[Fenwoodian]

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I only shoot manual-focus, premium, prime lenses. However, there are occasions when I find that it would be handy to be able to shoot an auto focus lens. Also, with my 65 year-old eyes getting worse by the year, I'm beginning to think auto focus lenses just might enable me to take photos further into my golden years.

That said, I sure don't want to have to give up the incredible image quality I'm getting with my adapted Zeiss and Leica R lenses just because of aging eyes. What am I to do?

Well, I just discovered how I can have my cake and eat it too. In other words, use my adapted Zeiss and Leica R lenses in the AF mode.

A few months ago I purchased a Pentax SMC Pentax-F 1.7x AF adapter. Never shot it "until today".

Below is the first photo I took with it. I attached this little adapter to adapted Zeiss ZF 35mm f/1.4 lens, and attached this combination to my Pentax K-1 camera, and shot away at f/2. WOW, am I impressed! The auto-focusing was fairly fast and dead on accurate. As many of you know, the Zeiss "Classic" ZF 35mm f/1.4 lens (with heavy Leitax adapter) is a fairly large and heavy lens - but this little adapter had no trouble at all with it.

Just put your camera in the AF mode and fire away (well, it does help if you manually move your lenses' focus adjustment to somewhere close to your shooting distance before shooting). My favorite way to use it is in Live View with back button focusing. Another side benefit to using this AF adapter is that it will speed up the taking of photos a little bit (not as much as a fully auto-focus lens, but maybe half way between an AF lens and the MF lens without this adapter).

Some of you will ask, "does this adapter reduce the image quality of photos taken with it?". This AF adapter does have 6 optical elements in 4 groups inside of it. Being an expensive Pentax product, it is well made with premium optical glass inside. Having said that, if you are a pixel peeper, maybe you will be able to detect a tiny TINY drop in sharpness if you look really hard. So, if you are a photographer who demands as much sharpness out of their gear as is possible, then you may want to not use this AF adapter. However, the great majority of photographers will not be able to detect a reduction in an image's IQ by using this AF adapter.

While many of you are already familiar with this AF adapter, I guess that I thought it would not work on my "adapted" Zeiss and Leica R lenses. Well, I'm here to tell you it works just fine on adapted Zeiss and Leica lenses. So, if you love Zeiss and Leica R glass like I do, here's a little accessory that you just might want to consider trying out for yourself (especially if your eyes are not what they used to be)!

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Last edited by Fenwoodian; 06-25-2018 at 10:46 AM.

[Kevin B123]

I'm not familiar with this adaptor or technique.
Do you pre-focus manually, and then the adaptor fine focuses within the adaptor only?
If so that's cool.
You are 1.7 times your focal length though and that adaptor IQ would need to be good.

[Mr Bassie]

That is really cool ��

[vonBaloney]

Not sure what you mean about the "adapter moving it". The adapter doesn't move anything on the lens -- just moves itself back and forth -- that's why main lens has to be in the ballpark focus-wise. So doesn't matter how big the lens is. (What would it move anyway if they aren't AF lenses?)

[Fenwoodian]

Not sure what you mean about the "adapter moving it". The adapter doesn't move anything on the lens -- just moves itself back and forth -- that's why main lens has to be in the ballpark focus-wise. So doesn't matter how big the lens is. (What would it move anyway if they aren't AF lenses?)

You are 100% correct.

[Fenwoodian]

Do you pre-focus manually, and then the adaptor fine focuses within the adaptor only?

Yes.

The adapter has a limited range it can move. So on every lens (especially those with a longish throw) you need to manually move the focus ring on the lens to "about" the distance you are from your subject.

I'm not a very good judge of distances, but I had no trouble guessing the approximate distance to the subject and setting the focus ring on the barrel of the lens to that distance before employing my back button focusing (that allowed the AF adapter to do the last bit of fine focusing).

[Fenwoodian]

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Here's a shot I just took with my Leica Elmarit - R 180mm lens at f/2.8 hand held on this AF adapter on my K-1. What you are seeing is a 100% blow up.


I was very surprised with the sharpness I see here.


With the AF adapter, I can turn my manual-focus Leica 180mm f/2.8 Elmarit lens into an auto-focus 306mm f/4 lens on my K-1. Heck, I could even use this combination for my back up birding lens.

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Last edited by Fenwoodian; 06-25-2018 at 11:49 AM.

[Fenwoodian]

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Here's the full sized image the above 100% crop was taken from

[IMG][/IMG]

[Fenwoodian]

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Here's another hand held test photo.

Nice detail in the fense...

[IMG][/IMG]

[LensBeginner]

Not sure what you mean about the "adapter moving it". The adapter doesn't move anything on the lens -- just moves itself back and forth -- that's why main lens has to be in the ballpark focus-wise. So doesn't matter how big the lens is. (What would it move anyway if they aren't AF lenses?)

Well, it still has to move the whole lens back and forth. amended

@OP, regarding "sharpness", multiplying a lens has to do fundamentally with one parameter: resolving power.
As long as it's good, results will probably be good.
Aberrations will be magnified as well but they're already there.
It's not uncommon to find vintage lenses with very good resolving power, maybe traded off with some PF.

[vonBaloney]

Well, it still has to move the whole lens back and forth.

Huh? It doesn't move anything on the base lens whatsoever, nor is there any linkage to do so. (What would it move on a manual focus lens?) The adapter just moves its own internals forward and back to focus.

[LensBeginner]

Huh? It doesn't move anything on the base lens whatsoever, nor is there any linkage to do so. (What would it move on a manual focus lens?) The adapter just moves its own internals forward and back to focus.

Aaaah now I get it... I never thought it could be internal focus... now your phrase makes sense, thanks for clarifying.
You wrote "itself" in the first post, and I've never looked too closely at the pictures of that thing on the internet, I've always thought it had an helicoid and half the barrel moved together with the "host" lens.

[vonBaloney]

Aaaah now I get it... I never thought it could be internal focus... now your phrase makes sense, thanks for clarifying.
You wrote "itself" in the first post, and I've never looked too closely at the pictures of that thing on the internet, I've always thought it had an helicoid and half the barrel moved together with the "host" lens.

Yes, so of course the opposite is also true: focusing the base lens has no effect (no direct effect) on the adapter -- they are connected electronically if it is an 'A' lens, but not mechanically. (Which is the whole magic -- it provides AF to lenses without any AF mechanism.) And the position the adapter is in (internally) will affect where you need to focus the base lens. The official way to use it is to put the base lens at infinity and that's that, but in practice for lots of things you need to ballpark focus the base lens. (You can also just turn off AF and use it as a 1.7 teleconverter manual-focus only, but you should AF on something far away first to put the adapter in its best position.)

One thing I discovered only a couple days ago is that the adapter doesn't like Sigma AF lenses (Pentax AF lenses work fine) -- if will give you shifted aperture readings (which isn't so bad, just annoying) but more importantly wrong aperture physical settings (depending on the lens it will close down several stops too far making it effectively impossible to for instance stop down to f/4 on an f/2.8 lens -- it will go straight from wide open to something like f/6.3. So if you're using it just as a 1.7x teleconverter on AF lenses, third-party lenses may be a problem. (Problem is known on Sigma, I don't know about Tamron.)

[Fenwoodian]

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I just tried my Pentax-M 300mm f/4 lens on this Pentax 1.7x AF adapter. I then put this combo on my Pentax D-70 APS-C body.

That's the full frame equivalent of a 765mm f/5.6 lens!

I took about 20 test photos, and on all but one, they were unusable and pretty blurry with low contrast.

Below is the only photo that turned out half way acceptable. I focused on the telephone pole in front of this McDonalds drive-through (maybe 80 yards from me).

In this photo you could make out the telephone pole number (2/3rds the way up on the pole).

Sure, having a 765mm lens would be fun, but the quality of this slow lens set up is wholely unacceptable to me, so I doubt that I will ever again put the 1.7x AF adapter on my Pentax 300M lens.

[IMG][/IMG]

[vonBaloney]

You will find that the adapter sometimes needs AF focus adjustment and that the adjustment needed can vary from lens to lens. It is worth it to manually focus a few shots critically to see the potential of a combo. (Just turn off AF.) Like any TC, you need a pretty good base lens to get sharp results.