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Which 90mm f/4.5 or f/5.6?

carstenw

Active member
I am looking at which 90mm lens I am going to get to match my 210mm APO-Symmar f/5.6, and have come up with the following choices:

1) Schneider 90mm f/5.6 Super Angulon MC

2) Schneider 90mm f/5.6 Super Angulon XL

3) Rodenstock 90mm f/4.5 Grandagon-N

The prices are all okay with me, with the MC Schneider being a little cheaper.

All of my past experiences tell me that when it comes to wide angle lenses, I should spend a little more and get the better lens, otherwise I will be sorry. Therefore I lean towards the XL or Grandagon-N (what is the Sinaron and Caltar name for this lens?) I prefer a lens which is usably sharp in the corners wide open, even if I do need to pay a little more for it.

I am wondering how useful the wide open settings are for each of these lenses. From what I have read, the widest setting is sometimes sharp in the middle, for focusing with a bright image, but not so sharp in the corners. What are these three lenses like wide open, in the corners? Are the corners usable wide open for focusing, and for imaging?
 

carstenw

Active member
Is the Grandagon-N f/6.8 worth considering here? I understand that the Schneider f/6.8 is not that great compared to the other lenses mentioned?
 

Jack

Sr. Administrator
Staff member
Frankly, I'd get one of the f8's -- as sharp, as easy (or difficult) to focus and half the weight. Again, the Schneider 90 f6.8 is an older Tessar design, not a more modern plasmat.
 

routlaw

Member
Carsten

I have the Caltar version of the Rody 6.8 lens and it is great once you stop down to at least F8 or better yet F11 though Rodenstock claims the lens is optimized for F16-22. Wide open its worthless for IQ IMO. I doubt many owners use it this way and no doubt not what Rodenstock had in mind when they designed the lens either.

That said in dim light, ie indoors architectural, dimming of the day, the corners of the Rody 6.8 lens even with a bright screen can be fairly dark making it somewhat more difficult for foreground focus. I once rented the Rody 75 mm f4.5 and found it easier to work with indoors for the architectural project than my 90/6.8. The two lenses were both about the same size, requiring a 67 mm front filter. The 90/4.5 does have a much larger image circle allowing quite a bit more movement but it comes at the cost a lot more weight 700 grams vs 460 and a larger filter mount @ 82 mm.

Hope this helps.

Rob
 

carstenw

Active member
I am only planning on getting two lenses in total (90+210), so the weight really doesn't bother me. If I were buying a whole slew, it would add up, but an extra pound is no problem. On the other hand, the 90/5.6 XL is apparently absolutely huge, so I guess I am less inclined to get that one. Large image circle though.

The weights are:

Schneider:
90/5.6 XL: 665g
90/5.6: 570g
90/8: 360g
Rodenstock:
90/4.5: 700g
90/6.8: 470g

So the max. weight saving would be 340g, or less than a pound. I think I could just cut the chocolate one weekend and save that on my gut, so for a lens it really isn't that relevant ;)

I am more concerned about focusing performance, since Berlin is relatively far north, the days are short in winter, I often photograph in the shade on overcast days, and even at dusk.
 

carstenw

Active member
Thanks Rob, that kinda confirms what I have read about that lens before, i.e. for shooting a bit stopped down, great lens, but not wide open. Since I tend to shoot wide open regularly, I think I would want the option of better performance there, so I will get one of the other lenses.
 

redrockcoulee

New member
The Grandagon or its Caltar equivalent 6.8 are great lenses with good coverage whereas the Schneider 6.8 is a very small lens whose coverage is barely 4X5. Oft times with LF you pay (in money and weight) for greater coverage. Look at the specs for the XL it may be way more lens that you want in terms of size and coverage. IIRC it has enormous coverage and what you will be paying for is not sharper images but coverage that far exceeds your camera's capacity for movement.
 

carstenw

Active member
Yes, the 90XL is too large for me. I do need to be able to fit in a small suitcase ;) I don't think this lens's rear element would fit through the hole on my camera! The other lenses are more modestly sized, including the Rodenstock G-N 90/4.5, although it is heavy.
 

Jack

Sr. Administrator
Staff member
Actually, I was hoping to hear a little about corner sharpness wide open on these fast 90s. Anyone?
Any of the fast Plasmats basically suck for resolution wide open, and almost all the fast ones are spec'd for f11 and the slower ones for f16, 16 - 22 being the sweet spot for all of them WRT balance of resolution and aberrations.

If you want a chance with a fast aperture LF lens, you need to look at a Tessar design -- my favorites were the Schneider Xenars...

One other thing re focusing fast LF glass, and that's focus shift as you stop down -- and yes, they all do it to some degree. So bottom line, IF you want the best focus you'll get close wide open, then stop down and tweak, so a lot of the time you'll be doing your critical focusing at your shooting aperture anyway...
 

carstenw

Active member
I guess it is finally time for me to go look up what Plasmat, Tessar, and so on mean. I have been putting this off :) Are the mentioned lenses all Plasmats?
 

pellicle

New member
Jack

Frankly, I'd get one of the f8's -- as sharp, as easy (or difficult) to focus and half the weight.

interesting comment at a time when I find myself yet again wanting a Nikkor 90mm f8 to replace my Fujinon 90mm f8.

this image from the weekend was at f8 because I just wanted to see what it looked like (didn't think to take one of the same at f11~16, which is where I normally use the lens ... I wasn't thinking comparison of sharpness then ... am now).



generally speaking I seem to find it sharper at close focuses than at infinity ... is this a characteristic?

and should I start this as another thread?
 
S

SCHWARZZEIT

Guest
Actually, I was hoping to hear a little about corner sharpness wide open on these fast 90s. Anyone?
About a year ago I tested several Schneider LF lenses. The Super Angulon XL 90mm was among them. The overall performance of this lens is excellent. However, wide open you'll get all sorts of aberrations the further you go from the center. I only tested this lens at f/8, f/11, f/16 and f/22. Here are the results in lp/mm:
f/8: center: 80; corner: 45 horizontal, 60 vertical
f/11: center: 90; corner: 64 horizontal, 71 vertical
f/16: center: 85; corner: 62 horizontal, 67 vertical
f/22: center: 72; corner: 58 horizontal, 62 vertical

The camera I used for this test was a Linhof Technikardan 45 loaded with Kodak Imagelink HQ, a high-contrast microfilm to minimize the loss in resolution from the capturing medium itself. You'll probably get slightly less resolution when used with normal films. The magnification ratio was about 1:19.
The f/8 center performance is most likely not the best the lens can do. There's always a margin of human error in focusing accuracy. I only took one or two shots on each aperture. On such narrow DOF you'll easily lose resolution on a flat test target when you're slightly off. But when your focus is accurate the center performance of these modern lenses in exceptional.
Even though the corner resolution at f/8 isn't bad there's some obvious astigmatism visible which is going to be far worse at f/5,6. It's much better at f/11 and gone at f/16.

What are you planning to shoot wide open with a 90mm?
 

carstenw

Active member
Gravestones :) And later, perhaps some environmental portraits. I'll have to see. For portraits the corner performance is not likely a hindrance anyway.

My initial aim was more for being able to focus wide open though. I see that you also live in Berlin, so you know how dark it gets at the moment in the late afternoon, and I need to be able to focus on dark objects in the shade on an overcast day in the late afternoon in the winter... I have been carefully avoiding Jack's advice to get an f/8 lens, since he has loads more light than me most of the time (although I am sure he has tried focusing in darker situations). Is the XL sharp enough to focus on something in a corner, wide open? What about the MC or the Rodenstock? What about focus shift, as mentioned by Jack? I tend to think that it would be easier to focus wide open at f/5,6 and then make a correction at the shooting aperture than focusing directly at the shooting aperture, but I really don't know, having only ever used a Crown Graphic with some old Kodak lens, and not all that much at that.

If I need to stop down to f/8 to focus, I may as well get an f/8 lens, although I would really much prefer something faster. The XL is really huge, and I am not even sure that the rear element will fit through the opening of the Chamonix 4x5 front standard, so I am thinking more about the Rodenstock at the moment, and perhaps the older MC lens.

Here are some early shots from my current long-term project:

http://whimster-photography.com/cemetaries/
 
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Jack

Sr. Administrator
Staff member
generally speaking I seem to find it sharper at close focuses than at infinity ... is this a characteristic?
Yes and no... Most manufacturers optimize their lenses for specific image magnifications. For normal "taking" lenses this is usually 1:12, 1:10, or 1:8, though they perform well several steps on either side of that spec. IIRC, Rodenstock determined that 1:10 was ideal for 1:6 through infinity and spec their N lenses to that. However, they realized most taking distances tend to hover closer than infinity, so spec their wider S line to 1:8, where it performs very well from 1:4 through 1:40 -- and the difference at infinity is negligible. (Most manufacturers claim 1:50 and beyond as infinity, though some choose 1:100.) Macro lenses are usually optimized for 1:1 and claimed "usable" from 2:1 through 1:3 or so, though many shooters use them happily at infinity.

Bottom line for LF resolution is this: The naked human eye can at best discern about 6 lines per mm in a print. This means for a 4x5 neg, all you need to do is lay down 24 LPmm across the frame and a 16x20 print will look sharp. However, if you want a 32x40 to look sharp, you need more like 48 LPmm, and this is where the lesser lenses will show their weaknesses...

Also, there is a tradeoff in resolution vs aberrations vs DoF. Aberrations diminish as you stop down, while diffraction increases thus you need to experiment a bit to find any particular lenses sweet spot. With most modern Plasmat designs, that is likely going to be near f16 to 22. Next, diffraction may not be critically detrimental until after f45, so now you need to balance desired total DoF against absolute resolution --- often times, having a little less specific resolution in one area of a print in lieu of having better total resolution throughout the print though additional DoF is desired.
 

pellicle

New member
Jack

Yes and no... Most manufacturers optimize their lenses for specific image magnifications.
...

often times, having a little less specific resolution in one area of a print in lieu of having better total resolution throughout the print though additional DoF is desired.
thanks for that well thought out answer ... I had blown a few sheets on some subjects back in 2001 when I bought the Fujinon 90mm and back then felt that the sweetspot was somewhere between f11 and f22 .. as it happens that's about the middle of the marked range which seems to work well for me. Sometimes I find myself using f5.6 as I don't want to venture too far into the dark side and wind up with massive reciprocity calculations ...

For example, looking at this image on flickr the section in square "note" is this:



the above image also linking to flickr for a 100% crop of a 2400dpi scan from an Epson 3200 (stated because I realise this isn't the pinnacle but wanted to give some data on methods)
 

Jack

Sr. Administrator
Staff member
You can definitely see the aberrations at work in that shot due to the wider aperture.
 

Jack

Sr. Administrator
Staff member
Well I guess it could be a scanner artifact... What I am seeing is not really sharp edges anywhere in the image that also have a sort of distorted blur. But I'm also not seeing any grain, and we should, so it could very well be a bad scan.
 
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