fgianni
Trainee Amateur
I bought a 75 summilux from cameramate.com, and I have 20 days to return it (14 now), it has a very slight retrofocus (seems about half to one inch) at the closest focusing distance, in most cases it falls between the DOF of the lens, but of course makes focusing at f1.4 and short distance a bit of a hit and miss.
I am not an expert of Leica lenses, so I'd like to know if this is within accepted tolerance.
Should I keep it or send it back?
Cheers
I am not an expert of Leica lenses, so I'd like to know if this is within accepted tolerance.
Should I keep it or send it back?
Cheers
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J. Borger
Well-known
I do not know if it is the lens. All i can tell is the 75 lux is not reliable to focus close-up and wide open with the R-D1. At least not with mine. I have no problems with the 50 or 35 summiluxes wide open close up though.
I bought my 75 lux brand new ... tested it in the shop because i was afraid about focus because of the short rangefinderbase... 4-5 shots wide open .. bang ... all perfect in focus .. so i bought it.
But like you say at 1.4 close up it is hit and miss as it turned out using it more frequently.
THis is in line with the experiences Sean Reid had testing the fast lenses. He had no problems with the noctilus but found the 75 lux not reliable too.
I also miss the framelines for the lens in day to day use.... so my wonderful brand new 75 Lux is sitting here on the shelf waiting for the digital M. I can and do not want to part with it because the pictures it is capable to produce are soooo beautiful. Besides the price of this lens is 35% higher new this time compared to the time i bought it (this never happened to me with any type of foto equipment
) .
Could you clarify the "retrofocus"?
I will follow this thread with curiosity.
Han
I bought my 75 lux brand new ... tested it in the shop because i was afraid about focus because of the short rangefinderbase... 4-5 shots wide open .. bang ... all perfect in focus .. so i bought it.
But like you say at 1.4 close up it is hit and miss as it turned out using it more frequently.
THis is in line with the experiences Sean Reid had testing the fast lenses. He had no problems with the noctilus but found the 75 lux not reliable too.
I also miss the framelines for the lens in day to day use.... so my wonderful brand new 75 Lux is sitting here on the shelf waiting for the digital M. I can and do not want to part with it because the pictures it is capable to produce are soooo beautiful. Besides the price of this lens is 35% higher new this time compared to the time i bought it (this never happened to me with any type of foto equipment
) . Could you clarify the "retrofocus"?
I will follow this thread with curiosity.
Han
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jaap
Jaap
I think it's certanly within the tolerance. And the limits of accurate focussing. I think the lens is ok. If you want absolute accurate focussing you have to adjust the given camera in combination with the lens by a leica service centre. And even then you should notice some out of focus shots caused by the limits of the human eye.
fgianni
Trainee Amateur
J. Borger said:
For retrofocus I mean focusing behind the rangefinder indication.
My test is as follows: I put a ruler an a white surface, with the 0 pointing towards the camera, and the opposite end pointing away from the camera, then I focus on the 8inch number, I take the shot, refocus on the 8in and repeat about 10 times.
What I get with the 75 lux is that every shot is actually focused behind the 8, sometimes 8 is in focus, at other times not, the 9 and 10 in are consistently in focus.
Since the DOF behind the focused distance is greater than the one in front, it is difficult to evaluate precisely how much the lens is retrofocusing, but my guess is between half and one inch.
Essentially at close distance wide open, if I want the eyes in focus I’d better focus on the tip of the nose (quite difficult), if I focus on the eyes I am more likely to get the ears in focus than the eyes.
I can live with it, bracketing focus helps, but I’d like to know if this is between accepted tolerances for such a lens, if it is not I’d rather send the lens back and try to source a better one; but if it is there is no point in replacing it, another one is likely to have similar issues.
fgianni
Trainee Amateur
jaap said:
To reduce the effect of the limits of the human eye I take 10 shots or more, and I found consistently that the focus is behind the subject of about 1/2-1 inch.
I too thought that it is the worst possible condition (closest range wide open) and it could well be within acceptable tolerances, I just wanted to hear what others think about it.
fgianni
Trainee Amateur
jaap said:
I always wodered why they don't put a simple screw to move the RF so you could calibrate it yourself easily.
Or maybe a screw on the lenses to move the focusing helicoidal?
Or more likely I am talking rubbish since I know very little of RF camera and lenses
jaap
Jaap
Francesco,
The 75mm lux demands the very most of the rangefinder. If you adjust your camera in combination with the 75 lux you''ll be out of the problems i think. But I can give you no garantees ! In case you won't adjust the camera you got to live with it! Or avoid 1.4 and even 2.0. By the way wich camera do you use on the 75 lux ?
The 75mm lux demands the very most of the rangefinder. If you adjust your camera in combination with the 75 lux you''ll be out of the problems i think. But I can give you no garantees ! In case you won't adjust the camera you got to live with it! Or avoid 1.4 and even 2.0. By the way wich camera do you use on the 75 lux ?
fgianni
Trainee Amateur
jaap said:
It is an Epson RD-1, a bit short RF lenght, but the 1:1 magnification helps.
At f2.0 I am covered with the DOF, so the issue is just 1.4 short focusing distance.
Funy that with my 20D I can focus spot on with a canon 85 f1.2
Looks like nowadays autofocus is significantly more accurate than RF focusing.
J. Borger
Well-known
fgianni said:
Perhaps there is a reason the Canon does not focus as close as .7 meter.
If i back-up with the 75 Lux to about 1m ..... focus is a lot more reliable, even at 1.4.
Han
fgianni
Trainee Amateur
J. Borger said:
However the DOF of an 85mm f1.2 at 1m is most likely less than the DOF of a 75mm f1.4 at 0.7m, while the FOV must be similar.
jaapv
RFF Sponsoring Member.
I think you'd have to get the camera adjusted, the lens is probably correct. As adjusting the lens is not straightforward, because it has to do with the angle of the metal flange that moves the arm of the rangefinder I would really try the lens on a Leica first. The backfocussing you notice is not really surprising, given the extreme test and the wider tolerances of the RD1. Does the RF agree with the lens at infinity?
fgianni
Trainee Amateur
jaapv said:
The RF agrees at infinity with the 75 lux and any other lens I have, also the RD-1 RF agrees with Hector's Noctilux and my Nokton classic wide open and shortest focus distance.
So really the only issue is the 75 lux.
I am not sure about having the camera adjusted because I don't want to lose accurate close focus with all my other lenses just to gain it on the 75 lux.
Remember that on the RD-1 the DOF is about 1/1.22 of the DOF on a full frame Leica, so on a Leica the problem may not be visible.
As I said if this kind of inaccuracy is common (as it seems it is) then I am not bothered, I can focus and move my head 1/2 inch backwards before taking the shot.
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jaap
Jaap
that's logical with an slr focus accuratie increses with highspeed lenses. With Rf high speed only demands more of the range finder without having increasing focus accuracy.fgianni said:
jaap
Jaap
The 1:1 finder may help yes but the cropfactor of the RD-1 won't help you at all. Compared with 35mm your 75 lux "acts"as a nearly a 115mm lens !! So to give you an advice (if I may)be content with the results of the combo RD1/75mm lux. I think the results you get with it will not get better anyway ! I said before adjust the combo but at second thoughts I think that won,t make things better!
fgianni
Trainee Amateur
jaap said:
Actually it acts as a 115 only for FOV, for DOF is a "only" a 91mm
However I tend to agree with you f1.4 on a 91mm can be really critical, and perfect RF coupling may be beyond the tolerances available, so I am not sure if adjusting the lens combo is going to make things better.
Overall I think that I'll keep the lens and be content with what I can achieve, maybe the Digital M will have AF?
jaap
Jaap
I think the digital M will also have a cropfactor wait for the Digi Zeiss Ikon if you want a full frame digi
fgianni
Trainee Amateur
Back-Focusing, that is the term I should have used , not retrofocus.
Retrofocus is a lens design principle, not a defect, sorry for the confusion.
Retrofocus is a lens design principle, not a defect, sorry for the confusion.
jaap
Jaap
Your confusion was clear
Huck Finn
Well-known
My guess is that it's an issue of focus shift due to the limits of the lens design. On the new 75 Summicron, Leica introduced a floating element for the first time on a telephoto lens in the M-system. If a floating element is needed on a lens at f/2, I would think that it would need it all the more on one at f/1.4.
The Summilux design is almost 25 years old. It's interesting that Leica introduced a Summicron at this focal length rather than update the Summilux. I don't know, but it makes me wonder if the combination of speed & focal length aren't just too much to overcome to make a lens that can focus accurately close up & wide open.
Huck
The Summilux design is almost 25 years old. It's interesting that Leica introduced a Summicron at this focal length rather than update the Summilux. I don't know, but it makes me wonder if the combination of speed & focal length aren't just too much to overcome to make a lens that can focus accurately close up & wide open.
Huck
jaapv
RFF Sponsoring Member.
jaap said:
The crop may be 115, but the DOF is more like 90 mm. That is the math of different formats.....