Free Shipping on ALL Products
camera reviewsbest cameraslens reviewsphotography tipscamera forumvideo toursphotography bookssupport me
It is currently Sun Oct 26, 2014 2:58 am

All times are UTC




Post new topic Reply to topic  [ 5 posts ] 
Author Message
 Post subject: iris closing on OM lens
PostPosted: Sat Apr 10, 2010 12:43 am 
Hello,

I purchased on eBay an Olympus Zuiko Auto-S 50mm F1.8 lens (the lens is marked "made in Japan"), Serial No. 5870379. Although used, the lens appears to be in near-mint condition.

I also purchased an adapter to fit this lens onto a new Panasonic DMC GF1 micro 4/3 camera body. I take pictures through a research microscope, through a telescope, and just for fun. In the first 2 of these cases, focus is critical. One of the main reasons for selecting this camera is the live on-screen enlargement capability (which is super) as a focusing aid. The adapter works ok as far as coupling the lens to the camera. There is, of course, neither "auto" nor electrical connection.

Here's the problem, with the OM lens mounted on the adapter, the iris opens and closes smoothly, but only when holding the rectangular button on the side of the lens. Inside the lens are 2 spring-loaded articulators that are clearly designed for automatic control of the iris. If I hold one of these at its limit, it has the same effect as holding the rectangular side button, i.e. the iris opens and closes smoothly as the f-stop is changed. Left to its own devices, the lens stays wide open.

Bottom line: I don't know if I have a lens that isn't working the way it should or if there's some function of the lens that I just don't know about or if I have an adapter that doesn't do what it should.

It is clear that lots of folks use adapters to connect any number of lenses (including the Olympus OM Series) to any number of cameras. I have fair experience with Pentax & Vivitar lenses, with adapters to paste them onto bayonet or screw mount cameras, and with adapters to paste cameras to telescopes and to microscopes, however...

I have a problem here and I'm hoping someone can make some helpful suggestions. If my problem points to the adapter, perhaps you could suggest a brand that you know works with OM Series lenses.

Thanks in advance for your help,
richardmaple


Top
  
 
 Post subject:
PostPosted: Sat Apr 10, 2010 6:35 am 
Im not clear on what the question is...

So can you or can you not stop the lens down when its attached?


Top
  
 
 Post subject: iris closing on OM lens
PostPosted: Sat Apr 10, 2010 5:11 pm 
Atomic hi and thanks for your response,

The question is, do I have a bad lens or a bad adapter?

If I hold the lens in my hand and turn the diaphragm ring, the iris does not open or close...it stays wide open.

If I press and hold the smooth rectangular button on the side of the lens and turn the diaphragm ring, the iris opens and closes as advertised.

I have 2 different OM adapters, an OM to 4/3 mount and an OM to Micro 4/3 mount.

The OM to 4/3 adapter has a "sticking out articulator" that engages a spring loaded "thingie" at the back of the OM lens. With the OM lens attached to this adapter, yes, turning the diaphragm ring opens and closes the iris. But this adapter does not fit onto my Micro 4/3 camera.

The OM to Micro 4/3 adapter lacks the "sticking out articulator." With the OM lens attached in this adapter, no, turning the diaphragm ring does not open and close the iris...the lens stays wide open unless I press and hold the smooth rectangular button on the side of the lens and turn the diaphragm ring...then the iris opens and closes as advertised. This adapter does fit on the camera.

Most lenses that I'm familiar with, you hold them in your hand and turn the diaphragm ring...the iris opens & closes. This particular OM lens looks like a mint condition lens. So, maybe the Olympus OM Series is different...in which case I probably need a different adapter.

However, if the OM lens is faulty...that's a whole different story and I probably need a new lens. I need to know from someone familiar with the OM Series lenses, whether what I'm describing is normal for the OM lens...or not.

...and if it is normal, where can I find an adapter that not only, "...fits any OM lens to any Micro 4/3 camera..." but which also pushes the spring loaded thingie at the back of the lens...so the diaphragm ring works too.

Thank you in advance for any help offered,
richardmaple


Top
  
 
 Post subject:
PostPosted: Sat Apr 10, 2010 6:25 pm 
Oh ok, I think I understand.

I dont have any OM lenses but I do have numerous M42 lenses. Your lens is fine. The fault seems to lie in the m43 adapter. As you noted, the APERTURE [not iris] closes properly when you mount it to the 4/3 adapter because the adapter is designed to make it so. However the m4/3 adapter you have does not seem have this function.

When you press the button on the lens itself, the button that closes down the aperture, does the aperture stay down after you release the button? Is there some way to keep the button pressed down?

Some of my m42 lenses have a little switch on the side that changes the lens from Auto to Manual aperture. Auto aperture means that when I stop the lens down, the aperture doesnt close until the camera body pushes the pin in when its taking the picture. This function allows for easier focusing and composing since the view from the viewfinder is much brighter when the lens is wide open.
-When I selected the switch to MANUAL aperture, then the aperture closed down immediately as I selected the aperture I needed. This was I guess for cameras that could not control the aperture in the camera body. This is good for us because our cameras cannot control the aperture with our digital bodies. So this is the mode we should leave the lens in if we want to stop down the lens.

I DO have a lens that CANNOT be switched from Auto to Manual. Meaning its always in Auto and hence I am limited to shooting wide open with it when i have it mounted on my camera.


Top
  
 
 Post subject: iris closing on OM lens
PostPosted: Sat Apr 10, 2010 7:58 pm 
Atomic hi and thanks for the quick response.

I'm certainly hoping that you're right and the lens is ok. It seems to be in excellent condition and even kludged onto the camera and using the diaphragm ring while pushing the button and taking a picture...I'm impressed. My bumbling is only because this is my first Olympic lens.

My guess is that the rectangular button on the side is a preview button ( I have one built into my Pentax 35mm Spotmatic...it works also as a meter switch).

M42 is a great standard. Works with both my microscope and telescope (as well as the Spotmatic), bellows & extension rings. I have a nice Vivitar 90mm f2.5 macro lens with a M42 mount...so of course I have a M42 adapter for my new Panasonic GF1. This is a brilliantly designed camera and the more I play with it the more I like it. The Operator's Manual...not so much.

Again, thanks for your feedback. This forum is really efficient for information transfer.

Be well,
richardmaple


Top
  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  

All words, images, videos and layout, copyright 2005-2012 Gordon Laing. May not be used without permission.
/ How we test / Best Cameras / Advertising / Camera reviews / Supporting Camera Labs

Webdesign by Alphabase IT
Powered by phpBB® Forum Software © phpBB Group