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Focusing too near
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PostPosted: Fri May 15, 2009 1:27 pm    Post subject: Focusing too near Reply with quote
Hi everyone, this is my first post on this forum. I'm having focusing problems with my Auto Rikenon 1.4/55. It seems to focus too near everytime. I have tried to focus manually with tripod to be sure and the focus is everytime nearer than it should be according the finder.

Have others had this problem, I'm using Olympus E-400. Should I just try a different adapter or can it be something with the lense?


PostPosted: Fri May 15, 2009 1:46 pm    Post subject: Reply with quote
Adapter nor manual lens can't cause front-focus. I think the camera body need adjustment.


PostPosted: Fri May 15, 2009 1:49 pm    Post subject: Re: Focusing too near Reply with quote
Melankhton wrote:
Hi everyone, this is my first post on this forum. I'm having focusing problems with my Auto Rikenon 1.4/55. It seems to focus too near everytime. I have tried to focus manually with tripod to be sure and the focus is everytime nearer than it should be according the finder.

Have others had this problem, I'm using Olympus E-400. Should I just try a different adapter or can it be something with the lense?


It seems strange what you say.
If it was an autofocus lens, the problem could be the autofocus.
But since it's a manual lens, I can only think of two possible problems, either the registration of your focusing screen (in which case the problem should happen with all your lenses), or a problem with your... eyesight.
Since you check visually the focus in the viewfinder, you see what you get, so the problem can not be the lens and can not be the adapter.


PostPosted: Fri May 15, 2009 2:23 pm    Post subject: Reply with quote
Thanks for the fast reply. Well nice to know that the adapter or the lense can not cause that. On the other hand I do use glasses and have a slight refractive error in my eyes. I don't think that the problem is the camera body because it focuses correctly with the AF kit-lense. The Auto Rikenon is my first MF lense so maybe my focusing skills are just not that good. Maybe I just need more practising and have my eyes checked.

On the brighter side I'm quite pleased with the Rikenon lense apart from the focusing problems. I haven't found that much pictures taken with it, so maybe I'll send some samples to the forum later on. When I get them correctly focused that is. Wink


PostPosted: Fri May 15, 2009 2:47 pm    Post subject: Reply with quote
It is a known problem with fast lenses (there should be a sticky about it).

The focusing screen is accurate for lenses with a maximum aperture of f2.8.

The focusing is erratic for brighter lenses because the DOF of the screen is limited to f2.8.

I have the same lens (a Tomioka-made Auto Reflecta version) and also had focusing error with the original screen of my Pentax.

If it is possible, use a split-focusing screen.

Edit : here is an article explaining better http://www.jayandwanda.com/photography/dslr_man_focus/man_focus.html


PostPosted: Fri May 15, 2009 5:20 pm    Post subject: Reply with quote
Melankhton wrote:
Thanks for the fast reply. Well nice to know that the adapter or the lense can not cause that. On the other hand I do use glasses and have a slight refractive error in my eyes. I don't think that the problem is the camera body because it focuses correctly with the AF kit-lense. The Auto Rikenon is my first MF lense so maybe my focusing skills are just not that good. Maybe I just need more practising and have my eyes checked.


Ok so you have one MF lens, which focuses incorrectly, and several AF lenses which focus correctly.

The optical path in your camera may be off. In mine, some careful shimming of the focus screen and then fine tuning the MF system via a cam put it spot on. (There was a separate cam to fine-tune the AF system, which takes a different optical path).

Or, maybe the diopter adjustment for your viewfinder is not set correctly. Be sure its as sharp as possible.

Or, thirdly, you need more practice. However, in that case I would expect to see a random mix of front and back focusing, not a consistent error in one direction.


PostPosted: Fri May 15, 2009 7:11 pm    Post subject: Reply with quote
Thanks for the advices and the link Jieffe . That actually explains a lot. The focusing screen is maybe just not up to the needs of the fast lense. I seriously have to think about investing on split screen to help with focusing. Especially if I happen to invest on some other manual lenses.

I only have one AF lense and one MF lense. Unfortunately I don't have anything to compare the Rikenon to. The AF kit-lense seems to focus spot on correctly. Comparing these two is not easy either. As far as I can tell the AF one focuses correctly. I have to check the diopter settings and optical path as ChrisLilley suggested.

I originally just thought that maybe I could save some money and buy a fast manual lense and adapter instead of a really expensive Zuiko 4/3 lense. Seems like there is no free meals:( Thanks all for your advises!


PostPosted: Fri May 15, 2009 7:42 pm    Post subject: Reply with quote
You can buy excellent MF lenses for very little money ... and you will, believe me. You already are doomed Wink

IMHO the splitscreen is a necessity. As a matter of fact, when I ordered my new K200D, I bought the same day a splitscreen on Evilbay.


PostPosted: Fri May 15, 2009 9:42 pm    Post subject: Reply with quote
Melankhton wrote:

I only have one AF lense and one MF lense. Unfortunately I don't have anything to compare the Rikenon to.


Just set AF off on your AF lens and try focusing it manually...


PostPosted: Sat May 16, 2009 2:48 pm    Post subject: Reply with quote
I redid my tripod test with the Rikenon and the Zuiko kit-lense on AF and MF mode. Seems like i jump into conclusios before testing enough, I may have just front focused by mistake. Jieffe's post and link has a point though, it is really hard to manually focus on large apertures and small finder. At least that is the case with E-400's finder and screen. I have to seriously consider purchasing the split screen.

Thanks for the tips, sorry to bother you with mundane questions.

Here's a couple of shots taken with the lense, both wide open if I remember correctly:


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