You're welcome. Hope you got the G lens, that will do the trick. I have a 105 G and a 210 G, and had a 150 G which I sadly had to let go. All are fantastic for murals. Post some pics of paper processing adventures when you get to that step, that's where the real fun is - tie with cutting big sheets from rolls.
Yes, the 300 Rodagon-G looks just about perfect. Hopefully, I bought it before someone else did. Now... I need (I mean "want") a 150-G.:D
Can someone correct me if I'm wrong with my calculations?
The calculation I'm using to determine necessary lens focal length to achieve a minimum of 112 inches print length is Lp=Dp/Fl * Lf, where Lp is "Length of print", Dp is "Distance from film to print", Fl is lens Focal length and Lf is Length of the film. I have at least 4270mm distance from film plane to easel... a tiny bit more really.
Here's how I calculated for 56x112mm film...
Lp = 4270mm/135mm * 112mm
Lp = 3543mm or 139 inches
And for 8x10" film...
Lp = 4270mm/300mm * 244mm
Lp = 3473mm or 137 inches
I realize this formula isn't absolutely precise but it's close enough, right? That extra 20 inches print length is a bit of built-in fudge-factor or, better yet, ability to crop a bit if necessary.
Wow. That is a good price on a 300G. But since this is going to be used with 8x10 film and is engineered for 20x magnification, that's a sixteen-foot wide print. I don't know what the low end of
the G is per recommended magnification ratio. Would be easy to find out, but is probably suitable for your use, much more so than any taking lens if that focal length. But you'll need some elbow room!
Here's Rodenstock's web page with their specs. Scroll down to the table of Rodagon-G info. They're optimized for 8x-30x with optimum performance at 20x. I'll be using this one from 12x-15x.
I finally found a phone number to call Cameraquest. I spoke to someone who told me that was an old web page and he doesn't know if they still have the 300-G. He said he'd return my email in a couple of days. I don't know if I can hold my breath for that long.....
Regarding post #23, the formula shown is incorrect.
For a negative whose format rectangle measures 56mm x 112mm and 4270mm of negative-to-print distance and using a 135mm lens, the magnification is 29.6X.
That makes the dimensions of the projection approximately 1657mm x 3315mm = 65” x 130”.
For an 8” x 10” negative whose format rectangle measures 195.5mm x 245.5mm and with 4270mm of negative-to-print distance and using a 300mm lens, the magnification is 12.1X.
That makes the dimensions of the projection approximately 2365mm x 2970mm = 93” x 117”
You can print whatever fits inside the projections.
Perhaps an Apo-Ronar might prove good enough. If you haven't seen it, here's a video of a German photographer using a 1800mm Apo-Ronar for a 50x90" Ilfochrome (interesting parts: 21:30-41:35 and 57:34-end): http://www.ereignis21.de/Ereignis21.mp4
Thank you, Ian. Can you post the formula you're using?
They can be expensive. An alternative is the 'poor-man's' high magnification enlarging lens. That is, use a lens with a longer focal length. For example, when I'm projecting 8x10 on the wall for up to 50" I use a 'standard' 360mm enlarging lens. Realize that, just like large format photography with lenses that 'just cover' you problems arise at infinity, not close-up. So when enlarging, small magnifications are like close-up and you don't need a lens with great coverage. The more magnification you need the more it is like a camera lens at infinity, thus you can run out of sharp image circle.
Originally Posted by Old-N-Feeble
UPDATE: I saw above that you may have got a bargain priced Rodagon G 300! Good work!