Sigma SD bodies... why not just switch mounts???

I've been reading the comments on the sigma SD cameras and am surprised

so many people are uptight as hell about the camera mount - and being

stuck to sigma lenses.. why don't you just put a nikon or canon mount on the

thing if it's that big a problem..?? What'll it cost?? $80 ??? MAYBE...?? Not

more than $120, surely!!

 

Jonathan

Why didn't I think of that...

Great idea. Jonathan, do you have a source for these mounts by any chance? I'd like one to use the KM Maxxum lenses.

 

(I'm going to guess that it's a little teensy bit more complicated than it might seem....)

http://www.d-shell.net/

Yeah, just take the mount out of an ald canon body and make it fit on a Sigma. Then simply use a hex editor to edit the firmware so this Sigma body actualy knows how to AF these things.

Yeah.... there's this new thing called manual focussing. Crazy huh?? Well,

the sigma mount I SAW appeared simple enough. Just phillips screws.

You'll lose AF or any lens control - but if you actually care about your glass -

it should be irrelevant. Though I didn't consider that the body might NEED

some sort of electrical signal coming FROM the lens. Does anyone know if

this mightb e true - or would one have to ask a Sigma Tech. At the very least

though - all you skeptics - I'd read somewhere (here or DP review) that one

could also get adapters (although I really can't understand how that would

work since it would change the lens to sensor distance.

 

Perhaps it's a question for Mr. Grimes to answer...?

 

J.

Given that the flange to film distance is likely to be different for Canon and Sigma - I seem to remember reading that Canon's was one of the lowest, hence the availability of adaptors to use lenses such as Leica R - I can't see this having a chance of working.

Will the replacement mounts be the same diameter and thickness, have the same size screw holes, in the same places?<br>Will the rear of the non-Sigma lenses clear the Sigma electronics contacts and the dust shield right behind the mount? <br>With no electronic connections, how will you stop down the lens aperture, or will you be content to always shoot wide open?<br>And what's so great about the Sigma body in the first place to make any of this worthwhile?

Well, it's actually more common to have the odd Canon lens converted over to Sigma mount. The typical SD body owner already has some Sigma mount lenses. There are several people who do this and sell the converted Canon lenses on a popular (but unmentionable) auction site (hence refered to as PAS).

 

The conversion of the body to Canon mount is much easier than Nikon mount. Canon and Sigma share a 44mm registration distance, so you don't have to "build up" the mount to hit the 46.5mm Nikon registration. The Sigma AF protocol is a copy of the Canon protocol (serial messages, contact arrangement, etc) so if you just connect a Canon flange to a Sigma body AF, exposure control, and metering all work. A Nikon lens will be restricted to manual focus and stopped down metering.

 

You'll need a Canon service manual to provide the correct part numbers for ordering. You can find these online in PDF form, or for sale on PAS. You'll need the lens mount, several spring clips that attach to the back (separate part numbers). You probably want an EOS3 manual, I think that's the first one where the mount is a decent quality solid metal.

 

If you don't want to permanently deface the SD body, you'll also need a front "bullnose" from Sigma parts and service, so you'll also have to track down a Sigma service manual.

 

When the recent UK price reductions for SD10 hit the US, I'm going to try this myself.

 

Have fun.

I think Sigma would benefit if they scrapped their mount and switched to the 4/3 mount used by Olympus. It's an open standard and wouldn't cost them anything to licence it. If they did that then possibly they might sell some cameras in the U.S.

Wow, so many questions. But none are really hard...

 

Craig - yes, the Maxum lenses are about the most complicated. Your mount conversion would need to duplicate the Minolta mechanical aperture linkage, or you would always have to compose, focus, meter, and shoot with the lens stopped down to its smallest aperture. Personally, I wouldn't try this conversion, it's much uglier than the Canon conversion.

 

Bas - sarcasm aside, the Sigma SA protocol is an exact copy (serial messages, signal levels, pinout) of the Canon protocol. Just connect a Canon flange to a Sigma body or a Sigma mount to a Canon lens, and it works...

 

Jonathan - Sigma bodies can operate just fine (in stopped down metering mode) with a mount conversion that is purely mechanical. You can put a SD10 on a T-mount and use it on telescope or microscope, or use a simple adapter for M-42 lenses (something very popular with SD10 shooters).

 

Steve - The Sigma registration distance is the same as the Canon.

 

Paul - the Canon mount has a larger diameter than the Sigma, but there is room to machine the Sigma front area to fit the Canon mount. You'd have to add some support structure so that there would be places for the screws to land. As I mentioned before, the Canon protocol and Sigma are identical, connect the Canon mount and the lenses stop down just fine. The Canon lenses do clear the dust protector. As for "what's so great about the Sigma body in the first place to make any of this worthwhile?", several things. First, the dust filter, which removes with a single screw, is also the IR blocking filter. Remove it, and the Sigma SD10 shoots an ISO 400 equivelant in IR. My Nikon D100 shoots an ISO equivelant of 10. The Sigma offers 40x the IR speed. With the right filter, you can pull UV off the blue channel, IR off the red channel, and do wide spectrum imaging at high speed in a single shot. Canon users, unless they want to pay big $$$ for the specialty 20Da (astrophotography edition) have no IR solution that gets them past fractional ISO, like ISO 0.2. A converted SD10 gets them almost 1000x more speed. And, they're going for the equivelant of $600 in the UK ;)

 

Bob - as far as why you didn't think of that. It seems to be your nature to look for things to ridicule, rather than looking for way of helping people. This is quite an unfortunate attitude for a moderator of this siet and the author of many of this sites technical articles. I've only recently come in contact with you, so I don't know how long you've ehxibited such behavior. Have you recently had a personal tragedy that has left you bitter?

John, I don't see Sigma moving to 4/3, for a number of reasons.

 

First, they would have to release their entire lens line in 4/3, while still maintaining it in SA mount for the existing SD9 and SD10 users. Right now, all they have to do is release some of the more popular and better selling lenses in SA mount, for the Oly E-1 and E-300 users.

 

Second, they would need a 4/3 system sized sensor. Right now, it sort of looks like Foveon (the company) is in a "holding pattern". I don't think Sigma sales volumes are high enough to justify the R&D for new sensors.

 

Third, that "open standard" is a sticky issue. It's not a requirement that an "open standard" be free. You might have to pay royalties to use it, or you might have to pay money (or sign an NDA, or both) to get access to it. The only requirement for an "open standard" is that it be availiable, to everybody, on the same fair and reasonable terms. I believe that the Oly 4/3 system fails on this definition of "open". I've called and written both Oly and Kodak on numerous occasions, to try to get access to the standard, or at least find out what the licensing terms are. Can't even get a "no, you can't have it" response.

Good to know about the registration on Sigma cam, Joe. This gives a bit more leg room to work/mount lenses.

 

With its removable filter, the SD-10 is an attractive camera for me for UV/IR captures (although, the D70 with its flimsy filter is great).

 

Stop down metering (does the SD-10 meter with anything? I hope it is not like the Nikons) is not a big deal.

I had been told that the same person who designed the Canon mount also designed the Sigma mount. I didn't realize that they were so similar. I wonder what S.K. Grimes would charge to modify a Sigma to take the Canon lens?

I think Sigma just needs to just offer the SD body with an EOS mount. After all, the Kodak SLR/c (EOS mount) uses an EOS-mount body sourced from Sigma. The SLR/c body is based on the SD-10 body.

Thanks much for the encouragement, Joseph...! Anyway - since my interest

is in the nikkors, it seems to me the way to approach this would be to take a

pirated nikkor mount and mill the backside down a mm or two and then

drill & countersink new holes in the nikon mount to interface with the

tapped sigma mounting holes - and just leave the electrical connections at

this point broken.

 

I suppose the alternative - though only really cost-effective if you're

planning to use one or two lenses - would be to have existing nikkors fitted

with a sigma mount on the lens end - though you'd need to add a spacer to

compensate for theexpected thicker mount on the nikon body that the

sigma lacks. Perhaps this would be the more likely way to go if you want to

retain the potential for future use of sigma and sigma-mount lenses.

 

Well, despite having raised the ire of a few souls, I am glad that I launched

this somewhat contentious post. I've certainly gotten more than I'd hoped

for from it - which are details in how to actually go about something like

this.. as well as (hopefully?) made a few people consider possibilities they

might not previously have....

Jonathan, Why trouble yourself so much?

 

Pick up a Nikon-EOS adaptor and you are set!

Sorry - not really interested in the EOS - just trying to make the sigma work

for me.

 

(yes, yes... I KNOW you were trying to make a joke...!)

Vivek - yes, the Sigma meters with anything, stopped down. The only DSLRs currently on the market that don't have stopped down metering are the Nikon mount ones: Nikon D70 and D100 (if D100 can be considered to be "on the market"), Fuji S3, Kodak SLR/n.

 

John - that's a rumor that I haven't heard. Interesting. And it's probably worth a call to Grimes.

 

Peter - ah, if we could just get an SLR/c bullnose and front mount cheaply out of the Kodak or Sigma oarts department...

 

Jonathan - you're welcome. Putting a Nikon flange on the Sigma body means going in the other direction, though. You don't have to mill away material, you probably have to add a couple of mm. Picture a large washer under the mount. I would pull the front mount off a Nikon BR-3 ring. You can get a used BR-3 under $10, and it's got a lens locking pin and spring loaded release lever. There is a fellow who sells a retrofit kit for manual focus Nikkors. Remove the Nikon mount and add the Sigma mount. He also has a Nikon adapter for SD10 cameras, but the registration distance difference means you lose infinity focus.

 

Jonathan and Vivek - Even though I have Nikon lenses, my first choice would still be to put a Canon mount on the camera. A Canon mount SD10 will be highly sellable (as long as Sigma doesn't bring one out, themselve). And you can use an off-the-shelf Nikon to Canon adapter...

Oh my god. All the possible permutations are making my HEAD spin.

 

Let me see if I understand this - WILL any of the current (or not current)

dSLRs actually TAKE, say, a nikkor manual F-mount lens and automatically

stop it down? Or is that an impossibility? Would the Nikon and Fujis do this,

for example?

 

Or is it just the cameras you do a mount switch on which you would need to

manally meter at the working aperture?

 

enlighten me. I'm all over the map. I'm going from c8080 to D70 to 10D to

20D to SD10 to E1 now to poss. S2 or D70 again... though I REALLY have a

soft spot for the sigma and olympi.

 

Someone help me get my priorities straight!

 

Jonathan

Vivek - sorry I thought you were poking fun at my originating post. Maybe

this IS a possibility. I'm starting to think that lack of aperture linkage might

be much more of a pain than I was hoping. I mean - I KNEW what it would

involve.. I'm just starting to think realistically about it.

 

J

Joseph - about losing your 'infinity focus' with this method... this is

PRECISELY why I was suggesting milling the back of the nikon body ring.

 

Jonathan.

Jonathan, if you put a Nikon lens on a Sigma or Canon camera, you will have to meter at the working aperture. You compose and focus wide open, then stop down (using the aperture ring on the lens), meter, and shoot. If you put a Nikon lens on a Nikon D70 or D100, you won't have metering at all, but you can set the aperture using the ring on the lens, and the camera will remain wide open for focusing and composing, and automatically stop down when you shoot.

 

The registration distance and loss of infinity focus are an issue if you try to build an adapter that goes from the Sigma mount to the Nikon mount. The Nikon registration, at 46.5mm, is longer than the Sigma at 44.0mm. If you managed to hold a Nikon lens so that its bayonet interleaved with the Sigma bayonet on the camera, and held it exactly 2.5mm farther from the camera, you'd have infinity focus. But the bayonets would interfere, and you would not be able to turn and lock the lens.

 

If you remove the Sigma bayonet from the camera totally, and substitute the Nikon bayonet, this will not be a problem. Assuming that the metal parts of the mounts are about the same thickness, the Nikon lens needs to be 2.5mm farther from the sensor than the Sigma lens, so you will need to space the Nikon mount farther out from the camera. Unless, of course, the mount you get from a Nikon camera is more than 2.5mm thicker than the Sigma mount you're replacing, in which case you would have to mill the back until the Nikon mount was exactly 2.5mm thicker than the Sigma mount.

Yes - okay - this all makes sense to me. Actually - I was operating under the

assumption presented by the LAST scenario. Somewhat silly as far as

assumptions go - but I assumed the difference in thickness was inherent in

the mounting ring - thus my thinking that milling would be the answer (2

posts ago and elsewhere).

 

Here's another silly question - looking for clarification;

 

Why wouldn't you be able to meter on a nikon body with an AI-S lens??

 

Also - NOT TO PRESS your generosity with me... is the LEGACY canon glass

supposed to be superior to that of the LEGACY Nikkors??? I find that hard to

believe. MAYBE in the higher focal lengths... but it's only the shorties I care

about.

 

Jonathan

Several questions again.. let me try to answer a few that were intended for Joseph.

 

1. Only with the current D2Hs and D2X, you can use your AIS lenses and meter. No other digital (D70, etc) Nikon/Fuji/Kodak will allow you to use your AIS lenses with metering.

 

2. I don't know about any legacy of any brands. If you have Nikon lenses, use them. Most are excellent performers. Same goes for Canon, Tamron, Leica, Minolta, etc brands.