BEOON advice please - functional checks prior to purchase

[Steve Ricoh]

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Mitch - opening the aperture doesn't make any worthwhile difference. (I've engaged focus peaking and magnification to assist.)

 

If I place the negative strip so it straddles the top of the baseplate (ie closer to the lens by 9 mm approx) I can focus fine.

 

Referring to Pop's post in #95 above, if the FL of the El-Nikkor is 52mm as stated in the data sheet, that's 2mm longer than the design aim of the BEOON (requiring 50mm, and I've not seen a tolerance stated). So doing the arithmetic, the extra 2mm of lens FL requires a shortening of the lens to negative of 8mm. And by resting the negative on top of the BEOON baseplate, this shortens the distance by 9mm (approx), so it's in the right ball park.

 

Any further ideas?

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[IQM]

Mitch - opening the aperture doesn't make any worthwhile difference. (I've engaged focus peaking and magnification to assist.)

 

If I place the negative strip so it straddles the top of the baseplate (ie closer to the lens by 9 mm approx) I can focus fine.

 

Referring to Pop's post in #95 above, if the FL of the El-Nikkor is 52mm as stated in the data sheet, that's 2mm longer than the design aim of the BEOON (requiring 50mm, and I've not seen a tolerance stated). So doing the arithmetic, the extra 2mm of lens FL requires a shortening of the lens to negative of 8mm. And by resting the negative on top of the BEOON baseplate, this shortens the distance by 9mm (approx), so it's in the right ball park.

 

Any further ideas?

 

We've all been following this thread and I know you read about the same problem I had with my Summarit.

 

I suppose the only way to know for sure is if someone has the same lens as you have and are able to achieve fine focus.

 

Good luck!

[Steve Ricoh]

The image that follows was camera scanned on the BEOON using the Summilux 50 ASPH with tubes A+D, as per the instruction manual. (Infinity at f11)

M6 Beoon-2 by -Steve Ricoh-

 

Having read the user manual there's no mention of using an elarger lens, and what extension tubes to use. But I'm not surprised by that.

Edited September 9, 2017 by Steve Ricoh

[Guest Nowhereman]

Steve - Sorry, I merely suggested f/5.6 because this seems to be the optimum aperture of your El-Nikkor. This is also the aperture at which I'm using my Focotar-2 50mm: it focusses perfectly using the B+C+D tubes. I found that these are the tubes to use in a posting on RFF — after first panicking that I couldn't get it focus correctly. In a web search I just tried to find what is the exact focal length of the Focotar-2 50mm, but could find any specs on this. I had assumed that all 50mm enlarger lenses, which apparently all use M39 mounts, would work with these three tubes.

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[a.noctilux]

EL-Nikkor 2.8/50 N may have different physical length (not optical length ! ) compared to Focotar 50mm.

 

I had difficulties to use EL Nikkor 50 N at 1:1 with rings B+C+D and even I use some others rings of 15mm (14020) in place of C and some combinations with shorter or longer rings.

Beoon is too tall, even in reverse EL-Nikkor, in focus the slide about 1cm nearer than 1:1 mask .

When I managed to find the good distance, the result from EL-Nikkor is not as good as Focotar at border of frame.

[Doug A]

I'm probably going to regret opening this can of worms, but here goes...

 

All these discussions of the lens focal length (or physical length) are completely missing the point. The BEOON was designed to work with a Leica 35mm camera and a 50mm Leica camera lens and the recommended extension tube combinations printed on the BEOON base are based on that combination. 

 

If the Leica 35mm camera is replaced by anything but a full frame digital camera that will focus at infinity with an M or LTM lens the printed combinations will not work. If it is replaced by an APSC camera the printed combinations will not work. If it is replaced by any DSLR or by any other digital camera that that will not focus at infinity with an M or LTM lens the printed combinations will not work. As far as I know, the only digital cameras that will work with the printed extension tube combinations are a full frame (24x36) Leica or a Sony A7whatever.

 

If the 50mm Leica camera lens is replaced by any lens that will not focus at infinity on an M mount or LTM compatible camera the printed combinations will not work. If it is replaced by any enlarging lens the printed combinations will not work. If it is replaced by any camera lens, macro or otherwise, that will not mount on an M mount or LTM compatible camera and focus at infinity the printed extension tube combinations will not work. As far as I know, the only lenses that will work with the printed combinations are nominal* 50mm M mount or LTM compatible camera lenses.

 

* The difference between a 50mm, 51mm or 52mm lens is irrelevant. There will be a minor difference in the coverage but it will be small compared with the differences of actual frame sizes of negatives from different cameras (my Barnack frames are a lot bigger than my Nikon F frames).

 

With anything other than a full frame M or LTM compatible camera and a nominal 50mm M or LTM compatible camera lens all bets are off. It's up to you to find something that works. 

 

If the distance between the mounting flange and the focal point or optical node of the substitute lens could be determined it could be compared with that of a nominal 50mm M or LTM camera lens and the length of the necessary extension tube combination calculated.

 

I couldn't find that number so I photographed a ruler and digitized the negative with an APSC X-E2, a 50mm Schneider Componon enlarging lens, and a variety of extension tube combinations, determined the total extension tube lengths that were a little too long and a little too short and interpolated the results, arriving at 40mm. I bought a 40mm tube and it works perfectly. 

 

Your mileage will almost certainly vary.

Edited September 9, 2017 by Doug A

[Guest Nowhereman]

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Doug A - As stated previously, the BEON works perfectly with the Focotar-2 50mm enlarger lens and the B+C+D tubes.

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Alone in Bangkok essay on BURN Magazine

[pop]

....

With anything other than a full frame M or LTM compatible camera and a nominal 50mm M or LTM compatible camera lens all bets are off. It's up to you to find something that works. 

....

An M (Typ 240) is a full frame M compatible camera. A 50mm Summarit-M is a nominal 50mm M compatible camera lens. Yet a Leica M (Typ 240) with a Summarit-M 1:2.5 50mm will not be able to focus to the bottom of the base using the arrangement of rings engraved or printed on the foot of the BEOON. The BEOON is too tall for this particular combination.

[Doug A]

 

Doug A - As stated previously, the BEON works perfectly with the Focotar-2 50mm enlarger lens and the B+C+D tubes.

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Alone in Bangkok essay on BURN Magazine

 

 

Hi Nowhereman,

 

You've proved the point I was making. The legend on the base of the BEOON says that for 1:1* you should use tubes A + D, and you've found that does not work. 

 

What sensor size is the camera you are using? If it is full frame your combination won't work for APSC, and vice versa.

 

* For APSC the ratio is more like 1.4:1 the closest approximation on the BEOON is 1.5:1 which uses tubes A + C.

 

--Doug

[Doug A]

An M (Typ 240) is a full frame M compatible camera. A 50mm Summarit-M is a nominal 50mm M compatible camera lens. Yet a Leica M (Typ 240) with a Summarit-M 1:2.5 50mm will not be able to focus to the bottom of the base using the arrangement of rings engraved or printed on the foot of the BEOON. The BEOON is too tall for this particular combination.

 

Something is wrong here. You have the camera attached to the top of the BEOON with the supplied bayonet adaptor ring. You have tubes A + D attached directly to the bottom of the BEOON. You have the lens attached directly to tube A. And you can not lower the camera/extension ring/lens combination enough to focus to the bottom of the base?

 

I just tried that setup with a 50/2,8 Elmar and was able to lower it considerably past the point of focus.

 

Are you using just tubes A + D?

[Steve Ricoh]

From reading around (and dare I say it on RFF too) I hear reports of the knurled focusing ring and hence the minimum height adjustment being on limit with the Focotar-2, so I assume it's marginal, but that's ok if it works for you. When it comes to the El-Nikkor 50 f/2.8, with B,C+D, it simply doesn't work, the BEOON is too tall at the minimum setting.

 

I would like to hear from anyone who has managed to obtain focus with the Nikkor 50 f2.8 at 1:1 on an M240 FF, or variant, specifically the spacer dimensions used, because I don't believe it's possible with those supplied with the BEOON.

[Doug A]

pop,

 

Forgot to mention, you do have the lens focused at infinity, right?

[Guest Nowhereman]

Hi Nowhereman,

 

You've proved the point I was making. The legend on the base of the BEOON says that for 1:1* you should use tubes A + D, and you've found that does not work. 

 

What sensor size is the camera you are using? If it is full frame your combination won't work for APSC, and vice versa.

 

* For APSC the ratio is more like 1.4:1 the closest approximation on the BEOON is 1.5:1 which uses tubes A + C.

 

--Doug

 

Doug - No, not at all. With an M-Mount lens you use tubes A + D: I've used it this way with the DR Summicron 50, focussed at infinity. Then, for substantially better corner performance, I've used it with the Focotar-2 50mm enlarger lens, which has fixed focus and has an M39 mount. This works with the B + C + D tubes, but this combination is not defined in the manual. I've used full-frame cameras; the M9, MM and M10.

_______________

Alone in Bangkok essay on BURN Magazine

[Guest Nowhereman]

From reading around (and dare I say it on RFF too) I hear reports of the knurled focusing ring and hence the minimum height adjustment being on limit with the Focotar-2, so I assume it's marginal, but that's ok if it works for you. When it comes to the El-Nikkor 50 f/2.8, with B,C+D, it simply doesn't work, the BEOON is too tall at the minimum setting...

 

Steve - This is not what I'm seeing with the Focotar-2 50mm: the focussing point is well below the 1:1 mark on the column, so it's not at all at the limit — the column can be moved up or down substantially more than 4mm. There are also 40, 60 and100mm Focotar lenses; perhaps that is where the confusion of being at the limit comes in.

_______________

Alone in Bangkok essay on BURN Magazine

[Avatar]

An M (Typ 240) is a full frame M compatible camera. A 50mm Summarit-M is a nominal 50mm M compatible camera lens. Yet a Leica M (Typ 240) with a Summarit-M 1:2.5 50mm will not be able to focus to the bottom of the base using the arrangement of rings engraved or printed on the foot of the BEOON. The BEOON is too tall for this particular combination.

 

Hey! I was going to say that! 

 

Doug A - Pop tested that configuration after I posted the exact problems of not being able to focus, even though following exact recommendations that come with the Beoon. Summarit focused on Infinity. The only way to achieve focus was flipping over the mask, which obviously brings the negative closer to the lens. Using an M246.

 

I then ordered an enlarger lens and do not have a problem with focus.

Edited September 10, 2017 by Avatar

[pop]

...

I just tried that setup with a 50/2,8 Elmar and was able to lower it considerably past the point of focus.

 

Are you using just tubes A + D?

So did I. I performed a brief test, using the Summarit-M 1:2.5/50 and the Elmar 1:2.8/50. The Elmar achieved focus and the Summarit did not. I said so here: https://www.l-camera-forum.com/topic/276151-beoon-advice-please-functional-checks-prior-to-purchase/page-4?p=3350345&do=findComment&comment=3350345.

[Steve Ricoh]

Hey! I was going to say that! 

 

Doug A - Pop tested that configuration after I posted the exact problems of not being able to focus, even though following exact recommendations that come with the Beoon. Summarit focused on Infinity. The only way to achieve focus was flipping over the mask, which obviously brings the negative closer to the lens. Using an M246.

 

I then ordered an enlarger lens and do not have a problem with focus.

Avatar - can you tell me which enlarger lens are you using successfully? In focus, how much adjustment do you have - is there sufficient to go out of focus again, past the critical focus point, at the short end?

[Steve Ricoh]

EL-Nikkor 2.8/50 N may have different physical length (not optical length ! ) compared to Focotar 50mm.

 

I had difficulties to use EL Nikkor 50 N at 1:1 with rings B+C+D and even I use some others rings of 15mm (14020) in place of C and some combinations with shorter or longer rings.

Beoon is too tall, even in reverse EL-Nikkor, in focus the slide about 1cm nearer than 1:1 mask .

When I managed to find the good distance, the result from EL-Nikkor is not as good as Focotar at border of frame.

I'm wondering how the physical length can lead to focusing problems, I thought focal length was key (eg the physical length of Zeiss and Leica lenses may differ, but they both deliver 50mm focal length, and on camera both focus at infinity and throughout the range equally well). Any optically knowledgeable people out there who can explain the significance?

 

Much like you, I'm finding the column is approx 1cm too tall with B/C/D. I think you're saying you didn't manage to find an alternative ring / tube that enabled the Nikkor 50 to focus (it's important to be able to go past critical focus at the short end, otherwise it's difficult to acquire perfect focus) ? In which case I can save my money looking for and buying other rings. We have a phrase in English 'throwing good money after bad'.

Edited September 10, 2017 by Steve Ricoh

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[pop]

The "optical formula" describes the relation between the distance from the subject to the lens, the distance from the lens to the image plane und the focal length.

 

In the special case of macro photography at a scale of 1:1 it's solution is simple: the distance from the subject to the image plane (the sensor) is four times the focal length. A difference of focal lengths of 1.5mm leads to a difference in height for the BEOON of 6mm.

 

This solution is a bit of a simplification because the extension of the lens is constant for all focal lengths: you use the same set of rings for all lenses with a nominal focal length of 50mm.

[Steve Ricoh]

The "optical formula" describes the relation between the distance from the subject to the lens, the distance from the lens to the image plane und the focal length.

 

In the special case of macro photography at a scale of 1:1 it's solution is simple: the distance from the subject to the image plane (the sensor) is four times the focal length. A difference of focal lengths of 1.5mm leads to a difference in height for the BEOON of 6mm.

 

This solution is a bit of a simplification because the extension of the lens is constant for all focal lengths: you use the same set of rings for all lenses with a nominal focal length of 50mm.

Thanks pop, no mention of the physical length of a lens playing a part. It's all down to the FL I suspect.

 

Incidentally, FL of Summilux 50mm f/1.4 ASPH (which works) is quoted by Leica as being 51.6mm. The El-'blessed'-Nikkor is quoted by Nikon as being 52mm, a difference of 0.6mm. With the 4x factor this equates to 2.4mm. So near but so far in terms of the BEOON design, which after all was designed for a 50mm camera lens set at infinity.