Right lensboard for Tachihara 5x4

Hi.

Which lensboard is the right choise for Tachihara 5x4?

Centred or not centred, like Linhof (i mean the hole for the lens)?

I noted that Linhof lensboard has the hole about 5mm out of it's centre (down).

At the shifting scale of the Tachihara, there is exept the numbers, a letter L

between, number 0 and 1.

What is this for?

Thank you for your answers.

Tachihara 4x5 accepts both. There is a scale on the front standard.Dot mark on the scale is for centered and letter "L" is for Linhof board.

If i have a lens that just cover 5x4, mounted on a linhof lensboard (that is not centred), i must to shift to the letter L for avoid vignetting?

Whille with all my lenses, i have no vignetting, using my 75 f\8 that has a coverage 181mm at f\16 (i am using ever, more than f\16) and raising at num. 1 i am finding dark corners upside.

What i doing wrong?

Hi. I'm not sure that I have the answer for you, but one thing that occured to me is

that wide angle lenses often need a centre-filter to be able to use the extremes of

their image circle. It might be worth writing to Scheider (who I've found very helpful

in the past) and ask if this lack of a centre filter might explain what you're seeing

(and if so which centre-filter you'd need to get to remedy it).

 

All the best,

 

Jonathan

Hi Christos, I have a Tachihara 4x5 too, but mine came with 10 free lensboard when I bought it new. They are all centered.

 

I don't think you really need a center filter with a 75 mm, I have made many shots with mine without major issues, with shorter focal lenghts, there is reason for it.

 

Your issue with dark corners at the upside of the photo may be due to an issue I have occasionally run into too: with my Super Angulon 75mm lens, I actually need to drop the lower rail bed in some cases. With such short focal lengths, you actually start registering the end part on of the lower rail bed of the Tachihara on film if you do not perform a drop bed, or move the back panel to the front. The wide angle lens is simply to wide to keep all parts of the camera "out of the way"...

 

I have made a quick sketch of what I mean, sorry for the drawing quality...<div></div>

Marco very usefull your design.

Thank you for your time.

Jonathan i use a schneider c.filter while i have this inconvenience.

Probably is that it's need some bed drop to avoid this vignetting.

I'll try this that Marco said.

Thank you again.

Christos,

 

As said, you can also move the whole backpanel including groundglass forward, instead of dropping the bed. You need to unscrew the large brass knobs to the left and right and below the groundglass for that.

 

However, I find the construction of the sliding mechanism of the backpanel one of the weakest points of the Tachihara. If you look closely at the underside of the camera, you will notice that the black metal sliders that hold the backpanel onto the bed, and are supposed to allow sliding, actually have two tiny brass screws screwed into them that compensate for a gap in between the black metal sliders and the wood of the bed. These screws scratch along the brass covering of the underside of the bed and will easily get damaged. It's a fragile construction... I am therefore am a bit hesitant of using this option too often, although it's quicker than dropping the bed.

 

It would have been much better if the black metal sliders had some kind of Teflon covering, to allow them to slide easily yet have a perfect fit. Maybe, if I find something suitable, I will replace the tiny screws myself with some other more robust material.

Thank you again Marco, for your perfect explaination.

Very usefull.

From which focal length do you need to drop the "bed"?

Can't say exactly... I have three lenses, 75, 150 and 210 mm. Only the 75 has given me some issues, but not always, it depends on vertical shift (rise / fall). With even shorter focal lengths, problems will be bigger.

 

Ok, so I have now done a quick test. Even with the 75 mm, you are most of the times OK, it's only when you lower the front panel (fall), that the railbed may block the image.

 

Testing this showed that the railbed becomes an issue if you shift the front panel more than about 1 cm down (at 1.5 cm the railbed became visible). Of course, if you do a front tilt, you may run into issues much quicker.

 

To test this yourself:

 

1) Put the camera in a normal (not bed-dropped, as in the top drawing of the image that I posted) position with your 75mm lens installed.

2) Tape a piece a *bright white* paper down on the wooden front end of the railbed. Since the wood is dark, and the railbed will be completely out-of-focus, you will otherwise not be able to detect it on the groundglass.

3) Shine a very bright light on top of the piece of paper, so as to make it detectable on the groundglass.

4) Look at the groundglass with the lens in the "0", so no vertical shift position, you will probably NOT detect anything now.

5) Now vertically shift the front panel 1.5 cm down (fall).

6) Look again at the groundglass, you will notice a vague, out-of-focus white border at the topside of the groundglass (image is of course upside-down), this is the "wide angle issue" or vignetting...

 

By the way, here's a nice webpage with some photo's showing viewcamera movements, including drop bed an incline bed:

 

http://www.imagedancer.com/view_camera_movements.htm

Excelent tecnically explanation Marco.

I'll do the test, following your instructions to discover finally what is my problem.

I apreciate a lot your help and all your advices.

Thanks again for all your time.