Conspiricy Theory

[E. von Hoegh]

Prof_pixel, I'm open to being educated. I would love to know what's wrong with my image of the process. But that probably goes too far into hybrid workflow for this forumn. Is there a good single source I can use to do so?

http://www.largeformatphotography.info/forum/showthread.php?81340-IQ180-and-8x10-assessment

The horse's mouth.

 

[E. von Hoegh]

I have shots showing the two formats quality and the difference is quite distinct, the 10x8 shots are way ahead and that's despite the 5x4 images being shot with a modern 1980's MC 150mm Rodenstock Sironar N lens and the 10x8 with a pre-WWII 12" Dagor (factory coated after WWII). Same tripod.

Every negative shot with my 10x8 cameras is higher quality than an equivalent made with one of my 5x4's. My normal print size is the same for both 5x4 & 10x8.

Ian

What Ian said ^.

8x10 blows 4x5 out of the water.

 

[E. von Hoegh]

What I'd like to see is a film comparison between a 'well shot' 4x5 and a 'well shot' 8x10 at the same final print size. I suspect the 4x5 would be sharper because of issues like lens quality and film plane sharpness.

Hardly. Do you have any experience at all with 8x10 and 4x5?

 

[pbromaghin]

prof-pixel - thank you. It looks like a great thread, mostly from people with large brains. 150 posts!

This really is good - I've been doing hybrid work flow for a few years. It hasn't been real satisfying and much of it remains a mystery, mainly because after a whole day of twiddling bits I just can't bring myself to do much more of it at home.

 

[Prof_Pixel]

Hardly. Do you have any experience at all with 8x10 and 4x5?

None with 8x10, but I've shot a lot of 4x5 in the past.

 

[E. von Hoegh]

None with 8x10, but I've shot a lot of 4x5 in the past.

OK. With 8x10, you have four times the area of 4x5. This means that with good technique, four times the information is available. Most LF lenses reach their diffraction limit near f:22 or a bit below, by f:32 any modern lens (and many older lenses) will be diffraction limited. So using a good modern lens at f:16 or so, a good filmholder, a solid camera and tripod, and - very important - good technique will get you 8x10 negatives with an incredible amount of detail. You really have to see a good one to believe it.

Then you have the scanning, which I am far from competent - let alone expert - at. But 70-80 mp is regarded as a fair equivalent of 6x6 or 6x7 film, 4x5 is considered as around 300-350 mp, 8x10 at around 1.5 gigapixel or more, depending on the lenses and film used.

What the test actually does is compare a crappy scan of a not-very-sharp 8x10 with a digital back. The digital back, by the way, does a superlative job.

 

[Prof_Pixel]

OK. With 8x10, you have four times the area of 4x5.

I though that real world issues, like lens field flatness and fall-off, general lens quality issues and film plane flatness in its holder pretty much negated the size difference so that an 8x10 didn't actually capture 4 times more information.

What the test actually does is compare a crappy scan of a not-very-sharp 8x10 with a digital back. The digital back, by the way, does a superlative job.

Agreed - I just hated to see people 'hung-up' on the scanning resolution non-issue.

 

[Ian Grant]

None with 8x10, but I've shot a lot of 4x5 in the past.

Your comments remind me of what I read in my youth.

In many older photo books there's an assumption that the larger the format the less important it is that technique is perfect, the large negative size it's assumed will hide many faults.

Maybe that was once partially the case in the 1930's through to the 1950's when 35mm and other miniature formats like 127 & 120 were not really achieving the high quality we expect today.

When I began using 5x4 commercially in the late 1970's I never realy gave the isuues a thought but bwas always as tight with 5x4 as I was with 35mm & 120. Much later when I began shooting LF for personal work I thought about the raesons, the qualities of different formats more seriously. That was the point when I realised I expected the best from all my equipment, I wanted to be able to enlarge a 6x6 (cm) portion of a 5x4 negative and have the same quality as a 120 6x6 negative. I wanted similar when i moved to using a 10x8 camera and I got what I expected.

My point is that old books hawked myths that have been long gone, but those myths pervade even today in the background.

Ian

 

[lxdude]

Agreed - I just hated to see people 'hung-up' on the scanning resolution non-issue.

Hardly a non-issue. The comparison is faulty in part because of the scanning.

 

[E. von Hoegh]

Hardly a non-issue. The comparison is faulty in part because of the scanning.

Yes, they really stepped on their cranks with that so-called "test".

 

[E. von Hoegh]

I though that real world issues, like lens field flatness and fall-off, general lens quality issues and film plane flatness in its holder pretty much negated the size difference so that an 8x10 didn't actually capture 4 times more information.

Lens performance really isn't an issue, and hasn't been for a good long time. Film flatness and proper filmplane location are real issues. The rest is up to the photographer.
When I made my first few 8x10 negatives with a good lens, I spent hours peering at them through a low power dissecting microscope, just picking out different details and gloating over the fact that I had 80 sqare inches of this stuff.

 

[lxdude]

Look at the tank with the letters 'AGR' on it. Look at the jagged edges. Those are not on the film originals. The scanning removed information, homogenizing fine detail into single-tone squares. It's not like the full image information from the film is somehow "compressed" into the smaller format's scale.

How can you expect a roughly 35 micron pixel to match a 5.2 micron pixel? It might seem that a 6 times larger pixel of the same scene on a format about 5X larger on the short side would make for a good comparison, but it does not, because the film resolves much smaller than 35 microns.

The fault is in trying to shrink the 8x10 to "match" the smaller digital through a low-res scan. A correct test would have enlarged the digital to match the 8X10. A comparison of more or less equal file sizes is meaningless, because full-information files are not equal-sized. Comparing equal-sized full-information prints from the originals would have been meaningful. Pixel-peeping one full-information image against one part-information image proves nothing.

 

[lxdude]

Hey guys, you can read all about it over at LFPF. One thread ran 32 pages.....

And a good one on the LuLa forum, too.