Thanks for the link, Brian
You're right off course, you can have an interesting discussion based on theory, but in the end only careful testing with your own equipment will tell,
best,
Cor
Thanks for the link, Brian
You're right off course, you can have an interesting discussion based on theory, but in the end only careful testing with your own equipment will tell,
best,
Cor
Forget shooting test charts at close range.
What effect does this have in real world shooting, where 0.005" isn't critical.
Because, don't forget, whilst you're spending time doing all this resting, real photo opportunities are being missed.
Lachlan.
You miss 100% of the shots you never take. -- Wayne Gretzky
I've got a few Fidelity, Riteway and Toyo's and always use the Toyo ones in preference to the others.
A 0.005 difference will shift focus. And I'm not suggesting that this be done at a close distance. This should be done simply as part of a basic lens test, which doesn't take long at all. Measure the distance (follow the link) and run through, what, maybe 8 sheets of film? The test is reasonably quick.
If someone doesn't care, hey, fine. I found out all of this because I had to replace my GG.
0.005" @ hyperfocal or infinity is bugger all focus shift. GG finish (rough v smooth), loupe quality, lens quality, lens mounting quality, tripod quality and/or atmospheric conditions will all come in to play, as,too, will the shooter's latent ability to focus.
These is all relevent when considering shooting wide open. Fairly moot when stopped down. All well and good shooting test charts; real world shooting for the most people won't show any easily-discernible difference between brands at anything but very, very big enlargements.
But, just ignore this if you intend to do massive blow-ups of test charts...
Lachlan.
You miss 100% of the shots you never take. -- Wayne Gretzky
lachlan's last post is accurate. If you are doing landscapes and portraiture, I've never had a problem. For technichal work, I imagine it makes a big difference.
Without wrestling with the math or tests I estimate a .005" focus error might cut the resolution of a fast lens in half. At the typical small apertures we use for LF, the comments of Lachlan are valid.
I just measured the thickness of some Ilford FP4 negatives... 0.20mm = 8 mils = 0.008".
The Ilford datasheet says the base is 7 mils thick (0.180mm), so the emulsion is 1 mil = 0.001" thick.
I believe a shift of 0.005" in the position of the film would make a HUGE difference in the focus.
Sorry to avoid "real world" experiments and confuse the issue with the facts.
- Leigh
+1 for Toyo. I use the 4x5 and 8x10 versions, and I'm happy with them. Compared to the regal's I've used, they are definitely a bit nicer in terms of fit and finish. Never had any light leaks or film flatness problems. The downside is that they smell horrible when new, like some sort of burnt plastic.. the smell does mostly go away eventually though.
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