That 1 Meter/3ft close focus limit

[Trius]

This could apply to some interchangeable lenses for RF as well, but in my mind it mainly applies to fixed lens RFs.

Other than cost considerations of lens design, why is it that fixed lens RFs generally have a close focus limit of about 1 meter? I realize parallax becomes a problem and cost (again) usually precludes moving framelines. But a standard focal length lens (~40-55mm) lends itself pretty easily to closer focus. Nearly any (cheap) 50 for an SLR usually can focus down to 45 cm or less, so I really don't think it's cost of lens design or manufacturing.

If my main fixed lens RF could focus to about 45cm/18 in, I'd be much happier. I've been able to use a supplemental diopter lens to get down to about 7 inches, and I loved it, but of course I can't use the RF for focusing.

Nothing I can change... guess I'll just have to give in to GAS and get an M body and the Nokton 40 SC. 😱

 

[venchka]

Huh?

Huh?

...

Nothing I can change... guess I'll just have to give in to GAS and get an M body and the Nokton 40 SC. 😱

What does that lens have to do with close focusing? Both the Nikkor 50/1.4 and 51.9mm/2.0 Dual Range Summicron focus to ~ 18". Naturally, the DR Summicron has a very elegant near focus viewfinder attachment. Then there are the various Canon Auto-Up attachments. One of which sits in a drawer at my house because it's matching lens was sent elsewhere long ago.

So, if you were to lay your hands on a Serenar 50/1.8 lens I could make you a great deal on the matching Auto-Up in the original case with the original instruction manual. As near as I can tell, I am the second owner. I've had it since forever and not used it.

Cheers!

 

[Trius]

Wayne, Wayne, Wayne... FIXED lens RFs! Remember, I had a DR in a former life, and I miss it.

Yes, there are auto-ups for SOME fixed RF models, and I had one with my C35 kit (now owned by GeneW) ... but AFAIK there were no auto-ups for Oly fixed RFs (I think the RC had a closeup lens available from Olympus, but no VF auto-up thingy) ... see my gear list for what I mainly have. 😉

So like I said, I would need to invest in an M body and something ... I was citing the Nokton 40 because it is FAST and has close focusing ... closer than the Nokton 50. Besides, I prefer 40 to 50.

And damn you for tempting me with the Serenar deal. I'll give it a think.

 

[jlw]

At such close distances, the view of the subject seen by the primary RF window would be considerably different from that seen by the secondary RF window, making it very difficult to achieve coincident focusing.

(At a distance of 1 meter, for a rangefinder with a Leica M baselength of 68.5mm, the secondary window is seeing the target from about 4 degrees off to the side... at a distance of 0.5 meter, it would be seeing it from about 8 degrees off to the side, which would be fairly significant for many kinds of subjects.)

 

[MartinP]

Isn't there some sort of dcument copier with a close-up lens and four legs coming out from the mount, with the body at the top of the pyramid as it were ? It held the camera at A4 (european paper-size) coverage off whatever you rested the legs on, but could also be used for 3d objects if you were sneaky.

Or make your own ? A three-dioptre lens should give a plane of focus 33cm from the film when the lens is on infinity - or is that an over simplification ?

 

[venchka]

You find a lens

You find a lens

Wayne, Wayne, Wayne...

...And damn you for tempting me with the Serenar deal. I'll give it a think.

Find a lens. I have a VI-T body to go with the Auto-Up. Meter too. It's all more than I can use since I bought Bubba. 😀

 

[ferider]

Check this out:

(from www.yashica-guy.com)

 

[ferider]

And one more:

(from http://www.trenholm.org/hmmerk/HMbook12.html)

 

[Trius]

jlw: Yes, but the ZI and at least some of the ZM lenses focus closer than 1m. I'm thinking it's just a cost thing. Of course, the ZI does have a very long RF base.

 

[Trius]

Roland: That's the type of auto-up/adapter I had on the C35. It worked amazingly well. It's just not very convenient. Did I mention it looks pretty dorky? 😀

 

[jlw]

jlw: Yes, but the ZI and at least some of the ZM lenses focus closer than 1m. I'm thinking it's just a cost thing. Of course, the ZI does have a very long RF base.

Yes, a bit closer, but I doubt if you'll find any that focus unaided down to 0.5 m, which is the distance you mentioned in your original post.

At such a close distance, the RF image would be looking fairly cross-eyed at the subject, even with a corrector prism like those shown in the Auto-Up photos in the thread (or on the 'goggles' for the Dual-Range Summicron, which does focus down to 18 inches, I think.)

I've got a Canon Auto-Up II for my VI-T that will allow the 50/1.2 lens to focus down to 15 inches. But when focusing on a 3-D object at that close a distance, I can see that the rangefinder image shows a slight "side view" compared to the main viewfinder image. It's still possible to line up the images, it just looks a bit odd. I suspect that this problem -- parallax between the viewfinder image and the secondary rangefinder image -- is one reason why manufacturers seldom design rangefinder systems to focus closer than 0.9 m or so.

[By the way, since we've drifted onto the subject of Auto-Ups, allow me to plug that my page about them is still available for viewing at this link (click it.)]

PS -- Attached is a very crude diagram I whipped up to illustrate the problem I'm talking about. As it shows, the closer you try to focus with a rangefinder, the greater the risk that the main window and secondary window will see completely different views of the subject, making coincidence harder to judge.

 

[Trius]

jlw: Thanks for the additional info. Makes sense. I still want a proper auto-up for my 35SP bodies, but they don't exist. Ah well.

 

[jlw]

Yes, within their limits Auto-Ups are pretty useful. I wonder if Cosina has ever considered reviving them?

They'd be in a good position to do it, since I believe all the Bessas (except the T) have the same rangefinder/viewfinder window geometry and could use the same dimensions for the prism attachment. And I'll bet that nowadays the prism (which is used only for aiming, not for forming the image) could be molded out of optical acrylics, cutting both the manufacturing cost and the weight of the unit.

Auto-Ups for a few of the most popular C-V lenses (35/2.5? 35/1.7? 50/1.5?) would be a compact and fairly inexpensive way to add versatility to a Bessa outfit, and I'll bet a lot of RF enthusiasts would find they're fun to use.

So, Voigtlander Auto-Ups seem like a great idea to me. (But don't trust me -- I'm the kind of nut who thinks a Bessa reflex housing would also be a great idea!)




Incidentally, as for the image quality possible with this type of attachment: A single-element close-up lens can be surprisingly good if you stop down the prime lens a bit (at last, a chance to use the term "prime lens" correctly, in the sense of a lens that's modified by another lens, and not just as a sloppy synonym for 'single focal length lens'!!!) And achromatic two-element close-up lenses, like the ones Minolta used to make and Nikon still does (I think) can yield genuinely excellent results.

 

[Trius]

jlw: I put a B+W close-up lens on my 35SP, shot some Reala and started a thread about it some time ago. No magnifier for the viewfinder, of course, so I had to do some experimenting to get the close focus distance and shoot "blind".

 

[VinceC]

I think focusing accuracy might also be a problem.

At 36 inches, the depth of field of a 50mm lens at f/1.4 is 1 inch.
At 15 inches, the depth of field of a 50mm lens at f/1.4 is just 0.16 of an inch. I believe that kind of accuracy is just too precise for a rangefinder mechanism in ordinary conditons. Plus, the lens would have to become larger to accomodate the extra focus helical space.

 

[Mikael.N]

the yashica gt focus down to 50cm if you alter the focus ring on the lens.But you cant get close focus and infinity then you must modifiy the focus twist.thus some one hawe pics of yashicas lens parts to see what must modify to get a longer focus twist.

 

[Trius]

Vince: Yes, and I would be using smaller apertures (as in the shot I posted) to increase DOF, at least most of the time.