Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Meade SolarMax III DoubleStack 70mm f/5.7 H-Alpha Solar Telescope w/ 15mm Blocking Filters

solar Meade imaging observing
  • Please log in to reply
90 replies to this topic

#1 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 21 May 2020 - 12:17 AM

I am thinking of purghasing this unit, about 3 grand, for observing and light imaging using a Sony A7RIV DSLR.  Anyone have experience with the Solarmax III?  It sure looks like a fine setup.  I have a Sony 200-600mm G and need a 1.3x teleconverter to get a full disk 60 megapixle image of the moon.  I have yet to get as single snapshot with that setup I felt was satisfactory.  Although if I could add a double stack Etalon in-front and a blocking filter after the finial objective of my 200-600, that could be fun.  

 

Really would like to know if the $3K for the Solarmax is worth the improved images of the sun and the use of it as a standard refractor?

 

Here is a shot with the A7R4 f/9 iso100 840mm using the 1.4x and the sony 200-600mm it was 1/25s so could have shook on the tripod

https://i.imgur.com/dB4BIR6.jpg


Edited by chemman, 21 May 2020 - 12:22 AM.


#2 statfreak

statfreak

    Ranger 4

  • -----
  • Posts: 326
  • Joined: 21 Feb 2020
  • Loc: Las Vegas, NV

Posted 21 May 2020 - 12:44 AM

 

I have yet to get as single snapshot with that setup I felt was satisfactory.

 

Our experts will probably reply tomorrow morning but FWIW, you'll want to put down that Sony 7R IV and get a dedicated monochrome CCD imager. H-alpha is one specific narrow band frequency and the green and blue pixels on the color sensor are wasted, whereas with a monochrome CCD, every pixel is used. You would get better images of the moon as well. There are more technical considerations but I'll leave it to those who really know what they're doing to go into greater detail.


  • AJamesB likes this

#3 marktownley

marktownley

    Cosmos

  • *****
  • Posts: 9,136
  • Joined: 19 Aug 2008
  • Loc: West Midlands, UK

Posted 21 May 2020 - 02:02 AM

Nice scope but I wouldn't waste your time trying to image with a DSLR, get a dedicated mono ccd/cmos camera.



#4 Highburymark

Highburymark

    Vostok 1

  • -----
  • Posts: 113
  • Joined: 20 Mar 2019

Posted 21 May 2020 - 04:00 AM

It’s a great price for a double stacked scope - particularly by European standards, though as you’re probably aware the two etalons are only 60mm, so it will operate as a 60mm solar scope.

#5 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 21 May 2020 - 09:02 AM

Our experts will probably reply tomorrow morning but FWIW, you'll want to put down that Sony 7R IV and get a dedicated monochrome CCD imager. H-alpha is one specific narrow band frequency and the green and blue pixels on the color sensor are wasted, whereas with a monochrome CCD, every pixel is used. You would get better images of the moon as well. There are more technical considerations but I'll leave it to those who really know what they're doing to go into greater detail.

At some stage I will probably get into Astro more but for now using the A7R4 dslr is more just trying to glean appealing imagery with a my everyday carry sensor.  I once was a photographic technologist professionally involved in collecting scientific data from any particular sensor using innovative imaging technology at every necessary temporal and spacial resolution. Read super-photo nerd.  Now my job is my hobby and my hobby used to be my job.  lol   I am hoping I can use the refactor without the front etalons and just drop the A7R4 or a full spectrum 36mp A7R behind the clear glass and get good images using the f/5.7 400mm or use a 1.4x or 2.0x GM adapter to achieve 800mm with a good prime image from celestial and terrestrial subjects.  I will need to fabricate a 2" draw tube with a Sony α bayonet that will replace the blocking filter draw tube.  I do have a couple industrial imagers I will play with on it but sooner or later will force myself to get a dedicated astro imager.  

 

I am hoping it will just be another part of my kit that will allow me to not only use it as a satisfactory prime lens but get the enjoyment of staring at the sun.  lol  

 

The 200-600mm Sony G at f/5.6-6.3 in my opinion yields very good images up to about 400mm and acceptable images upto 600.  Add in the 1.4x at 800mm are a good/fair and the 2.0x produce barely acceptable aesthetically but to me very good scientific images at 1200mm. 

 

These images are analytical to me.  The first is of Green Mountain, a small 10,500 foot mountiain in my back yard.  It is 100 megabytes and is a 19,008X12,672 pixel image using the A7R4 on a survey tripod on a Monfrotto 410 head using a 24mmGM lens. It is a 12 image pixel shift image.  There is a small red circle around a cave slightly above center.  

The second image is the same pixel dimension and 12 pixel shift but using the 600mm with a 2.0X GM @ 1200mm of the cave.  At 318 megabytes it is not for the bandwidth challenged.  

https://i.imgur.com/bgiSZ7z.jpg

https://i.imgur.com/Kc2BgjK.jpg

 

ps. Compressed at 5 in photoshop to achieve <50mb from the 100mb and 350mb original jpegs, losses apply. 


Edited by chemman, 21 May 2020 - 10:11 AM.


#6 Daniel Dance

Daniel Dance

    Eastern Voltage Research, LLC

  • *****
  • Vendors
  • Posts: 1,736
  • Joined: 08 Jun 2016
  • Loc: Eastern United States

Posted 21 May 2020 - 10:15 AM

I bought the same scope last week but with a 10mm blocking filter.

Works awesome!

 

Also get the Sky-Watcher dedicated mount which is $300 bucks i think.  It's worth every penny especially since you don't need to drag out a large EQ mount, do daytime polar alignment, and all that mess.

 

I just put my 70mm Coronado on the Sky-Watcher, press one button, and the sun is already aligned and ready to go.  Love it! 



#7 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 21 May 2020 - 11:30 AM

I bought the same scope last week but with a 10mm blocking filter.

Works awesome!

 

Also get the Sky-Watcher dedicated mount which is $300 bucks i think.  It's worth every penny especially since you don't need to drag out a large EQ mount, do daytime polar alignment, and all that mess.

 

I just put my 70mm Coronado on the Sky-Watcher, press one button, and the sun is already aligned and ready to go.  Love it! 

Can I ask where you got it?

 

I have been a customer of B&H for almost 20 years, I think they are just under $3K

 

And which Sky-Watcher are you using on it?  What payload would you be comfortable with on it?   


Edited by chemman, 21 May 2020 - 11:47 AM.


#8 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 8,905
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 21 May 2020 - 11:55 AM

Heya,

 

The SM3 70mm is a decent little device. It's a 70mm achromatic doublet that will do all wavelengths, and with the etalons installed it's a 60mm aperture. But, you can remove the etalons and then also do white light (photosphere) and/or calcium through the same instrument, so it's versatile in that way. But it's an achromatic doublet, so if you put a color sensor on it be prepared for the chromatic abberation that comes with fast achromatic doublets. It's not an ED/APO doublet, so it's not really a good imaging scope outside of narrowband use in my opinion due to this. It's a huge improvement over the SM2 series that used awful helical focusers; the SM3 line now comes with crayford focusers as stock which is great. Also, the SM3 line is all front mounted etalons unlike the previous SM2 line that had an internal etalon. The front mounted etalons are better performers just by being on the front, it has to do with angles. So from the Coronado point of view, the SM3 series is a great improvement in general on what they were doing before.

 

Something to keep in mind; you could get the etalons and simply mount them on a different, better telescope that can be more versatile, such as a high quality ED/APO refractor. PreciseParts (Miami based) can make the adapter needed to mount the etalons to a scope of your choice. This is what I did and vastly prefer this over a small short achromatic doublet with CA, making it a poor choice for imaging outside of narrowband. I mounted my SM60 etalons onto an ED80 which is an FPL53 based ED doublet with no CA, so it's excellent for imaging all subject matter including full RGB. My adapter came from PreciseParts and it threads into the lens holding cell so my etalons thread onto it and are completely secure (they're heavy, so I do not recommend lens cap methods of mounting etalons).

 

The only issue I would have is buying a new Meade instrument in general and whether or not there will be reliable support in case you have any issues. Meade is a concerning business at the moment. I'll just suggest you research them a bit and see what's going on. Might want to let the dust settle. But if you're not worried about support, then this is a non-issue.

 

I will say though that if you care a lot about having support, especially way down the line, Lunt is better in this respect by far and will handle issues right here in the USA. That matters to some, but it's worth knowing.

 

As others stated, lose the mSLR/dSLR for this use. Also, you will have to retrain most of what you think you know about photography when it comes to astrophotography and especially how solar system photography is done. The histogram is the histogram, so at least that will be familiar and about the same with what you know. But the imaging is done with video (ie: lucky imaging) not still images and the concepts of aperture (not to be misunderstood as focal-ratio, this is common to terrestrial photography jargon), focal-ratio and pixel pitch is important if you care to extract resolution (which is not to be confused with number of pixels as a sum). The ideal camera for this is a USB based CMOS monochrome sensor with small pixel pitch and high sensitivity. Literally the last camera type you want is a big dSLR/mSLR with its slow video capabilities and larger pixels which are insensitive due to OSC/Bayer Matrix configurations. Choosing a camera is based on what the resulting FOV will be, the pixel size relative to 656nm wavelength and its critical sampling point based on focal-ratio and sensitivity to the wavelength to allow for fast FPS recording with short exposure time (10ms or less). Explore this stuff a lot more if you want to get the most out of what you're getting into. Also, this is true for lunar imaging as well (since you mentioned shooting the moon above) in terms of getting a new camera, a dSLR/mSLR is not a good choice for that either. dSLR/mSLR are good for terrestrial photography and long exposure still photography such as deep space imaging (but still a poor choice for that too frankly because they're uncooled sensors, but they're at least good enough to start with there with appropriate expectations; but they're awful for narrowband solar system imaging via video). You mentioned you work with this stuff, so hopefully this is preaching to the choir and I apologize if I just text-walled you stuff you are already very well aware of.

 

Very best,


Edited by MalVeauX, 21 May 2020 - 12:12 PM.

  • marktownley, chemman and AJamesB like this

#9 Daniel Dance

Daniel Dance

    Eastern Voltage Research, LLC

  • *****
  • Vendors
  • Posts: 1,736
  • Joined: 08 Jun 2016
  • Loc: Eastern United States

Posted 21 May 2020 - 12:35 PM

Can I ask where you got it?

 

I have been a customer of B&H for almost 20 years, I think they are just under $3K

 

And which Sky-Watcher are you using on it?  What payload would you be comfortable with on it?   

$399.99

https://www.bhphotov...muth_mount.html



#10 johnpeter2

johnpeter2

    Explorer 1

  • *****
  • Posts: 92
  • Joined: 26 May 2018
  • Loc: Lake James area, NC

Posted 21 May 2020 - 07:56 PM

I would like to second what MalVeauX said regarding Precise Parts (great products), Meade (customer service problems), and Lunt (great customer service & products).  Meade's customer service was problematic even before its bankruptcy and the virus shutdown.  It was difficult to get in touch with them, and it was especially difficult to get someone knowledgable about their solar products.  My experiences were from last summer.  I hope they improve a lot in this area when things get back to normal.

 

John



#11 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 21 May 2020 - 10:07 PM

Heya,

 

The SM3 70mm is a decent little device. It's a 70mm achromatic doublet that will do all wavelengths, and with the etalons installed it's a 60mm aperture. But, you can remove the etalons and then also do white light (photosphere) and/or calcium through the same instrument, so it's versatile in that way. But it's an achromatic doublet, so if you put a color sensor on it be prepared for the chromatic abberation that comes with fast achromatic doublets. It's not an ED/APO doublet, so it's not really a good imaging scope outside of narrowband use in my opinion due to this. It's a huge improvement over the SM2 series that used awful helical focusers; the SM3 line now comes with crayford focusers as stock which is great. Also, the SM3 line is all front mounted etalons unlike the previous SM2 line that had an internal etalon. The front mounted etalons are better performers just by being on the front, it has to do with angles. So from the Coronado point of view, the SM3 series is a great improvement in general on what they were doing before.

 

Something to keep in mind; you could get the etalons and simply mount them on a different, better telescope that can be more versatile, such as a high quality ED/APO refractor. PreciseParts (Miami based) can make the adapter needed to mount the etalons to a scope of your choice. This is what I did and vastly prefer this over a small short achromatic doublet with CA, making it a poor choice for imaging outside of narrowband. I mounted my SM60 etalons onto an ED80 which is an FPL53 based ED doublet with no CA, so it's excellent for imaging all subject matter including full RGB. My adapter came from PreciseParts and it threads into the lens holding cell so my etalons thread onto it and are completely secure (they're heavy, so I do not recommend lens cap methods of mounting etalons).

 

The only issue I would have is buying a new Meade instrument in general and whether or not there will be reliable support in case you have any issues. Meade is a concerning business at the moment. I'll just suggest you research them a bit and see what's going on. Might want to let the dust settle. But if you're not worried about support, then this is a non-issue.

 

I will say though that if you care a lot about having support, especially way down the line, Lunt is better in this respect by far and will handle issues right here in the USA. That matters to some, but it's worth knowing.

 

As others stated, lose the mSLR/dSLR for this use. Also, you will have to retrain most of what you think you know about photography when it comes to astrophotography and especially how solar system photography is done. The histogram is the histogram, so at least that will be familiar and about the same with what you know. But the imaging is done with video (ie: lucky imaging) not still images and the concepts of aperture (not to be misunderstood as focal-ratio, this is common to terrestrial photography jargon), focal-ratio and pixel pitch is important if you care to extract resolution (which is not to be confused with number of pixels as a sum). The ideal camera for this is a USB based CMOS monochrome sensor with small pixel pitch and high sensitivity. Literally the last camera type you want is a big dSLR/mSLR with its slow video capabilities and larger pixels which are insensitive due to OSC/Bayer Matrix configurations. Choosing a camera is based on what the resulting FOV will be, the pixel size relative to 656nm wavelength and its critical sampling point based on focal-ratio and sensitivity to the wavelength to allow for fast FPS recording with short exposure time (10ms or less). Explore this stuff a lot more if you want to get the most out of what you're getting into. Also, this is true for lunar imaging as well (since you mentioned shooting the moon above) in terms of getting a new camera, a dSLR/mSLR is not a good choice for that either. dSLR/mSLR are good for terrestrial photography and long exposure still photography such as deep space imaging (but still a poor choice for that too frankly because they're uncooled sensors, but they're at least good enough to start with there with appropriate expectations; but they're awful for narrowband solar system imaging via video). You mentioned you work with this stuff, so hopefully this is preaching to the choir and I apologize if I just text-walled you stuff you are already very well aware of.

 

Very best,

OMG! You are killing me here.  Now look what you have done.  I have spent the last 15 years ignoring the previous 10 years of super deep imaging technology I was so involved in.  Now your words have spurned a thousand scattered new scientific ideas I must now peruse.  I am lucky that for the most part I hopped on this solar imaging scope because it was attractive and looked to produce good looking images.  Now I am thinking that your solar setup is more along the lines of what I should go for.  I only use dslr that I have because I have it and it produces good images I want.  If I can adapt it to my solar setup and get nice captures that my eye can see I am fine.  I can probably figure out a way to see with the same setup what my eye cannot.  That is why I have the full spectrum modified A7R.  I do know that those cmos sensors are less than ideal for collecting the images for truly quality astro and solar images, it would be nice to have the optics necessary and later assemble the proper sensor.  Until then get by with the dslr.   

 

So my first question is if I got an ED80(I do not know what that is) could I use it as a prime lens on my 60mp dslr and get satisfactory images(stars,birds)? Would it be as simple as adding SM60 etalons to get satisfactory images of the sun?   

 

So all of my previous life as a photographic technologist consisted of being briefed by scientists and engineers on what  needed to be imaged, what particular properties that system was expected to exhibit and the specific data needed to be gathered and the timescale involved in the entire process.  I then determined all that it took to satisfy all of the required results.   In this case I really don't know where to start.  I have an old school Meade SCT on a LX80 mount I limp along with.  In other words slightly <0 knowledge.  

 

Do you have any suggestions?  I personally don't know exactly where to start.  


Edited by chemman, 22 May 2020 - 07:52 PM.


#12 Gray

Gray

    Viking 1

  • *****
  • Posts: 963
  • Joined: 31 Jan 2011
  • Loc: Middle TN

Posted 21 May 2020 - 10:12 PM

Doing the numbers real fast if you use that scope for imaging, a ZWO ASI290MM would get full disc and add a 1.6x barlow to be very near  critical sampling.  I think they are $300 new.  Best of luck


Edited by Gray, 21 May 2020 - 10:24 PM.


#13 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 21 May 2020 - 10:16 PM

I bought the same scope last week but with a 10mm blocking filter.

Works awesome!

 

Also get the Sky-Watcher dedicated mount which is $300 bucks i think.  It's worth every penny especially since you don't need to drag out a large EQ mount, do daytime polar alignment, and all that mess.

 

I just put my 70mm Coronado on the Sky-Watcher, press one button, and the sun is already aligned and ready to go.  Love it! 

Why did you get the 10mm over the 15mm?  



#14 marktownley

marktownley

    Cosmos

  • *****
  • Posts: 9,136
  • Joined: 19 Aug 2008
  • Loc: West Midlands, UK

Posted 22 May 2020 - 01:42 AM

Just to throw  something into the mix here, the OTA for the Coronado is just a bog standard cheapo OEM piece of kit.  Like Marty says there will be chromatic aberration, and I will put money on the field not being flat at all.  Being a professional photographer both of these things will jump out at you.  With a better Quality refractor you could get a field flattener to go with it but at this point you're better just getting the proper camera to go with the Coronado.



#15 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 8,905
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 22 May 2020 - 12:03 PM

OMG! You are killing me here.  Now look what you have done.  I have spent the last 15 years ignoring the previous 10 years of super deep imaging technology I was so involved in.  Now your words have spurned a thousand scattered new scientific ideas I must now peruse.  I am lucky that for the most part I hopped on this solar imaging scope because it was attractive and looked to produce good looking images.  Now I am thinking that your personal solar scope is more along the lines of what I should go for.  I only use dslr that I have because I have it and it produces good images I want.  If I can adapt it to my solar setup and get nice captures that my eye can see I am fine.  I can probably figure out a way to see with the same setup what my eye cannot.  That is why I have the full spectrum modified A7R.  I do know that those cmos sensors are less than ideal for collecting the images for truly quality astro and solar images, it would be nice to have the optics necessary and later assemble the proper sensor.  Until then get by with the dslr.   

 

So my first question is if I got an ED80(I do not know what that is) could I use it as a prime lens on my 60mp dslr and get satisfactory images(stars,birds)? Would it be as simple as adding SM60 etalons to get satisfactory images of the sun?   

 

So all of my previous life as a photographic technologist consisted of being briefed by scientists and engineers on what  needed to be imaged, what particular properties that system was expected to exhibit and the specific data needed to be gathered and the timescale involved in the entire process.  I then determined all that it took to satisfy all of the required results.   In this case I really don't know where to start.  I have an old school Meade SCT on a LX80 mount I limp along with.  In other words slightly <0 knowledge.  

 

Do you have any suggestions?  I personally don't know exactly where to start.  

No worries, just trying to make sure you know what you're getting into and with what expectations. It's all too common to approach imaging with a dSLR/mSLR when one has a background of using them and not want to let go of using them. The sensors are actually very good, they're mostly Sony sensors without all the other complex stuff that goes into a "camera" for terrestrial use which is why the cost is so affordable for high efficiency, high quantum efficiency, fast FPS (fast data throughput), they're monochrome and are not plagued by an inefficient Bayer Matrix overlay, and are pretty good with noise. Some of the best solar images in the world by amateurs are done with almost laughably inexpensive cameras relative to the other equipment. But that said, none of it matters without excellent seeing conditions.

 

So, if you want to use you A7RIV, note you have 3.76um pixel pitch OSC pixels that will be less sensitive to Halpha wavelength (656nm). But, to image at the critical sample limit of your pixel size at that wavelength, you need to be operating around a focal-ratio of F14.1 (F14 rounded is good enough). Here's a calculator so you can calculate this yourself. Anything less than that is going to under-sample and literally lose data, low resolution, course image scale, no matter how many pixels are involved. So operating at F6.667 (which is what the SM3 actually is with its etalons, 400mm focal length, 60mm aperture, making F6.667, it's only F5.7 without the etalons using the 70mm aperture of the objective lens) is actually severely undersampling, so losing lots of data and not recording the resolution. So you use a 2x barlow, extender, powermate, etc, to bring your focal-ratio up to F13.3 (2 x 6.667). This is much closer to F14.1 that your 3.76um pixels need to critically sampling 656nm wavelength (Halpha). It's still only slightly under-sampling but it's close enough. And over that, it will over-sample, which gains zero resolution gain and instead just costs you light which requires more increase in ISO/Gain to be more sensitive to the signal and cost you noise and dynamic range. So your goal with your 3.76um pixels of your AR7IV is F14 approximately. F13~15 would be fine really but there's no reason to go higher than F14 at all, as there's no more resolution to gain and you're at the limit of the angular resolution of the aperture size at the airy disc at that point assuming perfect seeing conditions. Your sensor is much larger than the blocking filter. So no matter what, your imaging circle is the size of your blocking filter, so 10mm or 15mm depending on which blocking filter you get. So you will not be using very many of your pixels here at all (put a 10mm or 15mm diameter circle on the center of your 35mm sensor and that's all that is going to be used). To image, you will be using video. The faster the FPS the better. You have to freeze the seeing, so 10ms (1/100th) exposure time is likely as long as you want to go, shorter is better, to freeze seeing conditions. That limits you to 100 FPS possibly, if your system can handle that throughput of your sensor's data rate (knowing a lot of it is black space due to the blocking filter size), measuring several gigabytes in just a few seconds. You have to go shorter exposure to get faster FPS. You need fast FPS because that's how you get lots of frames to stack and align during brief moments of good seeing conditions, via lucky imaging. It looks like the A7RIV can go from 30 FPS to 120 FPS depending on different settings. If it can really do 100+ FPS that would be the one thing finally in its favor for this purpose. You will use as much ISO as needed to fill the histogram (which will be significant). Photographic speed is less important here (as in the focal-ratio number) because what really matters is the transmission of the filters (they will be very low, to be safe for human eyes).

 

It will work. But there's the information for you to start with.

 

The ED80 is an old workhorse telescope, nothing special, very inexpensive. It's an 80mm aperture, 600mm focal length ED FPL53 based doublet (F7.5). It has no CA during the day or at night in RGB. I use it for solar as well, because I like to get the most out of it as I have too many scopes and filters as it is (I use this at night for deep space imaging too, no false color at F7.5 with FPL53 glass at this aperture size). I use it because of the 600mm focal length and my 60mm etalon aperture produces F10 focal-ratio, which is critically sampled with my smaller 2.4um and 2.9um pixels of my cameras. There are many telescopes one could use out there for this purpose. But if you want to get the most out of it, it will be to choose one that has the resulting focal-ratio you need (with your etalon aperture size) to critical sample 656nm wavelength on a specific pixel size. So there's a lot of combinations to achieve this, and it's all completely calculable. It's generally much easier to just buy a pre-made dedicated solar scope (and cheaper). But most solar scopes are designed primarily for visual, and imaging is a second feature, so they almost always have less than optimal focal-ratios for the wavelength.

 

Anyhow, again, just more information so you can make the decisions on what to do best with your money and your expectations.

 

I highly recommend you take a look visually through a club or local scope to see what you can see with your eyes if you haven't already; and I really suggest a good solar handbook too, to learn the features you can see in different parts of the photosphere and chromosphere so you know what you're seeing and what you might image. It's a great thing, very dynamic, changes in minutes. And there's always something new to see in Halpha, every day!

 

Personally I'd say to skip the 70mm and try to go for a 90mm instead (even if its a single stack)! smile.gif

 

Very best,


Edited by MalVeauX, 22 May 2020 - 12:07 PM.


#16 Great Attractor

Great Attractor

    Vendor - ImPPG Imaging Software

  • -----
  • Vendors
  • Posts: 401
  • Joined: 23 Oct 2012
  • Loc: Germany

Posted 22 May 2020 - 01:26 PM

To just dip your toes and see how you like solar, a DSLR may be sufficient. In my very beginnings I got an OK-ish image by stacking just 7 RAWs:

 

get.jpg?insecure

 

(Nikon D40 + 102/1000 mm achromat, ND 5 solar film, artificial color added in GIMP)

 

Note that the above was taken in white light, I'm not sure how good a result you can get in Hα with an OSC sensor.


Edited by Great Attractor, 22 May 2020 - 01:26 PM.


#17 briansalomon1

briansalomon1

    Ranger 4

  • *****
  • Posts: 391
  • Joined: 21 Jul 2018
  • Loc: Oxnard CA

Posted 23 May 2020 - 11:01 AM

I agree with using external etalons and precise parts adapters. I would like to add that having had personal time using a 90mm III DS, I personally believe Lunt is more consistent in quality. If you buy directly from Lunt the warranty is solid and timely service available. They also certify all their new etalons meet a uniform specification and matching one to another is not necessary.

 

All that is not true about the Solarmax product.

 

As Mr. Yoesly has posted elsewhere the blocking filter diameter should at least match the FL of the telescope it's intended for. For instance, a telescope with a focal length of 600mm will show a full disk image with the 6mm blocking filter, a FL of 1000mm with a 10mm blocking filter and so on.

 

It's good practice to go a size up from what you'll need.



#18 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 23 May 2020 - 02:14 PM

@MalVeauX , I am looking at a Lunt Solar Systems 4" / 102mm f/6.6 ED Doublet Refactor and adding the external etalons using @briansalomon1 s idea of precise parts adapters and a blocking filter. 

 

The 714mm focal length will give me a nice full disk of the moon or sun at 20X with either full frame dslr.  In the future after reading and digesting the 6 or 8 astrophotography books I have collected I will buy a nice astro specific camera.  But much of the purpose in this is to have a new lens for the dslr.   

 

By using the A7R4 and it's 3.76um pixel pitch I calculate F14.1 but when I use the A7R full spectrum camera and it's 4.88um pixel pitch I get F18.3, would that be considered better?  Without the visible filtering on the A7R I have noticed around 2 stops more sensitivity.   

 

Not sure where to start matching the external etalons and blocking filter to the scope at a 102mm.  Is one etalon better than another?

 

your comments have been priceless @@MalVeauX , Thank you.



#19 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 8,905
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 23 May 2020 - 04:21 PM

@MalVeauX , I am looking at a Lunt Solar Systems 4" / 102mm f/6.6 ED Doublet Refactor and adding the external etalons using @briansalomon1 s idea of precise parts adapters and a blocking filter. 

 

The 714mm focal length will give me a nice full disk of the moon or sun at 20X with either full frame dslr.  In the future after reading and digesting the 6 or 8 astrophotography books I have collected I will buy a nice astro specific camera.  But much of the purpose in this is to have a new lens for the dslr.   

 

By using the A7R4 and it's 3.76um pixel pitch I calculate F14.1 but when I use the A7R full spectrum camera and it's 4.88um pixel pitch I get F18.3, would that be considered better?  Without the visible filtering on the A7R I have noticed around 2 stops more sensitivity.   

 

Not sure where to start matching the external etalons and blocking filter to the scope at a 102mm.  Is one etalon better than another?

 

your comments have been priceless @@MalVeauX , Thank you.

Heya,

 

If you use the 102mm F6.6 doublet with a 60mm etalon, you're looking at at F11.22 focal-ratio, if you wish to match it to 3.76um pixels you need F14, if you wish to match it to 4.88um pixels you need F18 as you calculated. So how to get F11 to F14 or F18? You would need a sub-2x barlow to do that. It's possible, a 1.5x is out there, you'd have to find it. Keep in mind that this is only if you wish to capture this angular resolution of 656nm at its critical sampling point for maximum resolution from the aperture at that wavelength, at the limit of excellent seeing and the airy disc. It's ok to under-sample a bit, knowing its losing data, it may still produce an acceptable image. Likewise, it's ok to over-sample a little bit, knowing its only costing you ISO/gain (so a bit more noise and less dyanmic range), but again may still provide an acceptable image. I just wanted to give you the numbers based on your comments.

 

Getting two external etalons will not be easy to source right now, without a package deal or used. It's really hard to find 60mm Solarmax II etalons (primary ones) for sale anywhere other than entire scopes (which the SM60II scope package has an internal etalon). The SM III series is not currently selling individual etalons. So unless you can source SMII series primary etalons somewhere, your option is to get a SM III 70mm scope package and just keep the etalons and shelf the little achromatic doublet it comes with and then get a precise parts adpater to match whatever scope you plan to with the t-max threads of the SM3 etalon(s). That's if you want to go with a Solarmax.  Pre-Meade Solarmax etalons are some of the best, but are discontinued and near impossible to source. Solarmax II etalons are ok but have variability to you really need to inspect them or buy from a place with a return policy. Solarmax III etalons, well, not much info on them. They dropped during a minimum cycle when there's less furious buying and reviewing with an active maximum peak going on. So not many can give you real data on the SM3 units.

 

You probably should also take a good long look at a modular Lunt while exploring this because Lunt recently started producing systems with modular parts to allow for multi-frequency imaging which seems to be what you're looking for.
 

Very best,



#20 hopskipson

hopskipson

    Gemini

  • *****
  • Posts: 3,297
  • Joined: 24 Jun 2010
  • Loc: Queens, New Yawk, Light pollution Headquarters!

Posted 23 May 2020 - 06:41 PM

Heya,

 


Getting two external etalons will not be easy to source right now, without a package deal or used. It's really hard to find 60mm Solarmax II etalons (primary ones) for sale anywhere other than entire scopes (which the SM60II scope package has an internal etalon). The SM III series is not currently selling individual etalons. So unless you can source SMII series primary etalons somewhere, your option is to get a SM III 70mm scope package and just keep the etalons and shelf the little achromatic doublet it comes with and then get a precise parts adpater to match whatever scope you plan to with the t-max threads of the SM3 etalon(s). That's if you want to go with a Solarmax.  Pre-Meade Solarmax etalons are some of the best, but are discontinued and near impossible to source. Solarmax II etalons are ok but have variability to you really need to inspect them or buy from a place with a return policy. Solarmax III etalons, well, not much info on them. They dropped during a minimum cycle when there's less furious buying and reviewing with an active maximum peak going on. So not many can give you real data on the SM3 units.

 

 

Very best,

There are still some SMII 60 mm etalons (primary and DS) left in some retailers. 

 

I recently purchased a SMII 90 DS scope for close to 1/2 price.  In the manual it describes all the etalons in the line including the primary stand alone for use on your scope with a blocking filter.  The funny thing is that to double stack it you get basically the same etalon.  So if you have a blocking filter you just need the "double stack" etalon.  My DS external etalon has the tilt wheel and "Richview" tuner.  One problem I can see with this set up of 2 external SMII etalons is that when you tune the primary and then screw in the DS you need to be careful not to rotate the primary.


  • MalVeauX likes this

#21 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 24 May 2020 - 03:22 AM

Heya,

 

If you use the 102mm F6.6 doublet with a 60mm etalon, you're looking at at F11.22 focal-ratio, if you wish to match it to 3.76um pixels you need F14, if you wish to match it to 4.88um pixels you need F18 as you calculated. So how to get F11 to F14 or F18? You would need a sub-2x barlow to do that. It's possible, a 1.5x is out there, you'd have to find it. Keep in mind that this is only if you wish to capture this angular resolution of 656nm at its critical sampling point for maximum resolution from the aperture at that wavelength, at the limit of excellent seeing and the airy disc. It's ok to under-sample a bit, knowing its losing data, it may still produce an acceptable image. Likewise, it's ok to over-sample a little bit, knowing its only costing you ISO/gain (so a bit more noise and less dyanmic range), but again may still provide an acceptable image. I just wanted to give you the numbers based on your comments.

 

Getting two external etalons will not be easy to source right now, without a package deal or used. It's really hard to find 60mm Solarmax II etalons (primary ones) for sale anywhere other than entire scopes (which the SM60II scope package has an internal etalon). The SM III series is not currently selling individual etalons. So unless you can source SMII series primary etalons somewhere, your option is to get a SM III 70mm scope package and just keep the etalons and shelf the little achromatic doublet it comes with and then get a precise parts adpater to match whatever scope you plan to with the t-max threads of the SM3 etalon(s). That's if you want to go with a Solarmax.  Pre-Meade Solarmax etalons are some of the best, but are discontinued and near impossible to source. Solarmax II etalons are ok but have variability to you really need to inspect them or buy from a place with a return policy. Solarmax III etalons, well, not much info on them. They dropped during a minimum cycle when there's less furious buying and reviewing with an active maximum peak going on. So not many can give you real data on the SM3 units.

 

You probably should also take a good long look at a modular Lunt while exploring this because Lunt recently started producing systems with modular parts to allow for multi-frequency imaging which seems to be what you're looking for.
 

Very best,

The 90 is on its way, had to do it.  I will suffer through  the rest.  Lol

 

It is the single though.


Edited by chemman, 24 May 2020 - 03:23 AM.


#22 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 8,905
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 24 May 2020 - 09:41 AM

There are still some SMII 60 mm etalons (primary and DS) left in some retailers. 

 

I recently purchased a SMII 90 DS scope for close to 1/2 price.  In the manual it describes all the etalons in the line including the primary stand alone for use on your scope with a blocking filter.  The funny thing is that to double stack it you get basically the same etalon.  So if you have a blocking filter you just need the "double stack" etalon.  My DS external etalon has the tilt wheel and "Richview" tuner.  One problem I can see with this set up of 2 external SMII etalons is that when you tune the primary and then screw in the DS you need to be careful not to rotate the primary.

If you can link me to a primary external solarmax 60mm or 90mm II series etalon (not just the double stack module with rich view tuning and a t-max tilter), that would be helpful. They're discontinued and extremely hard to find other than used. Not even available from Meade. So anything out there is old stock (which is fine). But just finding it in stock somewhere would be impressive.

 

The scope you bought, the 90mm SMII DS, it has an internal primary etalon and the external is the DS module. This is fine if you're only doing HA. The problem is the O.P. wants to use it for more than HA, so having an internal etalon makes that no possible. So only a SM3 series will do that. Or Lunt. Or a self-made scope using any refractor and adapting external etalons to it.

 

And it's true as you pointed out that rotating things can matter, they sometimes "clock" themselves. Mine are both external and attach to the front. But I use a Solarmax 60 Primary and a Solarmax 60 II DS module, both on t-max tilters using an adapter to mount to an ED80 refractor.

 

The 90 is on its way, had to do it.  I will suffer through  the rest.  Lol

 

It is the single though.

It only hurts once. Honestly, the 90mm is a life-time class scope. You'll never outgrow a 90mm solar scope. And later on, you can add a double stack 90mm etalon to this system at any time. Both the SM2 and SM3 series etalon (heck and if you can find a SM1 series unicorn) can be stacked. The bigger aperture is worth it if you're all in for HA. The maximum will return in the next few years and you'll be delighted for a few years with what our star does.

Congrats on the 90; great scope!

 

Very best,



#23 hopskipson

hopskipson

    Gemini

  • *****
  • Posts: 3,297
  • Joined: 24 Jun 2010
  • Loc: Queens, New Yawk, Light pollution Headquarters!

Posted 24 May 2020 - 10:40 AM

https://telescopes.n...wtm-tuning.html

 

https://telescopes.n...ning-17307.html

 

And from the SMII manual under Double Stacking both etalons are the same module.

 

https://documentclou...1b-14457e00e612

 

 

 

 

 



#24 chemman

chemman

    Viking 1

  • -----
  • topic starter
  • Posts: 655
  • Joined: 21 Jun 2011
  • Loc: Colorado

Posted 24 May 2020 - 10:42 AM

Thanks for the help on this @MalVeauX.  I will be interested to see what kind of results I get imaging through the scope without the etalon and bf.  Photoshop is always available.  I knew I would have to expand on the closest star we have after the last eclipse.  I watched it from dead center totality near Casper Wyoming, the most moving experience I have ever had.  Now I must stare at the sun and glean what it has to offer.  

 

Maybe the CA will be something I want in  the scope in 2024, lol.  

 

This was my first time.  

https://imgur.com/gallery/CufJave


  • MalVeauX and statfreak like this

#25 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 8,905
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 24 May 2020 - 10:54 AM

Unfortunately these are not in stock. I contacted them last week. They display a shipping estimate but there's no estimate because there's nothing coming from Meade unfortunately (marked discontinued by Meade on their site and they are not returning communication for weeks so far). The primary etalons that come with a blocking filter are not in stock anywhere. Only the left over double stack modules with rich view tuning and no blocking filter can be found in stock it seems.

 

There's also some sort of difference between the primary & DS modules; even the SM3 etalons are not the same, the primary etalon is on a t-max tilter and the second etalon has rich view and a t-max tilter from what I can tell from photos (which may be incorrect), as I do not have a physical SM3 set in my hands (I only have physical experience with PreMeade SM1 series and SMII series which I have). I've yet to find anyone two has taken two of the SMII series "double stack" etalons and stacked them both (two rich view tuning etalons). When I tested two separate SMII 60 DS etalons individually without a primary etalon, it was pretty clear to me that it wasn't the same as a primary etalon. But, that could be anecdotal on my part. I ended up sourcing a pre-Meade SM 60 primary etalon and double stacked that with a rich view DS SM60II series etalon together. I would be delighted to find confirmation of two double-stack rich view etalons being stacked together with good results, that would make things so much easier.

 

I think it will be some time, but hopefully Meade will release the etalons for SM3 series individually.

 

The only reason I'm even interested is because frankly I consider two 90mm front mounted etalons to be the best ratio of aperture and etalon position to price ratio while still being a portable scope. I consider it end-game and life-time level. A good mix of full disc and medium resolution. Being able to select a donor scope that is good for terrestrial, daytime and night time use and also being to generate a more imaging-favored focal-ratio with the etalons is a big part of this for me as most scopes are frankly visually oriented but I'd rather it be good at both (without adding barlows/extenders where possible). So being able to get SM90 etalons for example (any version, of course would prefer PreMeade unicorns, but there's not much info on the SM3 ones yet but I'm not holding my breath on them) and adapt and stack them onto a donor scope would be the best way to get this system made without being forced into the package deal, or with a rather mediocre achromatic doublet that is fast which is not useful in many ways, despite being flexible to be a standard scope without the etalon filters. I would much rather for example put these on a 1200mm donor scope generating F13, with decent glass and a big blocking filter. That would be an end-game scope in my opinion and reasonable to use well into old age (still quite a big scope though). Problem is.... getting those etalons that are front mounted and getting good ones.

 

Very best,
 


Edited by MalVeauX, 24 May 2020 - 12:21 PM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: solar, Meade, imaging, observing



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics