Hoya HMC auto tele 300mm F5.6 lens

[GWT]

I picked up an Olympus mount 'Hoya HMC auto tele 300mm F5.6' lens for my OM1 today but once fitted the focus spot didn't want to respond to focusing - the lens did seem to focus but not the spot.

I'm thinking that the lens may be broken in some way or perhaps it's an issue with third party lenses?

Has anyone else experienced this issue before?

 

[Tony Whitney]

My experience is that those focusing spots never work with long lenses and it's best to forget them...TW

 

[back alley]

i agree with tony!
you have to be perfectly centred to use the central spot and even then it's a crap shoot.

 

[GWT]

Ah….Ok, thanks guys for the heads up - so I might possibly have the same issue even with an Olympus version?

It's a bummer as the lens is really clean but I'm not sure I could live with that blurry disc, slap bang in the centre of what I'm trying to focus on...

My experience is that those focusing spots never work with long lenses and it's best to forget them...TW

i agree with tony!
you have to be perfectly centred to use the central spot and even then it's a crap shoot.

 

[gustavoAvila]

There is nothing wrong with the lens or your camera.

The standard focusing screen (1-1 or 1-13) does not work well with slow lenses.

Replace the screen with a 1-4, 1-7 or 1-8.

See the following link for further details.

http://www.mir.com.my/rb/photograph...ympusom1n2/shared/accessory/screens/index.htm

 

[Kate-the-Great]

^ I don't have any specific OM experience, but I'll echo what Gustavo said.

The focusing screens on older (pre-autofocus era) SLRs are optimized for fast lenses; f/2 and the like. I've had several where the focusing spot starts to lose effectiveness at f/4- they weren't designed for f/5.6 and slower lenses.

Newer screens are manufactured differently so that they don't darken with modern f/2.8 / 4 / 5.6 lenses, at the expense of brightness with fast lenses.

 

[ferider]

F5.6 and above is where split image and micro prism focus screens stop working. You need to use the matte area of your screen for focusing. Which is why many 300mm lenses (OM zuiko, Nikkor ais, etc) have a max. Aperture of f4.5.

This has nothing to do with screen brightness, but is a physical/geometrical effect.

Roland.

 

[GWT]

OK, well that sounds more promising - I will keep my eye our for a new screen!

Thanks guys!

There is nothing wrong with the lens or your camera.

The standard focusing screen (1-1 or 1-13) does not work well with slow lenses.

Replace the screen with a 1-4, 1-7 or 1-8.

See the following link for further details.

http://www.mir.com.my/rb/photograph...ympusom1n2/shared/accessory/screens/index.htm

^ I don't have any specific OM experience, but I'll echo what Gustavo said.

The focusing screens on older (pre-autofocus era) SLRs are optimized for fast lenses; f/2 and the like. I've had several where the focusing spot starts to lose effectiveness at f/4- they weren't designed for f/5.6 and slower lenses.

Newer screens are manufactured differently so that they don't darken with modern f/2.8 / 4 / 5.6 lenses, at the expense of brightness with fast lenses.

 

[GWT]

Hi Roland, many thanks for your input. So are you saying that a replacement 1-4 focus screen won't help with the Hoya due to the slower aperture?

F5.6 and above is where split image and micro prism focus screens stop working. You need to use the matte area of your screen for focusing. Which is why many 300mm lenses (OM zuiko, Nikkor ais, etc) have a max. Aperture of f4.5.

This has nothing to do with screen brightness, but is a physical/geometrical effect.

Roland.

 

[ferider]

It's an all matte screen with no focus spot. So it's like focusing you split or micro prism screen off center (which I do with an om-mount Tokina 400/5.6, for instance).

Best,

Roland.

 

[GWT]

Oh, OK so the 1-4 screen will allow me to focus without the horrible blurry large dot in the centre.

That would be much better, thanks again Roland.

It's an all matte screen with no focus spot. So it's like focusing you split or micro prism screen off center (which I do with an om-mount Tokina 400/5.6, for instance).

Best,

Roland.

 

[GWT]

My 1 - 4 focus screen for my OM1 arrived today!

All fitted and the Hoya is now focusing fine, many thanks to everyone who posted - it was much appreciated.

 

[JP Owens]

I really start feeling my 64 years when I read a post by someone that never had to deal with the challenges of manual focusing aides in SLRs! Fortunately for my aging eyes, autofocus is generally faster that I ever was manually focusing.