Lens for 6x7 enlargement.

[NDP_2010]

I recently got a new enlarger that can do 6x7 negatives and it came with a 135mm lens. I previously had a 35mm enlarger with a 50mm lens, but I find that the 135mm lens does not make a very big print with 6x7, approximately only 8x10 (i have beseler 45mx2) and the 50mm lens the corners are not getting any light with a 6x7 negative. Is the 50mm lens too wide?
What sort of lens would be good to get up to 16x20 on this enlarger?
Can anyone reccomend a specific lens that is reasonable quality.

Thanks.

 

[martyryan]

for 6x7 I use a Nikkor 80mm f5.6 six element lens.

Marty

 

[Rick A]

I have a Wollensak 90mm that will cover 6x9cm that works very well for me.

 

[NDP_2010]

If i am getting 8x10 with a 135, what size will I get with a 80-90mm lens?

 

[Rick A]

That depemds on how tall the column is. I would think at least 11x14 or maybe 16x20.

 

[jeffreyg]

My forty year old 75mm El Nikkor easily does 16x20 with 6x6 an is very sharp so I would think that a 80-90mm would suit your needs.

http://www.jeffreyglasser.com/

 

[martyryan]

I have a Beseler 23c II with the XL column and can make a 16x20 with room to spare.

Marty

 

[Ian C]

If you raise the head as far up as possible and measure the distance from the negative down to the surface the print rests on (top of easel if you intend on using it) and post this dimension, then we can quickly calculate the dimensions of the largest focused projection so long as you state the format and focal length of the lens you intend on using.

The calculated dimensions are generally quite close to what your equipment will actually produce.

 

[polyglot]

80mm is the shortest length (and therefore will give the largest magnification) you usually want to use with 6x7. Some 75mm lenses will work but many will give you bad corners and you'll only get 6% more magnification from a 75mm. There are also the occasional wide-angle (greater angular coverage) enlarger lenses to be found, which mean you can have a ~60mm lens cover 6x7 and make prints the next size up with the same column height.

If you get 8x10" with 135mm, you will get about 12x16" with 80mm (use the ratio of the focal lengths). Perhaps slightly more or less since the focal lengths are nominal only and you may have been cropping somewhat and/or not right at the top of your column to get 8x10".

Edit: when you ask "is the 50mm too wide", well there's isn't such a thing as too wide unless you want to make a tiny print. The problem is that it has insufficient coverage and you will see only a little circular image from the middle of your neg if you use a typical 50mm enlarging lens.

 

[whlogan]

Try a 105mm Nikkor. Its what I use.
Logan

 

[likemarlonbrando]

I use an 80mm rodenstock and it works great. 80-90mm is pretty standard for 6x7

 

[hpulley]

With my Nikor 6x7 enlarger all the way up my 90mm lens prints 16x20" with a 1" border. I need to use my 75mm lens to completely cover 16x20" paper with no border at all. I bought the 75mm lens first for use with 6x6 and then got the 90mm for 6x7 but honestly the 75mm lens really isn't bad in the corners, especially if you go all the way up for no borders on 16x20, then the farthest corners are off the paper anyways. Made me wonder if I'd wasted my money on the 90mm but it is a bit sharper.

 

[Gerald C Koch]

It depends on the design of the lens and its coverage. For the average enlarger lens this would be the diagonal of the negative expressed in mm rather than cm. A 60 x 70 mm negative would need a 90 mm lens. Anything shorter and you run the risk of falloff in the corners.

 

[NDP_2010]

thanks for the info.
How much optical difference is there between different brands of the enlargning lenses? in the 80-90mm range?
Am I cutting myself short by buying certain lens?

 

[hpulley]

Designs basically have a number of lenses. Generally you want a 6 element design if you can find and afford one. There are wide angle lenses which will cover larger paper too. 90mm doesn't have a lot of choice compared to other FLs.

 

[kiku]

Try a 105mm Nikkor. Its what I use.
Logan

Ditto! A 105mm El Nikkor for me and 6 x 7 negs. Howard Tanger

 

[Bob-D659]

There are some slight differences between enlarger lenses, I have a brand new 50mm Componon-S and also a 50mm Componon from the early 1960s. The old one was cleaned to remove a little haze from almost 50 years of usage in a university darkroom. I did see a tiny difference in resolution. Make a 16x enlargement with each lens, and you can barely see the difference with a 10x loupe when you look at the two prints.

Was it worth buying the new lens. Yes, but not for any difference in image quality. Now I don't have to remove a lens from the auto-focus D659 and put it in the big 4x5 Durst and then fine tune the adjustable lens mount for focus in the other enlarger when I put it back.

 

[rjmeyer314]

To a pretty good approximation the magnification of the negative is given by M=(D/f)-2, where D is the negative to paper distance, and f is the focal length (all in the same units).