I cant see an answer. I want to do a composite picture of a fishing boat going across a harbour. I want the boat in full focus.but...

steve7cat Loc: Swindon uk

I had a search already I cant see an answer. I want to do a composite picture of a fishing boat going across a harbour. I want the boat in full focus.but the aperture as wide as possible to avoid blur. I have a depth of field calculator but I would need to know the distance to the boat is there an easy way or device I can use in the field to determine this?
thank you

boberic Loc: Quiet Corner, Connecticut. Ex long Islander

steve7cat wrote:

I had a search already I cant see an answer. I want to do a composite picture of a fishing boat going across a harbour. I want the boat in full focus.but the aperture as wide as possible to avoid blur. I have a depth of field calculator but I would need to know the distance to the boat is there an easy way or device I can use in the field to determine this?
thank you

Go to a Golf shop and look at a rangefinder. But the question is why do you want a wide aperture. The best way to avoid blur is with a faster shutter speed.

steve7cat Loc: Swindon uk

thank you i will have a look on ebay now. If I have a wide aperture that will increase the shutter speed, If it still blurs I would have to up the iso but I like to leave that as low as I can.

steve7cat Loc: Swindon uk

ah I had a look at the price, I think I need to find someone who likes golf and borrow one for the day.

rmalarz Loc: Tempe, Arizona

Faster shutter speeds require a larger aperture with a fixed ISO.
--Bob

boberic wrote:

Go to a Golf shop and look at a rangefinder. But the question is why do you want a wide aperture. The best way to avoid blur is with a faster shutter speed.

steve7cat Loc: Swindon uk

yes

steve7cat Loc: Swindon uk

i have just found you can hire a rangefinder for £8 a day that will do nicely

ggttc Loc: TN

There are smart phone apps for that purpose but I haven't found one that is reliable. Go to google play store and look around.

steve7cat Loc: Swindon uk

ok how does it do that?

Apaflo Loc: Anchorage, Alaska

steve7cat wrote:

I had a search already I cant see an answer. I want to do a composite picture of a fishing boat going across a harbour. I want the boat in full focus.but the aperture as wide as possible to avoid blur. I have a depth of field calculator but I would need to know the distance to the boat is there an easy way or device I can use in the field to determine this?
thank you

Don't waste time and effort!

First, your camera will tell you the distance close enough to do this calculation. First you can just look at the distance scale on the lens, but you can also check the Exif data for focus distance.

But second, try a few experiments with a DOF calculator. Say for example your boat is 200 meters away, with a 100mm lens shooting at f/2.8 the DOF is from 75 meters to infinity! If the lens has a 600mm focal length, shooting at f/4, at a 500m distance the DOF is almost critical... 26 meters deep. Anything more reasonable, and the DOF is even greater.

The point is you don't need to calculate it, because it would require contriving something highly unusual to arrange a circumstance that gives too narrow a DOF.

steve7cat Loc: Swindon uk

thank you

John N Loc: HP14 3QF Stokenchurch, UK

If the measurement is not to critical (I'm guessing you are moving towards the infinity setting) and you know roughly where the boat is and where you are going to stand you can position it on google maps and get an as the crow flies distance.

steve7cat Loc: Swindon uk

Thank you everyone, lots of different ways to find the distance, i played with the DOF calculator, and the distance scale on a couple of my lenses, which I had never looked at before, it looks like the lens is accurate enough measure of distance. I can only guess the distance from home. but if I use my maximum aperture of f3.5 if the boat is only 50 metres out . I would have a depth of field of 40 metres which is plenty for a small fishing boat.I will look at google maps, I can get a good idea of the scale from home.

Architect1776 Loc: In my mind

steve7cat wrote:

I had a search already I cant see an answer. I want to do a composite picture of a fishing boat going across a harbour. I want the boat in full focus.but the aperture as wide as possible to avoid blur. I have a depth of field calculator but I would need to know the distance to the boat is there an easy way or device I can use in the field to determine this?
thank you

Laser range finder.
Use one all the time to measure buildings to the 1/32 inch.
Leica makes a great one.

BebuLamar

Architect1776 wrote:

Laser range finder.
Use one all the time to measure buildings to the 1/32 inch.
Leica makes a great one.

The most only about 300ft. I think the OP needs to measure further away.