AF-confirm T-mount

I couldn't find this topic by searching, so I'm posting a new thread.

I have a 500mm Soligor mirror lens that actually takes pretty decent pictures- it's just tough to focus manually at f/8. I tried one of the AF-confirmation chips, and it helped for a while, but the epoxy didn't hold and it popped off. (I'm leaving it off, since I don't want it to fall off when the lens is mounted and get caught-up in something inside the body!)

Is anyone aware of a GOOD QUALITY AF-confirmation T-mount that I can use on my Canon digital/EF mount bodies? There are some on eBay, but it's hard to tell from the pictures if they're any better than the chip I bought to glue on. One that's pinned or screwed would be better, since it wouldn't pop off if the glue didn't hold.

I might try to sand the epoxied surfaces on the chip and T-mount and try it again, but I thought I would solicit some advice here first. Any help would be greatly appreciated!

I don't have an answer, but what's an AF-confirmation chip?

Buy another chip and glue it on your self. Yes, clean area first.

gasrocks wrote in post #11867002
Buy another chip and glue it on your self. Yes, clean area first.

I think I'll give this another try. I'll roughen the surface of the T-mount and the back of the chip with fine sandpaper, then re-epoxy.

Cokeman:

The T-mounts have no electronic interface. So, no communication with the camera body regarding aperature or focus. Aperature is no issue with a mirror lens- there is only one aperature, and you simply use aperature priority. Focusing on a plain screen at f/8 is rather challenging, as depth of field is very shallow. The AF confirm chip mates with the EF contacts on the body, and makes the camera believe that there is an AF lens attached, in manual focus mode. This at least gives an AF confirmation light and beep when focus is achieved.

So even if the camera isn't controlling the focus, it can use this dummied-up electrical contact to let the photographer know when the current manual focus is really in focus?

I guess I see the value in that, but it makes me wonder - why doesn't canon build in AF confirmation for lenses that don't feed back AF information.

Does the chip just feed back the AF confirmation for center-point focus? Or does it have a way of picking a focus point?

I've been meaning to look into a t-mount for my el-cheapo telescope - I'll have to keep the AF confirmation chip in mind as I look.

Cokeman wrote in post #11887513
So even if the camera isn't controlling the focus, it can use this dummied-up electrical contact to let the photographer know when the current manual focus is really in focus?

I guess I see the value in that, but it makes me wonder - why doesn't canon build in AF confirmation for lenses that don't feed back AF information.

Does the chip just feed back the AF confirmation for center-point focus? Or does it have a way of picking a focus point?

AF confirm isn't known for its high accuracy, quite the opposite in fact, its the least accurate MF method, but I use it for hand held TSE shots. I consider the most accurate means of manual focusing to be Live View 5-10X, which usually means tripod use. Canon does have AF confirm for its MF EF lenses as they are still auto aperture and supply the camera body with lens identification. You choose your AF manually or use all points automatically. For example the new TSE lenses and Zeiss ZE lenses will respond to AF confirm. Micro adjust will change the calibration of AF confirm response for a given MF lens. You didn't mention what body you have, but only 1D bodies will AF at f8. Otherwise the general problem is that as the max aperture gets to f8 there simply is not enough light for the AF sensor to be very reliable.