RRS B150: Macro Focusing Rail

[Craig Gerard]

Anyone using or familiar with the RRS B150 Macro Focusing Rail?

http://reallyrightstuff.com/ProductDesc ... using-rail

Craig

[AndrewC]

Yes, now what's the question ?

Andrew

[Craig Gerard]

Thanks Andrew,

Looking for general, overall impressions at the moment.

Particularly interested in the precision of the lead screw. What are the smallest moves you can make with this rail (approximately).

Fine focusing is precise. Camera to subject distance can be adjusted in minute increments for super-fine focus; lead screw delivers 1.25mm of travel per full revolution.

It appears to be a fine piece of gear.


Craig

[SONYNUT]

your hand would either be in front of lens or in front of viewer while using it...

[AndrewC]

your hand would either be in front of lens or in front of viewer while using it...

No, the camera actually sits up quite high

[AndrewC]

Thanks Andrew,

Looking for general, overall impressions at the moment.

Particularly interested in the precision of the lead screw. What are the smallest moves you can make with this rail (approximately).

Fine focusing is precise. Camera to subject distance can be adjusted in minute increments for super-fine focus; lead screw delivers 1.25mm of travel per full revolution.

It appears to be a fine piece of gear.


Craig

It works pretty well but could be better if they put a larger control knob on one end with tick marks but that is pretty easy to DIY. You can adjust movement from either end. The stage has a quick release for large movements, can get locked in place if you desire. Really worth the dollars ? Hmmm.

[SONYNUT]

your hand would either be in front of lens or in front of viewer while using it...

No, the camera actually sits up quite high

not high enough for my hands...lol

i have enough issues with my arca..

[AndrewC]

...
not high enough for my hands...lol

..]

... buy some new hands then

[SONYNUT]

but then they won't match my feet

[ChrisLilley]

Anyone using or familiar with the RRS B150 Macro Focusing Rail?

http://reallyrightstuff.com/ProductDesc ... using-rail

Well, it looks very pretty, costs a lot, and is woefully imprecise even for 1:1. At higher magnifications, its merely an expensive rough focus and needs to be coupled with a separate fine focus mechanism.

The knob is tiny and the thread pitch is 1.25mm per turn. OK if you often want, say, 5mm steps, I guess.

[AndrewC]

..
The knob is tiny and the thread pitch is 1mm per turn. OK if you often want, say, 5mm steps, I guess.

Umm, thread pitch is listed as 1.25mm but I think it is actually 1.27 (it's a 1/4x20 thread). It is perfectly good for controlling something like 250micron steps (1/4 turn) (312um if you are being picky). A 5mm step would be 4 full turns. I've "indexed" the larger knob on mine by adding some white paint into the knob knurling at 90deg intervals

I'm not quite sure what you are basing your comments on. Do you actually have one or are you just interpreting the catalogue ?

[SONYNUT]

where did you see 1/4 20 for the adjuster...i only see it for mount screw...

probably a 8mm 1.25 metric adjust screw

[ChrisLilley]

I'm not quite sure what you are basing your comments on. Do you actually have one or are you just interpreting the catalogue ?

I'm interpreting the catalog, and comparing the precision, which seems completely inadequate, to that of the comparably-priced Stackshot which is (just) adequate.

I appreciate that your report is based on hands-on experience. On the other hand you are saying you can get reliable 300-ish μm steps and I can get reliable 10-ish μm steps, which seems to argue in favour of my point.

If that style of leadscrew-in-an-AS-plate is of interest, then there is also this, from Chris Hejnar

which looks to have better knobs. Travel is stated to be 1.06mm per turn.

But for a manual unit, an industrial X slide with micrometer seems more precise, much more accurate, and at least in the US widely available on ebay at a lower price point.

[AndrewC]

where did you see 1/4 20 for the adjuster...i only see it for mount screw...

probably a 8mm 1.25 metric adjust screw

Last time I was playing, a piece of 1/4-20 stud seemed to mate perfectly, but then at these dimensions it would be hard to tell with a naked eye. Strange that an American company would use a metric screw, and if they did why not pick a 1mm pitch ? M6 is the nice screw for making drives over here - enough heft and a 1mm pitch.

[AndrewC]

...

I'm interpreting the catalog, and comparing the precision, which seems completely inadequate, to that of the comparably-priced Stackshot which is (just) adequate.

I appreciate that your report is based on hands-on experience. On the other hand you are saying you can get reliable 300-ish μm steps and I can get reliable 10-ish μm steps, which seems to argue in favour of my point.
....

The Stackshot is being turned by a stepper motor, not by hand so it isn't really a valid comparison. It would be like me saying that when your battery is flat or there is a power cut the StackShot precision is about 1/4" or however precisely you can nudge your tripod !