4x5 image circle question?

[stradibarrius]

with a 4x5 how much movement should I have if my 150mm lens has a 245mm image circle?

[Bob Salomon]

A 150mm Apo Sironar W had a 252mm circle and that allowed 63mm of rise and 56mm of shift in landscape format.
A 150mm Apo Sironar S has a 231mm circle and allows 50mm of rise and 45mm of shift in landscape format.

So your lens will be between these numbers if it has a 245mm circle.

[Gem Singer]

The image circle needed to cover 4x5 is 153.7mm (diagonal of the 4x5 format).

You should have 91.3mm of movements to play with.

Probably more than the average 4x5 camera is capable of handling.

[Leigh]

The image circle needed to cover 4x5 is 153.7mm (diagonal of the 4x5 format).
You should have 91.3mm of movements to play with.
Sorry, Gem, but that's not exactly the way it works. Your value is the diagonal offset, which doesn't match available camera movements.

Available movement is to the point where the image circle hits the corner of the film. Here's a diagram to illustrate the calculation:

http://www.mayadate.org/pix/ImageCircle.png

In this case there's about 48mm horizontal and about 54mm vertical movement (+ and -) available (landscape mode, transpose for portrait).

I use the full size of the 4x5 negative for the calculation even though the actual image area is slightly smaller.
This compensates for some light fall-off near the edge of the image circle.

- Leigh

[Gem Singer]

So call me a liar over 10.3mm, Leigh.

All I was pointing out was that the OP had ample room for movements on the 4x5 format.

(What would I do without Leigh constantly pointing out that he is more knowledgeable about photography than me?)

[Leigh]

I did not call you a liar, Gem.

I was trying to explain, for the benefit of the OP and others, how the calculations are made.

If you took my attempted clarification as an insult, I sincerely apologize.

- Leigh

[Jim Michael]

Well you're both right since the max you'll get is the sum of your x and y movements, and you'll need to take the max movement available for the specific camera into account to know for sure how much of the IC you can use. Leigh's diagram is useful in demonstrating those limits.

[Gem Singer]

Leigh,

I did not take your, so called, "clarification" as an insult. It seemed to be another an attempt on your part to prove that when it comes to photography, you are the ultimate authority.

I've been involved with this forum for over ten years. I seldom ask questions, but I do attempt to share what I've learned from 65 years of photographic experience with my fellow members.

I learn something new about photography every day. That's what I enjoy about the hobby, and that's what has kept my interest for all these years.


If you add up the vertical and horizontal movement possibilities that you showed on your diagram, it totals to 102mm of movement capability.

I referred to the difference between the image circle of the OPs' lens and the diagonal of the 4x5 format- 91.3mm.

The difference between your exact measurement and my rough estimate is only10.3mm.

As I pointed out, there aren't many cameras that will allow 100mm of movement.

[Leigh]

Gem,

I was trying to explain to the OP how to calculate the answer, so he won't have to ask next time.

It's the old "Teach a man to fish..." thing.

If you have a problem with that, too bad.

- Leigh

[ic-racer]

Well you're both right since the max you'll get is the sum of your x and y movements, and you'll need to take the max movement available for the specific camera into account to know for sure how much of the IC you can use. Leigh's diagram is useful in demonstrating those limits.

Since the OP did not specify, you could look at it a number of ways. Another interpretation is that the max vertical movement is 54x2 from the diagram = 108mm from top to bottom.

[Gem Singer]

Leigh,

Your opening statement on post #4: "Sorry Gem, but that's not exactly the way it works" was the remark that led me to my conclusion.

Let's just agree to disagree, and leave it at that.

[stradibarrius]

Thank you my question has been answered.

[Leigh]

Another interpretation is that the max vertical movement is 54x2 from the diagram = 108mm from top to bottom.
You'll note in my post #4 that I said the movements were + and - the values shown, so total would = 2* those values.

- Leigh