maintaining infinity while extending rear bed

Joe Washington · Dec 21, 2017

hello, I am new to 4x5 format and recently purchased a Toyo field camera. in order to shift the rear standard I have to extend the rear bed by about 1 cm. I assume I therefore also have to move the front standard back an equal distance from the infinity stops to maintain the same setting for infinity. Is this the normal procedure or am I complicating things? Thanks for any input. jw

voceumana · Dec 21, 2017

It is normal for any camera with a rear extension to have to shift the lens back to compensate for any rear extension.

I'll have to check my Toyo to see if I have to extend the back to shift. Note that you can always buy a second set of infinity stops and mount them back for the back extension position--when they fold down, they are out of the way and won't interfere with using the front stops. Although, I generally don't use the infinity stops because I have several lenses.

Joe Washington · Dec 21, 2017

thanks, I considered that as an option but was already planning on an extra set of stops for my next lens, if I had to do this for two lens I would have 4 sets of stops and that seems excessive. I figured I would attach some kind of scale along the bed so I could keep the same distances between the standards, but I haven't been able to find any discussion of how others deal with this or if necessary, even the view camera books - Simmons, Adams, don't go into details, but maybe that's cause most cameras don't require extending the bed to use the shift?

ic-racer · Dec 21, 2017

If you are using the ground glass to focus you don't need the infinity stops. Those are required to use the rangefinder (Linhof, Wista, Horseman, Graphic) or if you are zone focusing with no movements (using a focus scale on the front rail like shown above). As soon as you apply any swing or tilt the infinity stop is no longer accurate. Even after rise or shift, I wouldn't trust it. I'd consider the infinity stops a detriment when using the ground glass as I like to be able focus beyond infinity to zero in on correct focus.

Joe Washington · Dec 21, 2017

thanks for that, it does seem intuitive to forget about the infinity stops and just go with what you see on the ground glass, but I don't understand how you can focus on "beyond infinity", - maybe less than infinity, but that's where racking out on the front standard comes into play.

WilmarcoImaging · Dec 21, 2017

Joe, yes if you perform a rear standard movement, it will alter the focus, assuming the image was focused prior to the rear standard movement.

I have a Toyo 45AII, so if you are referring to a 45A or 45AII, I assume you are swinging the rear standard. Strictly speaking there is no rear shift, by which I mean the rear standard does not move laterally. It moves fore and aft, and it also swings, which is a differential combination of fore-aft movement between left and right sides.

Joe Washington · Dec 21, 2017

thanks. I do have the 45AII, and you are probably right about the swings vs shifts which I still cant keep straight in my mind. I am talking about tilting the rear on a vertical axis, not laterally moving it left or right. it does seem the infinity stops would facilitate quicker setup etc, but then realized I had to extend the rear bed to get swing and that would throw off the infinity setting. what do you do? seems like even estimating the rear extension and applying an estimated equal amount, or a little more to the front standard in the same direction would suffice before fine focusing? tell the truth, all I have shot so far is tests to calibrate the ASA of film I will be using, and I will be developing those in a day or two. so basically I just need to mess around a bit but was hoping someone could save me some time with a definitive answer. in the end I'm just hoping you can trust what you see in the ground glass.

WilmarcoImaging · Dec 21, 2017

Joe, I don't use infinity stops for any lens. I get the camera set up, rack the focus out about 1/3 of the way, then lock it down. Then I install the lens, and move the front standard in and out until the image is roughly focused, then lock down the front standard. From there, it is a game of minute adjustments. This is my procedure for all lenses.

With experience you will know roughly where the front standard needs to be, for each lens. By racking the focus out a bit before installing the lens, you don't need to readjust the front standard for swings or tilts, unless you are using a relatively large swing/tilt. The necessary compensation after a tilt or swing can be done with the focus knob, which for me is easier.

Marco Gilardetti · Dec 22, 2017

Joe Washington said:
thanks for that, it does seem intuitive to forget about the infinity stops and just go with what you see on the ground glass, but I don't understand how you can focus on "beyond infinity", - maybe less than infinity, but that's where racking out on the front standard comes into play.

"Past infinity" is a physical concept, like imaginary numbers, negative masses, time going backwards, and so on. In order to take a picture, you don't really need to understand it, and you're not going to use it in practice anyway. Forget about it if you find it is confusing for you.

Joe Washington said:
seems like even estimating the rear extension and applying an estimated equal amount, or a little more to the front standard in the same direction would suffice before fine focusing? tell the truth, all I have shot so far is tests to calibrate the ASA of film I will be using, and I will be developing those in a day or two. so basically I just need to mess around a bit but was hoping someone could save me some time with a definitive answer. in the end I'm just hoping you can trust what you see in the ground glass.

Now, indeed, you're uselessly complicating things (as you feared in the first post). As Wilmarco has already written, infinity stops are useful only if you're using a coupled rangefinder or a sportsfinder handheld, so you can't check the image on the groundglass. If you're using the tripod and the groundglass and/or any movements, infinity stops are not necessary. As a matter of fact, I own only cameras with useless old infinity stops made by previous owners, that don't match with any of the lenses that I use. You just need to place the lens a little more backwards than usual, and then rack the front standard until your subject is in focus on the groundglass. That's all.

E. von Hoegh · Dec 22, 2017

Joe Washington said:
thanks, I considered that as an option but was already planning on an extra set of stops for my next lens, if I had to do this for two lens I would have 4 sets of stops and that seems excessive. I figured I would attach some kind of scale along the bed so I could keep the same distances between the standards, but I haven't been able to find any discussion of how others deal with this or if necessary, even the view camera books - Simmons, Adams, don't go into details, but maybe that's cause most cameras don't require extending the bed to use the shift?

You check focus on the groundglass, simple as can be.

Dan Fromm · Dec 22, 2017

Hmm. Infinity stops prevent unintentional swing. The problem with infinity stops is that using more than a few focal lengths can require more infinity stops than will fit on the bed. With my Graphics, I use a piece of metal with an inverted top hat section that fits snugly between the rails to square the front standard.

Joe Washington · Dec 28, 2017

thanks everyone for the comments. Kind of surprising that the Toyo manual directs you to install the stops, but after having done so I can now see that they are not needed. the only value i see other than rangefinder focusing is an established 0 reference point to compensate for long bellows extension, but that will rarely affect my type of work and I can always reference the scales provided on the bed in the few cases it may be necessary. thanks again. jw

ic-racer · Dec 28, 2017

Joe Washington said:
the Toyo manual directs you to install the stops,

You can print the Horseman focus scales I posted above and use them on the Toyo "Free Scale" (in conjunction with the infinity stop) if you want to explore all the possibilities of that camera and try some hand-held 4x5 work.

maintaining infinity while extending rear bed

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