300mm lens on a 370mm bellows camera

[JeffD]

I currently have a 210mm lens on my 4x5, which has 370mm of bellows extension. I would like a longer lens. Of course, I realize that I could use a 300mm lens focused at infinity.

What I am wondering, is, how close could I focus considering my limit of bellows? This is probably simple math, but I am unsure how to calculate.

Would you consider a lens of this focal length with this camera?

I am thinking that landscape scenes where I might want to use this would probably be focused at infinity anyway, but, I guess I am wondering how much leeway I would have for closer objects, and wondering if the focal length might be to limiting consider my camera.

 

[Dave Wooten]

I think the 210 is a good lens for 4 x 5 and 5 x 7. You have plenty of room with 370mm of bellows....to see how close you can focus, put on the 210 lens and rack your bellows all the way out, then move the lens toward a house lamp, when lamp is in sharp focus that is your minimum distance and image size for that lens at full bellows extention....you won't have any depth of field, of course.

hope that helps

also I would not hesitate to use the 300 mm with 370 mm bellows

 

[JeffD]

I am pretty familiar with what I can do with the 210 lens- I guess I am wondering how close, in feet, I can focus a 300mm lens with aprox. 370mm of bellows draw...

 

[wildbill]

My shenhao goes to about 360mm and my 300mm Nikkor M lets me get about 4-5 feet if i remember right. Basically i can focus on the ground with the camera pointed straight down on my tripod. My results using this lens this way aren't the sharpest though. Hope this helps

 

[MichaelBriggs]

I am pretty familiar with what I can do with the 210 lens- I guess I am wondering how close, in feet, I can focus a 300mm lens with aprox. 370mm of bellows draw...

There are fundamental optical equations that answer this equation. Rather than retyping them, I will give a link: http://www.photo.net/learn/optics/lensTutorial

If you want precise answers, there are some tricks to applying the equations with a complicated lens: where on the lens do you measure the distances to? For most lenses (i.e., not true telephotos), you will do fairly well to measure distances to the aperture diaphragm. This gives you a little bit of extra extension since the aperture is a bit in front of the lensboard. To be perfectly exact, you have to look up on the datasheet or measure the location of the principal planes.

An approximate answer, good enough to give you an idea, is 1/d_obj = 1/300 - 1/370 implies d_obj = 1580 mm = 1.6 meters. So you will be able to focus fairly close, but not closeups. The image will be about one quarter life size.

 

[medform-norm]

I have the same thing to deal with. My camera doesn't draw bellows beyond 360/370mm. But the solution is nigh: if you have a 300m lens and you want to focus up close but your rails doesn't allow this, why not build a little tubus on your lens board to give that extra bit of length you need? I've seen it done on other cameras as well (Makiflex) and it doesn't mean that there will be any vignetting if the tubus is done right. Of course your 300mm lens should not be a 1,5 kg monster, for in that case, your tubus will need an extra tripod support, a thing to be avoided IMHO. One tripod is enough trouble to deal with.

 

[JeffD]

An approximate answer, good enough to give you an idea, is 1/d_obj = 1/300 - 1/370 implies d_obj = 1580 mm = 1.6 meters. So you will be able to focus fairly close, but not closeups. The image will be about one quarter life size.

This is just what I needed. I believe that most situations I envision using this lens (i.e. landscapes), I don't really think I'll need to focus closer than a a few meters, so this should be perfect.

Thanks to all!