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SMBooth
05-27-2011, 03:56 AM
Looking around for a 90mm to fit to a 6x17. I have narrow down the choice to either the Rodenstock Grandagon 90mm f6.8 (or Caltar -N) or the Fujinon 90mmf8. The Nikon f8 is a little out of the budget. Both will cover quite OK but Ive read the Grandagon is designed for less light fall off at the edges. Is this true, and is it worth the extra dollars to pick up the Grandagon over the Fujinon.
If any one has either for sale quite welcome to PM me

Steve Goldstein
05-27-2011, 07:24 AM
You'll need to be careful about the flange focal length, there's several mm of variation between lenses and if you don't have the right cone (for an existing camera) you'll never get it to focus. I sold a very nice old Fuji 90mm to someone on the Large Format Photography Forum (I think, could also have been APUG) a couple of months ago, he ended up returning it for this very problem...

ChuckP
05-27-2011, 08:08 AM
I would say that they are both newer design wide angles with similar fall off. Older lens designs like the Angulon (not super) will have more fall off.

SMBooth
05-27-2011, 08:52 AM
Steve: I know the Grandagon film/flange is 94mm while the Fuji is 98mm. This is a DIY 6x17, so at the point to pick a lens before finishing off the nose cone, but a bit of packing solves most things.
Chuck: Yes I have a Angulon f6.8 and it certianly does not have the image circle.

Ole
05-27-2011, 09:13 AM
Image circle and falloff are two different things. A pre-WWII Angulon does have the image circle, at f:64. But it has almost cos^4 falloff, and any center filter will reduce the image circle due to vignetting.

Anything Biogon-like has cos^3 falloff or close to that. Super Angulon, Grandagon, Fujinon, or others. There isn't that much difference in falloff.

Klainmeister
05-27-2011, 09:38 AM
I've used the fujinon 90mm, which I believe is the same used on the Fuji 6x17 and can attest to it's quality. Sharp to the corners when stopped down past f/11. Only downside is that it needs a center weighted filter.

Hikari
05-27-2011, 09:45 AM
All of these lenses will be about the same. The Rodenstock will be a little better for focusing on ground glass. All of them will need to be stopped down to eliminate mechanical vignetting. Natural vignetting will always be a problem, you can't change physics. Whether you need a center filter would be your choice. I have used both lenses on 4x5 and 6x12. They are both fine lenses.

SMBooth
05-27-2011, 09:46 AM
I've used the fujinon 90mm, which I believe is the same used on the Fuji 6x17 and can attest to it's quality. Sharp to the corners when stopped down past f/11. Only downside is that it needs a center weighted filter.

Thanks, do you have any examples with and with the CF, I assume you mean the f8 revision of the fujinon 90mm. Ive got a feeling that a CF is an advantage with all of the 90mm at f8 and less of a problem as you go to f6.8 - f4.5. But as the numbers go down, the price goes up..

SMBooth
05-27-2011, 09:31 PM
I would I be right in saying that just because a faster lens has a greater image circle, the vignetting or edge falloff start around the same distanse from the centre of the lens, or does a F4.5 with a 235mm IC show less fall off on a 6x17 image then a f8 with 216mm IC because the IC is bigger and the falloff is further out.

jbbooks
05-30-2011, 10:29 PM
Just a suggestion, but you might look at a 120mm f5.6 APO-Symmar before you commit to a 90mm. When I was playing with a 6x17 back on a 4x5 camera, the lens I found most useful was a 120mm f8 Super-Angulon MC with its Schneider center filter The 90mm lens I used with it, a Super-Angulon XL, which I did not have a center filter for, was too wide and had too much of a hot spot in the center.

While I know the 120mm Super-Angulon covers, if I were to play with this again, I would try the APO-Symmar. Slightly faster, smaller and cheaper; it should have less fall off and still have plenty of coverage for an application that did not require any movements and would not need a center filter.

ChuckP
05-31-2011, 07:27 AM
I would say that a 120 APO-Symmar would have more light fall off compared to a 120 Super Angulon. The Super Angulon is a wide angle design that has less fall off.

David A. Goldfarb
05-31-2011, 07:56 AM
With any 90mm lens on 6x17, you're probably going to want to correct the falloff to some extent, either on the lens or in the darkroom, particularly if you shoot color transparency film. If you shoot B&W and don't mind lots of falloff, maybe it won't matter as much, but if you correct it to some extent, it gives you more compositional flexibility. More falloff tends to drive the subject to the center of the frame, or stated alternately, when the subject appears in the falloff zone, you may just find that image to be unsuccessful when you look at the contact sheets or transparencies, because these things can be hard to judge on the groundglass.

Even with a center filter--even the filter supposedly "matched" to the lens--the correction isn't 100%, but might be visually acceptable. If center filters actually corrected falloff fully, which they could only do at a specified focus distance and aperture, they would usually be around three stops and would presume a shooting aperture of around f:22. At one point, such filters were made, and they didn't sell particularly well, because they were impractical, so most of the available center filters tend to correct about 1.25-2 stops at f:22 and leave an aesthetically acceptable amount of falloff. Heliopan may still have a 3-stop center filter. I have several wide lenses, and I haven't had any particular problems like banding with "unmatched" center filters, and I haven't found it necessary to purchase "matched" center filters with only slight differences in density.

Steve Goldstein
05-31-2011, 07:08 PM
I have one of those 3-stop CFs, made by Schneider and marked 8/90mm. It doesn't appear in the literature in their online archive, but they recently sent me a scan of a 1967 document that lists it. The document is slightly wrong as it says exposure time should be extended 3x while the filter measures 3 stops, but it has the correct physical dimensions. The front threads are 82mm, unlike the later IIIa and IIIb which are 86mm. It also lists filters for the 65mm and 75mm Super Angulons.

Send me an email if you want a copy of this 1.9Meg PDF.

jbbooks
05-31-2011, 11:13 PM
I would say that a 120 APO-Symmar would have more light fall off compared to a 120 Super Angulon. The Super Angulon is a wide angle design that has less fall off.

Let’s see—if you go to the following link, you will find an information chart for Schneider lenses. The chart lists eleven different centerfilters made by Schneider for use with their Super-Angulons, older Super-Angulons and for their Super-Symmar Aspheric lenses. There are no centerfilters recommended for use with their APO-Symmar lenses.

https://www.schneideroptics.com/pdfs/photo/LensCharts.pdf

So, according to your logic, Schneider does not recommend centerfilters for those lenses that really need a centerfilter, but does recommend them for those lenses that do not need them so much. :laugh:

SMBooth
05-31-2011, 11:17 PM
I actually decided to get a Fujinon 105 f8 because of the 250mm IC until a Nikon 90mf8 came my way at a very reasonable price. Going to hold of of the CF until I get camera finished and some shots from it.
Thanks for all the help

polyglot
06-01-2011, 12:00 AM
I would I be right in saying that just because a faster lens has a greater image circle, the vignetting or edge falloff start around the same distanse from the centre of the lens, or does a F4.5 with a 235mm IC show less fall off on a 6x17 image then a f8 with 216mm IC because the IC is bigger and the falloff is further out.

Lenses have a natural cos^3 or cos^4 falloff with respect to angle and because a given film size subtends a greater angle with a shorter focal length, there will be more falloff than with a longer focal length. Different lens designs lead to different amounts of this natural falloff.

It's got nothing to do with coverage, which is generally where mechanical vignetting kicks in and gives you a distinct image circle. And likewise, a faster lens does not necessarily have greater coverage at all - tele lenses (where the rear nodal point is well forward of the rear of the lens) generally have less coverage than you might expect from their focal length.

David A. Goldfarb
06-01-2011, 06:59 AM
I have one of those 3-stop CFs, made by Schneider and marked 8/90mm. It doesn't appear in the literature in their online archive, but they recently sent me a scan of a 1967 document that lists it. The document is slightly wrong as it says exposure time should be extended 3x while the filter measures 3 stops, but it has the correct physical dimensions. The front threads are 82mm, unlike the later IIIa and IIIb which are 86mm. It also lists filters for the 65mm and 75mm Super Angulons.

Send me an email if you want a copy of this 1.9Meg PDF.

I have a Schneider center filter from that era for my 65/8 Super-Angulon, and like yours, it's marked with the name of the lens, but it actually measures about 1.5 stops, so 3X rather than three stops. Thanks for the offer of the document. I'll send you an e-mail.

ChuckP
06-01-2011, 09:32 AM
Let’s see—if you go to the following link, you will find an information chart for Schneider lenses. The chart lists eleven different centerfilters made by Schneider for use with their Super-Angulons, older Super-Angulons and for their Super-Symmar Aspheric lenses. There are no centerfilters recommended for use with their APO-Symmar lenses.

https://www.schneideroptics.com/pdfs/photo/LensCharts.pdf

So, according to your logic, Schneider does not recommend centerfilters for those lenses that really need a centerfilter, but does recommend them for those lenses that do not need them so much. :laugh:

Well a lens like the Symmar drops off at cos^4 and the Super Angulon drops off at cos^3. So I would say that a 120mm Super Angulon would have less fall off at any angle off the center line. Center filters aren't used on Symmars because they don't have the kind of wide angle coverage that would need them. They only cover 72-75 degrees compared to the 100 or so for the Super Angulon.

Ole
06-01-2011, 01:34 PM
On the other hand, a plain old Angulon would need a center filter more than a Super Angulon would, even if both are wide angle lenses.

Cos^4 is the falloff expected from a simple symmetrical lens with no "fancy tricks" - a perfect pinhole would give cos^4 fall-off. By using a large strong negative element to "tilt the pupil", also known as Biogon-type (even if the Biogon wasn't the first), the fall-off will approach cos^3. Most lenses come nowhere close to this ideal, and the difference really only gets significant when you get around 45 degrees off the lens axis - meaning about 90 degrees coverage. The wider the angle, the larger the difference. At 100 deg angle of view, a cos^3 lens loses about two stops, a cos^4 lens almost three.

jbbooks
06-02-2011, 02:50 AM
Well a lens like the Symmar drops off at cos^4 and the Super Angulon drops off at cos^3. So I would say that a 120mm Super Angulon would have less fall off at any angle off the center line. Center filters aren't used on Symmars because they don't have the kind of wide angle coverage that would need them. They only cover 72-75 degrees compared to the 100 or so for the Super Angulon.

What I posted was based on what the OP said in a prior post, which led me to believe that the camera that he was intending to use the lens in is one which will not allow movements:

What he wrote, in part, was, "This is a DIY 6x17, so at the point to pick a lens before finishing off the nose cone..."

The point I attempted to make was that I thought the OP ought to consider a longer focal length than 90mm for his fixed lens, non-movement camera. When I tried that format, I found that the 120mm focal length was much more useful than the 90mm. We can agree, I hope, that is a subjective conclusion and there is no basis, other than individual preference, for his choice of focal length for his camera. I simply suggested he ought to consider another.

If I am correct in that the OP's camera will not have movements, there is no need for him to use a lens that has an image circle larger than 179mm, the approximate diagonal of the 6x17 format. A 120mm f5.6 APO-Symmar has an image circle large enough to cover that and using a larger, heavier, perhaps slower and more expensive lens that needs a centerfilter, such as a 120mm f8 Super-Angulon, is not necessary.

If I am wrong about the coverage of an APO-Symmar or about the intended use of the lens in a camera that does not have movements, then I stand to be corrected. On the other hand, if I am correct about the coverage of the APO-Symmar and that no capability for movements will be available in the OP's camera, then there is no reason for any concern about the fall off in exposure for the APO-Symmar as opposed to the fall off in a Super-Angulon. For its smaller angle of view, the fall off in the APO-Symmar is negligible and, as you recognize in your post, above, it does not need a centerfilter.