Request advice on double stacking a new Meade SM90 to Coronado SM90

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Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Sun May 07, 2017 8:22 pm

Hello Solar Chat

Assistance required in how to remove the Red Glass ERF from a Coronado SM90 and from a Meade SM90.

Way back in 2005 I purchased my Coronado SM90 and T-Max Tuner, it threaded straight onto the objective cell of my TV101 and has served me well all these years.

I recently acquired a Meade SM90 with Richview Tuning for double stack duty and I can say that straight out of the box it works, I have achieved a substantial improvement in contrast of surface features however at the expense of a slightly dimmer view.

For now and as it arrived I thread the T-Max of my new Meade SM90 onto the objective cell of my TV101 and my Coronado SM90 & Etalon onto the front of the new Meade SM90 / Richview Etalon. This is the only threading that is possible at the moment.

I can tilt the ghosts away and tune for contrast but the view is a little bit dimmer than I like due to the optical train having 2 red glass ERF’s.

Plan A, my understanding ( please correct me if I am mistaken ) is that I can replace both the replace the Meade and Coronado Red Glass ERF's with a single front mounted Baader D-ERF, thereby regaining a brighter image and with luck removing one or perhaps two of the ghosts.

However there may be some reason to retain the ERF on the Richview Tuner due to the way the richview operates and if so then my plan B is to remove the Red Glass ERF from only the Coronado SM90, retaining the Red Glass ERF on the Meade SM90 and threading the Meade SM90 onto the front of my Coronado SM90 thereby presenting the ERF of the Meade SM90 at the front of the optical train.

For my plan B I would need an adapter to mount the Meade SM90 onto the Coronado SM90 and I have contacted TS to ask if they have such an adapter.

Either my Plan A or Plan B would require I remove a Red Glass ERF and hence my request for assistance.

Thank You and Best Regards

Carl
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by Merlin66 » Mon May 08, 2017 1:03 am

Hmmm
The loss of transmission (lower brightness) is due to the narrower bandwidth being achieved more than the impact of two ERF filters.
You can remove the ERF from the original SM90 but the gain will be minimal.
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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Mon May 08, 2017 7:17 pm

Thanks Merlin

Hopefully removing one ERFwill recover a little of the lost brightness.

Best Regards
Carl
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TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by Bob Yoesle » Wed May 10, 2017 4:19 pm

Hi Carl,

Depending on your blocking filter, at least one RG630 filter (as used in the ERF) is required for good UV and visual blocking. When I replaced one of my BF30's ITF on an RG630 substrate with the Beloptick IR/UV ITF replacement filter, the image was not acceptable with just the Baader DERF. I had to re-install a RG630 ERF (Lunt w IR blocking) for this particular arrangement to work.

Therefore, Plan B is the way to go. I also believe the Richview tuning requires the ERF. Besides, the 2005 SM90 likely has a bit better performance, and should be the "primary etalon" located closest to the objective. The Meade SM90 II is better suited as the secondary etalon, as once the T-Max tilt is used to remove ghost reflections, the Richview tuning can be used to get the etalon back precisely on-band.

To remove the SM90 ERF you will need to look for a small hole filled with black silicone on the back of the black anodized etalon cell, usually close to the etalon serial number. Remove the silicone with a pin, and use a very small hex wrench to remove the small set screw which secures the etalon cell to the gold anodized etalon cover. One you've removed the etalon cell cover you will be able to see the ERF cell threaded in from the inside. You can then either remove the entire ERF cell or the ERF retaining ring with an appropriate brad or spanner. The retaining ring and/or cell itself is sometimes secured against loosening with an additional blob or two of silicone you will need to remove.

Good luck ;-)
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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Fri May 12, 2017 12:10 pm

Hi Bob

Thanks for the reply, I appreciate your input and will implement Plan B.

My Blocking Filter is a Pre Meade BF10, I replaced the rusty ITF with a Maier Photonics ITF a few years ago and since then have used it with a Beloptic UV/IR cut filter in front to ensure minimum thermal cycling and hopefully prolong the ITF's life. All has functioned well and views are very good.

Yesterday ( Thursday 11th May ) I spent all day under clear blue skies checking and confirming that the 2005 Coronado SM90 did indeed perform better than the new Meade SM90. For every one else viewing in H-Alpha the sun was probably a bit bland, there was only a small and low contrast filament and a few small proms, for me however it was perfect.

I knew what to expect from the various current GONG images, sure enough in double stack mode after tilting and tuning I could easily see the small filament, the small proms and a single area of brightness.

Using the 2005 Coronado SM90 single stack the proms were easily seen, the filament could just be made out but not the bright area.

The Meade Richview SM90 in single stack gave a much brighter image, the proms were easily seen but not the filament or the area of brightness.

For now what I have is quite useable and until I receive the adapter that will allow the Meade SM90 to mount onto the front of the Coronado SM90 I will enjoy what I have.

Best Regards

Carl
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by marktownley » Sat May 13, 2017 9:21 am

Sounds like you're going to have a very versatile setup.
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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Sun May 14, 2017 8:27 am

Hi Mark

Thanks.

Your web site is an excellent place to visit.

Best Regards
Carl
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by fjabet » Sun May 28, 2017 2:52 pm

Two ERF do eat some light. It is RG630 so the transmission is about 75% in Ha band. When I was using my DS SM60, removing one of the ERF was noticeable.
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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Wed Jun 14, 2017 10:49 am

Hello

I thought I'd give an update on my progress.

First was the purchase of the CO.AP190 that threads onto the front of a Coronado SM90 allowing the Meade Richview SM90 to be threaded in front.

Remarkably cheep at GBP 35.oo and a perfect fit.

Tilt Tuning followed:- first the Tilt for the Coronado SM90 as primary Etalon same as in it's single stack days, then thread on the Meade Richview SM90 and Tilt the first ghost out of the field of view then rotate the Richview Tuner ring for the brightest view.

Record the settings so that they can be repeated.

At this point I still have 2 ERF's but can say that the contrast and detail I'm getting exceeds what I see on a good GONG image, more detail on Filaments and Prominence, more contrast on Plage and Faculae seem to stand out and be more distinctive.

All in all a success.

I have made an attempt at removing the ERF from the Primary ( Coronado SM90 ) etalon but failed. I purchased a set of small Hex Wrenches and the 0.89mm size fits, I got the retaining screw out but was unable to get the etalon and ERF out of the housing. I'll try again after I've equipped myself with a couple of jam jar lid openers so that I can apply a bit of torque and hopefully separate the parts. If I can that will be a plus but if not I can live with what I've achieved.

Best Regards
Carl
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by Merlin66 » Wed Jun 14, 2017 1:42 pm

Carl,
I thought when you removed the index pin from the front element, the ERF section just unscrewed from the body, leaving the etalon sitting in the body.
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https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Thu Jun 15, 2017 12:33 pm

Hi Merlin

For the Meade Richview unit that is a possibility, I see that there are a pair holes on opposite sides of the tuner ( adjascent to the 2nd T of instruments and 2nd O of Coronado in attached photo ) looks to me would fit a filter wrench.

But I'm a bit timid when it comes to disassembling the Richview Tuner as I don't know the principle it uses and may muck it up.
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Thu Jun 15, 2017 12:39 pm

Attached photo of Richview tuner showing holes for lens / filter wrench and Double Stack showing TV101 OTA with Coronado SM90 and Meade SM90.
Attachments
UNADJUSTEDNONRAW_thumb_7.jpg
UNADJUSTEDNONRAW_thumb_7.jpg (334.49 KiB) Viewed 1205 times
UNADJUSTEDNONRAW_thumb_9.jpg
UNADJUSTEDNONRAW_thumb_9.jpg (214.39 KiB) Viewed 1205 times
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Wed Jan 03, 2018 10:11 am

During the last month I've completed the modification of my Double Stack as follows:-

First - Removal of the Red Glass ERF from the Primary Etalon ( that is the 2005 Coronado SM90 etalon closest to the scope ) doing this resulted in a brighter image as there is now only a single Red Glass ERF at the front of the scope on the Meade SM90 Etalon. A big improvement.

But doing this did little or nothing for the ghost reflection, in fact I saw a set of extra reflections, I'm sure weren't there before and that were much smaller in diameter.

Second - Placed black felt stickies on the bright metal discs that are visible on the front side of the Coronado SM90 etalon and on the back side of the Meade SM90 etalon.

Result - virtually no ghosting at all.

I'm delighted, I get the bright image of a single stack, the contrast of a double stack and no annoying ghosts.

Best Regards

Carl
IMG_0694.JPG
IMG_0694.JPG (659.68 KiB) Viewed 780 times
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by marktownley » Wed Jan 03, 2018 8:06 pm

Glad all is well carl.
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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by Merlin66 » Thu Jan 04, 2018 12:29 am

Carl,
""Placed black felt stickies on the bright metal discs that are visible on the front side of the Coronado SM90 etalon and on the back side of the Meade SM90 etalon.

Result - virtually no ghosting at all.""

A neat idea, I'm glad to hear it worked well for you.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by CarlDD » Fri Jan 05, 2018 7:05 am

Thanks Mark and Merlin

The end result has been worth the effort.

Best Regards

Carl
In Frequency of use

TV (Renaissance ) 101 on Gibralter mount with Skytour used with SM90 / SM90 / BF10, Denk Standard with Power x Switch and 32mm Takahashi Abbe Orthos.

Borg 77 Achro, TeleVue Binovue with 28mm Takahashi Erfles now mainly for Solar White Light with 82mm IDAS UHB RS Filter.

OO OMC140, Maxbright BV's, a pair of 25mm Zeiss Aspherical Orthos, lunar and planetary.

Obsession 12.5 with AN, TV BinoVue, pairs of 32mm Baader Plossls or 19mm Pans, a 10mm Delos and oldies TV 12, 16 & 20mm NT2's

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Re: Request advice on double stacking a new Meade SM90 to Coronado SM90

Post by Bob Yoesle » Sat Feb 03, 2018 3:12 pm

Hi Carl,

I did a similar mod with my 2003/2004 SM 90's awhile back, and removed both RG630 ERF's, and placed a Baader DERF110 on the front DS etalon, and had a quite noticeable improvement in brightness. However, I replaced a rusted BF30 ITF with the BelOptik UV/IR cut on KG3, which required the re-installation of an RG630 ERF on the primary etalon, as there was then no RG630 elemnt in the blocking filter (and I kept the DERF on the front DS etalon). This gives the brightest image overall.

So if you ever need more image brightness, consider replacing the blocking filter's ITF with the UV/IR on KG3. Allows shorter exposures and higher magnifications when seeing allows.

BTW - your gold tube TV 101 with the gold etalons looks awesome!
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