Bought an Old Carl Zeiss Jena focus block

Blame · Post by **Blame** » Tue Jan 27, 2015 12:42 pm

You will have to wait till it arives but my guess is paper weight.

You could wast an awful lot of time and end up with something that never really does the job. There is no real assurance that it will be accurate if you gear down the coarse adjust.

Better sometimes to fold rather than raise the bet.

steveminchington · Post by **steveminchington** » Tue Jan 27, 2015 3:43 pm

Blame wrote:There is no real assurance that it will be accurate if you gear down the coarse adjust.

Well that's all that is happening with a planetary gear system. Makes no difference whether you do it internally or externally. As long as you have some spring tension to take up the backlash (which you would have to do anyway if you mount it horizontally) it should be fine.

cadman342001 · Post by **cadman342001** » Tue Jan 27, 2015 5:46 pm

steveminchington wrote:As for your Zeiss focus block Andy, another option would be to remove the fine focus mechanism and couple a small reduction gearbox (with a 1/4" or 6mm dia. input/output shaft) to the coarse focus shaft. A worm drive gearbox will give a significant reduction ratio and they are not too expensive to buy.

Thanks Steve, and where would you buy such a thing ? hopefully online as I'm 1200 miles north of Brisbane !

cadman342001 · Post by **cadman342001** » Wed Jan 28, 2015 1:40 am

Well, I asked the seller if it would be possible to cancel the transaction and he agreed. Yes, I am now THAT person !

I'll probs order a 10X objective and then see what's around if the proxxon doesn't cut it (I'm assuming it won't for 10X ?)

rjlittlefield · Post by **rjlittlefield** » Wed Jan 28, 2015 5:37 am

cadman342001 wrote:I'm assuming it won't for 10X ?

Already addressed on previous page, HERE, "workable but fiddly".

--Rik

Blame · Post by **Blame** » Wed Jan 28, 2015 6:15 am

steveminchington wrote:
Blame wrote:There is no real assurance that it will be accurate if you gear down the coarse adjust.
Well that's all that is happening with a planetary gear system. Makes no difference whether you do it internally or externally. As long as you have some spring tension to take up the backlash (which you would have to do anyway if you mount it horizontally) it should be fine.

Dunno. Myself I am glad he could cancel. No real reason why a course adjust should be better designed than, say, a macro bellows. In theory they could linked to geared motors to deliver an automated system but posts in other threads put limits to the accuracy.

ANY such system is going to have friction. Motion is going to occure as tiny irregular sized jumps. It's what limits the accuracy of stacker shot.

cadman342001 , I think you were on the right path looking for a microscope assembly. The right one can deliver great accuracy. Might be a better idea next time to bid on a whole microscope so you get the XY positioning too. You can always resell any bits you don't need.

cadman342001 · Post by **cadman342001** » Wed Jan 28, 2015 8:12 am

I was looking at that a while ago (seem to recall a seller from S.Korea or Singapore which would be good) the biggest problem getting one from farther afield is they weigh 20 pounds. Some sellers seem to have reasonable shipping to where I am ie $70-100 but a lot of them quote crazy prices for shipping.

Also of course, there's the whole issue of returns if the fine focus doesn't work properly, most from the states say no returns from overseas sales anyway.

Is there a sticky anywhere with a list of the best bang for your buck scopes say for Nikon ? Labophot or Labophot 2 for example ?

Blame · Post by **Blame** » Wed Jan 28, 2015 10:10 am

Maybe you are better off just sticking to keyword "microscope" and waiting for something to turn up local.

If it looks good quality in the picture and the seller is willing to check fine focus for distance and stickyness then bid.

Normal rules. Wait for a poorly advertised deal. Ask questions early but bid at the last min.

I got a good deal on my "hund". Not the dog one would expect for a microscope I had never heared of.

cadman342001 · Post by **cadman342001** » Mon Feb 02, 2015 7:03 pm

Thanks. Yeah, patience is not one of my virtues

What about a Newport style xyz stage with micrometers for adjustment ? ie move the subject rather than the camera as I'm currently doing.

Is there a sticky on them Rik ? Not ideal for the lighting/set up I'm currently using but.

rjlittlefield · Post by **rjlittlefield** » Mon Feb 02, 2015 11:52 pm

cadman342001 wrote:What about a Newport style xyz stage with micrometers for adjustment ? ie move the subject rather than the camera as I'm currently doing.

Is there a sticky on them Rik ?

There's no sticky dedicated to XYZ stages. From an optical standpoint, it makes very little difference whether you move the subject or the camera. (Some very specialized illumination schemes work better if the subject does not move. Otherwise, it's a matter of convenience and personal preference.)

If you have not done so already, I recommend taking time to study the many setups linked from HERE (the reference list in the FAQs).

Also, be aware that there is now available on eBay an alternate source for XYZ stages, new, at significantly lower price than Newport and Thorlabs. See
http://www.photomacrography.net/forum/v ... 294#149294 and postings in reply to that.

--Rik

Chris S. · Post by **Chris S.** » Tue Feb 03, 2015 1:18 am

I have, or have tested, linear stages from each of the significant opto-mechanics companies, including Newport. I also have a number of microscope focus blocks from several companies. So far as I have found, these two classes of item are in no way similar or interchangeable. The focus blocks are much, much more pleasant to work with when photographing. On the other hand, linear stages can save space and be easier to integrate for movements in some axes--so these linear stages, too, have their place. But they are comparatively clunky. For your focus axis, I strongly recommend going with a microscope focus block. If you consider linear stages, I'd suggest you do so for x-y subject adjustment--and even then, be prepared to face a level of frustration.

If you look at my Bratcam, you'll note that it includes two microscope focus blocks and a high-quality Newport linear stage. In use, I greatly prefer the two focus blocks--the Newport stage demonstrates a degree of stiction that is completely absent from either focus block. After adjusting the Newport block, I need to jump up and down on the floor a few times, which tends to jar and settle the Newport stage. If I don't do this, I sometimes find that the Newport stage moves during image acquisition. This behavior has not changed before or after my disassembly and cleaning of the Newport stage. Perhaps if I found an exactly perfect lubricant for the Newport stage, it would function as well as the focus blocks. But every focus block I've used (having returned those that seemed unfit) easily beats every translation stage I've used, for lack of stiction, predictability, and smoothness. Add to this the fact that most focus blocks offer both coarse and fine focus, and you have a strong argument to use a microscope focus block for axial movement.

--Chris