Printable View
hi there.
given the light is not an issue (very powerful led)
how will such a lens perform when going 12x compared to a naturally suitable 210 or 240 of the same type.
negative size is 13x18 (5x7 inch)
would it be possible to use it wide open (f 6.8)?
any input welcome!
cheers,
chris
Should work fine, but I'ld stop it down a few clicks. Is this lens already installed on a horizontal enlarger? If this lens is on a 5x7 Durst, maybe Drew will chime in here as to the likelyhood of focusing that lens with the existing bellows and making a 60" image with that enlarger.
7 foot wide print. I assume horizontal projection.
Try it!
A shorter Rodagon G designed for 57 will still be optimized for the same magnification but would require far less extension and would perform optimally at a larger f stop giving shorter exposure times.
i just did 12 times with ordinary rodagon 210.
had to use several neutral grey gelatins to bring expose down to 7 seconds (!)
led changes the world of enlarging. but be careful with the magnifiyer. very harsh light.
stopping past f 8 brings up diffraction when doing such enlargement. all laser aligned.
will the rodagon-g 360 improve edge sharpness and (micro) contrast?
horizontal durst 138. making the huge lens work together with the lens revolver will be tricky but i will make it work.
I've done 60" wide prints from 5x7 using a 180mm f/5.6 Companon-S, stopped down to f/11 - and get sharp grain to the edges. Light source is a Heiland VC LED, powered down enough to give me 20 to 40 second(ish) green light exposures, plus 15 to 30 second (ish) blue channel exposures, which allows enough time to do my typical dodge/burn routines.
Chris...seven seconds? Are you masking these...or do you have really fast hands?
Hello. did 2 prints with this setup. print size is 200x150 cm which is in fact 11 point something times enlargement.Quote:
Originally Posted by John Layton
doing 60" wide means horizontal? that would be 8times.
makes a difference i guess.
i get excellent center sharpnes, corners are sharp, but not grainsharp.
7 seconds without dodging, just a stop or two of burning. fast and steady hands ;)
when working with handcoated paper long exposure times seem to eat contrast, 7 seconds is not enough though. was for first tests.
just to underline my basic question,
is a rodagon-g 360 an improvement? guess it has to be, no?
No, not for what you want. A 210 or 180mm Rodagon would perform better at 11x. Stopped 2 stops down from wide open. You do have a properly aligned enlarger and a glass carrier? If not you will never get optimal results!Quote:
Originally Posted by chris77
Properly aligned means film stage to lens stage to baseboard.
NO!!! Listen to what Bob said! A 360 is for 8x10 or larger. 5x7 requires a 180 or at most a 210 mm lens. If you have a 210 Rodagon, use it. It will handle 12x enlargement as well or better than a 360 G-Rodagon. And stop down 2 stops, you said your enlarger LED head had plenty of light! No enlarger lens is made to be used wide open. Also, if possible use a Unipla lensboard on the Durst, not the the turret.Quote:
Originally Posted by chris77
In my last post, I mentioned to use a Unipla instead of the Tripla turret with long lenses on the Durst L-138. These large boards can be used on the Durst L-138S or the L-184. Enlargers with the removable turret have a large plastic knob in front of the turret that is used to remove it. If you have a fixed turret, then you cannot use the Unipla board. I thought I'd post some photos of these boards:
First is the 3 lens Tripla removable turret and the single lens Unipla board. The hole opening of these two boards is the same diameter.
Attachment 198845
The Unipla can be used for lenses that stick out behind and prevent the turret from turning. I think it's also easier to align the enlarger with the Unipla than with a Tripla (fewer moving parts).
Lenses mount onto small boards called Laplas. The individual Laplas mount onto the Unipla. Lapla boards have threaded openings of either 25mm (Lapla 25), 39mm (Lapla 39 with Leica threads), 50 mm (Lapla 50) and others, or you can have custom threads cut if one is not available. I've routinely bought Lapla 25 boards to use to have custom larger threads cut to mount a lens. The Lapla with it's threaded lens then mounts on the Unipla ( or the Tripla). There are also recessed Laplas known as the Seipla, and the Setiopla which mount onto the Unipla.
Attachment 198846Attachment 198847
For lenses that are too large to fit a standard Lapla, you can get custom adapters made. Below is a 240 Rodagon in an SKG custom Lapla, plus a 180 and 135 Rodagons mounted in standard Laplas.
Attachment 198848
For lenses that were too large for the Lapla (like the 300 mm Rodagon, etc.), Durst made the Vapla, which was the large Unipla type flat board without the Lapla mountings and you could then screw a lens' mounting ring directly on the Vapla board. The lens would then screw onto this ring. Typically, the 210 mm lens is the longest you'd use on 5x7. A 210 lens can be made to fit on a Lapla and the turret, so the earlier L-138's did not have removable turrets, since there'd be no need to mount longer lenses.
Uniplas and Vaplas were available either at auction, or through Durst Pro-USA. With that company's demise, luck and the auction site are probably the best way to secure one. Hope this helps.