Sigma 30 F1.4 Art lens in A900

XKAES wrote: As I mentioned earlier, apparently some (most?) DT lenses over-ride the APS-C OFF setting -- somehow. With these lenses, IF you want the sensor to read FULL-FRAME, you would need to make some sort of adjustment to the lens. It might be as simple as covering up the three additional electronic tabs that newer lenses have -- as compared to the earlier, 5-contact, lenses. Of course, that means you lose any other features that use those contacts -- such as ADI flash. Probably a more sensible approach would be to find a similar, earlier, and undoubtedly much less expensive APS-C lens that does not over-ride the camera's APS-C OFF setting. Konica Minolta, and others, made a TON of APS-C lenses for the MAXXUM mount. The trick is finding the one(s) that meet your need(s).

Lenses such as the OP is asking about and all the Sony DT lenses I have are all lenses who's AF drive is in the lens , not the camera body .
If you cover up the three contacts you also have a manual focus lens .
The information contacts are still uncovered , as the data contact pin is the same regardless of if it's a five or eight pin lens .
So it would still crop the image .
IIRC with pins covered/damaged on eight pin lenses , the camera sees it as a fault and just comes up error .


If you cover up the data pin , you'll have neither AF or aperture control as the camera doesn't even know a lens is attached !

If someone's going to buy another lens for a full frame camera , I'd suggest buying a full frame lens , not a crop lens and trying to get it to work .

Trying to get something you already have to work is fine , but if you going to buy something , buy something that will work on your camera in the first place .

Full frame A mount lenses are plentyfull and cheap , and only getting cheaper .
Good time to buy .


Edited by neilt3 - 08 November 2021 at 15:55

Back to the original post.

The poster seemed to have gotten the lens to work full-frame with some vignetting using the "lens release button" -- whatever that is -- as evidenced in the two pictures. So I'm not sure if there is a problem.

My guess is that the OP wants to turn a APS-C lens into a full-frame lens which is not going to happen no matter what you do.

I think I misunderstood the original problem/question.

Some time ago, I bought the Sony APS-C 10-18mm F4 OSS lens to use with my QX-1 body. Obviously I also fitted it to my A7R just to see if it could cover full frame.
To my surprise, it DID cover full frame from about 12-15mm but did also vignette below and above that range.
I don't use the QX-1 much now and I sold that lens but I was pleasantly surprised to have a 12-15mm zoom for FF with OSS.

Edited by Idleidolidyll - 08 November 2021 at 19:59

The A900 and A850 are the only Sony full-frame cameras that force an APS-C crop when a DT lens is attached. Other models like the A7R allow them to be used with full-frame capture.

It is not that uncommon for APS-C lenses to more or less cover 135 full-frame format. Some "full-frame" sensors are less full than others too.

Edited by QuietOC - 08 November 2021 at 19:20

up date

Edited by AxitNitric - 09 November 2021 at 15:47

AxitNitric wrote: AxitNitric wrote: Many DT lens not or very little vignetting as: 30 F2.8 macro, 35 F1.8, sigma 30 F1.4... And it's very lightweight with good image quality I got a sigma 35 art and 30 art too but with the daylight the 30 F1.4 is very good with the same F, and it lightweight too. So I wonder to use it for the A900 camera I've tried to cover the lens contract with the body as 5 pin lens Minolta but only eror with no AF The A900 with 2.0 version firmware ALWAYS crop the images what ever ways I've tried Now I think there is an only way: A firmware 3.0 with a fix on this problem. Sorry for A mount that's Sony no more support

There will be no further firmware updates .
Sony's answer was to by an a99 or a99ii full frame camera for that option or rather an E mount full frame camera !
Or buy more lenses !!
Sorry ...

amrep wrote: If someone really wants to use a lens with a DT lens-ID on A900/A850 (and don't mind tinkering), just swap the lens contacts and ROM chip. Get a cheap full frame lens about the similar focal length (Minolta 28mm 2.8) as a donor. But I am not sure I would do this with an Art lens ... Exif will of course be altered.

And would end up as only a manual focus lens as you've no longer got the motor in the lens connected up to the camera .

You can't just replace five if the eight contacts , as the lens would report itself as the screwdrive lens and the camera would attempt to focus via the in body connection . Except the lens hasn't got a mechanical drive connection .

Even if you retained the other three contacts it would make no attempt at driving the focus drive via the HSM , as the lens chip would say it hasn't got one .

Plus you end up with a lens that could only be sold parts as it'd never AF again !




Edited by neilt3 - 09 November 2021 at 19:34