New Distance and Aperture Scales for Laowa 7.5

Started 4 months ago | Discussions
TheEye
TheEye Veteran Member • Posts: 4,760
New Distance and Aperture Scales for Laowa 7.5
5

As has been previously noticed by several people here, most of the aperture and distance markings on the 7.5 are off. It's pretty incomprehensible that Laowa screwed this up.

I made new scales that I printed, laminated, and stuck on top of the original markings.

I figured out the approximate actual apertures (better accuracy than +/-0.5 stops) for each click stop.

I figured out the actual distance markings for 5m/infinity, 3m, 1m, 0.5m, 02 and 0.12m. This was easily accomplished by placing a strip of sticky paper over the original focusing scale. Using 14x magnification and a tape measure and a focusing target, I marked the corresponding distances with an 0.3mm mechanical lead pencil on the paper strip. As it turned out, the only focusing distance marked just about correct was the closest focusing distance of 0.12m (hard stop). The infinity mark was ridiculously far off and the intermediate distances were also off.

I created new aperture and distance scales. I printed them on white waterslide decal paper. Decal paper has to be sealed before it can be immersed in water unless you use waterproof ink. Acrylic clear coat works but is rather fragile. I decided to instead laminate the decal's surface with glossy Scotch tape. While matte Scotch tape more closely matches the finish of the lens, the matte surface also makes the markings appear less crisp, so I decided to go with glossy tape.

I then cut out the aperture and distance scales with an X-Acto knife and straight edge. Then I placed the waterslide decal in water until the decal came off the paper base.
I tested a short length of decal on the lens and found adhesion of the decal to be poor. That's why I decided to use clear 5-minute epoxy resin, applied very thinly to the backside of the decal. I had to figure out how to line up the markings before attaching the decal. I used a cotton bud to smooth out the decal. Adjusting the decal was easy as the decal can be manipulated for a couple of minutes before the epoxy sets. Once the epoxy had begun to set, I wiped the decal with an alcohol prep pad to remove any excess epoxy.

Please note, I did not create a new depth-of-field scale. As it is, I get a bit more DOF than the DOF scale indicates which is preferable over getting less DOF than indicated.

That's how far the lens can be focused past actual infinity

The closest focus coincides obviously with a hard stop and was pretty much spot-on on the original scale.

Po Sen Tsui Regular Member • Posts: 200
Re: New Distance and Aperture Scales for Laowa 7.5
1

Wow, hard to imagine you go through all this, nice work!

I am a lazy person though, I simply use focus peaking to check

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Not an expert, not a pro, I just shoot for fun

 Po Sen Tsui's gear list:Po Sen Tsui's gear list
Olympus E-M1 II Olympus M.Zuiko Digital 17mm F1.8 Olympus 12-100mm F4.0 Panasonic 100-300mm F4-5.6 II Venus Laowa 7.5mm F2 MFT
TheEye
OP TheEye Veteran Member • Posts: 4,760
Re: New Distance and Aperture Scales for Laowa 7.5

Po Sen Tsui wrote:

Wow, hard to imagine you go through all this, nice work!

I am a lazy person though, I simply use focus peaking to check

Thanks. It's not the first time I had to modify markings on a lens. It didn't take all that long. Figuring out the correct markings took maybe 30 minutes. Creating the new scales on the computer and printing them took maybe an hour because I had to make a few adjustments. Laminating, cutting out and attaching the scales took maybe 15 minutes. I did not have to get any supplies. All in all it took me probably 2 hours over the course of 2 days.

luisflorit
luisflorit Veteran Member • Posts: 8,244
Re: New Distance and Aperture Scales for Laowa 7.5

Nice!

How far is your strip from the Laowa one, up to a rotation? Maybe a way to fix the laowa marking is to unglue and turn some ring...?

Thanks,

L.

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TheEye
OP TheEye Veteran Member • Posts: 4,760
Re: New Distance and Aperture Scales for Laowa 7.5

luisflorit wrote:

Nice!

How far is your strip from the Laowa one, up to a rotation? Maybe a way to fix the laowa marking is to unglue and turn some ring...?

Thanks,

L.

Thanks. Unfortunately, the markings are off by various amounts which are all in the several-millimeters range. Only the closest focusing marking is almost correct. It's like they designed the basic layout for the distance scale and forgot to actually calibrate the markings in the end. And why the aperture markings are off from 1.5 stops to half a stop beats me.

I really do like the optical performance and the mechanical quality of the lens. Otherwise, I would not have bothered making the lens more usable for zone focusing.

rb61 Regular Member • Posts: 315
Re: New Distance and Aperture Scales for Laowa 7.5

Po Sen Tsui wrote:

Wow, hard to imagine you go through all this, nice work!

I am a lazy person though, I simply use focus peaking to check

Help a rookie. ˙How do you use focus peaking to verify DOF?

 rb61's gear list:rb61's gear list
Olympus OM-D E-M10 II Olympus M.Zuiko Digital ED 40-150mm F4-5.6 R Olympus M.Zuiko ED 75-300mm 1:4.8-6.7 II Olympus 12-40mm F2.8 Pro Olympus 7-14mm F2.8 Pro +1 more
stateit
stateit Senior Member • Posts: 1,074
Re: New Distance and Aperture Scales for Laowa 7.5

TheEye wrote:
...All in all it took me probably 2 hours over the course of 2 days.

Customers say to me in my line of work, "But you were only here for two hours."
Yeah mate, but I've spent the last couple of days thinking about it... 

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karlreed Senior Member • Posts: 2,032
Re: New Distance and Aperture Scales for Laowa 7.5

stateit wrote:

TheEye wrote:
...All in all it took me probably 2 hours over the course of 2 days.

Customers say to me in my line of work, "But you were only here for two hours."
Yeah mate, but I've spent the last couple of days thinking about it...

Yeah, it took me about 6 years to work out how to point some 12v LED downlight as extra backing lights on my Peugeot 307 wagon.  It took a couple of hours to complete, but, the thinking time and observation time was spread over, well 6 years or more! Woth effort, they look as if they have been there since new.!

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karl reed "let's change the tone-civility is in!"

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pocoloco Senior Member • Posts: 2,366
Re: New Distance and Aperture Scales for Laowa 7.5

rb61 wrote:

Po Sen Tsui wrote:

Wow, hard to imagine you go through all this, nice work!

I am a lazy person though, I simply use focus peaking to check

Help a rookie. ˙How do you use focus peaking to verify DOF?

I use focus peaking for focussing....

although... with this lens.... I use it even more simplified...

F5.6 with focus to infinity almost all landscape / cityscape / street shots... never have to think about it... everything will be in focus!

F2 for close ups, and then I move the camera forward / backward and focus peaking to see if my subject is in focus!

F2 and focus to infinity for starry sky shots.

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Po Sen Tsui Regular Member • Posts: 200
Re: New Distance and Aperture Scales for Laowa 7.5

pocoloco wrote:

rb61 wrote:

Po Sen Tsui wrote:

Wow, hard to imagine you go through all this, nice work!

I am a lazy person though, I simply use focus peaking to check

Help a rookie. ˙How do you use focus peaking to verify DOF?

I use focus peaking for focussing....

although... with this lens.... I use it even more simplified...

F5.6 with focus to infinity almost all landscape / cityscape / street shots... never have to think about it... everything will be in focus!

F2 for close ups, and then I move the camera forward / backward and focus peaking to see if my subject is in focus!

F2 and focus to infinity for starry sky shots.

Yep, and DoF is not an issue really, it's a 7.5mm anyway

-- hide signature --

Not an expert, not a pro, I just shoot for fun

 Po Sen Tsui's gear list:Po Sen Tsui's gear list
Olympus E-M1 II Olympus M.Zuiko Digital 17mm F1.8 Olympus 12-100mm F4.0 Panasonic 100-300mm F4-5.6 II Venus Laowa 7.5mm F2 MFT
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