How to Manual focus properly????

AndyWest

AndyWest

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Andy
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Hi

Yesterday i bought this Asahi/Pentax 50mm f1.8/55 lens for £25 and i have it planted on the front of my Canon 400D.

Pentax03.jpg


When trying it out i had a lot of pics that were out of focus as i have never done manual focusing before. It's not so bad on subjects a few feet away but close up especially it's very difficult to get the focus right as all i have to go by is the bit you look through on the camera. I don't have live view so i can't zoom in from the screen and focus from there, all i have is the eye piece.

So... When focusing i turn the focus ring until the subject is in focus and then stop when the subject blurs. I then go back until the subject looks in focus but there is about half a turn on the lens where the subject looks in focus but when viewing the results on the pc they are out of focus.

So whats the best thing to do? now bare in mind that when i played with the lens it was quite dull even outside. Will this be easier when it's sunny. Also is it best to keep a distance from the subject?

If i turn the lens half way to between each time the subject blurs, would this be the place to shoot?

Your help much appreciated as this is good fun doing it without the camera's help (except for shutter speed).
 
AndyWest said:
but there is about half a turn on the lens where the subject looks in focus but when viewing the results on the pc they are out of focus.

So whats the best thing to do? now
Click to expand...

practice.. you already know more about that lens than the rest of us... the more you shoot the more you will get to know it and the more you will know what to do.. you already know that half a turn is no good. A lens like that isnt so off the shelf and you need to get used to its little ...erks


Simple answer I know.. but pretty sure its the right one :)
 
Some of those old Takumar leses were bitingly sharp. (y)

You have to remember that when this lens was in use originally, it would have been on something like a Pentax Spotmatic or SV - both SLRs which had a centre split image focusing aid, probably surrounded by a slightly larger microprism area, designed so that the image appeared to break up instantly either side of ideal focus. In fact this type of focusing sreen was common to most SLRs of that period.

If you intend using the lens a lot, you should be able get a split image focusing screen for your camera, which you should be able to fit yourself.

You're actually describing a pretty common problem with ground glass focusing screens - even many larger MF camera are far easier to focus with a split image type screen than a plain ground glass one.
 
Find a subject that is well lit, high contrast and sharply defined patterns/lines. Use your standard autofocus lens and check that you have a well focused image produced on your pc. Check the eyepiece dioptre adjustment and make sure you are seeing a well focused image in the viewfinder. Adjust as necessary. If you haven't got this adjusted properly then you won't be able to manually focus properly.

If all this checks out then use the manual lens and more or less practice what you've been doing - backwards and forwards between two ranges of blur and settle for a point in between. The range between these two points isn't half a turn - it's only a tiny bit.

Also bear in mind with a wide open lens you have a narrow depth of field and with close ups you could well have a large aperture. You are likely to see only a small area in focus. The dull lighting you mentioned will almost certainly have increased the aperture size limiting your depth of field.
 
You've got a pentamirror camera, which isn't as bright as a pentaprism.

Wide open at close range, you should really do your tests with the aid of a tripod, or brace yourself against a wall or firm-backed chair, as the shallow DOF won't accommodate a slight sway of your body.
 
All good advice, and I suppose it just takes practice. These lenses were designed for SLRs, which had huge, bright, viewfinders compared with a crop DSLR and it was a piece of cake with them. The aids (split image and microprism coller) were fine, but the pro cameras offered a range of different focusing screens and I still use a ground glass screen a lot of the time on an F2.

Best of luck. I'm 56, and my eyes can't handle MF on a crop body!
 
Thanks for the helpful replies. I think practice and practice some more! A tripod will be a great help here too. (y)

When i have time i'll have a play and post up some more pics.
 
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