Do You Think This Tool Might Be Useful?

[rpcrowe]

I use a lot of manual focus lenses, most of them are vintage but, some like the Rokinon 12mm f/2.0 are modern lenses which do not have auto focus capability...

Of course, using my Sony APSC cameras, I have both focus assist and focus peaking to assist me when I focus manually. However, I suspect that this little device might be a handy tool when using a manual focus lens...

What do you think?

https://www.amazon.com/Stanley-STHT7...r=8-1-fkmrnull

This specific model measures up to 30 feet. It looks interesting because of its diminutive size. There are several other models which can measure longer distances and which are being sold at different prices.

One thing would be a no-no and that is measuring the distance from camera to subject's eyes using this laser. The reason should be self evident...

[Shadowman]

I think it would be useful, I bought one about two years ago and use it often, I've even used it to help calibrate my projector as my Colormunki is designed to be positioned at a specific distance from my viewing surface.

[pschlute]

For manual focus nothing beats using your camera in Live View mode zoomed to 100%

[Shadowman]

For manual focus nothing beats using your camera in Live View mode zoomed to 100%

Live view only works for the initial focusing, in Richard's case he is focusing on a person's eye and if they move one cm the focus would be so off, he needs to position the model and not have them move until he clicks the shutter. A slow process but sometimes necessary depending on the DOF.

[mikesan]

So this gadget will give you the distance with an accuracy of 1/4". What are the chances that you can set your lens focal distance with anywhere near that accuracy?

[Stagecoach]

However, I suspect that this little device might be a handy tool when using a manual focus lens...

What do you think?

So you take a measurement from sensor plane to subject and the device gives you an extremely accurate reading of 13ft 9 and a 1/4 inches.

Is 13ft 9 and a 1/4 inches marked on the distance scale of any manual lens you have? No, and it's very unlikely you will be able to guesstimate between any markings with any accuracy, and that's assuming any lens marking are accurate.

This of course being more applicable the closer and wider you are shooting

[xpatUSA]

For manual focus nothing beats using your camera in Live View mode zoomed to 100%

Agreed Peter and, for me, magnified view ... none of this wimpy 100% stuff.

My eyes are getting bad enough to make old-style manual focusing quite difficult.

[rpcrowe]

It seems like this might be helpful in prefocusing when you expect to shoot action or a moving subject... Of course, you would not focus to 13 feet 9 and 1/4 inches but prefocusing to 3 meters would put me right in the ballpark. Several of my older manually focusing lenses have distance scales that are far more useful than those usually found on auto focus lenses. They also have DOF scales on these lenses. It is easy to find the hyperfocal distance with these DOF scales. Like my 135mm Zeiss Triotar which has a hyperfocal distance of abut 22.5 meters which will put you in focus from 10 meters to infinity. You don't need to know the exact hyperfocal distance, simply place the appropriate f/stop scale line to the right of the focus point on the infinity mark and you will see the closest point of focus at the appropriate f/stop line to the left of the focus point.

The old Triotar has a 270 degree focus throw between the closest point of focus at 1.5 meters and infinity. Plenty of room to be somewhat accurate even between the marked points. As an example there is about one inch of throw between 1.5 meters and 2 meters plenty of room to fairly accurately guesstimate the focus point...

[loosecanon]

The distance scale on a lens is only a rough guide, one reason why its not a graduated scale. Temperature, filters, zoom level annd general construction variability all mean it is a indication of where focus is. Focus any autofocus lens and look at the scale to see where it indicates. This is one reason what the infinity setting is beyond infinity otherwise adding filters or hot weather would prevent using the lens at infinity.

[Manfred M]

This is certainly not a tool I have ever seen an experienced high-end photographer use. I suspect it is because it doesn't work.

Who cares what the distance scale on the camera reads? What we want is a sharp image. How do we guarantee a sharp image? Shoot tethered on a large monitor (by viewing the image at 100%). High end shoots will have a digital tech monitoring the shots as the photographer is doing his work and feeding back to the photographer. Lower end stuff, the photographer is checking this for himself.

I do shoot tethered when working on assignments and it is the only reliable way of confirming the images are sharp.

[dem]

Three reasons why knowing that your subject is 2.45 meters away from the sensor is not going to help manually focusing an adapted lens.

1) Since the lens adaptors are often slightly off their perfect length, the lens marking on the adapted lenses is also off. This is especially noticeable for wider lenses, anything shorter than 28 mm. I have lenses that don't focus at infinity because the adaptor is too long or focus on infinity when the lens marking is showing 15 meters because the adaptor is too short.

2) the distance markings are sparse - there are no marks between 2 and 3 meters.

3) the distance markings are not linear - if there was a 2.5 mark, it would have been much closer to 3 meters than to 2 meters.

After some practice with a given lens+adaptor combination you can get the focus pretty accurate though if you work from the markings. Say, you learn that the subject at 2.34 meters is in focus when the lens marking shows exactly 2 meters. Then what you need to do is to place the camera 2.34 meters away.

As you say, it might not be a good idea to focus on the eyes using the laser...

[Manfred M]

As you say, it might not be a good idea to focus on the eyes using the laser...

I own a couple of similar laser based range finders. They all come with instructions to NOT shine these directly into someones eyes so as to minimize the risk of eye damage.