Linhof holders and precision

[David_892]

Can anyone give any info on these Linhof holders that I've just bought in Glasgo w; They are clearly marked Linhof in the standard(?) whitw lettering, West Germa ny is printed in raised characters, and they have DPa and APa, the APa has on ei ther side of the holder, an arrow pointing to a lever. Also, the little number is not stuck onto the top end of the holder, but on the hinged bottom end. But what I find most interesting is that instead of the aluminium solid sheet that t he film rests on, there is a pressure plate. I paid #50 for five (although abou t another five currently remain with Quiggs). Thanks for any help. One more thing, with reference to my previous 'little help here' question, I'v e squared that away - I've decided to use a 6x7 roll film back if it becomes nec cessary.

[M.]

It sounds like you mave have holders which can also be used to hold glass plates.

[Julio Fernandez]

Unless this is a onse sided holder I believe you have the standard holders. The lever is used to eject the film and prevents your getting your fingers on it when you remove it. The pressure plate is simlar to that on the graphmatic. These holders are very accurate. Sounds like you got a good buy.

[Sal Santamaura]

Julio's got it right, except that these holders are no more accurate than any others. I researched this some years back and received, through Linhof's US importer, a fax from the factory answering my questions on film plane positioning and flatness. The response stated that their holder design simply met normal standards, and claimed that depth of focus makes anything more precise unecessary (paraphrased from memory).

[Julio Fernandez]

Sal's information from Linhof most likely refers to ISO standards. The ANSI standard allows plus or minus 0.007" a huge variation. Sinar and linhof have tighter standards than ANSI. The ISO standard, according to Sinar is 4.85mm with a tolerance of plus or minus 0.05 mm. This works out to plus or minus 0.002". Linhof's holders may be not more accurate than other ISO holders but they will certainly be more accurate than US ANSI holders, read Lisco, etc. Sinar's holder is guaranteed to plus or minus 0.001".

[Sal Santamaura]

If you're saying that Linhof holders meet an ISO standard of 4.85mm for septum depth, then there is another problem. That works out to 0.191" instead of the ANSI 0.197" T value for 4x5. If your camera sets its ground glass at 0.190" to account for flim thickness of 0.007" as most do, we have an automatic discrepancy of 0.006" +/- 0.002" to begin with. In any case, Linhof was probably very forthcoming in its response, since septum depth is only one factor that determines emulsion position.

I know of only one way to insure ground glass and emulsion fall into identical (for practical purposes) planes, and that is to use the Schneider Hi End Back system. When one's work warrants this precision, such as large aperture closeups using short focal length lenses with the camera pointed down, only such a matched set of vacuum camera back (with its own ground glass) and dedicated holders can deliver. For more distant subjects using normal or longer lenses, such as landscapes, Linhof's suggestion to rely on depth of focus probably makes sense.

[Julio Fernandez]

Sal: you are a thorough guy, good stuff but you are making me do more work. OK. The two standards ISO, ANSI are not exactly identical. Without film the ANSI, holder depth, should be (0.197") 5.0038mm. The ISO holder depth is 4.85mm. Accordingly, there is a discrepancy, ANSI being 0.1538 mm deeper. Another issue is film thickness. Most people quote 0.007. This is only true for color negative films: Fuji and Kodak are (0.007") 0.1778mm. -I do not know what B&W pos or negative film thickness are. This is not true for color transparency films. According to my measurements, Velvia, Astia are 0.0090-0.0095" and some old Ektachrome I measured at 0.0090"; for transparency film lets use an average of 0.00925, (0.235mm). Why is it that negative and transparency films come in different thickness? I do not know and one would expect that manufacturers would settle on one common thickness.

When we load transparency film in the ANSI holders, holder flange to film depth becomes 4.770mm. For ISO holders and film, subtract 0.1538mm from above. According to the above there are several issues: One is that the standards are not identical. The other, larger issue is that the ANSI standard allows plus or minus 0.007, (plus or minus 0.18mm), while the ISO standard only allows plus or minus 0.05mm. Evidently, ANSI tolerates a variation which is 3.5 X as great as allowed for ISO holders. Now for the relationship between GG, film, and holder: You buy a holder, and assuming it is of good quality, it will be within a narrow, acceptable standard, preferably ISO. You load film in the holder. The first problem arises in that you will either have transparency, thicker film, which will be closer to the lens, or negative film, which will be further away to the lens. For simplicity let us assume we standardize on transparency film. Now, because the holder confirms to a narrow variation in standard depth to the lens, so will the film. (Assuming that film tolerances are narrower than holder depth). The next question is whether the cameras GG is calibrated to coincide with the lens to film depth in the holder loaded with transparency film. This is not a problem if your ground glasss depth can be adjusted. If it can and you have it properly calibrated, then you will have a perfect match, but a match to only one type of film. If you decide to change to negative film, then you will either have to readjust or require a second back calibrated for negative film.

I have a Linhof Master Technika, which, very cleverly, allows very precise adjustment of the GG depth. I calibrated my Linhofs GG for transparency film which I use exclusively and then left behind all this stuff and just take pictures. To establish a perfect match between lens to GG depth and lens to film depth all you have to do is to measure both and adjust one, i.e. the GG, since you cant adjust the holder. It does not really matter at all if your holders are ISO or ANSI holders provided their variations are small enough to be acceptable to you. More importantly, your camera GG should be adjustable. If the camera does not provide GG adjustment there is a problem. There is a technique that I have learned for testing holders thanks to this forum. It is time consuming and tricky but not difficult. I cannot afford Linhof or Sinar holders but have found Toyo holders to be acceptable and much better than Lisco. Some would argue that all this stuff is irrelevant. To me, the fact that reputable manufacturers such as Sinar and Linhof take the trouble to manufacture their holders to very tight tolerances and that my pictures taken with a properly calibrated GG are now (not before) extremely sharp is more meaningful than nay Sayers arguments. After all, with all the fretting that goes on about which lens costing one or more thousand dollars is sharpest, more people should instead worry if their $30 holder is good enough to do justice to thousands of dollars invested in lenses, and of course, that their GGs be properly calibrated. OK?

[Sal Santamaura]

Thanks for the compliment, Julio. Your extensive research and subsequent optimization of your *system* is very appropriate, and the emitome of thoroughness.

I believe the reason for your success in making "extremely sharp" pictures is that you've eliminated enough variables to keep the emulsion within depth of focus limits. However, you still do not have a "perfect match" between focal plane and emulsion. If you undertook demanding work, as described at the end of my last post, you could greatly benefit from the Schneider system. You'd be surprised how much your film is rippling and buckling, even though you've calibrated everything to get septums 0.009" behind your GG ground surface.

Your pointing out that transparency films are thicker is appreciated. I don't use them (or color negative films) in large format, only black and white, which is on a 0.007" thick base. My "solution" to this whole problem, which also overcomes a current lack of space that keeps the 4x5 enlarger stored in boxes, is to shoot 8x10 and contact print. At 1x "magnification," even the Lisco holders - - which I've depth checked at the store and limited purchase to those that fall within the ANSI standard for 8x10 (+/- 0.016") - - provide critical sharpness in my landscape work.

[Julio Fernandez]

Sal: you are absolutely right about buckling and film warp. The Schneider vaccum holder does eliminate that. Also, Sinar has a holder with adhesive backing, seem to recall it is only available for 8X10. In 35mm and MF, Contax has vaccum systems as I am sure you know. Good luck y'all.

[Sal Santamaura]

The Sinar adhesive holder is (was?) available in 5x7 and 8x10. According to a Sinar technical service rep I spoke with some years back, those holders are made for Sinar by an outside vendor; Sinar adds the adhesive strips. He said they are no more precise than Lisco holders in terms of septum placement or film channel depth.