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Da Yi 6x17 back for 4x5 [Review]
I kept seeing those Chinese made rollfilm backs that allow you to
shoot 6x17cm panoramas on 4x5 cameras, and wondering how well one would work - so I decided to order one and find out. Here are my first impressions for anyone else who's interested: First off, for anyone who's never seen one of these and is screaming "but 17cm is longer than 5 inches", I need to explain the principle. Yes it is true that normally one thinks of 6x12 as the longest rollfilm format that can be shot by putting a back on a 4x5 camera, and that the only 6x17 backs available have been those (like the Canham) made for 5x7 cameras. However, the Chinese have taken a logical approach to 'solving' this limitation: how does a 5x7 format changing back fit onto a 4x5? Answer, by using a set of tapering bellows in order to sit further back than the original 4x5 film plane, so that the light cone from the lens has room to spread further before it meets the film. The Da Yi does basically the same thing: it has a rigid body that fits into a 4x5 International back and holds the film further back. There is also a separate ground glass that fits in the same way, and with, of course, the same offset. Obviously this approach introduces some problems - see below - but it does provide a means to shoot 6x17 panoramas without carrying a 5x7 camera, or investing in something as expensive and specialised as a V-Pan or one of the Fuji or Linhof viewfinder cameras for the format. *** In the Box *** The parcel arrived from Hong Kong, very quickly and well packed. Inside the outer parcel was a smaller blue box which I presume is the original retail packaging. This contained the film back, the dedicated focusing screen in its holder, and two pairs of format changing masks. I didn't know the latter would be included: from pictures of the back I had gathered that it was designed to shoot 6x9, 6x12 and 6x17, but no mention in the text had said that the masks were included, they hadn't been in the pictures, and (to my chagrin) after I ordered my back _then_ they started being mentioned as included. In fact I have a Sinar Zoom back for doing 6x12 and given the issues surrounding having to move the film plane back I hadn't thought I'd want to use the Da Yi for anything other than 6x17 - but still, it was nice to get the masks as 'extras' and they may turn out to have some use after all - see below. There were no instructions, but the whole thing is obvious enough not to need any. One small black mark: no take up spool was included, so I had to raid one from another back. Not a big deal, but annoying. *** The Format *** By my measurement the film gate is 57mm tall, and the length seems to be just a hair over 170mm - so no short measure on size. The format changing pieces are black aluminium masks that slip into the film gate, resting just below the film plane and being secured at each end by two screws. So they are easy to put in and take out, but of course you can't do it mid roll - at only 8, 6, and 4 shots per roll for the three formats that isn't a big deal. Now for the interesting bit. The Chinese seem to have very literal minds where format is concerned: in general 6x9 is actually anywhere from about 78 to 84mm long, but on the Da Yi it is a generous 92mm; 6x12 is normally 112mm long (except with Linhof cameras and backs, where it is 120mm); with the Da Yi it is 124mm. These are the measurements on my example, of course they may vary a bit between samples. This is enough that I just might find I want to use the format changing masks after all - probably not often, but it is enough that I'm going to keep them safe rather than let them vanish into the junk box. *** The Back *** The back consists of two black anodised machined aluminium castings. One attaches to the camera and holds the film chambers, the gate, and the winder; the other is the back and clips on, this bears the film pressure plates. I say plates, plural, because rather than use one very long plate, the Da Yi uses a pair side by side, each seemingly pushed forward by a centrally fitted spring. The back clips on with two strong stainless steel spring clips: you slide it on and then push down on the clips to make them pop over a pair of studs. This attachment feels very secure and I have no worries about it coming off in use or transit. The dark slide is well forward of the film plane, about where it would be on a 'normal' 4x5 back so there's a lot of air between it and the film - maybe this would be a problem in very cold or humid conditions, but I don't think it's a big issue. The slide is only just slightly longer than the film gate - ie it starts to 'open' after being pulled out only a few millimetres, so make sure it's always pushed well home. It fits quite stiffly, but I think I might see about attaching an elastic band or something similar just to make certain it stays all the way in when in transit. Loading is just dropping a spool into one end - the bottom lugs at both ends can be pulled out against spring tension to do this - and pulling the film across to the take up spool, threading it and putting a few turns on the winder. Film counting is done through windows in the back, so 220 film is a no no. Then just wind till the relevant number appears in the right window. The back has three windows, one for each format, and by each it tells you which numbers to wind to: eg. for 6x17 you start by winding to the number 2, and your other shots are at 5, 8 and 11. Logical enough. Because it's aluminium the whole things is lighter than it looks, given that it is pretty big. *** The Focusing Screen *** This fits in the same way as the back, with the long narrow 6x17 ground glass set back in the same way. The glass is quite nice, with a fairly fine grind on it, so it's brighter than I expected. No Fresnel though, so when viewing it straight on the corners aren't very bright. There are very simple markings in nice fine lines: an outline of the whole frame, a central cross, and vertical lines for the edges of the 6x9 and 6x12 fields of view. One thing I hadn't expected was a nice bellows viewing hood. This pulls out about five inches on two pairs of folding struts and stays firmly put wherever you set it: it collapses small enough not to impede my focusing loupe, and pulled out it offers quite effective shading of the screen. It is attached, so far as I can see, with four screws so could be taken off by anyone who didn't want to use it. *** In Use *** I only unpacked it yesterday, so this is a very preliminary assessment: I haven't shot anything with it yet (lousy weather today) so have no results to examine. Overall the finish was a bit better than I'd expected. It's a simple piece of equipment, and my sample wouldn't have passed QC at Fuji, Linhof or Horseman - but there was nothing at all that I felt needed 'fixing' before I could use it, and no sharp edges. Loading was slightly awkward, with strong springs to work against, but at least I know there'll be tension there to help keep that long strip of film flat. Once I'd loaded the film in, but before winding forward to the first frame, I took out the darkslide and carefully looked at the film backing paper: it seems impressively flat, with the twin pressure plates seeming to do a good job, and little sign of the film curving away at the ends - this I'll examine closely once I have some shots to look at. Winding is by a knob, and one just slides up a window that covers the holes for viewing the numbers on the paper backing, and winds away. It feels smooth with a moderate amount of resistance - basically it's nothing fancy, but neither is there anything that could go wrong. I like the ground glass - it really is quite nicely ground, and the 'sweep' of the 6x17 image looks very enticing on the glass. That bellows shade over the GG is also a nice touch, and even when using a dark cloth I expect I'll find the shade useful as it will help keep the cloth 'out' from the screen. All in all it gives the impression that it will 'do the job'. *** Limitations of the Design *** There are inevitable limitations when you shoot with a back that sets the film back further than normal - the cost of having 6x17 on a 4x5 camera. One set of these relates simply to the film being set back: wider lenses may not be able to get infinity focus anymore, or you may need recessed panels or bag bellows in order to get the lens to focus and/or have any movements; and any rear swings and tilts are now well off axis, turning around a point that is in front of the film plane. The first of these is probably not such a big issue as it seems: what's the widest lens you have for your 4x5 that will actually cover 6x17 anyway? For me it's a 90mm, which won't focus to infinity on the Da Yi while fitted to a standard panel, but it _looks_ to me like it will once I've swapped it onto a recessed one. This limitation might be a bigger limitation if you want to use the back for 6x12 - I have 65 and 38mm lenses that cover 6x12, but I very much doubt that either will work with the format converting set on the Da Yi 6x17 back (they probably would with the 6x12 back that the same company makes, since this is of 'conventional' design.) The second one of these is a bit more of a nuisance, but if you're used to working with base tilt, say, then having your axis swing and tilt no longer 'on-axis' is at least a familiar thing to work with. The second set of limitations relates to the fact that the 6x17 film plane is now at the back of a 'tunnel' that reaches back from where the 4x5 film plane would have been. At the 'ends' of the frame this tunnel is necessarily only about 125mm long (5 inches) in order to fit, and then flares out to the full 170mm. At the top and bottom of the frame the tunnel could have started out four inches high and tapered down, and a normal 4x5 sized darkslide could have been used. Unfortunately the Da Yi designers didn't do it that way: the tunnel starts 57mm high, just as it finishes. To see why the 'length' - the taper of the tunnel at the ends of the frame - is an issue, you need to think about the cone of light from the lens. It is because this is a spreading cone that it is possible to shoot 6x17 on 4x5 at all: the light passes through the 4 inch wide opening at the back of the camera and continues to spread till it will cover the 17cm long film plane further back. This is no problem with wide angle lenses - the problem arises with lenses where the cone tapers too 'slowly' for it to pass through the 4x5 opening and then spread enough in the distance available to cover the full 6x17 frame: ie. longer focal lengths. Obviously the designers had to make a choice he set the film further back and it is impossible to focus wide lenses, make it too close to the original film plane and the angle of the ends of the tunnel is too steep for longer focal length lenses to cover the film plane. So this is, as I indicated above, one of the inevitable 'costs' of making a 6x17 back that can be used on 4x5, not a fault with this particular version of it. I need to experiment to find out just what is the longest lens I have that will still work with the Da Yi. Of course, as one exceeds this length all that will happen is some vignetting at the ends of the frame, so it may be that I'll find sometimes I use a lens that will still let me cover 6x15, say and I'll just crop it. A 210mm is a 'normal' lens for this format and I don't think that is going to be a problem: it's the longer focal lengths I need to experiment with. The parallel sides of the tunnel at the top and bottom introduce another problem (actually it applies at the ends too, but is less likely to arise there, in my use of the back anyway.) This is that moving the lens off axis from the film will tend to introduce vignetting. Two things could produce such off axis movement: shifting the lens or the back, and tilting the back. I did a little experimentation on these issues, just looking at the ground glass, and neither seemed as bad as I expected them to be. I used a 150mm lens, which is a moderate wide-angle for this format (about equivalent to a 35mm lens on 35mm film). With this I found I could apply as much rise and fall as my standard bellows would allow with that lens focused at infinity - about 10mm - which is a reasonable amount for landscape use. Next time I have some time and daylight I'll put on the bag bellows and see how much further I can go before I get vignetting. Next I looked at back tilt, and found I could get at least 10 degrees with this lens before there was any vignetting: again, as much as I'm likely to need in landscape use. Now, this issue will be more acute with movement along the length of the format, so swing or cross-shift with the back horizontal, or tilt or rise/fall with it in portrait format will probably be much more limited - but I'm likely to do this less often. I like vertical panoramas, but there are few occasions when the 3:1 ratio of 6x17 is really suitable for such compositions and I'm more likely to use 6x12 (or the 1:2 2/3 ratio of the X-Pan). Clearly I need to experiment a lot more, with different lenses and with bag bellows (and also by swapping my base & axis tilt rear standard for the base only one, which allows me to compress the bellows a bit more), with putting my 90mm into a recessed board - and with film in the back! *** Conclusion *** I like panoramas: I bought a Hasselblad X-Pan a couple of years ago and love it, and since then have wanted to do more work with panoramic formats on bigger pieces of film. But it isn't the mainstay of my work, or central to my enjoyment of photography. Rather, I often find myself working in a place where it would be nice to take some panoramic shots as well as whatever else I'm there for, and it will be one more string to my bow for the work I put with picture libraries. In this context, the Da Yi is (subject to seeing some actuall results!) looking like a winner. It was cheap, it isn't _too_ heavy or bulky, there's nothing to go wrong with it, and the limitations imposed by the design don't seem to be as severe as I thought they might be. If I was committed to panoramic photography as my primary interest I would get a V-Pan or one of the Fuji 617 models. Likewise if it was the mainstay of my professional work. If I wanted to shoot 6x17 with movements, but had no other use for a 4x5 camera I would, again, buy a V-Pan rather than this back plus a 4x5. If I alredy had a 5x7 that I didn't mind taking into the field I'd get a 'conventional' 6x17 back for it. If I was committed to panoramic travel photography I'd get a Fuji 617, and if I was a rich amateur enjoying playing with the format (nothing wrong with that) I'd get any of the above, or a Linhof. However, as a way to add this format to a camera I already own, at low cost and for somewhat more occasional use, the Da Yi works for me. For what I want from it, the price was right, and the limitations are ones I can live with. YMMV... Now I just have to work out how to scan the slides. Peter -- http://www.bard-hill.co.uk |
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On 1/25/2005 7:55 AM Bandicoot spake thus:
I kept seeing those Chinese made rollfilm backs that allow you to shoot 6x17cm panoramas on 4x5 cameras, and wondering how well one would work - so I decided to order one and find out. Here are my first impressions for anyone else who's interested: [long review snipped] I wish I could say "the check's in the mail" for this great piece of work you've posted here. Makes me reconsider my desire to get a Horizon[t] to do panoramas on the cheap. One question: are you sure of the spelling of this item (Da Yi)? I Googled for it unsuccessfully. Either it's spelled [spelt] differently, or it's one of the best-kept photographic secrets on the Internet. -- Today's bull**** job description: • Collaborate to produce operational procedures for the systems management of the production Information Technology infrastructure. - from an actual job listing on Craigslist (http://www.craigslist.org) |
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"Bandicoot" wrote in message ... I kept seeing those Chinese made rollfilm backs that allow you to shoot 6x17cm panoramas on 4x5 cameras, and wondering how well one would work - so I decided to order one and find out. Here are my first impressions for anyone else who's interested: Sounds very interesting. I hope you can post some outcomes. |
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"David Nebenzahl" wrote in message
... On 1/25/2005 7:55 AM Bandicoot spake thus: I kept seeing those Chinese made rollfilm backs that allow you to shoot 6x17cm panoramas on 4x5 cameras, and wondering how well one would work - so I decided to order one and find out. Here are my first impressions for anyone else who's interested: [long review snipped] I wish I could say "the check's in the mail" for this great piece of work you've posted here. Feel free... ;-) Makes me reconsider my desire to get a Horizon[t] to do panoramas on the cheap. One question: are you sure of the spelling of this item (Da Yi)? I Googled for it unsuccessfully. Either it's spelled [spelt] differently, or it's one of the best-kept photographic secrets on the Internet. The only place I've seen them is one seller on 'that auction site'. He described it as "Da Yi". On the back itself it is written as one, capitalised, word: "DAYI", but beside that there's a logo that is made up of a 'D' and a 'Y', supporting the two part spelling. The same seller also has 6x12 backs to fit 4x5. Looking at the pictures they look very simple, with masks to use smaller formats and winding based on a window in the back - ie. sort of like the 6x17 version but, obviously, not needing the backwards offset of the film plane. I haven't actually seen one of these, so no idea how well/badly they are made or perform though. Current listings from this seller are at: http://search.ebay.co.uk/_W0QQgotopa...sortpropertyZ1 This is the point where I have to say that I have no connection with the seller, get no kick-backs, etc. etc. Of course, if he wants to give me a kick-back, he should feel welcome... I originally found them by searching for 6x17 backs to see what the Canham ones for 5x7 cameras went for - I didn't find any and wasn't sure I wanted to go with carrying a 5x7 about anyway, so when these popped up, and after letting a few go by, I decided to try one as a relatively cheap way into making occasional use of the format. Peter |
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Bandicoot wrote:
The same seller also has 6x12 backs to fit 4x5. Looking at the pictures they look very simple, with masks to use smaller formats and winding based on a window in the back - ie. sort of like the 6x17 version but, The 6x12 back looks like the one I got last week from Shen Hao. It's simple but seems well made. But then I haven't had a chance to run any film yet. Nick |
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David Nebenzahl writes:
One question: are you sure of the spelling of this item (Da Yi)? I Googled for it unsuccessfully. Either it's spelled [spelt] differently, or it's one of the best-kept photographic secrets on the Internet. From Peter's excellent description and review it sounds as if this may be the same back as the Shen Hao sold by Robert White in the UK. The description at http://www.robertwhite.co.uk/shenhao.htm#Label617 has photos of the back, and says the longest lens you can use without vignetting is 150mm. |
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"Tim Rylance" wrote in message ... http://www.robertwhite.co.uk/shenhao.htm#Label617 $792US! Whew. Those extra 5cm really cost a lot! (gosh darned US dollar.) FWIW the Horseman 6x12 (actual 56x12cm) is well built and less expensive, can be printed on the more common 4x5 enlargers and with any lens that will fit in the camera. |
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In article ,
David Nebenzahl wrote: One question: are you sure of the spelling of this item (Da Yi)? I Googled for it unsuccessfully. Either it's spelled [spelt] differently, or it's one of the best-kept photographic secrets on the Internet. Both backs were mentioned (in separate articles) by Kerry Thalman in View Camera magazine. Badger Graphic URL:http://www.badgergraphic.com/ sells the DAYI backs in the USA. -- Brian Reynolds | "It's just like flying a spaceship. | You push some buttons and see http://www.panix.com/~reynolds/ | what happens." -- Zapp Brannigan NAR# 54438 | |
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"Tim Rylance" wrote in message
... David Nebenzahl writes: One question: are you sure of the spelling of this item (Da Yi)? I Googled for it unsuccessfully. Either it's spelled [spelt] differently, or it's one of the best-kept photographic secrets on the Internet. From Peter's excellent description and review it sounds as if this may be the same back as the Shen Hao sold by Robert White in the UK. The description at http://www.robertwhite.co.uk/shenhao.htm#Label617 has photos of the back, and says the longest lens you can use without vignetting is 150mm. Interesting - no, it isn't the same, though it obviously works in just the same way. The Da Yi seems to be made largely of machined aluminium castings, while the Shen Hao on Robert White's site looks as if it uses more sheet metal. Probably means the Shen Hao is lighter, though the Da Yi _may_ be more rigid - only experience with both would answer that one, and I'm not about to buy another 6x17 back just to find out! The bellows shade for the GG is different too: the Shen Hao seems to have it run on a rod at the bottom, whereas the the Da Yi uses a pair of folding struts top and bottom: I would expect that to make the Shen Hao's system more robust, but the Da Yi has the advantage that you can angle the hood up or down a bit. 150mm sounds about right to me for where I'd expect vignetting: a 150mm Symmar-S on mine is free of vignetting, but there isn't much room to spare for anything longer. What I'm beginning to wonder is whether a telephoto design lens that has a focal length longer than 150mm, but a flange to film plane distance that isn't any more than that might still be vignetting free - I need to experiment with that. Unfortunately I don't yet even know whether any of my telephoto lenses will cover 6x17, and currently they are all on the wrong lens plates (the whole point of me owning telephoto lenses is to be able to use long lenses with my 'travel' 6x9, which has limited bellows draw, so they don't genrally get fitted to a 4x5.) Anyone happen to know what the coverage circles are for the Schneider Tele-Xenar 180/5.6, 240/5.5 and 270/5.5...? (No, the figures aren't on Schneider's web-site!) Peter |
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