Focus throw

[pehrt]

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I am looking to get a Summarit 75 mm f/2,4. But I am worried about reviews that say the focus throw of this lens is very short, making it difficult to focus sharply. The smallest movement of the focus ring moves the focus away from where it is intended to be.

My questions: Is there a measurement for focus throw (such as, for example, how much focal distance changes for a 5 degree focus ring movement on a focal distance of 3 metres)? How does the focus throw of the Summarit 75 mm f/2,4 compare to foccus throw of other 75 mm lenses?

Thank you for any guidance.

[a.noctilux]

Welcome here pehrt,

The only Leica 75mm that I use with long focus throw is the Summilux-M 1.4/75mm.

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Compare the space between 2 , 3 , 5

Now I use mostly the Summarit-M 2.5/75mm which has short but precise focus throw with large rubber ring.

For the aperture F/2.5 and 90cm I have no complain.

Maybe the closer focus of F/2.4 that can be tough to focus closer with precision.

You can compare the throw in their images F2.4/2.5, here in this thread:

https://www.l-camera-forum.com/topic/308285-75mm-summarit-f24/?do=findComment&comment=3949051

 

 

[pehrt]

Thank you for your help. Very useful.

When I compare the distances between 2 - 3 - 8 on the Summarit focus ring (in the picture) with the distances 2 - 3 - 7 on my Elmarit 90 mm there is a very big difference. The Summarit 75 seems to be difficult to handle, too difficult for me. 

[logan2z]

I have a Summarit 75mm/2.4 and haven't noticed any difficulty focusing it, although I don't use it very much.  I do have an eyepiece magnifier that I sometimes use with this lens, but I've shot without using it too and focusing wasn't really an issue. 

It's a very nice lens, it's worth giving it a try.  

[Keith (M)]

I bought my Summarit 75mm f2.5 nearly ten years ago and although it is not in frequent use I can't say I have ever noticed a problem with focussing it.  

[pippy]

I, too, have a 75mm f2.5 which I use it quite a bit and actually find it easy to focus. Optically it's a wonderful performer and an essential part of my standard 3-lens kit. Obviously the Summilux needs a much longer focus-throw to accurately nail f1.4 but there is a world of a difference between shooting at 1.4 and 2.4/2.5 in the real-world.

There are a lot of scare-stories out there in WWW-Land. I'd suggest you go in to town and try one out for yourself before you write it off as being 'too difficult to handle'; IMHO it's quite the opposite. It's small, light, fast to use and handles really well but a lot depends on your own eyesight and your ability to use a RF patch accurately.

Philip.

[Knipsknecht]

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I, too, own the Summarit 75mm f2.4 - and I don't have any problems with the focus throw. But I have to admit that I never used it for close distance portraits. All in all it's a great performer and unless you absolutely need a faster 75mm lens, I would recommend the Summarit. 

[pehrt]

Thanks all for your advice. However I am still worried about being worried about getting it right with the Summarit 75/2,4. 

A few years ago I tried different 135 lenses for my 240 and 262 cameras. I found these lenses difficult to focus and when I compared the pictures with blown up details of Elmarit 90 pictures, I found that the Elmarit images were better. So for the time being I will make do with blow ups of 50 mm pictures. They will do for me. I mostly use my pictures for booklets about our grand children, so I need not resolution for large prints.  And I will keep looking for the Summarit 75/2,5 with a longer focus throw (and a lower price).

With best wishes for great pictures

Pehr

[a.noctilux]

Pehr,

I 'll relate you a secret ...😉

 

When I fell in Summarit-M mania, three years ago, after 2.5/50 and 2.5/35, I was actively searching for the new 2.4/75 sh, relying in the closer focus of 70cm.

I've never found the 2.4/75 but some 2.5/75 at good price came in the sh market, so I said to myself 'I'll give it a try (2.5/75)', to see that I barely use the close focus capability.

 

As written above, I used the "better/heavier" 75mm apo and Lux , and now the 2.5/75mm is so nice to use and carry that since then I only use the Summarit-M.

[pippy]

29 minutes ago, pehrt said:

...A few years ago I tried different 135 lenses for my 240 and 262 cameras. I found these lenses difficult to focus and when I compared the pictures with blown up details of Elmarit 90 pictures, I found that the Elmarit images were better. So for the time being I will make do with blow ups of 50 mm pictures. They will do for me. I mostly use my pictures for booklets about our grand children, so I need not resolution for large prints.  And I will keep looking for the Summarit 75/2,5 with a longer focus throw (and a lower price)...

Hello again, pehrt.

One thing you should remember - and take heart from - is that there is a VERY big difference between focussing a 135mm; a 90mm and a 75mm lens. At a guess when using a 135mm it is probably somewhere around 4 times as difficult to nail accurate focus using the rangefinder patch on an M. Furthermore f2.8 on a 135mm has a much slimmer depth of field than does f2.8 on a 75mm (all-else being equal). The difference in sharpness / success-rate between the 135 and the 90 would most likely also be present when comparing the 90 to a 75 - in the favour of the 75 of course.

Just a thought!

Still; it might be that cropping in to the 50mm image will be perfectly fine for your current needs so waiting for a longer focus-throw lens could be seen to be an anticipation to enjoy!

In the mean time I trust you will have a lot of fun snapping and playing with your grandchildren!

Philip.

[pehrt]

Thanks for sharing your secret. At present I cannot find any Summarit 75/2,5 on the second hand market, but I hope that one will come my way sooner rather than later.

Pehr

[adan]

I think the issue is not just the length of the focus throw, but also the lightness of touch (damping, friction) of the focus ring. There are times with Summarits (and some other recent Leica teles) where I take a picture, and the motion of pressing the shutter button alone (or even breathing hard) can cause the focus-ring to shift slightly under my fingertips.

The stiffer the focus action, the less likely this is to happen, and the longer the throw, the less likely that a tiny shift will cause a critical change in focus.

The issue with the f/2.4 Summarits is that they extend the focus range without increasing the focus throw (~95°), making them even more sensitive to tiny movements. As well as allowing the lens to focus into a close range where DoF is even tighter. They may work, but they are unnecessarily touchy.

IMHO any lens longer than 50mm - on a rangefinder - needs at least a 140° "throw," and stiffish focus, for reasonable focusing ergonomics. They are not 35s and 28s, and should not be designed with the same short throws that make wides a joy on an M.

Another reason I'd prefer to stick with 1980s lenses where possible (135 TE, 90 Summicron III, Tele-Elmarit II, 75 Summilux). Dr. Mandler understood this stuff, and they have well-damped throws of 150-180°.

However, regarding 75s in particular, the APO-Summicron does have a slightly longer throw than the Summarits (about 115°) and a stiffer action, thanks to driving the floating element on its separate helical.

And the 90mm APO-Summicron (designed in the 1990s) also has a long, firm focus action. 145° or so.

[Ko.Fe.]

It is shorter where DOF is significant and longer where DOF gets shallower.  Very smart modern design.

I like short focus throw, no time wasted. Left hand index finger is focusing, right hand index finger is pressing shutter release button once lens is in focus. 

If you need to have cap of tea between focusing and taking picture, I recommend to put rubber ring on the focus ring and slide it between ring and lens barrel to stop focus rotation. 

[Ko.Fe.]

13 minutes ago, adan said:

I think the issue is not just the length of the focus throw, but also the lightness of touch (damping, friction) of the focus ring. There are times with Summarits (and some other recent Leica teles) where I take a picture, and the motion of pressing the shutter button alone (or even breathing hard) can cause the focus-ring to shift slightly under my fingertips.

The stiffer the focus action, the less likely this is to happen, and the longer the throw, the less likely that a tiny shift will cause a critical change in focus.

The issue with the f/2.4 Summarits is that they extend the focus range without increasing the focus throw (~95°), making them even more sensitive to tiny movements. As well as allowing the lens to focus into a close range where DoF is even tighter. They may work, but they are unnecessarily touchy.

IMHO any lens longer than 50mm - on a rangefinder - needs at least a 140° "throw," and stiffish focus, for reasonable focusing ergonomics. They are not 35s and 28s, and should not be designed with the same short throws that make wides a joy on an M.

Another reason I'd prefer to stick with 1980s lenses where possible (135 TE, 90 Summicron III, Tele-Elmarit II, 75 Summilux). Dr. Mandler understood this stuff, and they have well-damped throws of 150-180°.

However, regarding 75s in particular, the APO-Summicron does have a slightly longer throw than the Summarits (about 115°) and a stiffer action, thanks to driving the floating element on its separate helical.

And the 90mm APO-Summicron (designed in the 1990s) also has a long, firm focus action. 145° or so.

I had Planar ZM and Nokton VM in 50mm. Both have short focus throw. Never had problem with focusing. In fact, it was more convenient than Mandler 50 Crons I also used.

[UliWer]

Since there has been some quibbling from users about lenses - in the 35 and 50mm range - being too slow (the third version of the 50mm Summicron being one example), Leica "listened" and shortened the focus throw for newer lenses. Now the 75mm Summicron has a throw exactly as long as the 50mm Summilux asph, which is much too short. For me the 90mm Summicron with a long throw is easier and quicker to focus exactly than the 75mm Summicron - even though the 90mm DOF is much smaller.  The Summarit might be not as bad as the Summicron, since at f/2.4 DOF is larger, which makes a difference.  

Edited April 14, 2020 by UliWer

[pippy]

37 minutes ago, adan said:

...regarding 75s in particular, the APO-Summicron does have a slightly longer throw than the Summarits (about 115°) and a stiffer action, thanks to driving the floating element on its separate helical...

The dampened focus action is the one area where (IMO) the Summarit's reputation for being a "poor-man's-Leica-lens-choice" and having variable QC issues might be merited. I only have a sample group of 2(!) to compare directly so the following might be errant nonsense but the 75mm has a mildly stiffer focus-action but a mildly lighter aperture-ring indentation whereas with the 90mm these differences are reversed.

The differences are so slight that had I not both to compare back-to-back I would never have noticed the phenomenon and neither one is even remotely what could be described as tight / loose in use. Both have a very positive feel in the hand. In fact from any other manufacturer these differences would go unremarked upon but as we are talking 'Leica' these things DO seem to matter somehow.

Philip.

[luigi bertolotti]

The short throw of my Summarit 75 has been an issue for me too... but I've came to the conclusion that is mostly a question of attitude.... my problem is that my most used 90 is the Elmarit - M, with a throw that is about double the Summarit... when I get the Summarit, I always feel something strange when focusing... but at the end I think that is a sort of psychological bias... you have the feel to "nail better" the RF coincidence with a comfortable long throw.. but if I use the Summarit for 2-3 days at the end I can focus fine it, and even more quickly than the Elmairit M.