Leica-R to Pentax bayonet

[Rolf]

Hi,

does anyone has experiences with such a bayonet.

Until end of last year Leitax offers this solution exclusively, but in the meantime there are few other sellers from HK/China on the market for a fraction of the costs.

Thanks for your assistance.

[Attila]

I bought cheap Chinese made one , it is perfect on G1 with Pentax adapter.

[Rolf]

Not sure that we talk about the same thing Attila.

I mean this one - for example

Click here to see on Ebay.de

[Spotmatic]

Interesting. I should finally buy myself a Leica Summicron-R 50/2 to test this solution out myself. I always wanted to have a Leica lens; maybe this is the perfect opportunity.

[pich900]

[Spotmatic]

[pich900]

[Attila]

[Rolf]

Ok guys, thanks for the comments.

I ordered a bayonet yesterday evening. Delivery time approx. 10 days to Germany. Will remove at one of my Leica lenses (maybe the 2/50) the F-mount and replace it with the Pentax bayonet. The rest of the conversion is already done at the moment.

Will post here in this thread some samples. Stay tuned !

[BRunner]

I'm using these "cheap" Pentax Chinese mounts. No problem at all with any of my lenses. Even the APO-Macro-Elmarit 2.8/100 with 10 screws is possible to convert. Machining quality is very good.

[Rolf]

Thanks for your comment.

I use for the Leica to Nikon conversion Chinese bayonets too. Normally it is not the question of material etc - the question is what is with tolerances ?

But I must say that in the past I have had focus problems with the original Lxxxxx bayonets too. Sometimes front focus, sometimes back focus when the focus indicator lamp is on.

With Live view it is at all no problem, but I do not use LV very often.

I´m a little bit unsure due to the price ranges for the Pentax bayonets. At the Nikon side the prices are more or less all the same from Chinese sellers but with Pentax there is a price range from more than 100 % as said in my first post.

Ok, I will see when the first sample will arrive.

Thanks again.

[Spotmatic]

[Rolf]

[SVP]

I think Peter is right. I can't see how plain mechanical (i.e. unchipped) adapters / mounts can be blamed for focus confirmation inaccuracies, it's all about the good or bad performance of the focus confirmation system inside the camera body.

[poilu]

[Spotmatic]

Rolf (and others of course),

First: it does not matter if there is a flanged adapter or not. Infinity focusing issues are only an issue at infinity, not at closer focusing distances. The AF subsystem still uses a part of the image to determine if a picture is sharp or not (phase detect AF).

If there's a discrepancy between the phase detect AF and what you see in the viewfinder then there's an interesting thing to think about. With chipped adapters I have the idea that the camera thinks that there's a certain AF lens on the camera (even if it's a manual lens). Now there could occur an interesting phenomenon. It's known that AF systems issue minimal focusing adjustments based on the characteristics of certain lenses. Have you ever thought about the fact that the wide open focus plane is not the focus plane anymore when a lens is stopped down? This is called focus shift (see here for an explanation: http://diglloyd.com/articles/Focus/FocusShift.html). The lens may be focused right when it's wide open, but stopped down the focus plane is somewhere else). What if the camera thinks there's an EF 50/1.2 lens on the camera which requires AF adjustment after being stopped down? This makes focusing certainly a very complex procedure.

Another problem is when there's a difference between the flange - AF sensor and flange - ground glass screen distances. But let's just assume the camera is calibrated well.

(IMHO Live View focusing is the best for us MF shooters, because focusing can be done when the lens is stopped down. And in this case what you see is what you get...)

[BRunner]

Another issue can be, that different lenses have different longitudinal aberrations at different wavelengths and phase shift sensors can react to them in different ways. It's the same issue like, front/back focus AF problems with some type of artificial lights.

[Rolf]

Few weeks ago I made the following test.

D700 & Leica 2/50 (wide open) & Leitax bayonet & tripod, focus manuell with cam focus indicator lamp, no chip = front focus approx 15-20 cm.

Changed the bayonet from Leitax to cheap Chinese, same test, nothing changed = back focus approx. 50 cm

Therefore I tought that the reason for this must be with manufacturing tolerances of the bayonet.

[Spotmatic]

I'd say that your D700 is defective. What subject distances are we talking about? A backfocus op 50cm is a lot if your subject is at 1m

[Rolf]

[koji]