Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

Started 6 months ago | Questions
Sweets
Sweets Contributing Member • Posts: 709
Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

Hello good fellows,

First things first: hope you all stay healthy in these Covid times and survives.

Well, since i've some time at home now i started first looking at the Samyang T-series cine lenses and... thought... let me d-click my old 28-105mm. So when turning the aperture ring on the lens it won't click any longer and will smoothly change the aperture: that's my goal.

Searched/googled, found it for the A and M primes like 50mm etc.. Not for zooms. Started opening my lens, removed the click etc and than... man o man, there's some smart rotating counterclockwise mechanism which is failed to get working again when re-assembling. So, closed my lens, no problem, but still....πŸ€”πŸ€”πŸ€”... wonder how to get this working again. The aperture ring is now off-connected from the aperture when i check the lens in my hand.

Any suggestions / advise are welcome hereπŸ˜€πŸ‘

btw it's a lens i wasn't using so no problem about that, but stil...

-- hide signature --

rgrds. Henk (K-1+DBG6 & -01, GF2+14042X & LBA).

 Sweets's gear list:Sweets's gear list
Panasonic Lumix DMC-GF2 Pentax K-01 Panasonic Lumix DMC-GX85 Panasonic Lumix G Vario 7-14mm F4 ASPH Pentax smc FA 50mm F1.4 +21 more
ANSWER:
This question has not been answered yet.
MightyMike Forum Pro • Posts: 40,585
Re: Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL
2

Good luck! somethings its better not messing with things

-- hide signature --

Mike from Canada
"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."
'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'
http://www.michaelfastphotography.com/galleries/VP-BDI_3a.jpg
http://www.airliners.net/user/SpeEedy/profile/photos?sortBy=photoFavoriteCount

KentG Veteran Member • Posts: 4,691
Re: Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

In most DSLR/SLR lenses the aperture ring and aperture itself are never really connected mechanically, unlike a Cine lens where the aperture is usually pure medchanical. That is because the SLR/DSLR is thru-the-lens viewing and metering. This means the aperture never closes with the aperture ring because it has to meter wide open so the viewfinder does not get dim at small apertures. It only closes down when you either trip the shutter or use the stop-down button. At all other times the aperture ring and diaphragm are never connected one to one mechanically. They were in the M42 era up until they added open aperture metering in some bodies. The "click" as you call it are the standard aperture values that allows the metering to figure the rest of the solution like the shutter time, ISO, etc. If you disconnected any electronic coupling, then the aperture is likely never going to function properly.

That is the reason most of the AF mount lenses are known as "broken" k-mount lenses, because they removed the mechanical lever from the camera that allowed the camera to tell what the aperture setting was mechancally and went full electronic. Lenses with no aperture ring are A lenses all the time, which means only the camera can stop it down electronically. That is KAF2 and up. KAF still had the lever but the the lever acted on the aperture's fixed values, the click stops, the  lever stopped at the click setting (stop-down mode). Without the click stops the lever will just push the aperture ring to the bottom I think. Of course you have to have a camera body with the lever still in it which goes back a ways.

Don't take this as a perfect explanation as I am generalizing things. but if the aperture does not close down when you turn the ring you are basically screwed as its de-coupled now.

Kent Gittings

 KentG's gear list:KentG's gear list
Pentax K-5 IIs Pentax K-S1 Pentax K-1 Pentax smc D-FA 50mm F2.8 Macro Pentax FA 150-450mm F4.5-5.6 +3 more
Sweets
OP Sweets Contributing Member • Posts: 709
Re: Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

MightyMike wrote:

Good luck! somethings its better not messing with things

Or… exiting to find out how an old not used any longer lens works….? πŸ˜ƒ

-- hide signature --

rgrds. Henk (K-1+DBG6 & -01, GF2+14042X & LBA).

 Sweets's gear list:Sweets's gear list
Panasonic Lumix DMC-GF2 Pentax K-01 Panasonic Lumix DMC-GX85 Panasonic Lumix G Vario 7-14mm F4 ASPH Pentax smc FA 50mm F1.4 +21 more
Sweets
OP Sweets Contributing Member • Posts: 709
Re: Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

Thank u all for the replies.

I'll try the same npw with my old fa* 24-70f2.8 which I also rarely-seldom use.

I think now I know what the spring is for: keeping the aperture open in 'A' position of aperture-ring to provide ttl. Removing de tiny bal which enables blocking/locking/clicking might not change anything else, I know now.

Thx πŸ™πŸ˜€

-- hide signature --

rgrds. Henk (K-1+DBG6 & -01, GF2+14042X & LBA).

 Sweets's gear list:Sweets's gear list
Panasonic Lumix DMC-GF2 Pentax K-01 Panasonic Lumix DMC-GX85 Panasonic Lumix G Vario 7-14mm F4 ASPH Pentax smc FA 50mm F1.4 +21 more
GossCTP Veteran Member • Posts: 5,334
Re: Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

Sweets wrote:

Thank u all for the replies.

I'll try the same npw with my old fa* 24-70f2.8 which I also rarely-seldom use.

I think now I know what the spring is for: keeping the aperture open in 'A' position of aperture-ring to provide ttl.

None of that makes any sense. It sounds like you are looking at the lock that keeps you from accidentally going into A mode when setting f/22.

Removing de tiny bal which enables blocking/locking/clicking might not change anything else, I know now.

Thx πŸ™πŸ˜€

-- hide signature --

rgrds. Henk (K-1+DBG6 & -01, GF2+14042X & LBA).

-- hide signature --

"Law and order" is anathema to liberty and justice.

 GossCTP's gear list:GossCTP's gear list
Panasonic Lumix DMC-LX5 Pentax K20D Pentax K-5 II Pentax smc FA 50mm F1.4 Pentax smc DA 16-45mm F4 ED AL +7 more
Sweets
OP Sweets Contributing Member • Posts: 709
Re: Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

GossCTP wrote:

Sweets wrote:

Thank u all for the replies.

I'll try the same npw with my old fa* 24-70f2.8 which I also rarely-seldom use.

I think now I know what the spring is for: keeping the aperture open in 'A' position of aperture-ring to provide ttl.

None of that makes any sense. It sounds like you are looking at the lock that keeps you from accidentally going into A mode when setting f/22.

Removing de tiny bal which enables blocking/locking/clicking might not change anything else, I know now.

Thx πŸ™πŸ˜€

So wise of you. Thx for your comment. I was talking about the spring under the plate on top, circular, one sees on one of my photo's. It's lenght is about 1 to 1.5 cm by 2mm.

Your 'lock that keeps' etc is on the side of the barrel.

Thx anywayπŸ˜‰

-- hide signature --

rgrds. Henk (K-1+DBG6 & -01, GF2+14042X & LBA).

 Sweets's gear list:Sweets's gear list
Panasonic Lumix DMC-GF2 Pentax K-01 Panasonic Lumix DMC-GX85 Panasonic Lumix G Vario 7-14mm F4 ASPH Pentax smc FA 50mm F1.4 +21 more
Sweets
OP Sweets Contributing Member • Posts: 709
Re: Can anyone explain me the aperture mechanism FA28-105 F3.2-4.5 IF-AL

So... finally i managed to remove the aperture click-ball-and-spring from my tammys: 28-75 and 28-300mm. Those were quite easy/simple. The Pentax FA-mechanism is more complex, to me.

Reason: want to do some filming experience before getting a Samyang-T-series....

Stay healthy overthereπŸ˜ƒπŸ‘

-- hide signature --

rgrds. Henk (K-1+DBG6 & -01, GF2+14042X & LBA).

 Sweets's gear list:Sweets's gear list
Panasonic Lumix DMC-GF2 Pentax K-01 Panasonic Lumix DMC-GX85 Panasonic Lumix G Vario 7-14mm F4 ASPH Pentax smc FA 50mm F1.4 +21 more
Keyboard shortcuts:
FForum MMy threads