View Full Version : Enlarging Back (as opposed to reducing back) Project

27-Mar-2011, 20:15
Hi everyone. I'm already in progress with this project but I wanted up post a thread to see if anyone had anything valuable to offer. I'm building an enlarging back for my 8x10 Deardorff. It will function much like a reducing back but will expand the capacity of the camera to 11x14. The back will attack to the rear standard in the same way that a typical spring back would and will either be a tapered box to which an 11x14 spring back will attach (however I have concern about weight) or it will be an 11x14 frame (possible rear standard) with a second set of bellows that connects to the rear standard in the same way. Struts would be used to collapse the back and when fully extended would keep the back parallel where it belongs. This option would also reduce weight. There may or may not be a support arm to support the extra weight on the rear standard if necessary. I'm wondering if anyone here has done this and if you can offer any insight. Thanks for the help.

Michael Roberts
27-Mar-2011, 20:38

27-Mar-2011, 21:08
Thanks Michael!! Steve and I have communicated in the past regarding some of his other projects but I didnt know he made one of these. I've PMed him. Thanks again for the link. Much appreciated!

Michael Roberts
29-Mar-2011, 06:02
You're welcome; glad to assist. I have done some thinking about this, too. My ideal design would be a collapsible expansion back--where the sides would fold in for easy storage/transport and fold out to fit into a rigid frame when needed to connect to the smaller camera back. Still trying to work this out in my head. I'm thinking the basic material would be wood, obviously would need hinges to connect to the larger rear frame, plus a liner of black-out cloth--sort of like a bag bellows inside a fold out wood frame. And I would want the sides, top and bottom to be tapered. The part I haven't quite worked out is the connection to the smaller camera back. The frame to connect to the smaller camera would be easy, but how to connect the fold-out sides, top and bottom of the expansion back to the connecting frame? Need to think some more about this.... Rigid expansion backs, like Steve's in the link above, work great for shorter lenses, but for longer lenses you need around 12 inches of distance from the smaller back to the film plane of the expansion back, and that starts to get unwieldy to haul around in the field (okay for studio and working outdoors near your vehicle, though). A collapsible back would solve that problem, but presents it's own problems....

I guess another possibility would be folding metal struts between the expansion back and the connecting frame, as you suggest, with a bag bellows in between....

In addition, with a lengthy expansion back, I think you are right that it would be a good idea to design the back to allow a supporting arm to a tripod leg or else a tripod mounting nut under the larger back to allow a monopod or second, lightweight tripod to be used for additional support.

I also think it's a good idea to try to plan ahead by thinking about the focal lengths of lenses you are most likely to be using. If, for example, most of your work will be done with shorter lenses, then you might be able to get by with a shorter, rigid expansion back light Steve's. Then, for the occasional longer lens, you could have a separate spacer like this:


For your weight concern, I have been working with balsa wood, which is extremely strong for it's weight, with a covering of 1/16 inch basswood to protect the soft balsa wood.

Tom Keenan
29-Mar-2011, 07:21
11 x 14 B&J Frame
Tom Keenan

29-Mar-2011, 11:55
Michael, you bring up a number of good points. I've found the struts that I thought I'd use but I need to figure out if they'll be strong enough to support the extended back. I planed to attach two struts to the top, bottom, and both sides. Tom has the extra rear frame (pictured above) which should be sent my way as soon as he invoices me and I pay for it. I'll use this frame to which the spring back will be attached. I've just ordered replacement hardware so that everything goes together smoothly. If the struts and bellows idea doesn't work I'll probably just make it a rigid extension with tapered walls to extend it out and up to 11x14. The balsa wood covered in basswood sounds like a good plan and I'll probably try that. It sounds like a much better idea then using the heavier hard woods I planned on using.

29-Mar-2011, 12:01
Oh, your spacer back in the link looks fantastic and looks very well done. Can you tell me how much it weighs with the spring back attached? I figure you're spacer back is 2 inches and weighs 1/2 a pound so if weight correlated to the extension then a 10 inch (about how much extra extension I intend to add) spacer would weigh 2.5 lbs plus the weight of the spring back which isn't much. I'm thinking about how well the rear standard of the camera would support that. Hmm.

Michael Roberts
29-Mar-2011, 14:28
yes, also factor in a 3lb film holder inserted into the spring back. So, that's why I think a monopod or lightweight tripod or tripod arm could be useful.

your calculations seem right to me. The weight of the 11x14 spring back will depend on the brand. The only ones I have on hand are a balsa/basswood I made and an 1899 ROC King which is also unusually lighter in weight, so I don't think those weights will compare to your back if it's a Deardorff or B&J.

Michael Roberts
29-Mar-2011, 14:58
I planed to attach two struts to the top, bottom, and both sides.

Francesco--You might think about attaching two struts each to the sides--might handle the weight better. Struts on top and bottom will be forced to support weight only with the thinner parts of the metal.

Oh--keep in mind my spacer is 11 and 1/2 inches square. So increase the weight for 16 inches needed for 11x14.

31-Mar-2011, 12:29
i started off doing something like this---expansion back to my 8x10---after figuring out the lenses I wanted to use and the rest of the bs, I determined that it's best to just make a whole 11x14 camera---particularly if you want to use longer lenses or extensions---the way I was going to use it, my 8x10 would have ended up being nothing more than a heavy complicated front standard---

if you have aback, then you're better off building a complete camera---simple boxes will do--and a LARGE lensboard up front.....OR---if you can use the BACK of your 8x10 as a FRONT standard to an 11x14---then you'll be in buisiness---i toyed with that as well.....BUT....long story short--now i got 3 11x14's....each with it's own purpose depending on application---lens extension you want to use makes a BIG difference on camera design with thiese bigger formats---even 8x10 is getting a bit awkward extension wise when it comese to the longer lenses or close-closeups. The extension back will not allow longer lenses or closeups without getting vignetting---and movement will be severely limited--

just my experience----take it with as many grains of salt as you want.

31-Mar-2011, 13:00
I did think about building a whole camera but decided that that was a little too large of an undertaking for me. The issues of extension and vignetting are the major issues of concern but realistically they are only issues if you're making a short extension back. A short extension back involves a short and extreme tapering out from the back of the 8x10 to the 11x14 frame. This short tapering is what causes the vignetting because it basically blocks light from reaching the outer most edges of the 11x14 film plane. The short distance is also what limits the increase in extension obviously. If you make a longer and more gradually tapered extension back then neither of these issues remain of concern as a longer more gradual taper prevents the blocking of light and provides extra distance form the lens to the film plane. Obvious downfalls are potentially more weight and stress on the rear standard but this could be remedied by including a support to help hold any extra weight.

I intend to make a longer more gradually tapered extension, either fixed using balsa and basswood or collapsible using bellows and struts. I'm waiting on all of the pieces parts to arrive and I'll make a determination as to which way to go.

1-Apr-2011, 08:59
well--when I got really into it I realized that a non-tapered box is easier to make than a tapered extension---and a non-tapered full sized box is the same as a camera--

if it's going to be long, then no taper is needed---just a quick CHOP from full size 11x14 (like studio camera) to the 8x10 back size---then you can use the bellows on the 8x10 for all they're worth until you hit vignetting---taper to me only adds complexity and alignment issues---

maybe make a "first draft" model with no taper first--then see if that works--save you a LOT of time and headaches.

OH--I got that olde pinholey and black taped up 2d 11x14 bellows still---I was toying with the idea of using those bellows to make an 8x10 extender myself---you know..the front of the bellows that used to go to the front standard would now mate with the 8x10 back portion--then you have the 8x10 on a separate support for movements and can use the extra 8x10 bellows and all your 8x10 lenses on theire boards---maybe try that---be easy to hook up bellows to a rear and front already done---AND you'll defacto have a camera---MUCH easier as all the craftsmanship is in the bellows--not fancy woodwork---AND it'll fold up.---easy 2 tripod mount too....etc etc etc....lots of work saved

1-Apr-2011, 15:11
You make a good point when talking about the advantage of just making a box (with no taper) and the stress that might save. I initially went the way of the taper because I thought it would just look better like a natural extension of the camera but in reality all I care about is whether or not it works. I think making a first draft simple box is a good idea and I'll probably do that and see how it works.

As to the 2d bellows you mention, the smaller end would fit the rear standard of an 8x10? If thats the case, would you be willing to part with them? How bad of condition are they in? The only thing holding me back from making a collapsible version with bellows is the difficulty and cost of getting large enough bellows. I can make them but I'd prefer not to have to do that. Let me know.

2-Apr-2011, 10:46
the bellows will work fine as taped up with tiny pinholes as long as you're not having the camera out in the sun with the darkslide out--it works for indoors/strobe---throw the dark cloth around the bellows to make sure---or add more tape--the big holes are taped up---you can HAVE it for free but pay for any shipping--when I sent them with frames to get new bellows ups store charged like 30 bucks---but I had them pack it though.

the front was for a like 7" frame---but it tapers outward quickly--in you can cut off the front portion till the taper goes to the 8x10 size in back--theres a NEW phippips camera bellows on ebay I noticed too---like a hundred bucks now---

post office would probably be cheaper I'm thinking, but they charge by the size---when I got to my storage today I try to remember to grab it and see what shipping will cost---

Or do you know someone in chicago that canpick it up that comes your way?

2-Apr-2011, 10:49
OH---and BLACK FOAMBOARD---man--you can construct ANYTHING you NEED out of that stuff---for a "first draft"......work out the kinks and hold it together with tape---you may end up using just that for ever.

2-Apr-2011, 10:50
YOU ARE AMAZING!!! I'm PMing you now! Thanks so much man!

2-Apr-2011, 10:58
Oh and great idea on using black foam board! Easy to cut and shape and practical for testing.

11-Apr-2011, 00:17
Ok folks, the expansion back is complete! I'm not a carpenter or anything so its not the prettiest thing in the world but it's what I needed and it works PERFECTLY!

The expansion back provides a seamless continuation of the taper of the original 8x10 bellows. I used a set of old 11x14 bellows (very generously given to me by johnielvis) to connect the rear standard of the 8x10 Deardorff to an 11x14 B&J rear standard. The expansion back adds an addition 15 inches to the 8x10 Deardorff and at max extension provides about 50 inches from lens plane to film plane!

I worked with several designs involving struts and telescoping arms that would have served as support for the 11x14 back but in the end I found that it just worked better as a free floating back supported by a second tripod. Used this way rear focus is actually possible and not that difficult and the rear standard has a full range of movements as well. I was concerned that alignment would be difficult but everything just falls into place. Super easy to get lined up.

If you look closely you'll notice some strange characteristics of the 11x14 back. I received the 11x14 B&J rear standard frame bare. I built it up with old stock Deardorff hardware. The 11x14 B&J spring back also needed pins so it received old stock pins as well.

Everything I needed for the project was acquired here on the forum, ebay, ACE Hardware, Lowes, and Michael's.

I do however still need FILM HOLDERS!!!

Big special thanks to:
johnielvis - generous donation of bellows!
eddie - 11x14 B&J spring back
Tom Keenan - 11x14 B&J rear standard frame
TheDeardorffGuy - ground glass clips that are on the way
attrevida (on ebay) - old stock Deardorff hardware
Michael Roberts - for the link that started it all and possibly some film holders in the future
Many others on the forum - for all the help, input, and ideas!
Rod Klukas and Chris Palmer - for the support, clarifications, and brainstorming
My dad for graciously helping me while constantly getting aggravated as we tried to figure this thing out!


Michael Roberts
11-Apr-2011, 07:18
You make it look easy! Congrats on figuring it all out!

11-Apr-2011, 10:38
Thanks! Oh and a slight correction: I shouldn't say it works PERFECTLY yet as I haven't been able to put film through it and really make a final determination but as far as I'm able to test i.e. putting a lens on it, focusing, checking for distortion and corner sharpness, it seems to work like a charm :) Can't wait to put some film through it!

Tim Meisburger
11-Apr-2011, 13:30
You are a maniac! I like it!

I have seen several plans for single sheet filmholders on the web. Perhaps you could knock one up and try it out shooting paper.

11-Apr-2011, 13:33
You are a maniac! I like it!

I have seen several plans for single sheet filmholders on the web. Perhaps you could knock one up and try it out shooting paper.
Thanks! :D I'm going to do a google search now but if you know of any links please send them my way!

13-Apr-2011, 19:14
HEY...THERE IT IS!!!!!!! couldn't see the pics all day--some maintenance issue on the pic server--anyway---GREAT---the way I imagined it...but much better constructed--it really looks better than I imagined somehow--I don't know how it's possible---man---that was FAST FAST FAST!!!!!