90mm center filter on 6x17

Hassasin said:

Also, to all in the know: are center filters made so universally that brand does not matter? I see how any one of them will change light distribution and help with dark corners, probably better than nothing. After all, expensive is always cheaper then the more expensive. But at the same time, would it not be optimal to use one made specifically by same maker?

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With Schneider Centre filters they aren't particularly specific to lenses, rather filter thread,,



Ian

Ian Grant said:

With Schneider Centre filters they aren't particularly specific to lenses, rather filter thread,,

View attachment 368833

Ian

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Looks like chart has specific lenses listed. I.E. IVa and IVb exactly same size and factor, but IVb just for 72XL, even if IVa also lists same lens among others, Only Schneider can explain this.

On the other hand, Fuji did make some specifically labeled as for the GX617 105 (and also another for the 90)

Hassasin said:

Was just going to start a new thread on this specific configuration. Thought 'bout Linhof Technorama before realizing Fuji's G617 will do for the very limited use.

As you have not used nor seen a need for a CF on 105 lens, what bugs me a bit is that Fuji did not even talk about CF for the G617, but then with GX617 they did put out CF's for 90 and 105 lenses. So far I have not been able to confirm the 105 for GX617 is optically same as on the fixed G617. Any ideas what happened there?

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I thought that when you purchased the original G617 new it came with a center filter. I know when I bought mine used it came with a fuji branded one

john

I used a 90mm Super Angulon XL on a 4"x10" camera....without a center filter, but always worked in B&W.

destroya said:

I thought that when you purchased the original G617 new it came with a center filter. I know when I bought mine used it came with a fuji branded one

john

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Fuji never spoke off a center filter on the G617, never had one in original kit. It changed with GX617, but as an option.

Hassasin said:

Fuji never spoke off a center filter on the G617, never had one in original kit. It changed with GX617, but as an option.

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Interesting how this is for a 105mm lens -- which I've got to assume is similar to the CM-W 105mm f5.6. Maybe not.

xkaes said:

Interesting how this is for a 105mm lens -- which I've got to assume is similar to the CM-W 105mm f5.6. Maybe not.

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The 105 on G617 is f 8.0

And just moments ago I have come across one Fuji CF actually marked "for G617". Whatever happened between putting out G617 and its instruction manual and getting seemingly dedicated filter is perhaps a mistery.

Note the filters for the G617 and the GX617 are both 2x (1 stop) filters, so they aren't nearly as strong as those listed for the Schneider lenses. I suspect that is because they weren't trying to fully correct the falloff; just mitigate it a little. It's a lot easier to account for one stop of filter exposure adjustments than the 1.5 stops, and two stops is starting to become a serious exposure correction at 4x the exposure... you either start using very long exposures (into reciprocity failure range, which add additional problems) or open up the lens, which reduces DOF and is a potential problem with zone-focused cameras.

Michael Mutmansky said:

Note the filters for the G617 and the GX617 are both 2x (1 stop) filters, so they aren't nearly as strong as those listed for the Schneider lenses. I suspect that is because they weren't trying to fully correct the falloff; just mitigate it a little. It's a lot easier to account for one stop of filter exposure adjustments than the 1.5 stops, and two stops is starting to become a serious exposure correction at 4x the exposure... you either start using very long exposures (into reciprocity failure range, which add additional problems) or open up the lens, which reduces DOF and is a potential problem with zone-focused cameras.

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That's well and good. I read a lot of people using the G617 without a CF for all their work and the fact it appears to have not been introduced with the camera maybe saying something to support the notion of being a moot device for most meals one cooks with it. Might be some sort of demand later on that made Fuji put one out. By the time GX617 was introduced, something must have changed.

Since color is not my thing, I'm becoming sufficiently confident spending money on one is not logical.

Well, at least you've stated your dedication to black and white shots alone. That simplifies things. I can't imagine trying to print, let alone publish, color shots without a center filter involved. But in black and white work, it's more a personal esthetic decision whether you can tolerate corner illumination falloff or not. Try it without the CF first. You can always add the filter later if necessary.

105 W standard lenses have less falloff than 90 mm true wide angles. There's also a significant weight difference, with most 90's being a lot bulkier and heavier.

Otherwise, the topic of CF interchangeability between lens brands is more involved than just thread fit. You do need to ask the specifics.

Michael Mutmansky said:

Note the filters for the G617 and the GX617 are both 2x (1 stop) filters, so they aren't nearly as strong as those listed for the Schneider lenses. I suspect that is because they weren't trying to fully correct the falloff; just mitigate it a little.

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I think it demonstrates that there is no hard rule about using CND filters. Light fall-off happened with lenses longer than 90mm -- it's just not as obvious, but that varies with the film, the lens, the f-stop, the subject, personal preferences, etc.

Dan Fromm said:

Short answer, it depends. For a full answer, see: http://www.galerie-photo.com/center-filters-for-large-format-lenses.html

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Dan: How was the selection determined for center filters from let's say Schneider being used on Nikkor lenses which does not manufacture CFs?

Hassasin said:

That's well and good. I read a lot of people using the G617 without a CF for all their work and the fact it appears to have not been introduced with the camera maybe saying something to support the notion of being a moot device for most meals one cooks with it. Might be some sort of demand later on that made Fuji put one out. By the time GX617 was introduced, something must have changed.

Since color is not my thing, I'm becoming sufficiently confident spending money on one is not logical.

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Regardless, you will have to compensate for the lens falloff if you want the corners of the frame to have sufficient exposure to not have muddy shadows. That is, if you are hoping for a certain level of even exposure across the frame in the final print.

You cannot ignore the optical properties of lens falloff. The lenses on these cameras (so not the super Symmar XL lenses) will all fall off at the rate of about cos^3 of the angle out from center. That equates to about 2 stops for the 90mm lens on 6x17 to the corner. you can reduce this some by stopping down, but you cannot eliminate this. It will actually be worse wide open. This 2-stop value is stopped down to normal working apertures.

The problem with a 2-stop falloff is that the shadow detail (even with B&W film) is going to be pretty thin unless you compensate. It will be especially bad if you are shooting chromes, where the latitude is quite narrow.

I like to think of shooting these lenses in this situation as exposing for the shadows and then "HOLDING BACK" the highlights with the center filter, because this is exactly what the CFs do. They cut back the exposure in the center of the field by the filter factor so that you can give the shot more exposure to correct for lens falloff into the corners without blowing out the center highlights.

This (holding back highlights) isn't a terribly big issue on B&W film because the latitude of the film is pretty large, but it is a big problem on chromes. However, even on B&W, if you have exposures in full sun and especially with specular highlights, you can get some pretty bulletproof highlights that can be hard to expose through if you don't use a CF and you are exposing to ensure the corners aren't thin.

This all comes down to aesthetics, though. If you like the falloff look into the corners, you may not need the CF at all, but if you are trying to achieve a relatively even exposure across the frame, a CF is going to be beneficial to keep things in the latitude range of the film and for you printing purposes later on.

Since the Fuji CF filters don't actually fully correct (they do about 1/2 the falloff correction for the 90mm lens, and about 2/3 the correction for the 105mm) you still need to be adjusting exposure even with the filter, but the CF puts the falloff into the realm where people often feel it looks "natural".

What I mean by that is if you care especially about the corner shadow detail, you really need to be giving a +2 stop exposure to the shots to ensure the shadows are held into the corners. The Fuji filters cut that to +1 stop in the center. You could just go with the +1 stop exposure of the CF filter, but again, if the corner shadow detail is important, you will be a bit under there, which may not be a big problem (it's certainly much better than being down 2 stops).

I normally do +1 on normal shots (with the CF), but if I'm worried about the corners, I'll go to +2. This is especially true if the exposures are getting long enough that reciprocity failure is happening... then I'm in +2 all the time. This approach (+2 stops) accounts for all of the falloff into the corners with the 90mm but it'll over-expose the center by 1 stop. It's a price I'm willing to pay when the corners are especially inportant.

Most of the later 90's are of very similar design, and spot on 1-1/2 stops of falloff at the recommended range of about f/16 to f/32. Center filters don't work correctly at wider stops.

Alan - you already know the answer to your question. The Schneider 90 Super-Angulon and the Nikon equivalent have identical falloff. I determined that with precise densitometer readings. That's the only way you can be certain. And that means reading the edges of the exposed film (of a gray target) and not just the edges, with the requirement of exactly the same density overall.

I'd have to re-read Dan's report for his own methodology; but logically, it must have been similar. A metering film plane probe could hypothetically be used with some view camera backs; but I don't know if those are subject to cosine errors at the corners or not.

I'll add that it's your decision to decide how to use CND filters

A. Don't use any -- or use some some of the time
B. Just use the one the lens manufacturer recommends for the lens
C. Use whichever CND filter you want on whichever lens you want

Whatever approach you prefer, it's really simple to run some tests to find out if your lens has enough fall-off (and at which f-stops) that you want to correct, and which CND filter provides the amount of correction you want.

Just because lens maker X recommends CND filter Y doesn't mean that it's the one you have to use. On the other side of the coin, just because lens maker X does not recommend a CND filter doesn't mean that the lens can't benefit from one.

DREW WILEY said:

Most of the later 90's are of very similar design, and spot on 1-1/2 stops of falloff at the recommended range of about f/16 to f/32. Center filters don't work correctly at wider stops.

Alan - you already know the answer to your question. The Schneider 90 Super-Angulon and the Nikon equivalent have identical falloff. I determined that with precise densitometer readings. That's the only way you can be certain. And that means reading the edges of the exposed film (of a gray target) and not just the edges, with the requirement of exactly the same density overall.

I'd have to re-read Dan's report for his own methodology; but logically, it must have been similar. A metering film plane probe could hypothetically be used with some view camera backs; but I don't know if those are subject to cosine errors at the corners or not.

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I was curious how Dan figured out the interoperability between all the different manufacturers of lenses and center filters, not just one of them in particular.

xkaes said:

I'll add that it's your decision to decide how to use CND filters

A. Don't use any -- or use some some of the time
B. Just use the one the lens manufacturer recommends for the lens
C. Use whichever CND filter you want on whichever lens you want

Whatever approach you prefer, it's really simple to run some tests to find out if your lens has enough fall-off (and at which f-stops) that you want to correct, and which CND filter provides the amount of correction you want.

Just because lens maker X recommends CND filter Y doesn't mean that it's the one you have to use. On the other side of the coin, just because lens maker X does not recommend a CND filter doesn't mean that the lens can't benefit from one.

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How do you run tests before buying center filters and lenses?

Hassasin said:

Looks like chart has specific lenses listed. I.E. IVa and IVb exactly same size and factor, but IVb just for 72XL, even if IVa also lists same lens among others, Only Schneider can explain this.

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Perhaps I look at it differently, it seems to be more about a lens' angle of view/coverage. rather than focal length, then throw in the physical restraints of the filter thread.

Schneider's XL range of lenses were exceptional and not matched by other lens manufacturers. The screenshot I posted was from a leading UK LF specialist, and from an early 2000s page, other sources state that there was more compatibility than shown there.

DREW WILEY said:

Most of the later 90's are of very similar design, and spot on 1-1/2 stops of falloff at the recommended range of about f/16 to f/32. Center filters don't work correctly at wider stops.

Alan - you already know the answer to your question. The Schneider 90 Super-Angulon and the Nikon equivalent have identical falloff. I determined that with precise densitometer readings. That's the only way you can be certain. And that means reading the edges of the exposed film (of a gray target) and not just the edges, with the requirement of exactly the same density overall.

I'd have to re-read Dan's report for his own methodology; but logically, it must have been similar. A metering film plane probe could hypothetically be used with some view camera backs; but I don't know if those are subject to cosine errors at the corners or not.

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But as Drew says we are talking about run of the mill 90mm WA lenses. Also there is no point on fitting a 90mm WA with huge coverage on a 6x17 camera.

I fitted a 90mm to the relevant cone & helical of my 6x17 camera, but never used it, I prefer my 75mm f8 SA, I liked it so much I bought a 75mm f5.6 for 5x4. A centre filter is needed.

Ian

Alan - I don't know if Dan truly figured it out or not. It seems he was using his Horseman back meter to achieve a reasonable approximation. His conclusions appear to be realistic.

When in doubt, go with the same brand recommended Center filter : Schneider for Schneider, Rodenstock for Rodenstock. But like I said, even the Nikon and Fuji SW's are so similarly designed that it turns out there is a high degree of interchangeability. But when it comes to more extreme 65's, 75's, and specialized designs like XL's, then all bets are off, and you'd either need to get access to a lens to test for yourself, or else ask around per someone else's actual experience with any particular combination.

Just like with lenses -- fortunately, not cameras -- I've bought and sold CND filters to get the ones that I want for the lenses that I have that provide the amount of correction that I prefer.

Whenever I've sold a lens or a CND filter (not often), I always ended up with a little more than I paid for it.

Alan Edward Klein said:

Dan: How was the selection determined for center filters from let's say Schneider being used on Nikkor lenses which does not manufacture CFs?

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Angular coverage used to select max. density, lens thread diameter for fit.

Dan Fromm said:

Angular coverage used to select max. density, lens thread diameter for fit.

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OK Great. Thanks for your work.