Who needs 5x4...???

Probably got a synthesizer now.

Dan

Going back to the original point posted of why do we need 5x4, the reason is simple...... for big prints!

At the size you are showing us your landscape pics you really cannot differentiate between film formats, especially when they have been scanned. At that size scanning a 35mm and 5x4 they both would look exactly the same.
When larger formats really come into their own is when they are printed to large sizes. Strictly speaking a 5x4 neg is 8x larger than your 645 so you can print 8x larger whilst keeping the same definition. In-fact because 5x4 film is also thicker and has a higher silver density so you also get twice the definition resulting in crisper images.

By all means if your prints rarely exceed A4 then larger formats are not are really not an issue and even the humble 35mm is perfect for the job!

I'm not sure I agree with this.

First, the mathematics. 5x4 is 5 times larger than 645 (in area), or roughly 2.5 times in height.

The same ratios for 35mm are 14 times and 4 times.

I think the height ratio is the one to use. If it is comfortable to view an A4 print at, say, 75cms, then a print that was 4 times the height should be viewed from 4 times the distance, say 3 metres.

I don't know about you, but I don't think my eyes would be able to tell the difference between the two, unless I were to go closer to the large print. If I were to do that, I would no longer see the "big picture"; in other words, I would lose the wood and just see the pixels, sorry, trees.

But then, I am a little short-sighted. It may be that younger, eagle-eyed, audiences would gain from seeing a print from the larger format. I unfortunately, wouldn't.

G

George has raised a very valid point - that of viewing distance. To keep the perspective correct, bigger prints should be viewed from further away, at which distance you need less resolution to maintain the quality level.

Equally well, wide angle shots viewed very close have normal perspective and only look odd when viwed from greater distances.

Conversley, when viwed far away, telephoto shots lose the telephoto look and give normal perspective.

I demonstrate this by using a large print taken with the SMC Pentax 15mm f3.5 lens. Anyone with short sight can view this print at unusually close distances and will find that suddenly the picture looks quite normal, losing all the ultra-wide look.

Try it and see...

You are quite correct of course, the main reason to choose 5x4 is print size and definiton. I'm also in agreement with John and George as well in that it all has to relative to the viewing distances...

However........ that wasn't quite the point of my post. If you took the time to read it properly and not just the headline you'll have read that by using 645 I was suffering less in the very strong wind that the other chaps in Scotland that week were struggling with their huge 5x4 set-ups.

Sometimes being smaller and being able to work quicker has its advantages...

I understand what you are saying but I totally disagree with any form of correct viewing distance.

To me that implies two things:

1) That you restrict the audience from viewing a photograph how they would like to.
I don’t know about any of you but I always study a photograph for the first time from the 'optimum' viewing distance then always move in to capture detail and less significant objects I might not have noticed further away.
A prime example of where you need to do this is with Gregory Crewdson's and Jeff Wall's photographs where the entire picture is typically made up of lots of small details.

2) That the technical quality of the photograph is so dire that you don’t want people to stand too close to see this for themselves.

From what you are saying a bill board will look fantastic as long as you are 100ft away, however I say 'it is awful quality that is hidden by the fact your eyes can not see the tennis ball sized pixels from 100ft away!'

As far as film format goes, going by printing area and using 35mm as a standard typically the rule of thumb because of inverse square law is:

35mm = 1
120 645 = 2x
120 6x7 = 4x
5x4 = 16x
10x8 = 64x

"Correct" viewing distance only refers to the distance required for the perspective to be correct and does not imply that you are forced to observe this. In fact, if you did, you would negate many of the advantages of using different lenses.

Large TV screens are designed to be viewed further away, and in the same way large prints are as well. It would be silly to attempt to view a 6 foot by 4 foot print by holding it in your hands, wouldn't it?

As the Image Size dialog box in PS will show you, ppi alters and image size can alter with it, so without interpolation you can change the size of an image. The bigger it gets, the lower the ppi and the further away it will have to be to maintain its apparent sharpness to the eye.

The smaller print that you look at closely is no sharper than the poster hundreds of feet away, it has the same amount of information in it, but in the small print it is so small that you can only discern so much. The eye's limit is about 4 lpmm in a moderately large print, if I remember correctly.