300mm vs 360mm Rodagon for low mag

[ic-racer]

I'm currently using a 300mm Rodagon for 8x10 negatives at 1x up to 2x (8x10 to 16x20) projection printing. The lens does not have a flat field at mag below 2x, but stopping down helps.

I happen to notice that the specs for the 360mm Rodagon indicate it has the same recommended mag range as the 300mm (2x to 8x), however, the 360mm is optimized for 2.5x rather than 4x.

So, I'm thinking the 360mm might perform better for me since I can only print up to 16x20.

RODAGON SPECS
range (optimum)

300mm Rodagon 2x to 8x (4x)
360mm Rodagon 2x to 8x (2.5x)

[Bob Salomon]

The 300mm Rodagon should have no problem doing what you want, assuming that you are using a glass carrier and your enlarger is properly aligned and that you are printing at the optimal aperture. And, of course, that the lens has not been dropped or otherwise abused. The same holds true for the 360mm Rodagon and the 240mm. All are corrected for optimal performance from 2 to 8x magnification. The 240 and 300 are at the optimal aperture at f11 and the 360 a half stop smaller.

If you are using a glass carrier and your enlarger is properly aligned then you might want to have the lens checked by service.

[ic-racer]

The 300mm Rodagon should have no problem doing what you want, assuming that you are using a glass carrier and your enlarger is properly aligned and that you are printing at the optimal aperture. And, of course, that the lens has not been dropped or otherwise abused. The same holds true for the 360mm Rodagon and the 240mm. All are corrected for optimal performance from 2 to 8x magnification. The 240 and 300 are at the optimal aperture at f11 and the 360 a half stop smaller.

If you are using a glass carrier and your enlarger is properly aligned then you might want to have the lens checked by service.

What I wonder is at 1x (technically outside of the range for both lenses) which one will have the most flat field. If I can open up one stop (11 instead of 16) and still have sharp corners that can save a whole minute in some cases (I have a lot of filtering in place: center filter, 30CC Yellow, Ilford MG filter, then F16... it all adds up)

Another thing I was thinking of trying it experimenting with element spacing to see if I could optimize the field flatness of my existing 300mm for 1x and 2x.

I have a spare lensboard so I was thinking of trying a process lens, but it seems the hole in the lensboard is designed for the 360mm Rogagon, so I though I might try that instead.

(OK so if you can read between the lines you can see I'm really just trying to justify the expense to my wife of filling that 92mm hole in my spare lensboard with some nice glass )

[Allen in Montreal]

Dale,

Sorry for the delay in posting this.
I know we do not have the same units, but for reference,
to make a print of only 11x14 with a 360 requires some real height. Forgive the all the junk in the picture, the Durst is still standing in a corner of the studio area.

When I first looked at this in real time, I knew it would never do in my height challenged darkroom and slowly sought out a Rodagon 300 (thank you Blair !!) and a Rodagon 240.

With the table dropped to the floor, the largest print I can make with a 360mm is a 16x20.
It is 89 inches to the top of the column, not the condensor head, total height on my unit as seen is 107 inches.

From the logistical point of view, I can't see using my 360.
if you want to borrow mine and try it out before you buy, let me know and i will ship it down to you.

At 1:1 with the 360mm, the negative stage is 79 inches high with the table at 24 inches from the floor.

[ic-racer]

Thank you Allen for positing those measurements. So my plan would be to just use the 360mm for my 'near 1:1' images.

Advantages over contacting are that I can get a white border (to match all my other prints) and I can crop out dust on the edges or crop out areas of inadequate lens coverage and straighten crooked horizons.
I have a line on a couple 360mm lens, when I get one I'll post my results.

[ic-racer]

Ok, so I got a 360mm lens and also what looks like a 300mm Process lens. I don't have the process lens mounted on a lens board right now, but the 360mm came on a Vapla.

So, as Allen pointed out, the basebaord and negative have to be pretty far apart. I was able to set it up for a 1:1 8x10 and check the edges, vs. the center. They both seemed to be at the same focal point, even wide open. So, my impression is that, indeed the 360mm has better field flatness for 1:1 use, compared to the 300mm Rodagon (non-G).

Next thing is to try to mount the process lens. I have a spare Vapla lensboard, but it has a huge hole. Perhaps I can make an adapter ring.

[ic-racer]

Ok, so to answer part of my question.

I obtained a 360mm Componon and it does not work very well at 1:1. It just is not very sharp at 1:1 when viewed with a grain magnifier. When I use the lens as intended (to project a 60" image on the wall) the resolution is fine.

So, I'll earmark the 360mm lens for 'wall projection.'

Next thing I have to test is a Eskofot Ultragon 305mm process lens. I need to get that mounted up on a Durst lensboard. I suspect that lens will be excellent at 1:1.

[ic-racer]

I spent this afternoon mounting my Eskofot Ultragon 305mm with a 65mm size onto an adapter plate to fit a Durst lensboard with a 93mm hole.

Initial check at 1:1 seems fantastic. I'll make some prints, but so far I will segregate my lenses by use as follows (for 8x10 negatives):

1x to 1.4x -> Eskofot Ultragon process lens
1.4x to 3x on baseboard -> Rodagon 300mm enlarging lens
3x and up on wall -> 360mm Componon

I have one more lens to play with, a Fujinar f4.5 250mm. I don't know much about it, I'll post some pictures. Initial test shows it to cover 8x10. It is just the right focal length to get back what I am missing by not being able to get the CLS2000 all the way to the top. I'm missing out on about 4" of maximum height and with the 250mm Fujinar, I can still fill the baseboard (about 40" across)

That Fujinar has a 65mm x 0.9 mount, with no ring or flange, so I guess I'm going to have SK Grimes make a flange or ring for it. I guess it will cost more than the lens is worth, but these 250mm that cover 8x10 are not that easy to come by (because all the folks with low ceilings want them I guess ).

[Allen in Montreal]

I read somewhere or other that the Fujinar was a pretty good lens, I would not be surprised if it turns out to a very nice glass and very sharp. They are not very common.
I am looking forward to hearing your report on the Fujinar.

[Joerg Krusche]

Hi,

I think it is not a great surprise that the Ultragon (a repro lens) is very good re. field flatness at 1:1 .. any good symmetrical repro-lens should perform like that i.e. zero field curvature at and adound 1:1.

best

joerg