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What’s a Lens Board?
A lens board is a photographic accent used to connect a lens to a big format digicam or an enlarger. Lens boards symbolize the oldest strategy to lens interchangeability in cameras, and as such are a predecessor to up to date bayonet mount techniques.
Normally fabricated from wooden, plastic or metallic, lens boards may be present in many alternative sizes and shapes. A typical lens board represents a flat rectangle or sq. with a gap within the heart, very similar to the Canham unit above. Some designs might characteristic finding notches, beveled corners and / or stepped edges to fascilitate mounting and light-proofness of the system. The rear (movie going through) aspect of the lens boards are at all times painted flat black to get rid of any reflections contained in the digicam physique.
How is a lens board used?
There are two levels to utilizing a lens board. While you get a brand new lens or a brand new digicam, it’s essential to set up your lens onto the suitable lens board. Every one of many lenses you routinely use together with your massive format digicam ought to be mounted onto a lens board. The mounting process is neither quick, nor one thing you usually wish to undertake within the discipline.
What are customary lens board gap sizes?
Lens boards are common, and any lens by any producer may be mounted on any board, supplied the board is drilled to the required dimension and the lens can bodily match. As a result of most massive format lenses come mounted in leaf shutters, lens board gap sizes are standartized across the shutters.
Lens board holes could also be drilled within the heart or offset, relying on the producer’s design. An off-center lens board gap could also be used to realize a preset quantity of entrance customary rise or fall to beat digicam design limitations. For instance, Linhof Technika 4×5 boards have the shutter gap situated off-center to align the optical axis of the lens with the middle of the movie aircraft.
Copal
The overwhelming majority of huge format lenses made after World Struggle II are mounted in shutters complying with the Copal nomenclature which is as follows:
- Copal #0 – 34.6 mm gap diameter
- Copal #1 – 41.6 mm gap diameter
- Copal #3 – 65 mm gap diameter
- Copal #3s – 64.5 mm gap diameter
Compur
An older lens might include a Compur shutter, which observe a unique sizing conference. Nevertheless, there are specific overlaps, as you’ll discover, which present the cross-compatibility constructed into the techniques.
- Compur #00 – 26.3 mm gap diameter
- Compur #0 – 34.6 mm gap diameter
- Compur #1 – 41.6 mm gap diameter
- Compur #2 – 52.5 mm gap diameter
- Compur #3 – 65.0 mm gap diameter
What are the completely different lens board sorts?
Flat
Flat lens boards are the only and most typical kind of lens board. They’re used for the overwhelming majority of lens and digicam mixtures. Mounting a lens onto a flat lens board will place the bottom of the shutter on the identical aircraft because the entrance customary of the digicam.
Recessed
Recessed lens boards are designed to shift the place of the lens into the physique of the digicam alongside the optical axis, thus successfully decreasing the flange focal distance. Merely put, a recessed board brings the lens nearer to the movie place. This can be wanted if the back and front requirements of a view digicam can not get shut sufficient for the lens to achieve infinity focus. Even when infinity focus may be achieved, a recessed lens board could also be used to permit the bellows to increase a bit, thus enabling restricted perspective management actions of the entrance customary. Relying on the digicam and bellows, a recessed lens board is perhaps wanted with any lens wider than 90mm for the 4×5 format.
These lens boards come in several depths to go well with completely different lenses and cameras. Widespread recess depths for Linhof recessed boards are 6mm, 12mm and 21mm. One other utility of recessed lens boards is to permit sure technical cameras just like the Linhof Technika and Wista 45sp to be closed with a lens mounted on them. Nevertheless, do your analysis and measurements if you wish to do that. Merely mounting any lens onto a recessed board doesn’t imply it is possible for you to to fold your digicam with it mounted.
Utilizing a lens mounted in a recessed board may be tough, as all of the controls of the shutter you usually entry from the aspect shall be crammed contained in the recess. Some producers like Linhof treatment this by equipping their recessed boards with cable launch extensions and auxiliary aperture levers and scales.
High-hat
High hat lens boards, are, unsurprisingly, the precise reverse of recessed siblings. Also referred to as extension lens boards, they bring about the lens farther from the movie aircraft, in entrance of the entrance customary. They’re used when the utmost bellows extension of the digicam will not be sufficient to realize the specified shut focus. High hat lens boards come each as fastened designs and adjustable fashions. The Wista board pictured above encompasses a threaded flange and replaceable extension rings of varied lengths.
High hat lens boards discover one other, extra restricted utility in technical cameras just like the Linhof Technika or the MPP Micro Technical. Utilizing vast lenses on these cameras brings the entrance customary again sufficient for the rails and mattress to get into the picture. To keep away from this, these cameras have the choice of dropping the rails down and out of the best way. Nevertheless, to drop down the mattress, you will need to preserve the entrance customary onto the brief set of rails that stay contained in the digicam physique. A prime hat could also be wanted on this case to retain the right flange focal distance.
Watch out for modifications in operation of the digicam that an extension lens board might introduce. Since you are bringing the lens meeting ahead, the lean/swing strategy of the entrance customary shall be affected. In case your digicam has axis tilt and/or swing of the entrance customary, it won’t function as such with a prime hat lens boards, as a result of the nodal level of the lens is not aligned with the lean axis. Rise, fall or shift actions won’t be affected.
Helicoid
Lens boards with helicoid focusing mounts are, actually, continuosly adjustable prime hat boards. They’re typically used with vast angle lenses due to the additional precision they supply. As well as, utilizing sure focal lenghts with some technical cameras could also be considerably simpler with a helical mount.
Moreover, calibrated helical mounts are top-of-the-line methods to make use of zone focusing with a big format digicam. For this, nonetheless, you will have to get a helical mount particularly calibrated for the lens you can be utilizing. Each Schneider and Rodenstock manufacture helicoid mounts with focus distances and DOF scales for his or her wider lenses.
Specialist
Some producers make particular lens boards for customized purposes. Arca Swiss, for instance, make a model of their 110mm sq. lens board with an digital Canon EF lens mount, which permits aperture management of digital lenses.
One other specialist lens board kind is the Sinar DB system, which foregoes conventional center-mounted leaf shutter for a behind-the-lens shutter. Based mostly on the standard Sinar 139.6 mm sq. lens boards, the DB boards are of the top-hat type, designed to place the entire lens in entrance of the shutter. Due to this design requirement, Sinar DB lens boards are particular for every lens. In additon, as a result of the lenses haven’t any shutters, they can’t be used on conventional massive format cameras with out modification.
The Sinar DB system is now discontinued, nevertheless it’s heritage continues as Sinar’s present eShutter line-up.
What are the completely different lens board requirements?
There are a number of in style lens board requirements, and they’re all based mostly round completely different producers’ digicam designs. There are lens board adapters that can be utilized to make a digicam settle for a unique (usually smaller) lens board customary. This manner, you need to use your lenses on cameras by completely different producers with out remounting them into completely different lens boards.
As well as, many photographers use lens board adapters to save lots of on bulk and weight. For instance, the Toyo 810GII makes use of 158mm sq. lens boards, which can show unwieldy to hold. With a lens board adapter, you need to use the a lot smaller and lighter Toyo 110mm sq. lens boards and even Linhof Technika boards, supplied your 8×10 lenses match on them.
Linhof
Established in 1887, Linhof is the oldest and hottest massive format images tools producers nonetheless in enterprise right this moment. The corporate has used a number of lens board designs over time.
The Technika 4×5 lens board is used on the Technika IV and all subsequent Technika and Technikardan 4×5 cameras. It’s also the only hottest lens board customary throughout the business. Its compact dimension helps preserve the majority of your package to a minimal, one thing most massive format digicam packages can undoubtedly use. A extra compact lens board can be useful whenever you retailer your lenses, particularly when you have a much bigger assortment, or when you retailer them in a dry cupboard.
The Technika 4×5 lens board measures 98.2mm x 95.8mm (3.868″ x 3.773″) with a double round light-trap lip on the again aspect. The board’s backside corners chamfered, and there are twin finding notches within the backside edge. This board is adopted by producers like Wista, Ebony, Tachihara, Walker, Chamonix, Shen-Hao and Inba amongst others. Just about all others supply adapters for his or her cameras to just accept the Technika 4×5 lens boards.
The smaller Technika V Tremendous 69 cameras use a 81.4mm x 74.4mm (3.205″ x 2.93″) lens board with double round light-trap lip, chamfered prime and backside corners and finding notches within the prime, backside and left edges.
The Linhof Technika additionally is available in a 5×7 format, which is a bit much less frequent than the 4×5 verison and makes use of a proprietary lens board. The Technika 5×7 lens board is 130mm sq. (5.1″) with a round light-trap lip and a finding notch within the heart of the underside edge.
Older Technika III cameras use a 100mm x 93mm (3.94″ x 3.66″) rectangular lens board with a round light-trap groove
The Linhof Kardan monorail cameras use an easier, 162mm sq. (6.37″) lens board with a sq. light-trap step and rounded corners.
Sinar
Established in 1948, Sinar is one other long-standing massive format images tools producer, and as such has used a number of lens board requirements over time.
The most well-liked Sinar lens board kind is a 139.6 mm sq. (5.497″) board with a sq. light-trap groove on the again. This lens board customary can be utilized in SKG Phillips and Horseman cameras.
Conscious of the advantages of a extra compact system, Sinar additionally gives a smaller lens board. Used on a few of their field-oriented cameras just like the P3 and the New Vue, the smaller board is 100mm sq. (4″) with a stepped edge all-round and a light-trap groove on the again.
Deardoff
Deardoff was one of many first large-format digicam producers, with manufacturing beginning within the Nineteen Twenties and spanning a number of a long time. Deardoff manufacture was halted within the 80s, and was resumed briefly just a few years in the past with a restricted manufacturing run fabricated from cameras assembled from previous inventory spares. As of right this moment, no new Deardoff cameras are made, however loads of the originals are nonetheless kicking.
All Deardoff cameras are fabricated from wooden, with the overwhelming majority of it being mahogany. Many of the unique lens boards are additionally fabricated from wooden, mostly mahogany veneered plywood.
Arca Swiss
Arca Swiss lens boards are available in three completely different sizes. The smallest one, used on their smaller F-line and M-line, is a 110mm sq. (4.33″) with rounded corners and sq. light-trap step. The larger dimension, reserved for his or her bigger monorails, is a 140mm sq. (5.51″) with the identical spherical nook and sq. light-trap design. The most important Arca Swiss lens board dimension is 171mm sq. (6.729″) with twin light-trap lips on the again. It could or might not have an indentation alongside the highest edge (pictured above) into which the lens board lock nests as soon as the board is on the digicam.
Cambo
Cambo lens boards are available in two sizes. The smaller one, used on their 2×3 view cameras, is a 123mm sq. (4.86″) with rounded corners, two finding notches on the highest nook and a sq. light-trap groove on the again.
The bigger Cambo lens board, used on their 4×5 monorails, measures a 163mm sq. (6.41″) with two finding notches on the highest nook and a sq. light-trap groove on the again.
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