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Dr Croubie
08-06-2014, 11:17 PM
Meanwhile, I thought I should add my thoughts to this thread, now that I've taken my DaYi back for a spin a few times, here's my mini-review.
Firstly, there are at least three types of 617 DaYi backs. There's one that fits a 5x7 camera, you can tell without measuring because the film plane is the same as for 5x7 sheets and the film spools face away from the film plane (afaik this one doesn't come with a GG because it's in the same plane as the 5x7 GG).

In the 4x5 versions the film plane is recessed from the regular 4x5 film plane so there is room for the film spools in front of the film plane (because 617 is wider than 4x5).
The only difference that I know of in the two 4x5 versions is the included masks for different sizes. My back has markings for 6x17, 6x12, 6x9, there's at least one other back that has markings for 6x17, 6x14, 6x12.
My back was 2nd hand and didn't have any masks included, not that I care because all I want is 617.
Of course, being Graflok you're only limited in your camera choice, you get a whole lot more movements and control than a 617 body but of course pay for it in weight.
Cost-wise, a 4x5 plus 617 back is a lot cheaper than a 617 body, I paid $450 from KEH, both new and used on fleabay can go for $550-650, so I consider mine a relative bargain.

The best thing about it is the included Ground Glass holder and Darkslide, ie you can focus each shot rather than rely on an external finder like with G/GX and certain Technoramae (I think maybe some of them have darkslides/GGs).
The GG holder has a very usable bellows-hood that folds to 2cm and extends about 11cm, even with the sun at my back it's easy to focus. The GG has a centre-cross and crop marks for 6x9 and 6x12.

I've mostly shot with my 90mm Fujinon SWD, and a bit with my 180mm Symmar-S MC, mounted on my Toyo G, bag bellows, lenses on Technika boards and a recessed Technika->Toyo adapter.
Firstly, the SWD is fantastic, and I'm probably not ever going to shoot a 617 on anything else (until GAS kicks in again). I've never run out of movements on it (that I've needed in real life at least).
Because of the recessed film-plane, DaYi recommend only to use 90-150mm lenses (or maybe 75-150?). I've found that true on the long end: using the 180mm the edges don't make it past the opening and it crops itself to about 614. One day I'll probably get a 110-150mm for 'longer' 617s.
I don't have a 75mm to try on the wide end, but I did try with my 65mm f/8 Super Angulon, on a recessed Technika board, on the recessed Technika->Toyo adapter, with the standards as close as they physically may go, it just doesn't hit infinity (I'd say it barely focusses further than a foot or two). Not that I was expecting coverage of 617 anyway, but it might have been nice to make some masks and shoot 612.

Problems I've had so far:
1: the first roll I shot I didn't load properly, the film slipped off the takeup spool and got crumpled, had to attack it in a darkbag to get the thing out.
92403
(this is what happens when RVP gets crinkled)
Now I load by putting the feed spool in, attaching to the takeup and rolling a bit on, then putting the takeup spool in place. Also, if I'm planning a dawn-shot again I'll load the night before, not at 6am.

2: the next roll loaded a lot better, but when I unloaded it, it wasn't very tight on the takeup spool so light got all in from the top.
92404
Still, given the huge film area, I managed to crop a good shot out of that.
Now, at the suggestion of someone here, I wind on for a few more turns after the film is done to tighten it up on the takeup spool. I've also bent the pressure-thingummy closer to the feed spool, and put in a washer under the feed spool, all to increase the tension on the feed spool, haven't had this problem since.

3: Efke R25 has thin backing paper, apparently. No problems with RVP50, 100F, or Ektar, but the light shining through the windows to see the numbers bled through the paper and fogged the film in the short period it took to wind on (there's a slide to cover it at other times)
92405
I'd be more upset except that I also got the same shot on 4x5 RVP and Portra, I think this scene deserved a squarer-aspect anyway (and it's somewhere nearby I can easily re-shoot).
Solution to that (so far) is just not to use Efke R25, I'm definitely planning on putting a whole lot of PanF and the new RPX25 through this thing. I've also inserted two ends of some Ektar to darken the film windows somewhat, that should hopefully fix the problem.

Anyway, that's all the problems I've found thus far, and solutions for them. Now that I've run through a few rolls I'm fairly confident that I won't have any other problems that aren't my own stupidity.

And for the hell of it, a shot that I like that didn't have any problems, on Ektar:
92406

analoguey
08-07-2014, 02:29 AM
Dr C

Wouldnt a 6x17 back on 4x5 necessarily translate to shooting 6x12 only? It is my understanding that since the rear standard is only 5" at the higher side or - that would be the max image size available?

David A. Goldfarb
08-07-2014, 03:24 AM
Dr C

Wouldnt a 6x17 back on 4x5 necessarily translate to shooting 6x12 only? It is my understanding that since the rear standard is only 5" at the higher side or - that would be the max image size available?

These are extension backs, so the full format is available with a modest range of focal lengths and subject distances.

analoguey
08-07-2014, 04:53 AM
So the GG would actually only show part of the image?

Sent from Tap-a-talk

polyglot
08-07-2014, 05:23 AM
They have a separate ground glass, 617 size, also offset to where the new film plane is.

Dr Croubie
08-07-2014, 06:14 AM
I don't really like posting fleabay links in stickies, because they'll be dead in 3 months, but whatever. This (http://www.ebay.com.au/itm/New-DAYI-Multi-Format-6x12-6x14-6x17-Roll-Film-Back-Holder-Magazine-4x5-Camera-/181170007315?pt=US_Film_Backs_Holders&hash=item2a2e92ed13) is like the back I've got, you can see the separate GG down the page. The top photo with the cover off also shows how it works, the graflok back has a hole in it (that's about 13cm wide), from there the light rays from the lens spread outwards to 17cm wide at the film plane (which is also why >180mm lenses don't work, the lens is too far from the film plane and the light rays don't spread wide enough to cover 17cm without getting blocked at the 13cm opening).