[David Ellsworth]

Paul Corfield informed me that such a thing as an AF confirm chip existed, and could be bought on ebay (thanks, Paul). I bought the "*EURO* ETTL AF Confirm Programmable Chip for Canon EOS" from the vendor "tagotech" (not sure if this is the best one; it's just the one I chose). This is for use with my new scope, the Explore Scientific 127mm triplet, with Televue RFL-4087 0.8x reducer.

I bought this chip mainly for the EXIF info (programmable focal length) and to fix problems the 40D and 450D have when there are no lens electronics (dark Live View exposure preview in 'M' mode, and the need to tape teleconverter pins). The focus confirmation is nice but I can do without it.

The AF confirm chip arrived today (it came from Singapore). It appears to be rugged and well-made, and it's easy to place in the proper spot using the provided template as a guide. (Ironically I didn't use the template because I didn't read the instructions until after gluing — I didn't know that thing was a template; I did the measurements manually, but they agreed quite well with the template afterwards.) Incidentally, the template appears to have been made using a 3D printer.

The bayonet adapter with chip glued on attaches satisfyingly to my camera. I was worried because at first, it was resisting strongly against my putting it on and I thought maybe I had glued it at too high a height, but then subsequent attachments of the bayonet adapter had just the right amount of resistance and click in satisfyingly. (I glued it on so the base of the chip was a hairline above the top of the bayonet.)

Focus confirmation works great, as long as I start with focus too NEAR (racked outward beyond proper focus) and rack the focus inward (towards the FAR direction) until the focus confirmation light activates. My initial impression is that this gives me focus just as perfect as if I had done it using Live View at 10x magnification. However — if I try to focus by being too FAR and focusing in the NEAR direction until the light activates, then focus is WAY off. Maybe that's because my scope with reducer is f/5.94 and not f/5.6, or maybe it's because of the scope's soft focus of violet; I don't know at this point.

The really great thing is that since the chip is reporting an aperture and focal length, my 40D is no longer confused about Live View exposure simulation! In 'M' mode the Live View exposure preview is exactly correct and I no longer need to futz around with switching to 'A' mode to focus then back to 'M' mode to take a shot.

I keep my 40D in AI Servo mode by default, using the special * button to focus instead of half-pressing, but AI Servo is apparently incompatible with focus confirmation. I have to switch to One Shot focus for focus confirmation to work (though I can still use the * button to do it).

This chip has a neat feature, in that you can program it to be either in AF mode or MF mode (and AF mode is the factory default); in AF mode, you can fully hold the shutter button and then have the shot taken only when you reach proper focus. This may be good for birds in flight. (It works whether AF is set as the * button or as half-pressing.)

I programmed the chip to be at f/5.6 (focus confirmation doesn't work at f/6.3), and programmed it to report a focal length of 755mm, because I've measured the Televue RFL-4087 reducer to be about 0.793x or 0.792x.

The only shortcoming of this chip that I'm aware of is that microfocus adjustment goes from 01 to 17 (default 09), and some other chips available on ebay apparently have 32 levels of microfocus adjustment. It would also be nice to have three extra pins for teleconverter communication, so the chip could automatically multiply its programmed focal length by 1.4 or 2.0, and multiply the aperture as well with a programmable maximum of f/5.6 or f/8 (depending on whether you have a 1-series body) or no maximum (if you don't mind losing AF confirmation) — but I don't think any of the chips available have this feature. (Heck, I wish that Canon had designed its TC communication protocol so that stacked TCs were properly EXIF'ed.)

I am going to order a second AF confirm chip to glue onto my T adapter so I can get proper Live View exposure simulation at 952.5mm (with no reducer, and optionally with teleconverters) and focal length in the EXIF. (Of course it'll have to be rounded to 952mm for this, as only integer focal lengths can be programmed — despite the fact that I've measured my scope to be 952.5mm plus or minus 0.1mm.)

[Musoman]

Did you buy the Televue reducer to widen the aperture from F7.5 to F5.94 to help with focus confirm you were after ?

I wondered because i have the SW Pro 80ED ( same as Paul C ) and thats an F7.5 aperture with a Focus Confirm chipped adapter and I've been using Focus Chip adapters for around 1.5 years with my old M42 + Pentax K mount lenses on my 40D, and previously with a 450D

I have the Focus Confirm chipped adapter on my scope but at f7.5 - mine Focus Confirms ok.

[thornlv]

Was thinking of geetting one of these for Nikon, what glue did you use to attcah it, do you think there is any danger of it coming off in the camera body onto the mirror or sensor ?

[Musoman]

When i first saw these loose chips, i bought one - very cheap. But i found it a night mare to glue on the right place, and i may have used incompatible glue, as it fell off not soon after.

The new loose chips seem to come with templates and such, which were not around when i first bought mine.

I bit the bullet and bought a proper EOS mount with the chip already installed. I use M42 > EOS chipped adapters and then epoxy ( 2 stage ) the adapter on whatever i need to

[Musoman]

Here's a photo of the M42 > EOS chipped adapter, epoxied onto the Cosina lens i bought. You've probably already seen this in the 100-300mm cosina thread

[Aegea]

Originally Posted by thornlv

Was thinking of geetting one of these for Nikon, what glue did you use to attcah it, do you think there is any danger of it coming off in the camera body onto the mirror or sensor ?

I just converted a Nikon 35 f/2 AIS with one of these chips. I used a 2-part 30 minute epoxy, hasn't fallen off yet ... seriously, if you prepare the surfaces correctly by scuffing them up with fine sandpaper and then cleaning with alcohol, epoxy should hold on very well.

[David Ellsworth]

Originally Posted by Musoman

Did you buy the Televue reducer to widen the aperture from F7.5 to F5.94 to help with focus confirm you were after ?

I did, and it works quite well. However I'd really like a wider reducer; in many circumstances, 755mm is too close. Especially since unlike true camera lenses, the focal length doesn't go down as you focus closer.

Originally Posted by Musoman

I have the Focus Confirm chipped adapter on my scope but at f7.5 - mine Focus Confirms ok.

Do you have the same problem as I do, namely that you have to approach focus from one direction only — and if you approach from the other direction, it gives focus confirmation incorrectly?

Originally Posted by thornlv

Was thinking of geetting one of these for Nikon, what glue did you use to attcah it, do you think there is any danger of it coming off in the camera body onto the mirror or sensor ?

I used to have two-part epoxy, but I used it up on various projects. What I had handy was Gorilla Glue, and that is what I used. The glue broke once, and I reapplied it. So far it hasn't fallen off again.

[Musoman]

Originally Posted by David Ellsworth

However I'd really like a wider reducer; in many circumstances, 755mm is too close. Especially since unlike true camera lenses, the focal length doesn't go down as you focus closer.

I assume you mean its not a zoom, when you said the focal length doesnt decrease in close focus, then the answer to closer focus is to add an ext tube, if you find 755mm is too much for closer bird photos.
I found that a bit of a pain, so i bought a cheap zoom lens and threw most of it away, but kept the zoom function and used this as an extra movable ext. tube.
So apart from the scope focus tube extending and retracting a few inches, i have an extra 2" of adapted zoom lens attached.
With that, i can now focus down to 15ft from the plane of the camera ( 13ft roughly from the end of the scope ), and as far as i can tell at the moment, to infinity in the other direction.

This is without barlows or TC's ..so 600mm

Originally Posted by David Ellsworth

Do you have the same problem as I do, namely that you have to approach focus from one direction only — and if you approach from the other direction, it gives focus confirmation incorrectly?

.

Not that i noticed .. do you mean if you've passed the focus point and have to come back / or not reached the focus point and have to move forward ? If thats so, again i havent noticed this.

I can always check my focus in Live View, as long as the subject is not going anywhere

[David Ellsworth]

Originally Posted by Musoman

I assume you mean its not a zoom, when you said the focal length doesnt decrease in close focus, then the answer to closer focus is to add an ext tube, if you find 755mm is too much for closer bird photos.

No, by "too close" I meant "too narrow a field of view". This can happen even when I don't need an extension tube to reach focus. My scope has 109mm of focuser travel, and I have extension tubes to add 80mm + 50mm if needed (though it's a pain to swap them on and off).

In fact this happened yesterday; I was photographing a Cooper's Hawk in my backyard, and the hawk filled the frame completely in vertical orientation. I reached focus without the need for an extension tube. When the hawk moved its head forward a little bit, it was cropped beyond my frame. :( Re-framing on the fly was not possible, because I had to put the tripod on the very edge of my balcony to get a good view of the hawk, and this was an awkward angle to put my head down to the viewfinder, so I used Live View. (Probably I need a right-angle viewfinder.)

I have a 100-400mm zoom lens, but at full zoom it has the light gathering power of about 65mm of aperture. So it'd nice to have wide capability with my 127mm telescope, too.

Originally Posted by Musoman

I found that a bit of a pain, so i bought a cheap zoom lens and threw most of it away, but kept the zoom function and used this as an extra movable ext. tube.
So apart from the scope focus tube extending and retracting a few inches, i have an extra 2" of adapted zoom lens attached.
With that, i can now focus down to 15ft from the plane of the camera ( 13ft roughly from the end of the scope ), and as far as i can tell at the moment, to infinity in the other direction.

Wow, I have not read your thread about this yet. It sounds like you have come up with a very creative solution.

[Musoman]

I see your point about the ' too close ' thing

As for the adapted zoom lens, i got the idea from Fernando on these forums.