Search found 3084 matches

by Merlin66
Wed Jun 20, 2018 2:54 am
Forum: Solar Scope Modifications
Topic: Do you have a skybender?
Replies: 30
Views: 730

Re: Do you have a skybender?

Instead of a 2” extension, with the associated back focus issues. I’m using a series of 48mm filter spacers, about 70mm long.
These then position the Baader CCD filter well inside the focuser and allow plenty of room. For the SkyBender etc.
by Merlin66
Mon Jun 18, 2018 11:00 pm
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: Littrow SHG prototype
Replies: 42
Views: 3763

Re: Littrow SHG prototype

I used the adjustable slit assembly from Surplus shed.
I intend to further improve by using a pair of stainless steel slit blades which I have and mount them on a parallelogram frame similar to Rousselle, see "Imaging Sunlight", p178.
by Merlin66
Sun Jun 17, 2018 10:02 am
Forum: Solar Scope Modifications
Topic: PST stage 4. The X-truder
Replies: 25
Views: 662

Re: PST stage 4. The X-truder

I ended up making my own based on a laser pointer and a 1.25” extension.
This proved to be more accurate than the commercial unit.
by Merlin66
Sun Jun 17, 2018 8:24 am
Forum: Solar Scope Modifications
Topic: PST stage 4. The X-truder
Replies: 25
Views: 662

Re: PST stage 4. The X-truder

I think you’ll find a laser collimator is much more accurate.
by Merlin66
Sun Jun 17, 2018 1:11 am
Forum: Solar Scope Modifications
Topic: PST stage 4. The X-truder
Replies: 25
Views: 662

Re: PST stage 4. The X-truder

To turn it into a digital spectroheliograph you don't need an exit slit on the spectrograph section....in fact a Littrow spectrograph design would be cheaper and probably more efficient.
viewtopic.php?f=8&t=20682
by Merlin66
Tue Jun 05, 2018 2:56 am
Forum: Solar Scope Modifications
Topic: Front ERF vs Internal ERF? Minimum size?
Replies: 26
Views: 684

Re: Front ERF vs Internal ERF? Minimum size?

Well, if nothing else, it shows that the Baader CCD filter reflects the majority of the incoming light and energy.
by Merlin66
Tue Jun 05, 2018 12:06 am
Forum: Solar Scope Modifications
Topic: Front ERF vs Internal ERF? Minimum size?
Replies: 26
Views: 684

Re: Front ERF vs Internal ERF? Minimum size?

If the filter is 100mm from the focus, it will be re-focusing the solar image 100mm in front - towards the objective.
Interesting.....
by Merlin66
Mon Jun 04, 2018 6:34 am
Forum: Solar Scope Modifications
Topic: KG3 IR Absorption vs IR Blocking filters? Same?
Replies: 81
Views: 2176

Re: KG3 IR Absorption vs IR Blocking filters? Same?

Hmmm Interesting arrangement!!
Have a filter element at a focus point is usually bad news in that every bit of dust etc. will be in focus.....
by Merlin66
Mon Jun 04, 2018 12:08 am
Forum: Solar Scope Modifications
Topic: KG3 IR Absorption vs IR Blocking filters? Same?
Replies: 81
Views: 2176

Re: KG3 IR Absorption vs IR Blocking filters? Same?

"" I have the solar focus directly on the second erf filter..."
Why?
Surely if your imaging, this final filter would be at some distance in front of the camera?? In my case about 30mm.
by Merlin66
Sat Jun 02, 2018 11:19 pm
Forum: Solar Scope Modifications
Topic: KG3 IR Absorption vs IR Blocking filters? Same?
Replies: 81
Views: 2176

Re: KG3 IR Absorption vs IR Blocking filters? Same?

Marty,
What you're proposing is exactly what I intend doing with my Omega CaK stack. A Baader CCD -B filter well in front of the stack.....
by Merlin66
Sat Jun 02, 2018 1:14 pm
Forum: Solar Scope Modifications
Topic: Front ERF vs Internal ERF? Minimum size?
Replies: 26
Views: 684

Re: Front ERF vs Internal ERF? Minimum size?

Valery,
I accept there are other good ERF's available, but unless you have access to quantified data on Baader D-ERF and others and prepared to share, I can only agree - "speculation".
by Merlin66
Thu May 31, 2018 11:14 pm
Forum: Solar Scope Modifications
Topic: Front ERF vs Internal ERF? Minimum size?
Replies: 26
Views: 684

Re: Front ERF vs Internal ERF? Minimum size?

Bases on numerous PST mods over the years,I always recommend the internal ERF be >50% the clear aperture andplaced as close to the objective as possible.
I also highly recommend the Baader D-ERF over the alternatives.
by Merlin66
Wed May 30, 2018 1:30 am
Forum: Solar Scope Modifications
Topic: KG3 IR Absorption vs IR Blocking filters? Same?
Replies: 81
Views: 2176

Re: KG3 IR Absorption vs IR Blocking filters? Same?

Guys,
If you search the forum for "ERF temperature" you'll find some interesting data.....
viewtopic.php?f=9&t=5719&hilit=erf+temperature
by Merlin66
Mon May 28, 2018 9:59 pm
Forum: Solar Scope Modifications
Topic: KG3 IR Absorption vs IR Blocking filters? Same?
Replies: 81
Views: 2176

Re: KG3 IR Absorption vs IR Blocking filters? Same?

What aperture and focal length scope did you use????
by Merlin66
Sat May 26, 2018 3:18 am
Forum: Solar Scope Modifications
Topic: KG3 IR Absorption vs IR Blocking filters? Same?
Replies: 81
Views: 2176

Re: KG3 IR Absorption vs IR Blocking filters? Same?

I think you'll find the UV-IR cut excludes the 393nm.....
The Baader CCD Blue filter could be an alternative worth looking at. (# 2458470B)
I've just acquired one for testing on my Omega CaK stack.
by Merlin66
Thu May 24, 2018 10:52 pm
Forum: This is SolarChat !!
Topic: Replacing the Rusted BF30 Filter
Replies: 54
Views: 1585

Re: Replacing the Rusted BF30 Filter

The size of the the solar disk image at a focal length of 450mm is 4.22mm.
by Merlin66
Thu May 24, 2018 7:06 am
Forum: Solar Astronomy Shop and Swap
Topic: Wanted: SM60 external etalon
Replies: 1
Views: 342

Wanted: SM60 external etalon

I'm looking to replace an original (pre SM60II preferred) external SM60 etalon which I was stupid enough to sell!
Prepared to pay a realistic price - delivery to Australia.
Can you help??
Ken
by Merlin66
Mon May 21, 2018 9:07 am
Forum: This is SolarChat !!
Topic: Replacing the Rusted BF30 Filter
Replies: 54
Views: 1585

Re: Replacing the Rusted BF30 Filter

Christian,
We really need to find an objective method of assessing the issues of NIR radiation Re solar observing/ imaging.
IMO there are no safety or performance concerns.
by Merlin66
Mon May 21, 2018 8:42 am
Forum: This is SolarChat !!
Topic: Replacing the Rusted BF30 Filter
Replies: 54
Views: 1585

Re: Replacing the Rusted BF30 Filter

Christian,
Agreed. But that’s the total energy....our visual systems function <700nm and the commercial CCD looses all sensitivity beyond 1100nm, beyond that we experience “heat”.
I have not seen any evidence that IR beyond 1200nm has any negative impact on solar observing.
by Merlin66
Sun May 20, 2018 4:46 am
Forum: This is SolarChat !!
Topic: Replacing the Rusted BF30 Filter
Replies: 54
Views: 1585

Re: Replacing the Rusted BF30 Filter

Mark,
I'd appreciate hearing your comments/ concerns with the IR >1500nm.
This region is well beyond the sensitivity of commercial CCD/ CMOS cameras and hence should have no impact.
by Merlin66
Sat May 19, 2018 9:29 pm
Forum: This is SolarChat !!
Topic: Replacing the Rusted BF30 Filter
Replies: 54
Views: 1585

Re: Replacing the Rusted BF30 Filter

TheSkyBurner <Name>? The safety requirements for extended VISUAL solar exposure is ND5 across the full spectrum. This does not obviously apply to imaging situations. There's a copy of the ICNIRP Review in the Solar Chat Reference Library. Rainer, Hmmm, sorry to hear the Astronomik didn't fit.....but...
by Merlin66
Sat May 19, 2018 6:46 am
Forum: This is SolarChat !!
Topic: First trial - T250 + CaK
Replies: 8
Views: 390

Re: First trial - T250 + CaK

Alex,
Very nice.
What’s the native focal ratio?
by Merlin66
Sat May 19, 2018 1:26 am
Forum: This is SolarChat !!
Topic: Replacing the Rusted BF30 Filter
Replies: 54
Views: 1585

Re: Replacing the Rusted BF30 Filter

Rainer,
My experience is with the Baader filter, but the Astronomik should work OK.
by Merlin66
Thu May 17, 2018 10:06 am
Forum: Solar Scope Modifications
Topic: Vixen VMC110L F9.4 Maksutov as Solar Scope?
Replies: 28
Views: 1378

Re: Vixen VMC110L F9.4 Maksutov as Solar Scope?

A photo of the set-up would help.... At this stage I assume you are using the PST Black box with the original PST blocking filter (?) This is only a 5mm aperture and designed for a focal length of 400mm - the mod really needs a larger blocking filter to give best FOV coverage. Generally a 10 or 15mm...
by Merlin66
Thu May 17, 2018 1:57 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Newton Rings and CCD Fringing
Replies: 4
Views: 398

Newton Rings and CCD Fringing

I'd like to investigate further the incidence of NR and CCD fringing. This only occurs when very narrow band filters are used in monochromatic light. So, these usually appear in solar Ha imaging. The NR are caused by interference between the cover plate and the underlying CCD/ CMOS chip. The extent ...