Modified SM40 - A Story of Evolution...

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Re: Modified SM40 - A Story of Evolution...

Post by marktownley »

Excellent! Glad to here this mod is working well for you ;)


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Re: Modified SM40 - A Story of Evolution...

Post by rsfoto »

Hi Mark,

I reread this whole thread again and a question came to my mind.

If I remove the outmost ERF from my SM 60 and replace it through a D-ERF from Baader with 75mm diameter ¿ Will the result improve for my DS 60 ?

Perhaps the same cell could be used ¿? and if not no problem making a new one :whistle:


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Re: Modified SM40 - A Story of Evolution...

Post by marktownley »

Bob Yoesle did this with his SM90 and reported increased image brightness and contrast. I got the same thing with my SM40...


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Re: Modified SM40 - A Story of Evolution...

Post by rsfoto »

Hi Mark,

Thanks. Will order one 75mm D-ERF :woohoo:


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Re: Modified SM40 - A Story of Evolution...

Post by Michel »

Salut Lulu105 oui mcn66 mais je n'avais pas pu venir au RAS 2012 , j'etais cependant present aux estivales webastro du 19 au 22 juillet dans le massif des Bauges.
Michel


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Re: Modified SM40 - A Story of Evolution...

Post by marktownley »

Just as an addition. I was curious about the lil' silver spot on the face of the etalon so peeled it back; there is a central spacer for the etalon beneath it. I guess it is there to reflect heat so that this spacer does not heat up more than the rest around the periphery and cause differential tuning effects. There is a black rubber nodule stuck on the back of the etalon face also.

I wondered about removing the silver dot and replacing it with a smaller one to maximise as much of the lil' 40mm etalon as possible, however the central portion of the etalon has no coating on it at all so, to do so would be pointless...

I figure this is the same setup on all the SMxx external etalons...


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Re: Modified SM40 - A Story of Evolution...

Post by DSobserver »

by the way I've discussed with one saler and he told me that the main action from the front SMxx filter is in fact to protect the fabry perrot from UV light 'cause electrical coating are quite sensitive to UV.

So in fact the best is for a DS system to remove the filter from the second unit


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Re: Modified SM40 - A Story of Evolution...

Post by etatsolarchat »

Mark your 70mm f6 refractor, Whats that telescope model?

Also anyone, new external etalons also use the ERF for the richview tuner mount, so if you remove the ERF you lose richview as well. If on a external double stack removed the internal ERF would it be worth losing the richview? Is having richview on two etalons redundant anyway? Or maybe replace the internal ERF with a optical flat blank glass?

Thanks


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Re: Modified SM40 - A Story of Evolution...

Post by colinsk »

I am lost. :oops:

What is Rich View?

Sorry.


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Re: Modified SM40 - A Story of Evolution...

Post by Merlin66 »

Colin,
On the new generation external Coronado etalons (SMII), besides having the original T-max tilt tuning they also have a secondary(?) tuning capability - this is the "Rich View" tuning feature.
Having never seen one I can't comment on the functionality. Does it compress the etalon gap? Add additional tilt? Make tea or coffee?? ;-)
Don't know.


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Re: Modified SM40 - A Story of Evolution...

Post by etatsolarchat »

Instead of a fix ERF its mounted on a threaded part, inside of the ERF in the center there is a plastic tipped bolt that presses up against the center of the etalon. I guess this moves the sweat spot around. In my opinion the design is somewhat questionable as well as the results. It also makes coffee, no tea :cheer:

Since the older models don't have the feature I wonder how useful it really is. I want to get 2 and stack like others here but the richview feature also add some play and a bunch of grease plus it goes away if I remove the ERF. I might look for an old external etalon..


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Re: Modified SM40 - A Story of Evolution...

Post by swisswalter »

Hi Ken

on my SM90 with rich view, there is a centered pin on the ERF wich rests on the center of the etalon. Turning the richvie ring, a force is applied to the center of the etalon and since the etalon rests on a foam ring, I believe that force is tilting the etalon a little bit, giving more contrast. I don't think that pressure is actually changing the space between the etalon plates.


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Re: Modified SM40 - A Story of Evolution...

Post by Merlin66 »

Walter,
Do you think/ feel that this arrangement gives a "finer" adjustment than the T-Max hinge/ tilt adjustment?
I have to assume there's some marginal benefit, or the adjustment would just be done with the T-Max as was previously the case?


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Re: Modified SM40 - A Story of Evolution...

Post by colinsk »

I am still confused? How does this assembly press in the center of the etalon without causing a distortion? The ERF has an assembly glued to the center?


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Re: Modified SM40 - A Story of Evolution...

Post by etatsolarchat »

yes exactly, so you remove the erf you also remove richview.

I don't think it's intention is to tilt the etalon as the pin presses right in the center, I think it may just deform the etalon slightly??


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Re: Modified SM40 - A Story of Evolution...

Post by swisswalter »

Hi Ken

yes the rich view thing is giving a much finer adjustment as the tiltinh unit. With the tilting unit you basically get rid of the gost image and fine tuning is made with the rich view mechanics.


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Re: Modified SM40 - A Story of Evolution...

Post by marktownley »

Pictures somebody please!


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Re: Modified SM40 - A Story of Evolution...

Post by swisswalter »

Hi Mark

you are so right. I'll try tomorrow to take some


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