Enlarging Lens for 6X7

[John Koehrer]

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

[CPorter]

Although you mention the cold light, Is there a condenser in there? That could screw every thing up.

Shaggy,

That rule of thumb makes sense. I think I will get a 90mm lens. To answer your question, no, the condensors must be removed when installing a cold light lamp. Thanks for the info.

Chuck

[Nick Zentena]

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.

[Bob Carnie]

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

[Tom Stanworth]

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.

[CPorter]

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.

Nick,

I will check the focus at the center, but can you elaborate on that statement? Thanks

CP

[Loose Gravel]

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.

[Nick Zentena]

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.

[kiku]

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

[Woolliscroft]

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