105mm for 6x9 and 150mm for 4x5 but

[Robert]

I think that the 105mm is considered the proper lens for 6x9 but lets say I decide to get just the 150mm I think the limitation will be the max size print I can make. Any other issues? How much will I miss out in terms of size? Looking at the beseller website it claims a 5x enlargerment is possible with a 150mm lens and a 4x5 neg. If I could get that with the 6x9 that would be more then enough. Is it reasonable to assume I'll get the same 5x enlargerment by just changing the negative size?

 

[Thilo Schmid]

Why not consider a 135mm lens?

 

[Robert]

Do be honest I'm sort of confused about those 135mm lens. What I think I know is they are designed for 9x12cm and aren't perfect for 4x5. It would be better for 6x9 but still a little long.

 

[paul owen]

I'd get the 135mm for both. I use a Schneider and it works as well with 5x4 as it does on 6x9!

 

[Thilo Schmid]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Robert @ Sep 17 2002, 05:13 PM)</td></tr><tr><td id='QUOTE'>Do be honest I'm sort of confused about those 135mm lens. What I think I know is they are designed for 9x12cm and aren't perfect for 4x5. It would be better for 6x9 but still a little long.</td></tr></table><span id='postcolor'>
Robert,

the specs say that the Rodagon 5.6/135 covers 4x5" while Schneider says that their Componon-S 5.6/135 covers only 9x12cm. This is the same as with 6x7 format and the Rodagon 4/80 and Componon-S 4/80 resp. The former does support it officially, the latter not.

I do have both and can tell you that both do cover 4x5" at usual working apertures. However, if you do have a larger glass negative carrier (e.g. 5x7") without masks, you may need to center position the negatives more precisely with a 135mm lens than with a longer one.

The 135mm will give you larger magnifications on your easel, but the 150mm lenses do have an advantage when printing on smaller formats (e.g. 8x10"): they leave more space for handling dodging and burning tools.

 

[Robert]

I got a 150mm with the enlarger about 2/3s of the way up I manage a 5x7 from a 6x9 negative. I might even get a 8x10 out of it if I lower the enlarger off the table. Considering the 6x9 is close to 50 years old and comes with guess focussing 8x10 is good enough. I'm kind of surprised at how good the old camera does.

 

[EUGENE]

Robert, I have been using the El-Nikkor f5.6 135mm for my 4X5 negatives for several years. It covers the 4X5 format and enables 16X20 enlargements on the baseboard of my Omega D-2 enlarger. I have never tried the combination, but I think I could make an 11X14 enlargement on the baseboard with a 6X9 negative and the 135 lens. The D-2 has a relatively short column, compared with the newer D-5XL, so the 135 lens is a compromise focal length with my set-up. If I were using the longer column D-5 XL, I would use a 150mm lens for 4X5 negatives. I do not believe that you will be able to get 5X enlargements on the baseboard with a 150mm lens and a 6X9 negative, unless you really have a long column on your enlarger, or drop the baseboard. You could project onto a wall, but that's a hassle. It would be more practical to use the 105mm lens, that is ideal for the 6X9 negative. Also, the higher you raise the enlarger head, the longer the printing exposure times, and the enlarger then becomes prone to vibration.

 

[David A. Goldfarb]

"Also, the higher you raise the enlarger head, the longer the printing exposure times"--Not true. At the same aperture, with the same negative, but different lenses (setting aside the issue of differences in light transmission due to the properties of the glass and coatings), the exposure time depends only on the degree of magnification. If you make a 5x enlargement from a 35mm neg with a 50mm lens at f:8, the exposure will be the same as a 5x enlargement with any other lens at f:8, because you are spreading the same amount of light over the same area on the baseboard.

"and the enlarger then becomes prone to vibration. "--This is true and worth considering.

 

[Robert]

The main limit on the size right now is the ceiling-) The enlarger doesn't have enough room above the table it's on to fully extend. It's extremely stable. The manual claims about 160lbs for the whole unit and after hauling it up onto the table I believe them. I've been thinking about making a lower table for it but I'm not sure about working at the 2foot height it would need to be. Does anybody work sitting in a chair? I'd really like my workbench back so I need to build something to put the enlarger on but the low working height is bothering me.

 

[EUGENE]

David, if Robert was to use a 135mm enlarging lens on his enlarger with a 6X9 negative. Let's say he was making an 8X10 enlargement. Then, he raised the enlarger head up to make an 11X14 enlargement from the same negative, with the same 135mm lens. Are you saying that the exposure time would not increase? It sure increases on my enlarger set-up. Now, if he were to change to a shorter lens, he wouldn't need to raise the enlarger head to make the 11X14. His exposure time would not increase. The distance between the enlarger lamp and the paper would remain the same. The higher I raise my enlarger head to make bigger prints, the longer my exposure times become (F stops remaining the same). I stand by my statement. Use the shortest lens that will adequately cover the format (in this case 105mm). It makes the enlarging experience much easier. And Robert, I have seen darkroom set-ups where a section of the ceiling above the enlarger was raised to accomodate a long enlarger column.

 

[David A. Goldfarb]

If you use the same lens and change the enlarger height, then you change the magnification and therefore the exposure time at the same aperture will be longer at the higher magnification. So yes, if you make an 8x10" with a 135mm lens then raise the head to make an 11x14" with the same lens, aperture, and neg, of course you will need a longer exposure for the 11x14". Agreed so far.

If you change lenses and make two enlargements of the same size at the same aperture, however, enlarger height will be different, but the exposure time will be the same. So if you make an 8x10" with a 135mm lens, then switch to a 150mm lens, it will be necessary to raise the enlarger head to make an 8x10", but the exposure will be the same as with the 135mm lens, because the magnification factor is the same. It will also be the same if you raise the enlarger head way high and project on the floor to make an 8x10" with a 300mm lens from the same negative, or if you project across the room and make an 8x10" with a 1000mm lens from the same negative, because in each case, you are making an 8x10" from the same neg.

It is true that raising the enlarger head to make a bigger print without changing the lens, as you say, will result in increasing the exposure time, but if you change lenses so that you are not in fact making a bigger print by raising the enlarger head, but making the same size print, the exposure will be the same, because the magnification factor is the same.

In general, I would agree that one should use the shortest lens that will adequately cover the format, though when the differences in focal length are small, there may be particular reasons--economic, optical, and otherwise--to prefer one lens over the other.