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View Full Version : Symmar-s 135mm f5.6 questions

Ben07
7-Jan-2018, 17:12
Hi, i'm new here. Soooo, i just bought a symmar on ebay for a project of mine and i would like to ask something. How much do i have to move the lens to get it to focus from it's closest focus to infinity? Would it be possible to use a helicoid to do this?

xkaes
7-Jan-2018, 17:30
Focusing at infinity will require ABOUT 135mm of distance between the film and the lens. How close you can focus depends on how much ADDITIONAL extension you can create between the lens and the film.

Ben07
7-Jan-2018, 18:06
Focusing at infinity will require ABOUT 135mm of distance between the film and the lens. How close you can focus depends on how much ADDITIONAL extension you can create between the lens and the film.

Ah, i see. Then if i wanted it to focus about a metre from me, roughly how much more do i need. Was thinking of using a helicoid.

Dan Fromm
7-Jan-2018, 18:53
It depends on where "about a metre from me" starts. If you want 1 m film plane to subject distance, with a 135 mm lens that means a magnification of ~ 1:5 and you'll need ~ 27 mm extension from the infinity position. A little more wouldn't hurt.

Ben07
7-Jan-2018, 18:57
Thanks. How did you get the 1:5? Any formula for it or something?

Bob Salomon
7-Jan-2018, 18:57
It depends on where "about a metre from me" starts. If you want 1 m film plane to subject distance, with a 135 mm lens that means a magnification of ~ 1:5 and you'll need ~ 27 mm extension from the infinity position. A little more wouldn't hurt.

But the helicoid that was made for this lens will not get you much closer then about 6’.

Ben07
7-Jan-2018, 19:06
Was thinking of getting one of those chinesr made ones from ebay and modifying it. Didn't know there was one made for this lens, i'll have look for it. Thanks

Dan Fromm
7-Jan-2018, 19:37
Thanks. How did you get the 1:5? Any formula for it or something?

Yes. Please see post #2 in this discussion.

If you want to learn more about close up work and especially the magic formulas, buy a copy of Lester Lefkowitz' book The Manual of Closeup Photography. Quite inexpensive used from booksellers who hawk their wares on venues such as abebooks.com, alibris.com, amazon.com, bn.com, ...

Ben07
7-Jan-2018, 19:46
Yes. Please see post #2 in this discussion.

If you want to learn more about close up work and especially the magic formulas, buy a copy of Lester Lefkowitz' book The Manual of Closeup Photography. Quite inexpensive used from booksellers who hawk their wares on venues such as abebooks.com, alibris.com, amazon.com, bn.com, ...

Will do, thanks.

Dan Fromm
7-Jan-2018, 19:51

Ben07
7-Jan-2018, 19:58

Thanks for the help, really appreciate it.

pchaplo
8-Jan-2018, 22:17
Would it be possible to use a helicoid to do this?

Ah, “helicoid” is the key term. No you would need a bellows if I understand you correctly.

Dan Fromm
9-Jan-2018, 05:17
Ah, “helicoid” is the key term. No you would need a bellows if I understand you correctly.

Why?

Ben07
9-Jan-2018, 18:20
Why?

Was thinking of extending the bellows and then use a helicoid for minor adjustments.

Ben07
9-Jan-2018, 18:21
Why?

Was planning to use the helicoid for minor adjustments only

Dan Fromm
9-Jan-2018, 18:52
Was thinking of extending the bellows and then use a helicoid for minor adjustments.

Thanks for answering a question that wasn't directed to you. Y'r answer raises another question. What in your project requires a bellows for gross adjustments and a helicoid for fine?

Most of us get along just fine with a bellows attached to a front standard that moves on a bed or rail. In other words, are you sure that you need the bother and expense of a getting a helicoid?

Ben07
14-Jan-2018, 19:20
Thanks for answering a question that wasn't directed to you. Y'r answer raises another question. What in your project requires a bellows for gross adjustments and a helicoid for fine?

Most of us get along just fine with a bellows attached to a front standard that moves on a bed or rail. In other words, are you sure that you need the bother and expense of a getting a helicoid?

Was planning to make a folding point and shoot and i had intend to mount different lenses on it. The bellow would be used to extend the the lens to the right length so about a 135mm distance for a 135mm lens, 90 for a 90mm etc and then focus it separately.

Dan Fromm
14-Jan-2018, 19:41
Thanks for the explanation.

Ben07
14-Jan-2018, 19:45
Thanks for the explanation.

I know it's weird, but it's gong to be fun to build.