Issue with maintaining focus

[Serge S]

Hi,

I have a circa 1920's Deardorff. And sometimes my images are a little soft.
I noticed the other day that the focus shifts a bit when I lock down the knob.

Any work around solution to this issue. I try to hold the body tight with my hand but it still moves a bit.
It becomes time consuming to constantly tweak it over and over again till I get it "right"

Thanks a bunch

serge

[Doremus Scudder]

You know the old joke:

Patient: "Doctor, it hurts when I do this."

Doctor: "Then stop doing that!"

If using the focus lock knocks your camera out of focus, then stop using it. My Wista DXs have the focus lock backed all the way out and jammed against the lock nut so I can use them as an extra focus knob. The cameras stay in focus just fine without the lock except when pointing them straight down with a very heavy lens.

If the focusing mechanism on your Deardorf isn't stiff enough to hold focus most of the time by itself, maybe you can tighten it up somewhat.

If you really want to use that focus lock, you'll need to find a combination of washers that doesn't transfer the movement of the knob (the torque) to the camera body. A couple of oversized nylon washers should do the trick.

Best,

Doremus

[Peter De Smidt]

You can also try adjusting the focus just a bit as you lock down the standard. For example, if locking the camera causes a 1mm rearward extension increase, focus forward 1mm and then lock the focus. Doremus's suggestion is easier, as long as inserting a holder doesn't cause the non-locked-down stand to move.

[Jac@stafford.net]

If you really want to use that focus lock, you'll need to find a combination of washers that doesn't transfer the movement of the knob (the torque) to the camera body. A couple of oversized nylon washers should do the trick.

A wave spring is another good choice.

[TroyG]

I shoot on an old Graflex Graphic View and my lock knobs would shift the standard a little. What I found is if I turn it until it starts to "Grab" but it isn't tight enough to impede movement, I can still turn the knob back into focus, then finish locking it down. Focusing with the knob partially locked actually makes it easier to get fine focus, the resistance helps me get it just right.

[John Layton]

It is indeed possible for a focus lock which is mounted coaxially to the focus shaft to cause some focus shift as this lock is engaged. I actually consider this to be a design flaw.

On the other hand, a shaft clamp...featuring a locking control (typically a lever) mounted perpendicular to the focus shaft, will not have this problem.

[Peter Collins]

Not sure the OP was addressing my condition: I have an "issue with maintaining focus." My mate reminds me frequently.

[Serge S]

Than you for all the suggestions.
I was away traveling when I posted and was out of Internet range.
Will look into the options suggested.
I will try leaving it unlocked as you suggested Doremus, as it may work, and that would be great!
It did try the partial lock down and focus, but it still shifts the focus out.

Thanks again

Serge

[Vaughn]

I am not sure this will help, but with my Zone VI 8x10, I grasp the focus knob tightly (not the body of the camera) when tightening the locking knob at the other end of the shaft. I give the focusing knob a little counter force to balance the rotation caused by tightening the locking knob.