RD-1 and 75mm Summilux cracked!

[fgianni]

Some of you might remember me posting a thread about a 75 summilux I bought that I could not focus reliably with my rd-1, I was unsure if I had to blame the lens, the camera, or my focusing technique.

In the end I decided that it was the short RF base of the RD-1 to blame.

However a couple of days ago I received a 2nd hand Nokton 1.5 from Kim Coxton (nice lens Kim, thanks), and I had the same problem with that one, so I sent the camera for repair (still in warranty), and being a member of the RD-1 owners club, I got a loan unit which arrived today.

Guess what: with the loan unit I can focus reliably the Summilux 75 wide open at the closest focusing distance (still a bit of hit and miss, but a lot more hit than miss)

Even the loan camera is not perfect since the RF is a bit misaligned vertically, being this the third unit I get I wonder: how many units must I go trough before finding one with no problems?

 

[saxshooter]

Whew. And for a second there I thought you cracked your lens. 🙂

 

[fgianni]

Whew. And for a second there I thought you cracked your lens. 🙂

Well maybe it was not the best title, I meant I cracked the problem, before I simply thought that the lens could not be focused reliably with such a short RF base.

 

[RML]

Maybe it's just me not being too concerned with perfectly alligned rf, one or two dead pixels, or what-have-you but my specimen is just fine. Am I really the only one who is more than satisfied with his first camera? I can't believe that but hearing all these tales of woe makes me wonder.

 

[fgianni]

Maybe it's just me not being too concerned with perfectly alligned rf, one or two dead pixels, or what-have-you but my specimen is just fine. Am I really the only one who is more than satisfied with his first camera? I can't believe that but hearing all these tales of woe makes me wonder.

Well on my first camera theshutter died after less than 1000 shots, I did not have very fast lenses at the time so I can't be 100% sure of the RF calibration.

On my second camera I could not focus wide open with the 75 summilux nor the 50 Nokton, with all the other lenses the DOF covered any miscalibration, however I did not buy a £2000 camera just to use slow lenses.

On this loan camera the rf is spot on, but vertically misaligned (even if just lightly) so you see a double image even when the focus is spot on, it can make focusing difficult in less than ideal light conditions, so I guess I would send back a camera like this one.

About the dead pixels they are a non-problem for me unless there are loads.

 

[LCT]

To focus accurately at f/1.4 with a 75mm lens one would need an RF baselength of about 60mm when that of the R-D1 is only 38mm.
Best,
LCT

 

[brightsky]

Ooooh!

I read the thread title and was horrified, thinking you'd literally cracked your camera and lens!
Glad to hear that's not the case. 🙂

Receiving a camera 99% free of defects shouldn't be impossible for unit that cost $3k.

At least Epson is sending out loaners now. I hadn't heard of this before. I'll keep my fingers crossed that the NEXT unit you get will be a good one.

 

[Huck Finn]

I remember your thread on this subject & the ensuing discussion. Thanks for updating us to clear up the matter.

Huck

 

[fgianni]

To focus accurately at f/1.4 with a 75mm lens one would need an RF baselength of about 60mm when that of the R-D1 is only 38mm.
Best,
LCT

Well the magnification plays a role too, and the RD-1 has a 1:1 magnification finder, I know that the lens can be focused more accurately with an M6 (or better an M3), however even with the RD-1 I can get accurate enough to get the subject within the DOF most of the times.

 

[fgianni]

I'll keep my fingers crossed that the NEXT unit you get will be a good one.

Thanks

I have my toes crossed too 😀

 

[Huck Finn]

To focus accurately at f/1.4 with a 75mm lens one would need an RF baselength of about 60mm when that of the R-D1 is only 38mm.
Best,
LCT

I'm interested in how you arrived at that figure or what your source is for that opinion. It seems high since there isn't a RF camera on the market with an EBL of 60 mm.

Here's another man's opinion - Erwin Puts - who says that an effective base length of 40.2 mm is required for normal accuracy - "when you are relying on superposition & contrast" & an EBL of 52.3 "when you need the highest accuracy based on vernier acuity." This seems consistent with Francisco's "hit & miss" experience.

Huck

 

[fgianni]

This seems consistent with Francisco's "hit & miss" experience.

Huck

We are talking about 90% hit and 10% miss, and if the subject is at more than 1.5m then it is just like any other lens

 

[Huck Finn]

We are talking about 90% hit and 10% miss, and if the subject is at more than 1.5m then it is just like any other lens

I'm glad to hear that, Francesco. The EBL of the R3A is 37 mm, which is very close to the 40 mm that Puts says is required for most situations, Of course, close up & wide open are the most challenging.

Best of luck with it. 🙂

Huck

 

[LCT]

I'm interested in how you arrived at that figure or what your source is for that opinion.

By the usual formula b' = (e * f^2) / (k * z) where b' is the effective base length, e the visual acuity (0.0003 at approx. 1 arcmin), f the focal length, k the aperture and z the circle of confusion (0.02mm).
Best,
LCT

 

[LCT]

I don't know what Puts may say but remember that the circle of confusion is not the same for 35mm cameras (0.03mm) and APS-C digicams (0.03:1.5 = 0.02mm).
According to the same formula as above we only need 40.18mm baselength to focus accurately a 75mm lens at f/ 1.4 with a 35mm camera.
Best,
LCT

 

[LCT]

Francesco, the VF magnification is taken into account in the formula above in that it is based on the "effective baselength" wich is the mechanical baselength multiplied by the VF magnification.
For instance the effective baselength of the R-D1 is 38.2 mm mechanical base length * 1.00 image magnification = 38.2 mm.
Now the effective baselength of a 0.85x Leica M is 69.25 mm mechanical base length * 0.85 image magnification = 58.86 mm which is much more than the minimum 40.18mm above.
Best,
LCT

 

[Sonnar Brian]

> I'm interested in how you arrived at that figure or what your source is for that opinion. It seems high since there isn't a RF camera on the market with an EBL of 60 mm.

Nikon SP-2005 and Nikon S3-2000.

And after reading the title, I was happy to see the weight of the 75/1.4 did not break the lens mount.

 

[neilsphoto]

FWIW, focusing a 75 'lux at close distance, wide open at 1.4 is a challenge on any M camera too. I do it all the time and I can never be 100% I've got it sharp. focus and reframe makes it even tougher.

Neil

 

[Huck Finn]

I don't know what Puts may say but remember that the circle of confusion is not the same for 35mm cameras (0.03mm) and APS-C digicams (0.03:1.5 = 0.02mm).
According to the same formula as above we only need 40.18mm baselength to focus accurately a 75mm lens at f/ 1.4 with a 35mm camera.
Best,
LCT

Thanks, LCT. Puts' numbers are based on .03 & .02 respectively, which then align pretty closely with your numbers.

Huck

 

[LCT]

To confort you folks, remember that a 75mm lens on the R-D1 = a 112mm one on a 35mm camera as far as FoV is concerned.
Do you think one could focus accurately a 112mm lens at f/1.4 on a Leica M?
Of course not.
We would need a 90mm EBL for that...
Best,
LCT