Topic: Another TLR and another calibration needed...

[sapata]

I have another TLR in need of focus calibration... what a surprise!

I noticed that when focusing at the infinity the image on the viewscreen wasn't really sharp so I decided to open the front panel to get access to the viewing lens.

The way I'm doing is by setting a laptop on the floor with the room in low light, open a website where I can see texts like a online newspaper for example, (control + and you zoom in the caracters at desired size) I then put a measure tape on the floor starting from the laptop screen and place the camera on the top of the tape at a certain distance, let's say 1.0 m to start.

I turn the knob at 1.0m and focus the image by rotating the taking viewing lens and looking through the viewfinder until Iget the image focused, In that way I have the image sharp at 1.0m exactly as shown on the knob.

I do this at different distances to make sure everything is alright and that's pretty much the way I fixed my Yashica and my Lubitel, but today I'm struggling to fix my Rolleicord!

I set the focus at the minimum distance and get the correct focus but as I go further with the camera and try different distances the knob scale won't match ! let's say I measured 1.20m, the knob will show 1.50m. At 2.30m measured with the tape the knob will show me 5.0m and I haven't got a clue why... any suggestions would be much appreciated !
Thanks...

[astrobeck]

not sure about this working for you...but I have to focus using my left eye.
My right eye is a bit "off".

Everyone has a dominant eye...

[Francois]

I think you'd better worry about infinity focus and let the rest fall where it does.
I don't know if the rolleicord has shims under the groundglass like the Mamiyas.

Here's a link to an exploded view of the Rolleicord
http://www.butkus.org/chinon/rollei/rolleiflex_exploded/rolleiflex__rolleicord_exploded.htm

Here's the long description on collimating the taking lens.
http://www.kyphoto.com/classics/collimator.html

[sethasaurus]

I only have an Rollei 1 (art deco) to examine, but as far as I know, the taking lens shouldnt need adjustment, unless somebody has alread tweaked it, or there is some problem with the focus mechanism.

Remember to keep the lens aperture open (f3.5 or so) so that you have a smaller DoF and accuracy for visual focusing.

Make sure also that the ground side of your piece of glass is at the film plane. If it's flipped, the thickness of the glass will make a significant difference at the closer distances.

[sapata]

I think you'd better worry about infinity focus and let the rest fall where it does.
I don't know if the rolleicord has shims under the groundglass like the Mamiyas.

Here's a link to an exploded view of the Rolleicord
http://www.butkus.org/chinon/rollei/rolleiflex_exploded/rolleiflex__rolleicord_exploded.htm

Here's the long description on collimating the taking lens.
http://www.kyphoto.com/classics/collimator.html

Thanks for the links Francois... I thought about the same (adjusting the camera at infinity) but wasn't sure.

I only have an Rollei 1 (art deco) to examine, but as far as I know, the taking lens shouldnt need adjustment, unless somebody has alread tweaked it, or there is some problem with the focus mechanism.

Remember to keep the lens aperture open (f3.5 or so) so that you have a smaller DoF and accuracy for visual focusing.

Make sure also that the ground side of your piece of glass is at the film plane. If it's flipped, the thickness of the glass will make a significant difference at the closer distances.

Sorry sethasaurus... I meant "viewing" lens, I guess the whole process is giving me head ache
I haven't even started cheking the taking lens but I'm assuming is fine, I'll check that as well...

[Jack Johnson]

When I recalibrated the rangefinder on my Iskra I just grabbed the nearest known-good SLR, picked a target, looked at the scale focus, and adjusted the rangefinder until the scale on the Iskra coincided. Matched four targets between maybe 1.2m and 10m over maybe two iterations and it's as close as my eyes are ever going to get, and seems to have made a noticeable improvement so far.

If I were doing my TLR I would probably use the same technique, unless I had reason to believe the viewing lens and the taking lens were off from each other. Or maybe that the focus knob had lost alignment and the DoF readings from the scale were off.