Rail length

[pkr1979]

Hi all,

I just ordered a 450mm for my 8x10 camera. The rail I got is about 50 cm (or thereabouts). I felt its abit short so i ordered a new one. The size is standard so got one thats two meters (also standard size). Now, this is a bit much so I figured Id shorten it... but what is a useful length? My bellows go out to about one meter if i remember correctly but Im not sure if this might be a bit long too? Or if its a good length for a 450?

Cheers
Peter

 

[B.S.Kumar]

For a 450mm lens, approximately 900mm will give you a half life-size image, 1800mm will give you a life-size image. Do you want to shoot macro?

 

[pkr1979]

I got a 210mm that might be easier for macro. Im not really shooting a lot of macro either.

 

[Dustin McAmera]

The diagonal of 8x10 is about 325mm, so a metre of rail gives you a triple-extension camera; only really a meaningful statement if you mount a normal-length lens on it, I suppose.

 

[B.S.Kumar]

A rail longer than 1000mm is overkill, unless you're planning to use very long lenses to focus at short distances.

 

[pkr1979]

Thanks guys. Made one 1000mm and one 750mm

 

[DREW WILEY]

There is no single answer. Depends what lenses you use, and how you use them. I routinely keep a 24 inch rail on even my 4X5 Sinar because I like to work with long focal lengths. But it's comprised of a 12 inch center section and then a 6 inch extension at both ends, so it takes mere seconds to shorten the rail if needed. When it comes to 8x10 format, the longest lens I use is a 600mm Fuji C, so 750mm of extension is ample, since I use shorter focal lengths for close-ups anyway, especially a 360 Fuji A.

 

[Mal Paso]

I have a 42 inch rail which focuses my 1200mm Nikkor tele to about 25 feet and my 600mm to 5 feet. Telephotos usually focus shorter than their given focal length. Infinity focus for the 1200mm is 775mm. It's one of the longest 8x10 lenses commonly available.

 

[Rod Klukas]

For a 450mm lens, approximately 900mm will give you a half life-size image, 1800mm will give you a life-size image. Do you want to shoot macro?

The formula is twice the focal length for 1:1 reproduction ratio. See Leslie Stroebel View Camera Technique page 125.

 

[Rod Klukas]

One more note: 1:1 or lifesize reproduction always requires 2 stops of compensation.