Komura 105mm f2.5...2 apertures rings. Why?

norm123 · Apr 9, 2018

Hi
Yesterday, I bought this lens for a friend of mine in a photographic flea market. Soon after, I realised that there is 2 aperture rings. One, at the front of the lens with clic stop and an another one just behind with no clic stop. This later, when you turn it, it comes darker as you close the lens but not the former one. I'm not sure how to use it and why it's like that. Here there is a mention of ''Aperture Preset Ring''. http://allphotolenses.com/lenses/item/c_1599.html

I need explication.
Norm

macfred · Apr 9, 2018

Preset Aperture Lenses – How They Work And Why https://35hunter.wordpress.com/2017...-how-they-work-and-why-you-need-at-least-one/

E. von Hoegh · Apr 9, 2018

macfred said:
Preset Aperture Lenses – How They Work And Why https://35hunter.wordpress.com/2017...-how-they-work-and-why-you-need-at-least-one/

Whomever wrote that seems to have no clue that lenses with click stops can be set between clicks. Also that auto-diaphragm lenses have fewer aperture blades to reduce friction.

norm123 · Apr 9, 2018

If I understood right, if I want to take a picture at f8...because my lightmeter said f8. I set the aperture ring (one with the clic stop) at f8 and do focus when the other ring is wide open (one without clic stop). After, I close this ring (without clic stop)
until I reach f8. If I stop the free moving ring at f5.6....the picture will be at 5.6, not f8. Am I right?

E. von Hoegh · Apr 9, 2018

norm123 said:
If I understood right, if I want to take a picture at f8...because my lightmeter said f8. I set the aperture ring (one with the clic stop) at f8 and do focus when the other ring is wide open (one without clic stop). After, I close this ring (without clic stop)
until I reach f8. If I stop the free moving ring at f5.6....the picture will be at 5.6, not f8. Am I right?

You are right. The link above pertains mainly to using preset lenses on mirrorless digital cameras.

John51 · Apr 9, 2018

You are correct, that's how they work. Although you can stop the free moving ring at f5.6 when the lens is set to f8, that isn't how they are intended to be used.

You rotate the free ring until it can't go any further. Then you are at the click stop aperture you set previously.

I prefer a preset ring to the lens or camera having a sliding button. Much easier to use.

norm123 · Apr 9, 2018

Thank you all for responding.

ac12 · Apr 11, 2018

The preset lens was an advancement of the manual lens, which did not have the preset ring.

We set the preset ring for the desired aperture. ie f/11 under constant light.
Set the aperture ring wide open, to focus.
Close the aperture ring till it hit the stop of the preset ring.
- Note, you had to be gentle. With some pre-set lenses you could PUSH past the preset ring position, because the preset ring was only in a detent, not locked. So if you set the preset to f/11, you could push past to f/16 or f/22. When you did that you also pushed the preset ring to that position.
- There were a few lenses where the preset ring was "locked," and could not be pushed.
Then released the shutter.
The repeat steps 2-4 for the next shots.

Preset lenses were a way for 3rd party lens manufacturers to sell lenses cheaper, by eliminating the complex/expensive auto aperture mechanism. And they were fairly popular back in the 60s and 70s.

The 3rd party preset lenses were not specific to a camera brand. They used a T-ring, which adapted the lens to your mount. So the store could stock a single lens and multiple T-rings to adapt the lens to various bodies.

Most LONG lenses were preset lenses. By LONG, I mean physically long. In fact my brother's 600mm broke down into 2 parts, to make it easier to transport. Those lenses could not be auto aperture, because they separated into 2 parts, and the aperture was in the front half.

In the slower shooting pace of those days, a preset lens was perfectly acceptable.

MattKing · Apr 11, 2018

Ironically, a preset lens is more convenient than a "standard" lens for those who like to use adapted lenses on mirrorless digital bodies, or non-compatible film bodies.

norm123 · Apr 17, 2018

ac12 said:
The preset lens was an advancement of the manual lens, which did not have the preset ring.

We set the preset ring for the desired aperture. ie f/11 under constant light.

Set the aperture ring wide open, to focus.

Close the aperture ring till it hit the stop of the preset ring.

Note, you had to be gentle. With some pre-set lenses you could PUSH past the preset ring position, because the preset ring was only in a detent, not locked. So if you set the preset to f/11, you could push past to f/16 or f/22. When you did that you also pushed the preset ring to that position.

There were a few lenses where the preset ring was "locked," and could not be pushed.

Then released the shutter.

The repeat steps 2-4 for the next shots.

Preset lenses were a way for 3rd party lens manufacturers to sell lenses cheaper, by eliminating the complex/expensive auto aperture mechanism. And they were fairly popular back in the 60s and 70s.

The 3rd party preset lenses were not specific to a camera brand. They used a T-ring, which adapted the lens to your mount. So the store could stock a single lens and multiple T-rings to adapt the lens to various bodies.

Most LONG lenses were preset lenses. By LONG, I mean physically long. In fact my brother's 600mm broke down into 2 parts, to make it easier to transport. Those lenses could not be auto aperture, because they separated into 2 parts, and the aperture was in the front half.

In the slower shooting pace of those days, a preset lens was perfectly acceptable.

So...Why the preset ring at this moment if the ring with continuous movement determine aperture?

E. von Hoegh · Apr 17, 2018

norm123 said:
So...Why the preset ring at this moment if the ring with continuous movement determine aperture?

It doesn't determine aperture, the preset ring determines aperture. The stopdown ring allows you to set an aperture, focus wide open & then close the aperture to the preset value rapidly, reliably, and without removing your eye from the viewfinder.
The type of usage described in the second post describes using a preset lens in aperture priority mode on a digital camera, not how the lens was intended to be used.

norm123 · Apr 18, 2018

E. von Hoegh said:
It doesn't determine aperture, the preset ring determines aperture. The stopdown ring allows you to set an aperture, focus wide open & then close the aperture to the preset value rapidly, reliably, and without removing your eye from the viewfinder.
The type of usage described in the second post describes using a preset lens in aperture priority mode on a digital camera, not how the lens was intended to be used.

Thank you..now it is clear.

Norm

Komura 105mm f2.5...2 apertures rings. Why?

Moderator

Privacy & Transparency

Privacy & Transparency