Front end replacement ERF for new "blue" PST??

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Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Guys,
It's been suggested to me that a PST with a dud ITF could be fitted with a front mounted 2" Baader 35nm Ha filter as a replacement ERF....
Any thoughts/ comments?? Optical quality?.....


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »


You might want to hold off buying one. I know for a fact that a company has developed a direct drop in replacement for the PST ITF and will soon be selling it. I have the prototype in my PST and it works great and took maybe 10 minutes to replace. My ITF only lasted about 3 years after it was installed in PST that was repaired by Meade for the rusted objective problem.

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Re: Front end replacement ERF for new "blue" PST??

Post by swisswalter »

Hi David

outch


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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Dave,
That sounds VERY promising!
Do you know when it will be made available?


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Sounds promising indeed dave!


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »



I'm hoping that filters will be availbale in the next few weeks. The company has made a couple of improvements that should greatly extend the life of the filters. They are using better coating material, the scribe is deeper along the edge and the edge is better sealed. I've worked with this company before in providing custom filters for my solar applications and have had excellent results. I told them that I believed that there would be market for a direct replacement filters for the PST and possibly other ITF used in other model solar telescopes. They sent me a prototype that has worked very well so they are going to make a production run and see how the sales go. As soon as I get the go ahead I'll let everyone know were to get them. By the way I have no connection with this company, just a happy customer that sugguested a possible product for them that would benefit PST owners.
Here is a picture of the prototype filter mounted in my PST focusing tube. I just unscrewed the retainer ring, dropped the rusted filter out, dropped the new one in and reinstalled the retainer ring. By the way you can help extend the life of any of these filters just by loosen the retainer ring so it just touches the glass. This allows the glass to expand during thermal cyclcing which causes less stress on the seal along the edge.

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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Sounds absolutely great to me! (If the pricing was better than the Baader 35nm Ha - it would be a definate winner!!)
Any transmission specs available??


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

The spec I saw showed that the filter is block out to 2500nm and then same into the UV. The bandpass is centered at 656 and is about 75nm wide with 65% transmission at 656nm. It is also MgF2 anti-reflective coated on both sides to increase transmission and reduce ghosting.
The 50.4mm Baader filter with 7nm bandpass looks to start to transmitt around 1150nm which might be problem in letting IR thru and teh cost for the 2" one looks to be around 640 Euros which is around $870.
I don't know what the cost is going to be but I'm hoping that is will be far less then the Baader unit and the price of $150 to $350 Meade quoted me on sending my PST back to them to just have filter replaced plus a couple of months wait. As soon I know more I'll be posting here.

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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Dave,
The Baader 35nm Ha filter blocks all the way into the IR but has some minor resonance leakeage. This is in the region well above the sensitivity of the CCD.
I just bought a 1.25" Baader 35nm filter for $80.


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Interesting. A filter with blocking all the way up into 2500nm is a plus. I'll definitely be buying one.


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Re: Front end replacement ERF for new "blue" PST??

Post by brianb11213 »

Sounds good ...
By the way you can help extend the life of any of these filters just by loosen the retainer ring so it just touches the glass. This allows the glass to expand during thermal cyclcing which causes less stress on the seal along the edge.
There are good reasons for never tightening retainer rings more than is necessary to prevent movement under gentle shaking. Compressing the edge of the glass distorts it optically & this can affect the optical performance. Refractor objectives are particularly sensitive to this effect; the mass market manufacturers usually overtighten the retaining rings (to prevent loosening during transit; people receiving "new" scopes with objective elements fallen out of the cell usually aren't too impressed) & this usually results in the scope having more contrasty images when slightly stopped down, the distortion caused by overtightening being restricted to the outer few mmm of the aperture.

For anything in a solar scope which is likely to warm up I'd respectfully suggest that allowing a slight rattle is probably better than just touching the glass. Use a dab of paint to prevent the retaining ring from unscrewing itself.


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Re: Front end replacement ERF for new "blue" PST??

Post by swisswalter »

Hi Brian

a very useful information. Thank you


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Hi All,
I got a message from the company that is making the replacement ITF filters, that they will be selling them for $75. Once they give me the go ahead I'll let everyone know were to get them. As I said before I have no connection with them except for being a happy customer.

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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Whoooo........
That sounds like GREAT news - and a very good price!!
Will these be available for the various sizes in the common scopes?
PST- Lunt & Coronado blocking filters BF5 - BF30 etc.


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Fantastic news! 8)


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Whoooo........
That sounds like GREAT news - and a very good price!!
Will these be available for the various sizes in the common scopes?
PST- Lunt & Coronado blocking filters BF5 - BF30 etc.

Right now, the diameter of the filter and transmission specs are for the ITF in a PST. If these sell well the company may offer other filters as well. It is my understanding that the Blocking Filters have a much different transmission curves then the ITF, those being much narrower bandpass.
I was sent two more "production" prototypes" to test. I'll report my finding when they arrive.

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Re: Front end replacement ERF for new "blue" PST??

Post by swisswalter »

Hi Dave

thanks for sorting that out for us


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Hi All,
I tested the latest production ITF replacement filter and it works very well. My PST is giving the best images that I can remember. The company that is making these filters is Maier Photonics. Here is a link to the filter http://maierphotonics.com/656bandpassfilter.aspx It is a drop in replacement and takes about 10 minutes to swap out the old filter with a new one.
I have no connection with this company except being a happy customer.

Happy Holidays and Solar Observing,

- Dave


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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Dave,
Thanks for the link!
Great news to PST owners.....IF THEY LIVE IN THE US
They don't ship O'Seas.....bumma!


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

That is a very formidable spec 8)

I shall be ordering one of those very soon...


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

The only thing I would like to see is the transmission graph above 1200nm...


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Dave,
Thanks for the link!
Great news to PST owners.....IF THEY LIVE IN THE US
They don't ship O'Seas.....bumma!

Nooooo!!! :ohmy: :unsure: :angry:


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

[quote]Dave,
Thanks for the link!
Great news to PST owners.....IF THEY LIVE IN THE US
They don't ship O'Seas.....bumma!

Nooooo!!! :ohmy: :unsure: :angry:

Send a note to Maier Photonics and ask if will sell you one. They need to know were the market is.

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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Good plan. Will do.


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Here is Maier's shipping policy. Drop them a note to see if they will ship to your location.

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"You can trust that your order will be quickly processed and safely delivered. We can ship products anywhere in the United States using the shipping method of your choice. When you place an order we will estimate delivery dates based upon the availability of your item(s), shipping method selected and your shipment?s destination. Our shipping charges are determined by the total dollar amount of your order, excluding applicable sales tax. Some products cannot be shipped to international destinations so please submit a message to us from the Contact Us page if you would like to discuss international ordering options. "


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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

I'm following up with them as we speak....let's see what happens.


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Hi All,
I just got this note from Maier Photonics about shipping the filter over seas

"If they contact me I can reply with email and attach a paypal invoice. It can be processed by credit card from there. I’ve done that before with Russian customers."

So it sounds like there should be no problems in selling the filters outside the USA.

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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Ok, email sent. I'll report back on what they say...


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Great news, they are happy to ship to me in the UK :)


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Great news, they are happy to ship to me in the UK :)

That is great news. I'm looking forward to what you think of the filter. It's Sunny here in Delaware, USA so I'm going out to use my PST with the new filter to see what is happening on the Sun.

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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Yes, i'm going to get one ordered and replace the rusting ITF in my BF10 - this isn't the original one, it's a replacement from a spare PST I had that has since rusted.

I going to send the original ITF to walter and hopefully he can measure the transmission against the Maier ITF, be interesting to see the difference.

Thanks for all your hard work with this Dave :)


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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Chris at Maier has also confirmed shipping to Oz.
He's also prepared to manufacture the ITF in larger sizes (to fit Coronado/ Lunt blocking filters!!??)


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

I've just ordered one. $6.55 for USPS First Class Mail International Parcel, or they do the uber quick, signed for and insured USPS service for ~$42. I just went for the cheaper option.

I can feel a review coming on soon :)


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Re: Front end replacement ERF for new "blue" PST??

Post by Merlin66 »

Mark, I've done likewise...it will be interesting to compare with the Baader 35nm Ha filter.
I need some feedback on preferred sizes for possible ITF replacements (Coronado/ Lunt). I'll measure the BF10/BF15 (and a BF30) ones I have here...what about other sizes/ variations.


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Hi All,
I worked with Chris Maier before. He made custom filters for a coronagraph I designed and I hosted a class were we built 20 of them in a weekend. Chris does great work and I very pleased with the replacement ITF he made for my PST. I'm sure if there is a market of larger units he'll add them to his product line.
I'm not happy that Meade quoted me a price of between $150 to $350 to replace me that only last 3 years and also told me that it take a number of weeks to complete the repair. On top of that I had the ship my PST to them. The filter just unscrews and takes maybe 10 minutes to change if you take your time.
Looking forward to the review by others. I hope that the words spreads that these filters are available from Maier so others can repair their PST and again enjoy observing the Sun with them. I have no connection with Maier Photonic except being a happy customer.

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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

This is great for the world of PST repairs. It's a shame that Meade are so slow, slovenly and expensive with their service for the PST. I'm sure Chris will do well from this. He should come and join us on the forum.

I will certainly and quite happily put together a tutorial video showing how to change the ITF over.


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Re: Front end replacement ERF for new "blue" PST??

Post by swisswalter »

Hi Dave, Ken and Mark

great News I read here. I'm more then willing to compare them with my UV/VIS gear


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Re: Front end replacement ERF for new "blue" PST??

Post by SMS »

Hello Folks,

I was able to try one of the new Maier Photonics ITF filters yesterday. The good news is that it is the correct size and does allow for Ha views but its throughput makes it very dim when compared to a Coronado ITF. I placed it in a BF5 and paired it with an SM40 on an 80mm f5 refractor. I also used a TV Binovue with 25mm EPs. It was immediately noticeable that the view was too dim. I swapped the BF5 for a stock Coronado BF15 and it was like going from a double stacked PST to the single SM40. To be sure that it wasn't just the BF5 blocking filter I replaced the Maier with the partially rusted ITF from my PST and it too was much brighter than the Maier. In a non double stacked PST this ITF is most likely okay but it would be, IMHO, useless if you double stack. I'm going to email Maier and see if he can make an ITF replacement with better light transmission.

Clear Skies,

Steve


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Steve,
The Maiers ITF was designed for a PST and not the BF5. diagonal. The transmission characterist of the BF-5 diagonal when matched with the SM-40 Etalon are different, and this why the image is dim. When I used the filter in my PST the image is bright and much brighter then my rusted ITF. As specs show the Maier ITF passes 70% of the H-alpha wavelength which I believe is higher then the original Meade ITF. There is a difference in how the PST works vs the SM40 with the BF series diagonals. For one the Etalon in the SM-40 already has a red long pass filter built in and the ITF in the BF series does not, while the ITF in the PST is combination of the both the red long pass filter and ITF. So if the Maiers filter is used with a SM-40 Etalon, the image would be much dimmer because now one has two long pass filters in the light path.
- Dave


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Re: Front end replacement ERF for new "blue" PST??

Post by SMS »

Hi Dave,

I'm concerned that when double stacked this is going to be too dim. It was extremely dim with the SM40. The rusted PST ITF in the BF5 was performing similarly to a brand new BF15.

Steve


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »


Steve,
Your rusted ITF from your PST must be different then what is being used now in them. It is possible that it is ITF from BF diagonal ? All the ITFs I have seen that have come out of a PST are combination of two filter systems. The ITF layer is used to block IR, these layer is deposited on red filter glass which is Schott RG630. The ITF layer blocks very little light at 656nm so almost all of transmission at this wavelength is mostly determined by the Schott RG630 glass, which over 70%. That is very high.
In the BF series diagonals the ITF layer I believe it is placed on clear glass. The red Schott filter has been moved to the front element in the SM-40 Etalon. So in both a PST and the Solar Max system that is using a BF series diagonal, there is only one piece of the Schott RG630 red filter glass. If you use the Maier’s filter in place of the original ITF in the BF diagonal you now have two piece and that dims the image. If each piece transmits 70% the two together drop it to 50%.
Here is a picture showing my original rusted PST ITF on the left and the Maier filter on the right. As you can see the Maier filter is transmitting more light. The Maiers filter was designed for a PST and not a Solar Max system so there must be difference in the two system’s ITF which are causing the dimming your seeing.


- Dave


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

You're spot on Dave, here is a pic of my rusted ITF from my BF10.







As you can see, it is on clear glass rather than RG630. I have put a ITF from a PST in place of the above, and have to say haven't had any problems with it on either my Coronado DS40 or my many PST mods...


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Re: Front end replacement ERF for new "blue" PST??

Post by SMS »

Hi Dave,

My PST is USA made circa 2006. The only difference that I can see between the three Coronado ITFs that I own are the two from the BF diagonals are edge blackened and the PST is not. I'm going to install the Maier in my PST and test it and I'm keeping an open mind. I to evenly illuminate the three ITFs but it's clear that the PST ITF is the brightest of the trio.

Steve


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Wow, what a little repository of information we're getting here. Good work chaps! :)


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Re: Front end replacement ERF for new "blue" PST??

Post by SMS »

After seeing Dave's, Mark's, and my own PST and BF ITFs I think that they are all essentially the same and Coronado uses or (used) whatever ITF filters that they had on hand at the time of production. I tried my PST with just a piece of KG3 and no ERF of any kind and I still got very nice Ha views at the EP. I do think it's MUCH WISER to use at least a red filter before the KG3 for IR safety but it isn't necessary to achieve Ha views. A Baader UV/IR plus a 610 LP at the objective end with the KG3 in the BF assembly has given me the best Ha views from my PST by a significant margin.


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

Steve,
Your picture clearly show that both your BF-15 and rusted PST ITFs are using clear glass as the substrate just like Mark's BF-10 ITF. So that is the difference of why the Maier's filter is causing the dimming when used in the Solar Max system. Mystery solved ! This is first I have seen a PST ITF being made on a clear substrate. I'm wondering if the 5mm blocking filter used your PST makes up for the absents of the red filter ?
I just had email exchange with Chris Maier and he can also make the ITF on a clear substrate. He just needs to know the transmission specs.

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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

Inspired, I took the PST ITF out of my BF10 (are you following this :P ) and compared it to the rusted ITF from the BF10...






As you can see, the ITF that was originally from the PST has a black ring around it's periphery that is labelled, and would certainly appear to be RG630 rather than clear...


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Re: Front end replacement ERF for new "blue" PST??

Post by marktownley »

I just had email exchange with Chris Maier and he can also make the ITF on a clear substrate. He just needs to know the transmission specs.

:woohoo: As much as possible @ 656nm - the nearer 100% the better :)

:thanx:


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Re: Front end replacement ERF for new "blue" PST??

Post by DavidG »

By the way the "edge blackening" shown on the filters is the epoxy seal that stops the filter from "Rusting". If it is not there then the life of the filter is GREATLY reduced. I wouldn't be surprised if the filter didn't last a year. That is real poor of Meade to let a filter be installed that they know is going to fail very quickly.

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Re: Front end replacement ERF for new "blue" PST??

Post by SMS »

Not to go too off-topic but I received on the 13th of December an SM II 90mm scope from Meade that not only had a chipped objective but was so dirty both inside and out that it appeared as though it was assembled outdoors in a windy desert. Meade is not putting quality first, IMHO.




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