Technika lens board light leak rant

[Harlan Chapman]

All my lenses are on Technica boards. They all fit just fine on my Ritter, Toyo, and Rittreck cameras and work very well.
Last fall I picked up a gorgeous 5x7 Sinar Norma from Will Whitaker (thank you Will!). To use it I purchased a nicely made Chinese Sinar to Technica lens board adapter on Ebay. It looks very much like the SK Grimes version:https://skgrimes.com/whats-new/2006-...hnika-adapters. Given the similarity in design I was confident my adapter would work just fine.
Sadly, all of my shots taken using this adapter are flawed with light leakage.
It turns out that the slot at the center of the bottom (top?) of the Technica lens board lets light through. The lens board adapters for my other three cameras all cover up this little slot and have no problem with light leaks.
This leaves me wondering what this slot is for? Have others had this problem?
I have ideas for a fix. The best I think would be to make the plate wider that engages the lens board edge with the slot to cover it up. It should be easy I hope and better than resorting to gaffers tape.
Thank you for listening,
-Harlan

[linhofbiker]

That slot fits around the location pin on the receiving board mount of my Technika IV and Kardan cameras.

[Greg]

Encountered the same problem one time back when. Fixed it with filing the edges of the slot down to bare metal and then filling in the slot with J B Weld.

[Len Middleton]

Harlan,

Frankly, I think the design is poor, in that the screws holding the lower strip should be aligned with the two notches on the lens board where they sit on the supports on the Technika front standard. That would set the lens board lower and and the centre notch would adaptor board be covered by the lower strip.

On a properly designed Technika adaptor board, it should be designed with just a circular opening and the opening would stepped to match the raised light trap on the back of a Technika lens board. I am not familiar with the SKGrimes adaptor. but given their reputation, I would expect it to have those feature.

Have a close look at the details of the Technika front standard to see how their configuration addresses the situation.

Hope that is helpful,

Len

[pepeguitarra]

Savage Graffer Tape.

[David Lindquist]

Am I seeing things? It looks like your lens is mounted to the back of the board? That looks like the circular light trap that's supposed to be on the back as well as the bevel at the bottom. Though this may have nothing to do with your problem.

Can someone confirm this for me?

David

[Havoc]

From your description I understand the issue is with the adaptor board, not with the technica board. So it could be useful to get a photo of the adaptor board alone.

Silly idea, but have you tried it upside-down? Maybe the upper slider does cover the slot.

[William Whitaker]

Hi Harlan,
As linhofbiker already pointed out, that slot mates with a locating pin in the original Linhof design that insures the board is centered.



The photo above is of my Technika -> Sinar adapter board. This was made from an original Linhof adapter which was cut down and then mounted to a Sinar lensboard. The Tech board rests on the silver buttons, but is located via the pin in the middle. (It's tiny, zoom in.) But that pin is clearly below the opening in the adapter and if the slot in your Tech board is cut properly, it should not admit light inside the camera.

I would suspect that your Technika board was not made true to the blueprint and that the slot is cut longer than necessary. Is it a generic board? Some are better than others and it pays to keep notes. The generic boards I've used with success and no issues have all come from Badger Graphic Sales. That's not to impugn or disparage other makes, but that's just my personal experience.

Short answer: black tape over the slot.

[Paul Ron]

Am I seeing things? It looks like your lens is mounted to the back of the board? That looks like the circular light trap that's supposed to be on the back as well as the bevel at the bottom. Though this may have nothing to do with your problem.

Can someone confirm this for me?

David

it does look like the lens is mounted on the back.

fill the slot with auto body filler or epoxy plumbers clay as a permenent fix... or use tape as a temp fix.

.

[Harlan Chapman]

Thank you all for your thoughtful replies. This is really helpful.

It turns out that there is a gap in the flocking on my lens board adapter right at the light leak point. This can't help. I'll replace the flocking and seal the gap. This should help, but I'm hesitant to rely on that for the perfect fix. Maybe combining that with Greg's JB weld idea will do it. And I'll be on the lookout for a better designed adapter that does it right overall for peace of mind.

Len, I see your point. The Ritter adapter I have (photo attached) has a machined step that definitely looks like it helps with the light seal.

David, it does look like the lens is on the board upside down. An optical deception from the photo makes it look upside down but it is not. Sharp observation though! I'm attaching a photo of the back side of that lens/board to show the raised area on the back that fits in the trap.
Thank you again for your help.