Enlarging Lens for 6X7

Don't know this enlarger, but have you been using it for 35 mm with a recessed lens panel? Is it possible to remove this panel and fit it the other way round, making it a domed panel? If not, check what other lens panels are available.
I choose a 105 mm lens to enlarge 6x7, this or 90 mm would be ideal, but I would expect an 80 mm Componon to work, too.

 

purely from a focal length point of view, I would go for a 105 ish, as you will have plenty of coverage (not always teh case with an 80 on 6x7) and same price as 80mm.

 

I use a 105.

 

I also use a 105. I can easily get 16X24 enlargements on the baseboard and 240X24 using a dropped bed.

Regards,

Gene

 

Nikon claims it's 80mm covers 6x7. Scheinder claims 6x6. Rodenstock I think claims 6x7. Like LF lens some of it is design. Some of it might be the lenses being limited by the manufacturer to have a smaller coverage.

I agree you're problem doesn't sound like a lens problem but an enlarger setup problem.

How much of an enlargement you can get from a lens depends on enlarger. I'm thinking of a wide angle lens for 6x4.5 use. 80mm limits me to just above 11x14.

 

Chuck,

the 80mm Componon does not cover 6x7, so your observation should be normal. I don't know your enlarger, however, it makes me wonder that it does not have enough bellows for 80mm@1:3.5.

A 90mm is usually the best choice for 6x7. A 100mm or 105mm is a good choice for a bigger enlarger. I would not recommend longer lenses, because part of their performance is wasted in this case.

IMO, the Computar 4.5/90 has the best price/performance ratio in this class. The Apo-Rodagon 4/90 isn't really better, but usually much more expensive. Although their original prices (both are discontinued for a while) have not been very different - AFAIK.

 

90-105 are all OK for 6x7. With the longer FL usually performing moderately better since you're using the central portion of the lens. The rule of thumb I've used in the past was Enarger FL=to camera FL for normal lens. So, 90mm(~normal for 6x7)=90mm for enlarger.
However, it sounds like you have run out of bellows on the enlarger.
Although you mention the cold light, Is there a condenser in there? That could screw every thing up.

 

I believe, but am not positive, the Computars have been discontinued or not imported for a number of years.

 

Before you spend any extra money.

Is the centre of the image in focus? Or can't you get any part of the 8x10 in focus?

If you don't have the bellows for an 80mm you won't have any more luck with a 90mm.

 

Chuck
If money is no problem , the best lens for this IMHO is the Apo Rodagon 90-4.5, I love this lens.

 

I say, go for a 100 Componon S or Rodagon 105. Cheap as Chips! In relation to the APO thing and another thread on APO lenses where the subject was discussed, I have now placed what Barry Thorntons findings were (I will point out that I am not suggesting that this is gospel only that he tended to be a thorough and objective person who placed great emphasis on 'real world results'). Testing three 80mm lenses; a brand new APO Rodagon, a Neonon and a Meogon, he printed three 18" prints (he was unaware of which lens was usd for which enlargement to ensure he could not cheat). He then showed the prints to others to decide which was sharpest. The verdict was that they were all so close to identical that nobody could chose a winner. He also commented (which I find a bit strange) that only at its best aperture (one stop down) was the APO Rodagon as good as the other two (which he knew were good lenses and were ones in his regular arsenal). At other apertures it was markedly worse. I mention this not because I am trying to scupper Bob's preference, merely becasue I read it yesterday whilst flicking thru the book once again and thought it might help someone decide if unsure of what to pay.

 

Tom, I'm no expert on reading MTF data, but from the charts of lenses, I think you (and BT) are right. Seems to me that APOs are intended for higher magnification than what might be typical for large or even medium formats. Maybe at higher mags, you'd notice the APOs. This would make sense for the use of them at one stop down.

I make 8x10s and 11x14s mostly and under the grain focusser the negs look sharp. The prints do too. In my system, it seems I'm stopped down 3 - 4 stops most of the time. I'm using symmetric Nikon, Rodenstock, and Schneider enlarging non-APO lenses and don't notice any difference in quality. I have printed the same neg with all three flavors and haven't been able to tell them apart.

There is so much photo legend about APOs that it would be fun to try one, but for now I think I can have more fun with something else.

 

Even if your lens doesn't cover 6x7 it should be able to get the 6x6 portion of the negative focussed fine. Unless the lens itself is damaged. If you've got soft corners on the long part of the negative then that would be the lens not covering the format. OTOH if you can't get any part of the negative to focus then it might not be the lens.

 

To Chuck1:
Hi Chuck, I have 4 El Nikkor lenses which I use as follows:

50mm for 35mm format
80mm for 6x6 format
105mm for 6x7 and 6x9 formats
150mm for 4x5 format

I believe 80mm to be too short for 6x7.
Kiku

 

I used to have a Rodenstock 105mm for 6 x 7, but now have a lens I have never seen anyone else using. It is a Taylor-Hobson, f4.5, 108mm Ental and will cover up to 6 x 9 (I also have an 80mm version for 6 x 6). It has been a revelation: incredibly sharp and contrasty. It beats my old lens and the Schneider 105 my last University used. I have no idea how old it is (does anyone know anything about the things?). It was made in Britain and we don't really have much of an optical industry any more so it is probably as old as me, but it is good. Regarding your focus problem, it came with an extension cone which goes between it and the lens board and which solves that one perfectly.

David

 

I've two B8s. Anybody care to have one?
The one now in use has the 2 1/2 inch lens cone.
I'm using a very nice metal 105 5.6 Nikor with 6x4.5,
6x6, and 6x7. I can print any of those formats, with
that cone and lens, from 3x5 to 11x14, maybe a
little more. Shop Ebay. Dan

 

Quite a few here, Chuck:
http://www.goodwinphotoinc.com/lens_boards_cones/lens_boards_cones.html
including a 1 3/4" board which could well fill the bill.

Regards,

David

PS: Out of idle curiosity, I dug out a formula which I haven't used since college:

u = f(1 + 1 /m)

u = object distance (lens to neg in an enlarger), f = focal length, m = magnification.
Assuming for ease of calculation that 6 cm of negative is enlarged to 20 cm of print, the magnification will be 3.33. In practical terms, this means you will need a total extension (bellows + lens cone) of 1.3 times the focal length to make an 8x10" from a 6x7 cm neg. This is 13.65 cm for a 10.5 cm lens, 10.4 cm for an 8 cm lens (which, as others have said, will be borderline on coverage).

 

I've got a bunch of stuff for the B8, even two of them,
both in very good condition, all from eBay. Shop eBay for,
omega b8 , and for, omega cone , and any other key
words which will locate.

Also, via Google locate, classic enlargers . Omega is a
specialty. Dan

 

Chuck,
as I already wrote, the Apo-Rodagon 4/90 and the Computar dL 4.5/90 are both discontinued. However, you can find them regularly on ebay and other second hand marketplaces. The Computar lenses were designed and sold by the US-Company of the same name. They have been manufactured by Kowa. The same lenses have also been sold under the Kowa label. These are more rare, but often even less expensive, because not everybody knows that they are identical to the renowned Computar (although they actually look the same). The Computar dL lenses have a typical design with large f-stop labels and an excellent mechanical quality that is immediately noticeable.