Experience with chinese helical focusing devise.

[Michael Dymersky]

Does anyone have any experience with the chinese helical focusing devise from ebay for Linhof Technika IV,V.Is the hole properly positioned off the center.It is compartible with Grandagon-N 65ml f 4/5. Michael Dymersky.

[sparq]

Does anyone have any experience with the chinese helical focusing devise from ebay for Linhof Technika IV,V.Is the hole properly positioned off the center.It is compartible with Grandagon-N 65ml f 4/5. Michael Dymersky.

I've received mine today, and while the device is quite well made, the lens hole is positioned way too high. You get a lot of unwanted rise with it.

[Caroline Matthews]

If it's anything like Chinese toothpaste, fish, etc., I would stay away!

[Rafael Garcia]

What is the device this post refers to? I've searched eBay and not found it.

[sparq]

Ebay# 140120417684

[IanG]

Michel, I just looked at the item your asking about and then read "sparq's" comments.

My Wista/Linhof lens boards were drilled off-centre, or more correctly higher than the vertical centre, by the UK importer, this gives the appearance of the lenses sitting too high, but is in fact the correct position.

So to answer your original question the positioning appears to be correct. My 75mm f8 Super Angulon sits in a similar focussing mount, and the 65mm f4.5 Grandagon while possibly slightly larger should be no problem. But this is on a 6x17 camera.

However there is a more likely problem on a 5x4. I use a 65mm Super Angulon on a recessed board which gives me greater flexibility for movements, using a helical focussing mount will bring the lens forward, meaning the front standard will need to be closer to the lens plane.

It is normal to use a recessed board for wide angles on a Linhof, in fact my first 90mm f6.8 "Linhof" Angulon came fitted to a Linhof recessd board.

Maybe you need to have a re-think.

Ian

[David A. Goldfarb]

Sparq (or anyone else who knows)--what lenses have you used with this helical and on what camera?

I was thinking of trying a 47mm with one of these on my Technika, but if the hole is positioned too high, it won't work, because there would be no way to change the position with camera movements on a Technika, and the lens should just cover the format.

[Kirk Keyes]

I've got one right in front of me. It has a Grandagon-N 75 f/4.5 in it, and that lens looks like it's placed exactly where my Grandagon-N 90 f/6.8 sits in it's Linhof recessed board. (The Linhof board is tan and the deepest one I could get.)

With the 75, I place the lens on the internal rail in my Technika IV. There is of course no shifts or rise with this arraingement, but I find it less of a pain to use the 75 on the helical mount than when I had the 75 in the deep Linhof board that I mentioned above - to use it then on the recessed board, I had to slide the front track on the Technika back, drop the front, tilt the front standard back vertical, and then slide the front standard half off the back of the front tracks... At least with the helical, I don't get the standard moving around when I try to cock the shutter like it did when the front standard was half off the front track.

As far as quality of the helical, it had some excess grease on it which I wiped off, and the bearings in the helical seems a little rough. Not as smooth as it could be, but it is very usable, especially for the price.

I plan on getting a 65 or 58mm someday, and I'll get a helical for it. Or I'll just save up and get a Technika 3000...

[sparq]

I'll try to make some comparative pictures of a flat lens board and the device. I can't see how the hole position could be possibly correct with a Technika IV - the lens center is clearly off the center of the GG. I mounted a Nikkor 4/65 on the board; but I have not taken any pictures with this combo, yet.

[sparq]

Here are few pictures of the device with Nikkor 4/65. See how high the lens center is when mounted on Technika IV.

[sparq]

Here are comparison shots of the device w/the wide Nikkor and of two flat lens boards. On the left, you can see SA 8/65 on #0 board; on the right the device w/Nikkor and a #1 board on top of it. This test is far from being geometrically correct, but I hope that it will give you an idea about the actual position of the hole on the wide angle device.

[David A. Goldfarb]

The last image in the first three is taken from above, rather than straight on, so it's hard to judge whether it is centered with respect to the groundglass. From the first two pictures, it looks like the helical is positioned below center as it should be, but then from the next two shots it looks like it might be above center.

Let us know how the pictures look with the 65/4. Are you getting vignetting from excessive front rise?

[sparq]

The last image in the first three is taken from above, rather than straight on, so it's hard to judge whether it is centered with respect to the groundglass.

How can you tell? :) It is taken from below actually; the asymmetrical bellows makes it look like from above. The center of the hole is a few mms (gross guess: 5mm) higher than centers of my flat boards.

I haven't had an opportunity to make any pictures with the device, yet.

[David A. Goldfarb]

Very tricky, but yes, I'd forgotten that the bellows is shaped like that, so it looks like you're looking down at it.