Focusing helical stiffness: Arca rm3di vs Alpa

[Nebster]

Today I got a chance to play with an rm3di for a few hours. The big focus ring was very precise, but I also found it stiff. My wimpy fingers were starting to feel sore after just a few spins of it. (I also have issues with my hands that make certain gripping motions more painful than they should be.)

I haven't had a chance to try an Alpa lens yet with their custom focusing helical. Can anyone who's used both comment on whether the ring turns more easily?

Thanks!

 

[Digitalcameraman]

Today I got a chance to play with an rm3di for a few hours. The big focus ring was very precise, but I also found it stiff. My wimpy fingers were starting to feel sore after just a few spins of it. (I also have issues with my hands that make certain gripping motions more painful than they should be.)

I haven't had a chance to try an Alpa lens yet with their custom focusing helical. Can anyone who's used both comment on whether the ring turns more easily?

Thanks!

Yes I think the Alpa focusing ring will be more like turning a 35mm focused ring. It is very precise too with the High Precision Focusing(HPF) option.

I have used them all and I understand what you are saying, the ring is much larger and needs to be turned further to archive the same distance.

I also think you will appreciate the calibrated lens scale on the Alpa lenses as it is either ordered in Meters or Feet, so if you 15 ft, you will see that number on the scale as opposed to using the chart to determine what number the distance is on Arca RMD3i.

 

[Nebster]

Yes I think the Alpa focusing ring will be more like turning a 35mm focused ring. It is very precise too with the High Precision Focusing(HPF) option.

Thanks.

My understanding is that the HPF ring is just a marking, but the underlying helical (and focus "precision") is unaffected -- right?

If that's true, I think the only reason I'd pay any extra for HPF is for resale value at this point, given how live view is kind of the ultimate focus verification technique. I imagine one or two longer/hyperfocal points are handy, but I can memorize a couple Arca numbers if that's what matters. The days of the laser rangefinding are numbering, and thank goodness.

 

[Paul2660]

The helical on the rm3di should not be stiff. If so that can be adjusted. Mine is very easy to turn however it's 4 years old with a lot of use. But I don't remember any issues in regards to stiffness. I will also say that using one in warm weather vs below freezing will make a difference as the cold will cause it to tighten up a bit.

You also need to consider the lens you want. Wide, medium or telephoto.

With a wide unless you looking for a very singular focus close up you won't be turning the focusing ring much at all

I would also consider movements i.e. tilt shift rise fall. Look at both Alpa and Arca closely as each brand handles thus differently.



Paul C

 

[Nebster]

Thanks Paul, I was duly impressed with the rm3di. I definitely plan to use a lot of tilt for my style of shooting, so the in-body tilt is nice. If/when I am using a wider lens I will be moving up close a fair bit, and in my quick test I found that even 45 or 90 degrees of turning was kind of painful... certainly much harder than spinning a nice focus wheel on a 35mm Zeiss lens, for example. Maybe this particular camera simply needed an adjustment. Or maybe I need an "adjustment" and have to learn how to deal with it.

 

[f8orbust]

@OP:

Remember, the A/S design was intended to solve a particular problem - that of accurately focussing a MFDB without live view.

If a CMOS DB is in your future - i.e. one with true live view - then the A/S helical becomes a solution looking for a problem. Of course, there are other aspects of the system that are great and which may still draw you towards it, but the throw of the helical is so fine it is difficult to see things 'pop' in and out of focus in real time compared to systems that move the lens fore/aft quicker/with less effort (e.g. the standard S/K helicals used by Alpa, Cambo, Silvestri etc. or bellows cameras like the Techno, Actus etc.)

Jim

 

[Nebster]

Remember, the A/S design was intended to solve a particular problem - that of accurately focussing a MFDB without live view.

Great point, Jim. I definitely am only going CMOS, which obviates half of the focusing features of a lot of these cameras. Fine by me, although a little awkward for the industry I guess.

I didn't have trouble seeing the "snap" on my subjects, but they were flat things with a lot of fine detail, so it was always obvious. However, it was a lot slower than it needed to be, and I've never had trouble nailing focus with much coarser, traditional helicals either.

 

[Paul2660]

@OP:

Remember, the A/S design was intended to solve a particular problem - that of accurately focussing a MFDB without live view.

If a CMOS DB is in your future - i.e. one with true live view - then the A/S helical becomes a solution looking for a problem. Of course, there are other aspects of the system that are great and which may still draw you towards it, but the throw of the helical is so fine it is difficult to see things 'pop' in and out of focus in real time compared to systems that move the lens fore/aft quicker/with less effort (e.g. the standard S/K helicals used by Alpa, Cambo, Silvestri etc. or bellows cameras like the Techno, Actus etc.)

Jim

This is the first thing I noticed when using the rm3di and live live. The focus delineation is so fine it's very hard at times to see the image pop into focus as images do with 35mm cameras. With the DF+ it was easy. Alpa with their helical and Cambo will operate more like using the XF IR DF+.

Great point.

Paul C

 

[dougpeterson]

If you were using a demo unit or just played lightly with one that was new-in-box you should know the R helical comes a bit stiff out of the box and then loosens up in the first dozen hours or so of operation after which it retains that level of fluidity indefinitely.

The Arca helical is significantly more precise and repeatable. Even if using Live View the clear and precise nature of the helical is useful. For instance if you want to do an A:B Test of two points of focus you can toggle between those two points with ease and precision. It also comes in handy when setting a hyperfocal or pseudo-hyperfocal point of focus since these can be set to a very stringent level of accuracy, and yet remain very easy to dial in.