Focusing with the Apo 2x Extender - how to?

[pridbor]

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I recently bought an Apo 2x extender, on advice from members of this forum, and mounted it to my R9 and Apo Telyt 180mm lens today.

I seem not to be able to use the center focusing "split eye" any longer!? It looks black on one half and I can't correct "a broken line" to go straight!

Maybe poorly described? But as soon as I remove the 2x unit, the native lens let me operate as I have forever with my "R" cameras.

Is this true for all lenses I mount on the 2x or is there something I'm doing wrong?

Thanks

Preben

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[jaapv]

The split image focus aid functions up to f 5.6 or so and the microprisms are little better. Sometimes it helps if you shift your eye out of the optical axis a bit, but the fact remains that focus aids do tend to black out at smaller apertures.
That is one of the reasons that Leica offered the full matte screen, which I preferred with long lenses in any case.
The clean view is more conductive to composing your image too, as the view through the standard screen is quite messy IMO. If you like to have some sort of focus aid for faster lenses, the microprism screen is a good compromise.

[masjah]

Preben,  Jaap is quite right. You could try moving your eye up or down slightly, and you might find that the blacked out semicircle changes from one to the other (upper to lower or vice versa). With a bit of luck, if you can find a nice vertical in the image which is split between the two halves, you can get the alignment by moving quickly to and fro from one to the other.  Otherwise just use the main part of the screen simply to focus for maximum sharpness. You might have to temporarily displace the camera to achieve this, but you won't get a significant error at these long focal lengths from the "diagonal distance being different from the direct distance" (if you see what I mean). It's not too difficult to focus in this way because you'll find that, with the extender, the focus is quite critical, and you rapidly (almost too rapidly sometimes) move in and out of focus, because the extender increases the "focus gearing". Hope this is clear!

 

[pridbor]

I have tried the trick moving the eye position with great results when I just used the lens by itself 🙂 as soon as I "add" the 2x I haven't had much success 😞

I did try the other trick moving to an area where I can focus with just the ground screen, and that works fine!

I have used the split screen for 25+ years on my R3 with my 50mm Summicron without ever thinking that it was "cluttered", but now you mention it, then it may become an issue for  me 🙂

Jaap, when your refer to "full matte screen" are you then referring to the "14344 - Uniform Ground Glass" ?

Thanks both

Preben

 

[wlaidlaw]

With the 2X APO extender on the 500MR-Telyt, even the micro-prisms are pretty useless. I am thinking of leaving my R9 with the standard screen but changing my R8 to a plain matte screen (14347).  Below is a shot of the screens available. 

Wilson

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Edited July 13, 2020 by wlaidlaw

[masjah]

Wilson, just for completeness, there is also the screen to which I alluded in another post, and which is on both my R8 and R9. It is 14387: Universal screen with grid division. It was introduced late on in the life of the R system  (a batch was made at the request of users) and postdates the printed label above as well as the printing of the camera user manuals. It's essentially an amalgamation of 14343 and 14346 above. Not everyone is aware of its existence!

[pridbor]

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Wilson, isn't the 14347 the total clear one not recommended for regular photography, or did you mean the 14344?

Preben

 

[jaapv]

Total clear 14347 is meant for microscopy.

[jaapv]

On 7/12/2020 at 10:13 PM, pridbor said:

I have tried the trick moving the eye position with great results when I just used the lens by itself 🙂 as soon as I "add" the 2x I haven't had much success 😞

I did try the other trick moving to an area where I can focus with just the ground screen, and that works fine!

I have used the split screen for 25+ years on my R3 with my 50mm Summicron without ever thinking that it was "cluttered", but now you mention it, then it may become an issue for  me 🙂

Jaap, when your refer to "full matte screen" are you then referring to the "14344 - Uniform Ground Glass" ?

Thanks both

Preben

 

Yes, I do.

[wlaidlaw]

I misread the diagram. I thought 14347 was a plain ground glass like a Visoflex uses. I thought the dots shown on the other screens, indicated some form of micro-prisms. In which case for the 500MR-Telyt I need a 14344 or 14346. 

I would like to buy the proper kit with the plastic removal/insertion tool included. Thanks for the "heads-up" guys. 

Wilson