What are the limitations to using non-ROM lens on R8?

greenspun.com : LUSENET : Leica Photography : One Thread

Hi all,

I'm new to Leica, having just purchased an R8 & 35-70mm Vario-Elmar-R f/4 (ROM) lens. I'm starting to look at adding something in the next higher zoom focal range (80-200mm f/4 most likely, as I don't like the weight of the 70-180mm f/2.8) and given Leica prices, I'm looking at used lenses.

Since I'm new to Leica lenses, I'm hoping for some guidance regarding what to look out for. Specifically I'm interested in what sort(s) of limitations I would face if I purchased a non-ROM 3-cam lens. I've heard that it only impacts flash photography using a dedicated flash (the ROM contacts being used to tell the camera what focal length it is set at, thereby allowing the camera to tell the flash how to set the flash's zoom). If it is only that, I'm not worried, since I don't plan to use a flash, especially not for focal lengths of 80-200mm. However, elsewhere I read that the ROM contacts are used for "exposure setting" and leaves me a bit more concerned.

Can anyone shed some light on this matter? Just what are the ROM contacts used for, and what limitations will I experience if I use a non-ROM lens with my R8?

Also, as mentioned, any used Leica-lens buying advice would be greatly appreciated.

Regards, John.

-- John Sheets (john_sheets@pacbell.net), October 03, 2001



With ROM, the R8 will know before firing what will be the real aperture (including vignetting which is different at each aperture and on each lens) in order to calculate more precisely the exposition. With lenses without ROM the camera will give an average result.

Leica said also that small lenses with ROM permit shorter time parallax than bigger because, thanks to the ROM, the camera knows the exact delay before the diaphragm is closed and can start earlier the process of firing. With a 280/2,8 at f8 it will be longer than with a 19/2,8 at same aperture, or than with the same 280/2,8 at f2,8. With lenses without ROM, the camera will always choose the longest delay.

With the APO-Extender 2X ROM (#11 269) the viewfinder will display the real aperture if used with a ROM lens, and the camera will know the new focal length of the lens (or zoom) and move the flash head accordingly. The same with the new Macro-Adapter-R (#14 299).

By the way, ROM are passive. They don't calculate anything. It's the camera which will calculate thanks the info stored at the factory inside the ROM. At the end of manufacture, or when retrofitting of older lenses, every Leica-R lens is individually measured and programmed in order to make sure that the potential accuracy of the exposure metering is maintained at each aperture. Two identical lenses may have different ROM's information inside.

If, after the lens left the factory, there is a problem in the diaphragm mechanism, the ROM will NOT know it.

Now, is all this really useful ?

I asked for the modification for lenses that I use with the APO-Extender 2X and/or flash. And I'm happy with the results (less mistakes).

That's all I can say.

-- Lucien (lucien_vd@yahoo.fr), October 03, 2001.

John: The ROM tells a Metz motor-zoom flash (with 3501 or 3502 module) what focal length lens is attached (or what focal length a zoomlens is set to)and the flash will zoom its reflector to match. That is the only ROM function which has ever been substantiated by users. The rest of them should be prefaced with "allegedly" or "supposedly" or "is said to" or some other disclaimer commonly used to avoid liability when passing on third-hand information. The Leica ROM lenses have their diaphragms actuated by the same mechanical linkage as non-ROM lenses, therefore it is highly questionable whether an electronic signal from lens to body could result in more accuracy than that provided by the cam. In any event, the only modes in which the camera controls the diaphragm position are T and P, and most serious photographers seem to favor A or M.

-- Jay (infinitydt@aol.com), October 03, 2001.

Interesting comments from Lucien. It seems rather complicated and god help it if Leica introduce a new lens - all the R8 ROMs will need to be reprogrammed. Personally, cynic that I am, I think its main effect is to zoom flash heads to the correct flash heading for the SCA 3501 system (i.e. it imparts focal length info) and it obviously does transfer some kind of aperture information as Lucien says because the aperture information is corrected in the viewfinder when using a 2 X ROMed convertor, but I think that that is about it. I suspect that the rest of it is to attempt to get us to buy ROMed lenses, or convert our lenses to ROM and thereby buy the R8 and hence get all these other somewhat dubious "benefits" of better exposure etc. I think you will find a three cam lens works just fine on the R8 and to me the benefits of ROMing each lens is just not worth it for flash info, since whenever I am using flash seriously it is always diffused or bounced so the zoom feature on 3501 compatible flashes is pointless.

So, I think there is some marketing guff in this information by Leica - I am not saying they are lying (I think), but I think in practice it is insignificant. Having just said this the ROM contact system is perhaps more elegant than old mechanical cams to transfer readings to the camera - but then you need an electronic camera to read it. I like manual cameras myself.

-- Robin Smith (smith_robin@hotmail.com), October 03, 2001.


If and when you buy additional used lenses for your R8, make sure that you buy 3-cam or 3rd-cam/R-cam lenses only. 1-cam and 2-cam lenses may also fit your R8 but with significant usage limitations.....

-- Muhammad Chishty (applemac97@aol.com), October 03, 2001.


All the information I gave you are coming from Leica Fotographie (7/98) on pages 30 and 31 and confirmed by Leica technician answers to the question I've asked during my visit in May 2001 at the Solms factory.

What I said about the ROM Apo-Extender 2X and macro-adapter is from my personal experience with those accessories used with ROM lenses.

May I add that not all the zooms with ROM are making the flash head zooming. The 70-180/2,8 and 105-280/4,2 are only locking the flash head on the minimum focal length. As an example: the ROM of the 70-180 will lock the flash head on 70mm. And a 70-180 ROM + APO 2 X ROM will lock the flash head on 105mm. No zooming. But on the other hand, they are the only Leica zooms that you can send to the factory in order to have the ROM added.

Regarding the improvement in accuracy, the correction of the exposition is made via the steps of the R8' shutter, not by the diaphragm, everybody understand that.

When I said "less mistakes", I was meaning, less mistakes from the user with flash head positions, that's all.

Now, honestly, I never saw any difference in accuracy with or without ROM or a difference of time parallax. ;-)

-- Lucien (lucien_vd@yahoo.fr), October 03, 2001.

Robin wrote:

> It seems rather complicated and god help it if Leica introduce a new lens - all the R8 ROMs will need to be reprogrammed.


Since the ROM are in the lenses, I don't see the problem here.

-- Lucien (lucien_vd@yahoo.fr), October 03, 2001.

Hi all,

Just a quick note to thank you for your speedy and helpful responses. I've gone ahead and purchased an 80-200mm f/4 3-cam (non-ROM) lens. Will see how it goes...

Regards, John.

-- John Sheets (john_sheets@hp.com), October 03, 2001.

Moderation questions? read the FAQ