Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-21-2007, 07:26 PM   #1
Senior Member
schmikey's Avatar

Join Date: Jun 2007
Location: Toronto, Ontario, Canada
Photos: Gallery
Posts: 152
Focusing and manual lens...

I have 2 manual focus lens: Pentax-A 50mm 1.7 and Kiron 28mm f 2.0 - both great lenses - I always centre the subject I am focusing on - since that is where the 'red square' is (real technical, eh) I would like to be able to have subject off centre - how do I achieve that (I know I can't focus lock) is there another technique for manual focus lens? I'm assuming there must be a way...

08-21-2007, 08:57 PM   #2
Veteran Member
Fritz's Avatar

Join Date: Jun 2007
Location: Tillamook, OR
Posts: 1,168
This is what I do with my K100d. Move the switch on the camera to MF (manual focus). Focus on the subject with the shutter button half pushed untill you get the focus confirmation (red square). Then recompose the picture with your in focus subject where you want it and push the shutter all the way down. Done!
08-22-2007, 01:32 AM   #3
Inactive Account




Join Date: Jun 2007
Location: Leeds, NE UK
Posts: 220
I find the "red square" really unusable. It often won't appear until I have focused several times. But on occassions I have just used the technique mentioned above. That's certainly what I do in AF in most situations. Moving the focusing point is too slow.
08-22-2007, 02:34 AM   #4
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
If you are having problems focusing with manual focus lenses are you sure you have the eyepiece calibrated for your vision?

There is a diopter adjustment so that you can correct the viewfinder for your vision, this way the image will be sharp in the fiewfinder when focused correctly.

Other than this, the suggestion of focusing and getting the in focus indication with the view finder seems good. Once focused, you can move the center of the viewfinder to what ever you want, and your subject will be in focus.

08-22-2007, 04:09 AM   #5
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 1,883
QuoteOriginally posted by pixelpruner Quote
I find the "red square" really unusable. It often won't appear until I have focused several times.
You do know that the red square isn’t the ”in focus” signal? You should be looking for the green dot in the info bar instead.
08-22-2007, 04:57 AM   #6
Veteran Member
Mike Cash's Avatar

Join Date: Jan 2007
Location: Japan
Photos: Gallery
Posts: 6,952
If you're going to manual focus a lot, there is really no substitute for replacing the original matte screen with a good old-fashioned split-prism. If you use a Chinese screen, you're only looking at about 30 bucks, and it is very well worth it.

Personally, I have turned the blasted red focus indicator off. It really only indicates which auto-focus point the camera is using and is not a reliable indicator of being in focus (as Gimbal said....use the green hexagon for that).

Also, be aware that when you make the diopter adjustment you should not be trying to get the image you see to be in focus with it. You should be trying to get the lines on the focus screen to be in focus.
08-22-2007, 06:02 AM   #7
Veteran Member




Join Date: Sep 2006
Location: Bangor, Maine
Photos: Gallery
Posts: 1,382
You always have good advise

QuoteOriginally posted by Mike Cash Quote
If you're going to manual focus a lot, there is really no substitute for replacing the original matte screen with a good old-fashioned split-prism. If you use a Chinese screen, you're only looking at about 30 bucks, and it is very well worth it.

Personally, I have turned the blasted red focus indicator off. It really only indicates which auto-focus point the camera is using and is not a reliable indicator of being in focus (as Gimbal said....use the green hexagon for that).

Also, be aware that when you make the diopter adjustment you should not be trying to get the image you see to be in focus with it. You should be trying to get the lines on the focus screen to be in focus.
Mike,

Thanks! I always read your posts because you come up with some very good points. Just wanted to thank you.

Regards,
Ken
08-22-2007, 07:44 AM   #8
Veteran Member
Tom M's Avatar

Join Date: Aug 2007
Location: Lincoln Park, NJ
Photos: Gallery
Posts: 782
I've been using the 'trap focus' technique. Essentially, I depress the shutter button completely then slowly rotate the manual focus ring until focus lock. As soon as the focus locks the shutter fires.

Below is an example. This shot was taken hand-held 300mm @ 1/20sec using trap focus. (I've taken better photos but this is the only photo I have at work in which it was taken using trap focus)



08-22-2007, 09:03 AM   #9
Veteran Member
arbutusq's Avatar

Join Date: Sep 2006
Location: Vancouver BC canada
Photos: Gallery
Posts: 380
QuoteOriginally posted by Tom M Quote
I've been using the 'trap focus' technique. Essentially, I depress the shutter button completely then slowly rotate the manual focus ring until focus lock. As soon as the focus locks the shutter fires.
I like this method. I'll have to try it. Another one that is quite useful on stationary subjects is to get approximate focus through the viewfinder and then move the camera till you get focus confirmation. This is the method I use as I have very bad eyesight.
08-22-2007, 10:42 AM   #10
Senior Member
schmikey's Avatar

Join Date: Jun 2007
Location: Toronto, Ontario, Canada
Photos: Gallery
Posts: 152
Original Poster
"I've been using the 'trap focus' technique. Essentially, I depress the shutter button completely then slowly rotate the manual focus ring until focus lock. As soon as the focus locks the shutter fires."

(I don't know how to copy and paste with the 'box' around the text...)

Tom I tried this but the shutter does not 'fire' - when I press the shutter button completely a picture is taken, then I manually focus, until subject is in focus - the green 'light' appears and then nothing else - is there a setting that I'm supposed to do first...

I do have a split focusing screen which does help - but I always focus the subject when it's in the center of the viewfinder - so what you are saying Fritz is that I can press the shutter button down half way, recompose the 'shot' and then take the picture - the same as focus lock using an auto focus lens.


Sorry for being a bit 'dense' but I would like to get to the bottom of this... I'm sure it's fairly simple - just not there yet for me
08-22-2007, 10:56 AM   #11
Forum Member
sjl7678's Avatar

Join Date: Aug 2007
Location: Rochester, NY
Posts: 50
QuoteOriginally posted by schmikey Quote
(I don't know how to copy and paste with the 'box' around the text...)
Click the "QUOTE" button under the post you want to quote. It'll open a reply page with the text already inserted into the box with QUOTE tags around it. Delete the text you don't need if you don't want to include it all.
08-22-2007, 11:12 AM   #12
Senior Member
schmikey's Avatar

Join Date: Jun 2007
Location: Toronto, Ontario, Canada
Photos: Gallery
Posts: 152
Original Poster
QuoteOriginally posted by sjl7678 Quote
Click the "QUOTE" button under the post you want to quote. It'll open a reply page with the text already inserted into the box with QUOTE tags around it. Delete the text you don't need if you don't want to include it all.
That's way too easy... thanks sjl7678 - my computer skills as well as my photographic skills need improving
08-22-2007, 11:21 AM   #13
Veteran Member
Tom M's Avatar

Join Date: Aug 2007
Location: Lincoln Park, NJ
Photos: Gallery
Posts: 782
Oops - I forgot to mention that even though you have a manual focus lens on the camera, you need to put the camera in autofocus mode single (AF-S).. THEN, depress the shutter all the way down and slowly rotate the focus ring on the lens until the shutter fires. This is called 'trap focus'.

I think you can figure out how it works. The camera has a non auto-focus lens on it so when you choose AF-S the camera can't/won't get focus unless you manually rotate the focus ring. Of course, as soon as focus is reached the shutter will fire because the shutter release is depressed fully.

Try it out and post back with your results!

EDIT: Seems I keep forgetting all kinds of good stuff regarding the 'trap focus' technique.. Take for instance that photo I posted above. It was dark, very little available light, too far away for the flash to fire an AF light to help get focus so, here's what I did. The lens is a 100-300mm Sigma f4.5-6.7 AF/auto-focus lens.

This works with AF lenses.

With the camera in green mode (I'm sure it works in other modes too), switch to Manual Focus. Fully depress the shutter button and slowly rotate the focus ring until the shutter fires. That's 'trap focus' for auto-focusing lenses and it's really useful for pics like the one I posted. At 300mm and f6.7 in such low light conditions getting the AF to work is pointless, and not even accurate! It makes hand-holding a 300mm @ 1/20th sec a little easier.

Last edited by Tom M; 08-22-2007 at 12:01 PM.
08-22-2007, 11:58 AM   #14
Veteran Member
Fritz's Avatar

Join Date: Jun 2007
Location: Tillamook, OR
Posts: 1,168
QuoteOriginally posted by schmikey Quote

I do have a split focusing screen which does help - but I always focus the subject when it's in the center of the viewfinder - so what you are saying Fritz is that I can press the shutter button down half way, recompose the 'shot' and then take the picture - the same as focus lock using an auto focus lens.

I think that depressing the shutter half way will just activate the auto focus point (red square). The others are correct that it is not "confirmed" without the green dot being solid in the viewfinder. Once you have obtained the correct focus, you don't have to keep the button half pressed. You can release it and point the camera wherever you want and snap a picture. As long as the switch on the camera is set to MF, you can take as many "out of focus" pictures as you want. The red square and green dot are just there to help you know when you have achieved focus. Since you have a split screen, I'm not sure that I would pay any attention to the electronic focus aids. Use the split screen to get your focus point, recompose and shoot.

I just reread what you wrote. I think that would probably work too. Try it!
08-22-2007, 01:11 PM   #15
Senior Member
schmikey's Avatar

Join Date: Jun 2007
Location: Toronto, Ontario, Canada
Photos: Gallery
Posts: 152
Original Poster
QuoteOriginally posted by Tom M Quote
Oops - I forgot to mention that even though you have a manual focus lens on the camera, you need to put the camera in autofocus mode single (AF-S).. THEN, depress the shutter all the way down and slowly rotate the focus ring on the lens until the shutter fires. This is called 'trap focus'.

I think you can figure out how it works. The camera has a non auto-focus lens on it so when you choose AF-S the camera can't/won't get focus unless you manually rotate the focus ring. Of course, as soon as focus is reached the shutter will fire because the shutter release is depressed fully.

Try it out and post back with your results!

EDIT: Seems I keep forgetting all kinds of good stuff regarding the 'trap focus' technique.. Take for instance that photo I posted above. It was dark, very little available light, too far away for the flash to fire an AF light to help get focus so, here's what I did. The lens is a 100-300mm Sigma f4.5-6.7 AF/auto-focus lens.

This works with AF lenses.

With the camera in green mode (I'm sure it works in other modes too), switch to Manual Focus. Fully depress the shutter button and slowly rotate the focus ring until the shutter fires. That's 'trap focus' for auto-focusing lenses and it's really useful for pics like the one I posted. At 300mm and f6.7 in such low light conditions getting the AF to work is pointless, and not even accurate! It makes hand-holding a 300mm @ 1/20th sec a little easier.
Tom - now I'm really confused... - I did try what you suggested but it still did not work - from your EDIT you seem to be saying that this is for auto focus lens... am I correct?

Fritz - I did try what you suggest and it seems to work... just tried it inside - I'm going to take Schmikey - my dog - for a walk - I will take my camera as well and try this outside...
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, centre, dslr, focus, lens, photography, subject
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K20D or Kx for manual focusing brencam Pentax DSLR Discussion 8 11-06-2010 01:15 PM
Focusing technique with fast manual lens Corvairfan Troubleshooting and Beginner Help 14 10-28-2010 09:09 PM
Focusing manual lens with OEM focusing screen, is a split screen really needed? skid2964 Pentax Camera and Field Accessories 16 09-17-2010 02:54 PM
Manual lens focusing: what is causing this? kerey Pentax SLR Lens Discussion 10 11-17-2007 02:51 PM
12-24 manual focusing taveren Pentax SLR Lens Discussion 1 06-29-2007 05:31 PM



All times are GMT -7. The time now is 08:36 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top