What is your technique to focus M lenses?


Pietrach

Link Posted 14/03/2012 - 15:32
I am struggling to get sharp photographs using manual Helios lens. I turn the focusing ring and rely on AF indicator to beep when the picture gets in focus. It does beep, I take a photograph and the success rate is very low. What is your technique?

PS - I did check BF/FF and it is as good as it can be.

Thanks

milamber

Link Posted 14/03/2012 - 16:15
I rarely have a problem focusing M lenses, but don't have any Helios lenses.

Bear in mind that the beep and red square isn't the focus confirmation, at least with my K-r. The green hexagon is the focus confirmation. They are always pretty close, but it might be enough if you are relying on the beep.

Check the diopter for the viewfinder is properly adjusted. If it's clear in the viewfinder, but not in the picture, then that might be the problem.

You could double check using liveview. I often find myself using that, particularly for macro and find it pretty accurate.

Lastly, perhaps use a smaller aperture to give greater depth of field.

All the above is based on my experience with the K-r. It should be pretty general advice, but you might not have liveview, for example, depending on your camera model.

trickletreat

Link Posted 14/03/2012 - 19:09
I used to have problems, but once you find the best way to get reliable focus it soon becomes second nature. If you are using the cameras af to alert you, then it is worth finding out if it is more accurate focusing to or from infinity, as the indication can cover a degree of focus ring rotation, and fall accurately at one end or other.
Here are some links I found useful.

link

link
link

Hope these help,

Nigel

Stuey

Link Posted 14/03/2012 - 19:52
Hi Pietrach

I don't have the lens you do but as mentioned above it is best to wait for the green hexagon as that is focus confirmation.

With my m42 preset lens I open the apeture to aid focus then stop down to take the picture.

With my m42 'auto' lens I switch to a which leaves the apeture wide open - focus and the switch to manual and take the shot - same thing - slightly different technique

My other mf lenses are later models (pk/m I think but without checking I could be wrong) and they hold the apeture wide open until the shot is taken so it is as simple as focus, presss the green button for the exposure and shoot

Patience and practice are key though - stick with it and I am sure you will be fine

For wildlife I try to prempt where they may be then pre focus and wait for the shot

Hope this helps


Stu
K10D, K5 plus plenty of clueless enthusiasm.

My Flickr site link

Pietrach

Link Posted 14/03/2012 - 20:38
All great advice, looks like I need to practice a bit more then.
Thanks and welcome more good advice.

milamber

Link Posted 14/03/2012 - 20:59
The other thing I forgot to mention it's worth having a play with 'catch in focus' if you have it (not sure which camera you have). It's not always appropriate, but will certainly help with moving objects. I sometimes use it for macro as well.
Last Edited by milamber on 14/03/2012 - 21:00

davidstorm

Link Posted 14/03/2012 - 21:54
All good advice above, but you must make sure the dioptre is set for your eyes and that the grid in the viewfinder is sharp. If this is set wrong you have almost no chance of accurately focussing.

Another technique that is almost foolproof is to use the Live View feature on the LCD screen and zoom in on the area that requires critical focus (zoom is achieved by repeatedly pressing the 'Info' button). However, this is only possible if you're using a tripod and the subject is perfectly still. Great for indoor still life shots.

Regards
David
Flickr

Nicola's Apartments, Kassiopi, Corfu

Some cameras, some lenses, some bits 'n' bobs

Frogfish

Link Posted 15/03/2012 - 05:33
Just to emphasise what Trickletreat said above as this was the biggest issue I found when I started using MF lenses :

Focus Confirmation = you can see this in your VF - it is the little green hexagon. When lit it shows you that the subject is in focus. Note however that there is a 'range' (also with AF) so it depends on whether you are focusing from Infinity DOWN to your subject or from minimum focus distance UP to your subject. For each lens one direction will always give sharper shots (and it does vary from lens to lens though for most of mine it is Infinity DOWN to the subject). This is easy to check on the K7/K5 by taking one shot from each direction and then using the side-by-side review mode and zooming in to see which is sharper, do this a few times and you will now be certain which it is.

Take a look at this link too : link
http://frogfish.smugmug.com/ Pentax. Pentax DA*300/4, Cosina 55/1.2, Lens Baby Composer Pro & Edge 80, AFA x1.7, Metz 50 af1.
Nikon. D800. D600. Sigma 500/4.5, Nikon 300/2.8 VRII, Sigma 120-300/2.8, Zeiss Distagon ZF2 21/2.8, Zeiss Distagon ZF2 35/2.0, Sigma 50/1.4, Nikkor 85/1.8, Nikon TC20EIII, Nikon TC14EII, Kenko x1.4, Sigma 2.0
Last Edited by Frogfish on 15/03/2012 - 05:33

milamber

Link Posted 15/03/2012 - 07:34
Frogfish wrote:
Just to emphasise what Trickletreat said above as this was the biggest issue I found when I started using MF lenses :

Focus Confirmation = you can see this in your VF - it is the little green hexagon. When lit it shows you that the subject is in focus. Note however that there is a 'range' (also with AF) so it depends on whether you are focusing from Infinity DOWN to your subject or from minimum focus distance UP to your subject. For each lens one direction will always give sharper shots (and it does vary from lens to lens though for most of mine it is Infinity DOWN to the subject). This is easy to check on the K7/K5 by taking one shot from each direction and then using the side-by-side review mode and zooming in to see which is sharper, do this a few times and you will now be certain which it is.

Take a look at this link too : link

I didn't know that. Very helpful, thanks.
Last Edited by milamber on 15/03/2012 - 07:35

johnriley

Link Posted 15/03/2012 - 08:45
Provided the dioptre correction has been done correctly, the focus ring is turned until the image looks sharpest in the viewfinder.

What's interesting is that what was once perfectly normal technique, using our eyes, seems to have become an issue where we look to the camera to tell us instead.

I wonder whether it's still not quite understood how to adjust the viewfinder. Point the camera at a blank wall or blank area, adjust the dioptre lever until the etched lines in the viewfinder are crisp.

Do not adjust the dioptre by viewing any sort of scene or subject as the eye adapts and the adjustment will not be correct.
Best regards, John

Pentaxophile

Link Posted 15/03/2012 - 09:21
1. The viewfinder on APSC cameras is quite small, and with no split screen, quite difficult to check critical focus with. (OK if you habitually stop your lenses down, as I suspect John does, as the dof masks focussing error).

2. The green hexagon light has a margin of error. Turn your focus ring slowly, and you will notice the green light come on, but it will stay on while the ring is turned until it goes off again. The optimum focus will be between the point where the light comes on and the point goes off. You can learn to anticipate where this point will be.

3. Manual focussing by eye - again, as you move the focus ring you'll notice the point where the image comes into focus and the point where it goes out of focus again; try and sense the optimal point in the middle where the correct focus will be.

4. Live-view focussing is with an enlarged view is the most accurate technique, and if you are shooting a subject many feet away, it doesn't matter if the camera moves an inch or two because you are hand holding it.
[link=https://500px.com/will_brealey/[/link]

johnriley

Link Posted 15/03/2012 - 09:49
Focusing error in very real, as has been demonstrated in the past many times, and I wouldn't want to diminish the difficulty that many people have with it.

It seems to depend very much on our eyesight. I know for example that my dad had dreadful problems focusing his Nikons, despite being a precision, close worker. Maybe he had just worn out his eyes with so many years of close concentration, who knows. He tried everything, struggling with focusing magnifiers to even focus landscape shots.

Sometimes lateral thinking is needed and if anyone has severe manual focusing problems and for whatever reason can't use autofocus, then just maybe a rangefinder system would be easier and more accurate for them.

The traditional advice is that rangefinders are more accurate up to about 135mm and beyond that SLRs are more accurate.
Best regards, John

Pentaxophile

Link Posted 15/03/2012 - 11:12
I would far rather use the screen on my K7, or purchase a K01 (which is even better as it has focus peaking) than resort to an expensive rangefinder system (with limited lenses to choose from). Live view is always 100% accurate as you are seeing 'what the sensor is seeing'.

Hopefully Pentax will one day release an EVF model which will combine the features of live view with a shielded, eye level viewfinder. Until then, stopping down to ensure decent DOF when using the OVF, plus resorting to help from the live view monitor for shallow dof focussing, are workable.
[link=https://500px.com/will_brealey/[/link]

johnriley

Link Posted 15/03/2012 - 11:33
Yes indeed, the K-01 is another lateral thinking solution, far better for Live View than the DSLRs.

In the context of the M series lenses a better solution perhaps.

The other possibility is the Q with the new K mount adapter, when that becomes available. Third party adapters are already freely available on Ebay, for all sorts of lens mounts, but I think I'll wait for the Pentax one.
Best regards, John

AnthonyB

Link Posted 20/03/2012 - 11:12
As my main job is TV Cameraman, finding best focus manually, very fast, is second nature. I wondered if stills might be trickier but it isn't. It's a directly transferrable skill. It's an instinct you develop through practice. I'd echo John's comment about people becoming reliant upon technology. If you've set up your viewfinder properly it really isn't that difficult. The only auto lens I've got is the kit zoom which, since I bought my M primes, I've not used at all. Manual all the way for me. I was snapping people round the dinner table on Sunday using just available light and the M 50 f1.7 wide open. Soft light from huge windows, quite flat, not much modelling. The vast majority of the shots were good with best focus.

Just practice. You don't even have to pop off a shot. Just wander around with the camera switched off finding best focus on objects and people. Rock through best focus back and forth and learn to recognise when you've hit the spot.

The slightly weird thing for me is that the direction of operation of the lens barrel on Pentax is opposite to the general convention. So infinity and MOD are reversed which still catches me out. I'll see that I need to focus forward or back but because of years turning the barrel clockwise for forward and anti-clockwise for back toward infinity I still sometimes forget myself with the pentax and go the wrong way first rather than just directly to best focus.
K-5, DA 1:3.5-5.6 18-55mm AL WR, M 1:2.8 28mm, M 1:1.7 50mm, M 1:3.5 135mm.
Last Edited by AnthonyB on 20/03/2012 - 11:20
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