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Author Topic: High resolution, scaled focus dial for the Actus??  (Read 3130 times)

BobDavid

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Re: High resolution, scaled focus dial for the Actus??
« Reply #20 on: May 18, 2017, 07:36:49 PM »

My hunch is that the Apo 80mm N and the WA 60mm Rodagons are capable of rendering 100 MP. Offhand, I don't know the image circles of the EL lenses. I'm sure the 80 would suffice.
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Hening Bettermann

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Re: High resolution, scaled focus dial for the Actus??
« Reply #21 on: May 19, 2017, 02:47:39 PM »

I have had a look at the Rodenstock site. I can't translate the MTFs to MP, but they are impressive. And the 60 mm will fill 6x6, the 80 mm 6x7. The prices are in the same range as the Actars.

Wayne Fox

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Re: High resolution, scaled focus dial for the Actus??
« Reply #22 on: May 22, 2017, 07:04:24 PM »

The new Actus DB2 does have a detente for the swing now, as well as for all other adjustments.  Several other changes have migrated into various versions of this camera including scales on the monorail, a few things moved around etc.

I assume these changes are also in the Actus mini, since the only difference is the block under the front which raises the lens/tilt/swing assembly, and in fact you can remove or add this block to turn a mini into a DB2 and vice versa.

I haven’t had the db2 long, but have enjoyed it.  I do wish the focusing adjustment was a little more “fine”, but it still works quite well for my uses, maybe more challenging for the OP’s use which sounds like focus stacking macro work.

Hening Bettermann

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Re: High resolution, scaled focus dial for the Actus??
« Reply #23 on: May 22, 2017, 07:15:25 PM »

Thanks for your reply, Wayne. - What you write sounds good. I have sent a little inquiry to Cambo, so I hope for an answer every day, then we'll know for sure. - I use focus stacking with almost every image, but it's landscape, not macro.

BobDavid

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Re: High resolution, scaled focus dial for the Actus??
« Reply #24 on: May 28, 2017, 11:07:09 PM »

Here's an easy fix for high resolution focus. The engraved scale on the left side of the focusing rack is precise. That's where you'll find a numeric scale for fine focus. If necessary, I'm sure you can find a finer scale/ruler to attach to the rack. Etch a fine line on the back standard for matching for lining up.
« Last Edit: May 28, 2017, 11:14:06 PM by BobDavid »
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Hening Bettermann

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Re: High resolution, scaled focus dial for the Actus??
« Reply #25 on: May 29, 2017, 11:46:44 AM »

Hi Bob,
thank you for your reply. As far as I can see, that scale is in whole millimeters. I think that's not precise enough. On my CY Vario-Sonnar 28-70, 5 mm of focus travel translates to 8.5 mm on the mm scale that I have glued around the barrel. That's almost twice as much.
Good light!

Hening Bettermann

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Re: High resolution, scaled focus dial for the Actus??
« Reply #26 on: May 29, 2017, 01:40:22 PM »

Here is the (relevant part of) the inquiry text I sent to Cambo on may 20th 2017:

"1-Could a dial counter like this

http://www.farnell.com/datasheets/2047529.pdf?_ga=2.34768481.1703625191.1494245462-1540928351.1494245462

be mounted on the shaft of the focus wheel? Watching your instruction video for mounting the focus whip, it looks like it should be easy enough, but I want to be sure.

2-Same question for the tilt and swing knobs"

Since I had not got an answer by yesterday, I re-sent the question and said that I was very disappointed not to have heard from them. So today I finally got this answer:

"Diameter of the shafts for focussing, shift, tilt and swing is 4,0mm."

The dial counter linked to is for a shaft of 6 mm or 1/4 inch. So it sounds like it is possible if one can find a dial counter for a 4 mm shaft. Or maybe make an adapter.

BobDavid

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Re: High resolution, scaled focus dial for the Actus??
« Reply #27 on: May 29, 2017, 05:59:52 PM »

Hi Bob,
thank you for your reply. As far as I can see, that scale is in whole millimeters. I think that's not precise enough. On my CY Vario-Sonnar 28-70, 5 mm of focus travel translates to 8.5 mm on the mm scale that I have glued around the barrel. That's almost twice as much.
Good light!

There are scales that you can easily attach over the Actus scale with hot glue or other adhesives. Here is an excellent resource for precision rulers, scales, and gauges: Starrett
« Last Edit: May 29, 2017, 06:03:34 PM by BobDavid »
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Hening Bettermann

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Re: High resolution, scaled focus dial for the Actus??
« Reply #28 on: May 29, 2017, 06:26:50 PM »

Hi Bob,

but the resolution of the scale does not increase for that, 0.1 mm is still only 0.1 mm. What i need is to have that 0.1 mm stretched out to say 1.0 mm :-)

Thanks for your concern anyway!

BobDavid

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Re: High resolution, scaled focus dial for the Actus??
« Reply #29 on: June 03, 2017, 01:34:27 AM »

Hi Bob,

but the resolution of the scale does not increase for that, 0.1 mm is still only 0.1 mm. What i need is to have that 0.1 mm stretched out to say 1.0 mm :-)

Thanks for your concern anyway!

I guess your only option is to go with a helicoid focusing mount for the lens. I don't think the the rack and pinion focusing mechanism on the Actus offers the precision you require. No matter how large you make the focusing knob and whatever method you devise to mach up tick marks with a pointer, the gearing ratio of the rack and pinion mechanism is too coarse. I've designed adapters, mixed and matched components from lenses, cameras, and have had parts machined to spec. I think the Actus is a great lightweight tool that works well in a variety of situations. The only way I think you will be able to successfully use the Actus platform for super precise stacking is by employing a helicoid barrel for the lens. ... Notice that there hasn't been a lot of chit chat on this thread. I think that's a fair indication you may be barking up the wrong tree.

The Actar lenses are fine. Cambo has a long history of sourcing optics to Schneider, Rodenstock, and now Samyang for the 24mm.  If you keep your eyes open, there are deals to be had on m39 enlarger lenses.
« Last Edit: June 03, 2017, 01:52:54 AM by BobDavid »
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Hening Bettermann

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Re: High resolution, scaled focus dial for the Actus??
« Reply #30 on: June 03, 2017, 05:33:02 PM »

Hi Bob
Thanks you for your comment. - So you don't believe in Jeffrey's solution with the micrometer dial for the focus? -  I wonder how much precision I need. As said, on my CY Zoom, I have applied a mm scale that translates 5 mm of focus travel to 8,5 mm on my scale. That's a factor of slightly under 2, not 10 as from 0.1 to 1.0 mm. This scale works fine for me. Otherwise, I would try mount a helicoid between the bellows and the camera. But it would interfere with short focal lengths.

BobDavid

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Re: High resolution, scaled focus dial for the Actus??
« Reply #31 on: June 04, 2017, 10:35:08 AM »

Hi Bob
Thanks you for your comment. - So you don't believe in Jeffrey's solution with the micrometer dial for the focus? -  I wonder how much precision I need. As said, on my CY Zoom, I have applied a mm scale that translates 5 mm of focus travel to 8,5 mm on my scale. That's a factor of slightly under 2, not 10 as from 0.1 to 1.0 mm. This scale works fine for me. Otherwise, I would try mount a helicoid between the bellows and the camera. But it would interfere with short focal lengths.

You may need the wide angle bellows for wide lenses. Perhaps a call to Steve Hendrix at Capture Integration is due. If anyone will be able to help you find a solution, it's Steve. I'm not sure you'd need focus staking with a wide angle lens, as the tilt movement and a smallish aperture should be able to help you. It's also possible you may run into focus breathing issues with a wide angle lens, and that would not be good.
« Last Edit: June 04, 2017, 10:42:46 AM by BobDavid »
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Doug Peterson

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Re: High resolution, scaled focus dial for the Actus??
« Reply #32 on: June 04, 2017, 10:40:07 AM »

Quick question: Have you compared to the Arca Swiss Universalis?
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DOUG PETERSON ([email protected]), Digital Transitions (Dealer for Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Profoto)
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BobDavid

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Re: High resolution, scaled focus dial for the Actus??
« Reply #33 on: June 04, 2017, 10:51:28 AM »

Quick question: Have you compared to the Arca Swiss Universalis?

No. I haven't used nor seen a Universalis.  I daresay comparing a Universalis to an Actus is comparing apples to oranges.  I read this in the blurb about the Universalis:

"1. Scheimpflug is More Important Than Ever

With higher resolution comes a higher level of scrutiny of the focus and detail. Especially for still life and product shooters, this means an uphill battle against depth of field. Judicious use of tilt and swing can make the difference between the entire subject being in focus in a single shot, and having to resort to time consuming and error-prone techniques like focus stacking."

I think the OP is looking for a less expensive option than the Arca Swiss Universalis. However, if he requires a tool that will pay for itself within a year or so, the Arca is a vastly superior product.
« Last Edit: June 04, 2017, 11:02:20 AM by BobDavid »
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Hening Bettermann

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Re: High resolution, scaled focus dial for the Actus??
« Reply #34 on: June 04, 2017, 02:43:09 PM »

In case Doug Peterson's question was addressed to me (,too):

Yes I have compared to the Arca Universalis. The main reason I opt for the Actus is the Actars. They are light weighted and moderately priced compared to the Rodenstocks. I have no old MF lenses.
Your link has me discover the soon to be released focus rail sled. However, it sounds like it measures the distance to the object in the field rather than the rail distance.

Bob:
In my part of the woods, the price for the Universalis DSLR is 2.618  €,  for the Actus GFX 2.677 (OK, 1.738 for the Sony E version). NO camera will *pay* for me, I am an amateur. I would be interested to hear your thoughts why you find the Arca vastly superior.

Thanks for your comments to the both of you.
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