Helios 44-2 Focus Calibration

[nathaniel]

Hi, this is my first post to the forum, I am infected with the manual focus lenses and am ready to use also Yalçın Aydın helped a little by the way I would like to thank to him.

My problem is with the Helios, as I mentioned in the subject. I just got it this morning, but I think it has a front focusing problem. No matter how much I try, the focus is always in front of the point I adjusted through 350D's viewfinder.

I cannot find any document in the internet to make calibration. Do you have any document or experiance about it?

[estudleon]

See, I hope this helps you.

http://www.kyphoto.com/classics/forum/messages/2/14504.html?1234843055

Rino.

[nathaniel]

Thanks for the fast response But unfortunately it did not help very much..Because I could dismantle it more than I expected I can take out the mount, the focusing ring, the rear element, the element before it and goes on..But I did not discover how the calibration can be made

[no-X]

If I understand well, the problem is not in the lens, but in the camera, because the viewfinder and chamber are not aligned. This is not problem for AF, but only for MF, because the viewfinder shows something different, than what is transfered to the camera sensor.

I'd recommend guaranty service for proper setting of the chamber.

Manual lens can't suffer from front-focus or back-focus

[rawhead]

[nathaniel]

[Attila]

Welcome Nathaniel!

[Farside]

If it's actually the camera, there's a small focus adjustment screw inside the mirror chamber.
http://tinyurl.com/adjust-350D-focus

[rawhead]

[nathaniel]

In my opinion, it is for AF calibration, too

I also cannot find any useful information about 350D's viewfinder calibration on the internet. I am using and enjoying my 350D but after this problem there is a voice inside of me telling to upgrade soomething else

[peterqd]

Hello Nathaniel!

Because the 350D is really designed for auto-focus, the viewfinder accuracy on these cameras is not always 100% accurate. Many of us have had to make adjustments to get it right.

The factory adjustment is done with one or two thin brass shims next to the focussing screen. If you are finding the camera is near-focussing when the viewfinder is correct it means the distance of the focussing screen to the mirror is too great, therefore an extra shim or some packing needs to be added.

This is quite an easy job. With the lens removed, hold the camera upside down with the lens mount facing away from you. Just inside the foam buffer for the mirror, sometimes hidden, is a little spring clip that holds the focus screen in place. With a ballpoint pen, gently press the clip to release it, and then the clip and the screen can be removed. The shim should be under the screen, be careful you note which way round it fits.

If you don't have an extra shim, you can pack out the original one using 3M Magic tape cut with a craft knife. You might need one or two extra layers before you get it right. It takes some patience and lots of testing. Use a tape measure for testing.

There is a thread about it here:
http://forum.mflenses.com/has-anyone-changed-the-focusing-screen-of-a-400d-xti-t11726.html

[nathaniel]

I cannot sleep if I don't try it Thanks.

[rick_oleson]

It's not just the screen's adjustment, it's also the screen's design: focusing screens in AF cameras are not really designed to focus on, they are just to give you a general sense of focus depth while also being as bright as possible (on a camera that 99% of the time has a slow zoom fitted to it). For this reason, the screen surface is made up of tiny lenses, each of which has about an f/4 aperture so that they very efficiently pass the light from your f/4 zoom lens. Unfortunately for manual focusing, this also means that the screen does not pass light from outside that f/4 circle - which in turn means it is blind to the shallower depth of field that you have with a faster lens. No matter how you adjust it, focusing an f/2 lens manually will be a crap shoot with that screen unless you stop down to f/4 or slower. You can replace the screen with a manual-focusing type to deal with this issue. It will be dimmer than your standard screen, and your AF lights won't show on it, but it will focus.

[peterqd]

Here's the PDF file showing how to remove and replace the screen in the 350D. This is from the Haoda website.
http://www.euphonium.plus.com/Drawings/Modification/screen-Haoda.pdf

If you feel like taking Rick's good advice to replace the screen you could look at the Haoda screens, which are quite expensive but good quality:
http://haodascreen.com/CanonDSLR.aspx For something cheaper you could try the cheaper Chinese screens on Ebay. Mine came from Virtual-Village, but I think this one is similar:
Click here to see on Ebay

[rawhead]

Or, you can go the more expensive way and get the KatzEye

http://www.katzeyeoptics.com/item--Canon-350D-Focusing-Screen--prod_350D.html


Like I did. OptiBright option is great if you have any darker lenses (anything with max aperture greater than f4~5.6). Sure it's $160, but it'll be the best $160 you'll spend on your camera if you're an MF buff

[nathaniel]

I've been adjusting the thickness of the shim for about 4 hours and at last I made it But instead of increasing thickness of the shim, I took it out completely So, according to my experiance, you have to decrease the thickness of the shim(s) if you have front focus problem through the viewfinder.

About changing the focusing screen; yes, I'd like to have a better one but 350D KIT price is around $320 in Turkey which is two times a Katz-Eye But I'm sure I will try something cheaper from ebay

By the way, I will add some photos to the gallery after a sunny day Because of this wonderful teamwork those photos will be ours

[nathaniel]

...and the sunny day at last

All of the are between f/2 and f/5.6..