View Full Version : lens trade-offs question

29-Jan-2008, 18:02
I'm relatively new to LF, have just one lens, a 150mm. At some point, probably still a ways off, I will likely get a 90mm. So I'm beginning to think about/research that a bit now. Of course I'm looking for something super sharp, very light, huge image circle and very bright image on the ground glass...and inexpensive as well.;)

But seriously, the thing I am most interested is finding a lens that is fairly easy to use in terms of viewing on the gg, and that gives good images. As I understand it, the advantage of a larger image circle is that more movements are permitted without vignetting. Does the size of the image circle affect the brightness of the image on the ground glass, in general?

I don't know jack about lens design, but part of me feels like a lens with a smaller image circle spreads the light out less, so it is brighter at all points. On the other hand, I feel like there might be some fall-off in brightness near the edges of the image circle, so a lens with a larger image circle will have only its brightest part on the ground glass as long as movements are not too extreme. Well, enough speculating on my part - if you have some knowledge on this, let me know what you think.

I suspect that there are differences between lenses having the same size image circle, due to number of elements, quality of optics, etc.

Any thoughts on particular 90mm lenses would be appreciated as well...

Jim Galli
29-Jan-2008, 18:13
Cake and eat it too as the brightest ones will also have the biggest image circle. You'll take a beating on cost and weight though.

When I began several years ago my second lens was a 6.8 75mm. I doubt I took a dozen pictures with that lens because even at 6.8 I couldn't see the image well enough on the GG. When it comes to wide angles, at least for me, brightness trumps everything else. I now have f4.5 75 and 90mm's. With longer than normal's I can focus at f9 and never think twice, but not with the wide ones.

29-Jan-2008, 19:34
So how about the light Nikkor f8, with an image circle of 235mm at f22, comparable to the Grandagon-N f4.5 and Super-Angulon f5.6. I'm assuming that they are roughly the same for brightness at f8 then, but the Rodenstock at f4.5 should trump the others at their widest?

29-Jan-2008, 20:19
The Nikkor f8 is certainly on my shopping list and is recognised as being a great lens. I don't think you'll have too much of a problem with the brightness on the GG, I have a Fujinon 90mm W f/8 at the moment and can focus OK, I just want something a little smaller for trekking. Of course the Rodenstock is going to be brighter but it's twice the weight. Or maybe a Schneider 80mm f/4.5 Super-Symmar XL if you've got the budget for it?

Ron Marshall
29-Jan-2008, 20:32
The Nikkor 90mm f8 is a bit tougher to focus in low light than my 75mm f4.5, but for me the lower weight is worth it.

It all depends on how far from the car you plan to go, and how much shooting you plan to do in low light.

Nathan Potter
29-Jan-2008, 21:51
Lens brightness depends only on the f/no and has nothing to do with coverage except for wider angle types that have light falloff at the edge of the field.

If you really want a bright image maybe you should hunt up a 120 mm Leitz f/2 Summar macro lens. I used this on my first 4X5 Leitz/Linhof modified 4X5 in the 60's. I never really adapted to these modern, dim f/4.5 lenses - but of course I like their superb resolving power.

Nate Potter

30-Jan-2008, 04:22
I'm not so sure lens brightness depends solely on f stop---for ground glass viewing that is. Film responds to light coming in at different angles pretty equally, but a wide at 5.6 vs a tele at 5.6 will show you that the apparent viewing brightness is markedly different. This is most probably affected by your ground glass construction as well, and of course, this is all without taking into account a fresnel.

in my limited experience with a 90 5.6, I wish it were a 4, or even a 2.8. Around sunset, it becomes hard to see at the edges!

Chuck Pere
30-Jan-2008, 06:10
I would say that if you have no problems carrying it and paying for it always get the 4.5 over the f8. I have used the Nikon 90 f8 for many years because of its smaller size. Also I didn't want to pay the premium for the 4.5. I do struggle at times trying to see the ground glass in low light. But I want to carry a few smaller lenses rather than a couple large ones. And for me the 90 doesn't get the highest use among the focal lengths. I'll add that I use the Nikon on 5x7 and it works fine with very limited movements. I find it a very sharp lens.

30-Jan-2008, 09:28
With B&H having Nikons on sale I bought the faster 90mm. I would have been equally happy with the slower but at the clear out price I went faster. It's bigger but then it's not my only heavier lens. I've also got lighter longer lenses so I can manage the total kit weight.

30-Jan-2008, 11:55
For me, weight and bulk drives what I'm willing to carry. And I supposed I'm a bit on the frugal side as well. I'm not interested in "how far from the car...", I hike a fair bit and want to have the option to carry my 4X5 stuff wherever the trail takes me. And water, food and clothing need to come along too.

I personally think the Nikon or Fuji 90 f8 lenses would be the best compromises for me. I already own a 65 f8 super angulon and know I can focus the f8 lenses. The compact Angulon 90/6.8 is appealing, but I think the added flexibility and image quality of the newer lenses would be preferable.

A 90mm is on my shopping list for next year.

Aender Brepsom
30-Jan-2008, 12:29
I was very happy with a Rodenstock 6.8/90mm. It was a stunning performer and fairly small/light without being really expensive. Focusing on the gg with a darkcloth was not difficult.