|
|
| (6 intermediate revisions by 2 users not shown) |
| Line 1: |
Line 1: |
| − | <h1>Draft of reworked [[Rangefinder (device)]] page</h1>
| + | ''removed draft [[Rangefinder (device)]] page - now in place'' |
| − | ''Comments? This is more accurate, but is it better?''
| |
| − | {{glossary}}
| |
| − | {{Flickr_image
| |
| − | |image_source= http://www.flickr.com/photos/captkodak/272750793/
| |
| − | |image= http://farm1.static.flickr.com/92/272750793_24f344bc6c_m.jpg
| |
| − | |image_align= left
| |
| − | |image_text= Voigtländer rangefinder accessory<br>(viewing side)
| |
| − | }}A '''rangefinder''' is a distance-measuring device, used in photography as a focusing aid. Cameras equipped with this device are called [[rangefinder camera]]s. There are two types of rangefinder: a '''coupled rangefinder''' has a linkage to the distance ring of the lens and lets you focus on a subject directly with the lens's focusing ring, while an '''uncoupled rangefinder''' allows you to measure how far away you are from a subject, and then manually transfer the measurement to the camera's actual distance ring. Accessory uncoupled rangefinders may be used with almost any camera with a focusing lens.
| |
| − | {{br}}
| |
| − | === Operation ===
| |
| − | {{Flickr_image
| |
| − | |image_source= http://www.flickr.com/photos/e-coli/327904794/
| |
| − | |image= http://farm1.static.flickr.com/141/327904794_c8454dc23d_m.jpg
| |
| − | |image_align= right
| |
| − | |image_text= View through a viewfinder with<br>superimposed rangefinder image
| |
| − | }}
| |
| − | The viewfinder photo here shows how it is used; the rangefinder is a ''coincident focusing device'', which displays two separate images. The main image is the entire frame of the viewfinder, while the secondary image is a small spot in the center of the frame. To focus on something, you aim the spot in the center at that something, which shows the two images. By turning the focus adjustment, you move the secondary image horizontally until it lines up with the main image. At this point, the rangefinder (and so the lens, if coupled) will be focused on the selected object.
| |
| − | | |
| − | In the example (right) the light image area in the middle shows the antenna doubled. That indicates that a distance selection change is needed to make a sharp image of that antenna. When the antenna lies in the sharpness plane the rangefinder shows it just once.
| |
| − | | |
| − | === Construction ===
| |
| − | {{Flickr_image
| |
| − | |image_source=http://www.flickr.com/photos/10025600@N00/105571617/in/pool-camerapedia/
| |
| − | |image=http://farm1.static.flickr.com/43/105571617_6ba4bcce48_m.jpg
| |
| − | |image_align=right
| |
| − | |image_text=diagram of rangefinder structure
| |
| − | }}
| |
| − | The rangefinder works by combining two images, from two windows, into the image you see, using a ''beamsplitter''. This is a "half-silvered" prism or a mirror which can either split light, by reflecting some and allowing the rest to go straight through, or (in a rangefinder) used in reverse to combine views. The light from the second window is channelled via a mirror, prism or lens which rotates depending on the rangefinder setting - causing the secondary viewfinder image to move with the distance control.
| |
| − | | |
| − | === Limitations ===
| |
| − | Rangefinders are very accurate focusing devices - typically up to about 10-15m (~30-40ft) distance, actually more accurate than through-the lens focusing screens on [[SLR]]s. The accuracy depends on the effective ''rangefinder base'' - the distance between the viewing windows times the magnification of the viewfinder. Standard and wide-angle lenses are not very sensitive to focus past about 10m, towards infinity, so this limitation is not significant - unless using longer lenses. Rangefinders are not usually accurate enough for long, telephoto lenses - as these are more sensitive to focus at long distances, past where rangefinders are accurate.
| |
| − | | |
| − | {{Flickr_image
| |
| − | |image_source= http://www.flickr.com/photos/martintaylor/367782286/
| |
| − | |image= http://farm1.static.flickr.com/144/367782286_8c3522b022_m.jpg
| |
| − | |image_align= left
| |
| − | |image_text= front of a coupled-rangefinder camera,<br>with characteristic little extra viewfinder window
| |
| − | }}
| |
| | | | |
| | <br style="clear:both"/> | | <br style="clear:both"/> |
| Line 53: |
Line 15: |
| | : Alan [[User:Awcam]] 30 March 02:39 BST | | : Alan [[User:Awcam]] 30 March 02:39 BST |
| | ------ | | ------ |
| | + | |
| | + | == Vox says == |
| | + | |
| | + | Thanks for all your recent edits since the fork took place--and all the photos you've contributed to the pool. <del>I've started a [http://groups.google.com/group/camera-wiki/ google group] where some of the more active editors & supporters can talk shop, although it hasn't been much used yet. It's invitation-only so if you would like to join just add a note mentioning Awcam and I'll approve you.</del>--[[User:Voxphoto|Vox]] 16:11, 25 February 2011 (PST) |
| | + | :Oh, headslap--you've been there for weeks. Sorry, was working from (distracted, faulty) memory about who still needed to be invited.--[[User:Voxphoto|Vox]] 03:52, 26 February 2011 (PST) |
| | + | |
| | + | ==Praktica image== |
| | + | |
| | + | Hello -- I guess that you are the AWcam whose photo is one of the two that appear in [[Praktica MTL 5]]. If so, could you please donate it to the Camerawiki pool? Many thanks! [[User:Zuleika|Zuleika]] 01:30, 11 April 2011 (PDT) |
removed draft Rangefinder (device) page - now in place
Hello Awcam
Thank you very much for adding such essential articles like that about CCDs and the one about Daguerre. You really have great ideas for corrections and enhancements which are helpful for this site.
Best regards, Uwe [U. Kulick 19:10, 28 March 2008 (EDT)]
- Thanks Uwe; apologies for my scattergun approach on some edits.
- Alan User:Awcam 30 March 02:39 BST
Vox says
Thanks for all your recent edits since the fork took place--and all the photos you've contributed to the pool. I've started a google group where some of the more active editors & supporters can talk shop, although it hasn't been much used yet. It's invitation-only so if you would like to join just add a note mentioning Awcam and I'll approve you.--Vox 16:11, 25 February 2011 (PST)
- Oh, headslap--you've been there for weeks. Sorry, was working from (distracted, faulty) memory about who still needed to be invited.--Vox 03:52, 26 February 2011 (PST)
Praktica image
Hello -- I guess that you are the AWcam whose photo is one of the two that appear in Praktica MTL 5. If so, could you please donate it to the Camerawiki pool? Many thanks! Zuleika 01:30, 11 April 2011 (PDT)
