Search found 117 matches

by mdwmark
Wed Oct 10, 2018 5:53 am
Forum: Solar Scope Modifications
Topic: Pst Cak filter secret -
Replies: 19
Views: 455

Re: Pst Cak filter secret -

Hi Apollo, Just checking , the GG395 and the KG3 are these hard coated of soft coated? If they are soft coated, then they will need to be used in the back of the telescope. Soft coating filters with that many layers would never come out 1/4 wave on transmission. On the KG3 , the SiO2 overcoat , is t...
by mdwmark
Sat Oct 06, 2018 5:06 am
Forum: Solar Scope Modifications
Topic: Pst Cak filter secret -
Replies: 19
Views: 455

Re: Pst Cak filter secret - Vengeance against chroma

There prices are right in line with everyone else. That $825 for a two cavity(I would think 2 cavity would do better then OD2) at 1 piece is a good deal. Your idea about how easy it is to make a filter may be true for an AR's or edge filter or something like a 10-20nm HW bandpass. But a ultra narrow...
by mdwmark
Sun Sep 30, 2018 6:03 am
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 206
Views: 6224

Re: Narrowest 393.37 ever by Apollo Lasky

Hi Group, OK Christian, I modeled an filter similar to the Chroma. My design came out 1.2Ang which I though was close enough. CW Ang HW Ang %of original transmission at zero deg 3934 1.2 100 At F/30 3933.79 1.23 96 at F/20 3933.54 1.28 86 at F/15 3933.30 1.7 70 at F/10 3932,3 3.2 40 at F/8 3931.7 4....
by mdwmark
Wed Sep 05, 2018 8:30 am
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 206
Views: 6224

Re: 393.4 bp0.1 - yes it does exist.

Hi Bob, the only reason I can think of why the .1nm filters has a lower contrast then the PST is that it is not fully blocked. Or it is not on band. There may be a leak in the long side blocking. It is not uncommon to have a blue/green leak that would drop the contrast of the image. Are you using a ...
by mdwmark
Tue Sep 04, 2018 6:07 am
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 206
Views: 6224

Re: 393.4 bp0.1 - yes it does exist.

My attempts with the nd 3.8 astrosolar film was for visial. I was not trying to image with it. The filter I was using had 75%T and it was to dark for my eyes.
Mark W.
by mdwmark
Tue Sep 04, 2018 2:14 am
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 206
Views: 6224

Re: 393.4 bp0.1 - yes it does exist.

Hi group, The point I was trying to show ,was the Hw of a filter can change depending how it is used and how it is designed. The perfect word calculations is the light is parallel to the filter. The transmission is just for references to show how it decreases with F#. There are at least 5 company's ...
by mdwmark
Fri Aug 31, 2018 4:28 am
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 206
Views: 6224

Re: 393.4 bp0.1 - yes it does exist.

What is all this about .1nm or .14nm at K-line. They will both give a great image. With the amount of T ,you will probably need some color glass or an ND filter to drop the transmission down or the exposure will be to fast for the camera. I ask Bob to check if the spacers where high or low index. So...
by mdwmark
Thu Aug 30, 2018 7:31 pm
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 206
Views: 6224

Re: 393.4 bp0.1 - yes it does exist.

Bob, You should ask about the design. It is a single cavity filter. The space layer is important to how narrow the filter will be at different F#. If they designed it with a High index space ,that would be the best. With a low index you can get narrower easier but will broaden out faster in F# lower...
by mdwmark
Sat Aug 25, 2018 1:03 am
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 206
Views: 6224

Re: 393.4 bp0.1 - yes it does exist.

That's a good company. They make high end hard coated filters. I see that they started to make amateur telescope filters(OPT has some). This must be a out of spec run from a job. The filter is spec at 393.37nm but is better at 393.44nm which is better for K-line. The way the transmission data looks ...
by mdwmark
Fri Aug 17, 2018 4:29 am
Forum: Solar Scope Modifications
Topic: The Double pass idea...
Replies: 20
Views: 956

Re: The Double pass idea...

double pass has been used with Lasers for a long time, if your working with a point source you fine. A star is a good point source. The sun is not, it has field angle. Lunt tried it with his 8" reflector and it didn't work. If it would have worked it would have been in uses years ago. That .25 deg w...
by mdwmark
Sun Jul 15, 2018 5:57 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: NEW direction in the solar narrowband imaging.
Replies: 53
Views: 2563

Re: NEW direction in the solar narrowband imaging.

The graph is for a simple 1/4 wave design. The high end etalons for solar will use a broad band mirror. So they are usually from K-line to Ha or Ha to the Ca lines in the IR.
The broad band mirrors will have more layers which means a higher cost.
Mark W.
by mdwmark
Sat Jul 14, 2018 1:08 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: NEW direction in the solar narrowband imaging.
Replies: 53
Views: 2563

Re: NEW direction in the solar narrowband imaging.

That is what I though it would look like. I guested 24Ang peak separation.
Attached is a coating design for Ha. The narrower peaks will be where the transmission is the highest. As the transmission drops the HW will broaden and the bottom of the curve will not be near zero.
etalon mirror Ha.gif
etalon mirror Ha.gif (9.62 KiB) Viewed 306 times
by mdwmark
Mon Jul 02, 2018 11:43 pm
Forum: Solar Scope Modifications
Topic: Baader Telecentric - Lower flux in blue/CaK?
Replies: 4
Views: 938

Re: Baader Telecentric - Lower flux in blue/CaK?

It may be something with the AR's. Must broadband AR's are designed from 400 to 700nm. If they where using TIO2 as the high index then you will be getting absorption from it(this is the most common design). It also maybe where the AR designed was centered. If they are a MGF2 AR centered at Ha then y...
by mdwmark
Thu May 31, 2018 9:01 pm
Forum: Solar Scope Modifications
Topic: WILL IT BURN? - ..Filter Killer..
Replies: 35
Views: 1671

Re: WILL IT BURN? - ..Filter Killer..

OK, I though the original concern was Daystar's statement that Quark didn't need an ERF. If they want to change blockers. That there concern. The filter is still safe to the eye even when a front blocker fails. I have been making Ha filters for 30+ years and have never hear of anyone having problems...
by mdwmark
Tue May 29, 2018 3:37 am
Forum: Solar Scope Modifications
Topic: WILL IT BURN? - ..Filter Killer..
Replies: 35
Views: 1671

Re: WILL IT BURN? - ..Filter Killer..

BUT , when you move in and out to focus, you will run into that problem of high heat.

Mark W.
by mdwmark
Mon May 28, 2018 11:45 pm
Forum: Solar Scope Modifications
Topic: WILL IT BURN? - ..Filter Killer..
Replies: 35
Views: 1671

Re: WILL IT BURN? - ..Filter Killer..

I was thinking, The front of the telecentric is not at prime focus. So it will be hot but not as bad as prime focus. If your using an F/5 then I don't think it would make much difference. I'm not sure the distance for the Quark but I would guest about 45mm in front of prime focus would be a good pla...
by mdwmark
Mon May 28, 2018 9:37 pm
Forum: Solar Scope Modifications
Topic: WILL IT BURN? - ..Filter Killer..
Replies: 35
Views: 1671

Re: WILL IT BURN? - ..Filter Killer..

Yep, I know. Over the years repairing filters, I have come across many that where damage using to fast of scopes. Like your burning ants analogy. 100mm F/15 with no ERF will melt a .54" spot in the delrin of the front plate and take out the blocker over time. The point of the front mounted ERF was t...
by mdwmark
Fri May 25, 2018 11:02 pm
Forum: This is SolarChat !!
Topic: Messing With a Sodium Quark - 22nd May
Replies: 21
Views: 945

Re: Messing With a Sodium Quark - 22nd May

Hi Mark, Working with Na, you will find there is a very small window where you have a increase of contrast. They advertiser it to be 0.5Ang. If you can keep it in the center of the line at .5Ang Hw(F/40). This is the maximum Hw were the cells will still be highlighted. The Hw really need to be in th...
by mdwmark
Sun May 20, 2018 2:55 am
Forum: Solar Scope Modifications
Topic: Replacing the Rusted BF30 Filter
Replies: 56
Views: 2728

Re: Replacing the Rusted BF30 Filter

You got me worried here. When you start replacing part without knowing the design. If you look at the blocker filter. It will be between .6nm-1nm HW. I'm petty sure its a standard coating. Well put it at 656.3nm +/-.3nm. Just the bandpass will turn back on at about 700nm on the red side and 480m on ...
by mdwmark
Sat May 12, 2018 5:10 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: The ultimate solar imagers filter?? The ultimate visual?
Replies: 2
Views: 546

Re: The ultimate solar imagers filter?? The ultimate visual?

Hi group, Being in this group I try to explain and I don't try to get free advertising or talk down about other systems. The SO-1, 0.3A (name change to RG18 but the same price) are all Research level uniformity. They all have three cavity hard coated blockers, (so the blockers are very unlikely to e...
by mdwmark
Tue May 08, 2018 7:49 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Baader Triband SCT
Replies: 19
Views: 1446

Re: Baader Triband SCT

Hi Group, I've seen Schott's ERF. But not a 220mm one, it might have been 160mm. They take an thin RG630 and laminate it to a coated bandpass. The one at the show was about 4mm thick. I asked how it would keep the 1/4 wave they clam, if it was in the heat. The problem I have with this idea is that I...
by mdwmark
Mon May 07, 2018 8:15 pm
Forum: Solar Scope Modifications
Topic: A high quality telecentric 3X made by itself
Replies: 15
Views: 1541

Re: A high quality telecentric 3X made by itself

Hi Group, For the FS78, I have the Zmax design and the one I did with OSLO edu. The Sky 90 was done with Zmax and used Thor lens. Images shot with the sky 90 telecentric where still quite good. Even thou it looks like your pushing the limit on the spot diagram. Mark W. S-1 sky 90.pdf S-1 fs78(SO-1.5...
by mdwmark
Sat May 05, 2018 4:05 am
Forum: Solar Scope Modifications
Topic: A high quality telecentric 3X made by itself
Replies: 15
Views: 1541

Re: A high quality telecentric 3X made by itself

OK, I'll dig them out. Your F/99 really would not be that much better then an F/45. The image size would be large. If you where going for a collimated system. Then you will fine that the over all performance of the system will work it best when it is not at "infinity " but at about F/60. Then your b...
by mdwmark
Fri May 04, 2018 7:11 am
Forum: Solar Scope Modifications
Topic: A high quality telecentric 3X made by itself
Replies: 15
Views: 1541

Re: A high quality telecentric 3X made by itself

Hi, When it come to designing telecentrics with stock lens, sometimes you need to be creative. Also the higher the power the harder it will be. For an FS78 I used two -lens to make an bi concave lens. The front side was an -200mm then a -50mm back to back with an positive meniscus lens to get to a g...
by mdwmark
Thu Nov 09, 2017 9:11 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: H-alpha Zeiss APQ 130
Replies: 26
Views: 2781

Re: H-alpha Zeiss APQ 130

OK , I forgot to say. The AP telecentric was designed for his old 6" F/12. It was an 2X telecentric. So the idea was to stop the 6" scope to 4" to get to F/36 where it work well. It will work on a 100mm scope, but it won't really be a telecentric. All solar filters will move off band from the extra ...