Canon lens and the ASI 2600MM

In the previous post I suggested a configuration to use in mating DSLR lenses to the ASI 2600MM camera + ZWO 7x36mm EFW. A first test of this has been done, with good results. Here's a simple stack/stretch of some Heart Nebula H alpha data taken using an old Olympus lens with a Canon adapter, mated to the ASI with a thin Canon to M42 adapter + thin spacer rings for 1.4mm

Things to be aware of are 

• The wind was gusting to 30mph the entire time data were being collected.
  
• North is to the right; you can see a substantial drift in RA probably because this is a temporary rig and utterly out of RA balance (PHD was squawking a lot) 
• Focus was far from perfect
• This was 2x2 in-camera binned and roughly calibrated using dark frames from 10C cooler calibration, no flats, no bias. 
• Stretch was just the PixInsight STF
  

Evidence of the drift is seen along the top (west) edge of the image where there is a thin band of partial coverage. As a result of the probable bouncing due to PHD's problems we expect stars to elongate in RA during the ten-minute exposures, and that's just what we see in this composite image of the center and four corners:

 The center shows the poor focus and evidence of the RA drift. (RA drift is in the vertical.) 

Stars at the corners compare well with the center stars. While they show the same soft focus and RA elongation, there's no evidence of aberrations resulting from improper spacing between lens and sensor. 

Sharper focus might well show defects, but this is not bad for a windy night, no balance, and a $40 Olympus 200mm f/4 lens (stopped down to f/5.4).

And one last little observation about the pricing of astro gear. The Canon lens adapter for my SBIG ST-8300 cost me $300. Things were far less expensive for the ASI. The Canon/M42 adapter plus the thin spacing rings came to $75. Over half of that was for the general purpose rings that will see duty in additional ways.

ASI 2600MM; FSQ-106EDX4 imaging trains

ASI 2600 Glitch:

First, bad news then the good: My new ASI2600MM Pro was delivered last month. As it sometimes happens with new things, not all is well. The camera's temperature sensor was not reporting. From reading forum posts, it appears that ZWO, like every other maker of advanced astronomy gear, has occasional blips in their quality control. A non-functional temperature sensor is not common, but it does happen.

I got in touch with OPT (the vendor) and they had ZWO contact me with the fix. The fix is so simple I wondered if it could possibly work: Shoot some compressed air around the sensor's flat cable, pop open the little clip holding it in place, shoot some more air in, jostle but do not disconnect the cable (that part was left very vague in the instructions), close the clip, and button the camera back up.

It worked!

FSQ-106EDX4 Imaging Optical Trains

CAVEAT: I have not taken delivery of the FSQ so none of the following has been verified in the field. A vendor post on CloudyNights suggests delivery may have to wait until February!

Now on to the main topic: how to get ready for imaging with the FSQ-106EDX4.

The imaging cameras will be an ASI2600MM Pro and a modded Canon T2i. I'll be using the FSQ in two modes: native f/5 and f/3.65 using the CR 0.73X focal reducer, and I would like to use the ASI with my existing EOS lenses. (I resisted the temptation to buy the 0.6X reducer, opting instead to save a thousand dollars and make the optical train a little more user friendly.)

I'll be imagining with two devices: a Ha-modded OSC Canon T2i and the ZWO 7x36mm EFW (M42 connections, optical thickness 20mm) with ASI2600MM (backfocus of 12.5mm after removing the tilt plate).  The following configurations are based on what Takahashi has published about their adapters (see link below) and forum comments on CloudyNights.com.

FSQ106 Native Mode + ASI2600:

The FSQ focuser has a travel range of only about 30mm, so back focus should put the sensor near the center of this if possible. Sources suggest this is at a distance of 163mm (178mm minus half the travel range) beyond the end of the focuser. Already in the optical train are the 645 RD adapter (TKA36581, 10mm backfocus), CAA-250 (TKP86200, 38.5mm), Aux Ring S (TKA38205, 27.5mm), and Coupling TW (TKP36003, 34.2mm); their total is 110.2mm. This has stepped us down from M98 to M54 thread and we still need about 53mm. To get us down to M42, we use Blue Fireball's adapter with thickness 6.9mm. Now we add the EFW (20mm) and 2600's backfocus (12.5mm without the tilt plate) and we're at 110.2 + 6.9 + 20 + 12.5 = 149.6. We add a simple 12mm M42 spacer and get 161.2. You could use a 5, 10, or 15mm spacer, or even a thicker M54/M42 adapter. "Close" is good enough.

REVISED 8/11/2022 The diagram above is not longer correct. FSQ106 + CR 0.73X Focal Reducer + ASI 2600

Takahashi says the optimal distance from FR back to sensor is 72.2mm. The camera backfocus and filter add to 32.5mm, leaving 39.7mm for adapters that will take us down from M56 to M42. The M56 adapter in the diagram proved to be problematic so instead I'm using these adapters: Blue Fireball M56(f) -M48(m), M48(f)-M42(m), and M42(f)-M42(m), with respective lengths of 12.1, 16.5, and 10mm. This gives a total of 38.5mm, about 1.2mm short. I used the Hocus Focus plugin for NINA to see if this was close enough. The plugin suggested I need to add 3 focuser steps, which translates to a mere 0.011mm. In other words, the plugin agrees with the new setup. I will add another 1.2mm to the adapters and run the plugin again to see what it says.

It's not clear to what extent vignetting will be an issue, but my hope is that it will be largely correctable using flats.

Canon EOS lens + ASI2600

(Note: This has been tested and shown to work. See later post.) The backfocus target here (per the ZWO documentation) is to put 43.8mm between the lens and sensor (26.3 for their adapter and 17.5 for the camera with tilt plate attached). I want the EFW in this train, though, so I remove the tilt plate and use a thin Canon lens to M42 adapter (10mm). This puts it at 10 + 20 + 12.5 = 42.5. Thin spacer rings are used to bring this up to the required value.

Incidentally, this configuration is the reason the tilt plate is missing in all the other configurations. 

Correction: Cam sides of scope and FR are M56 female

 

FSQ-106 Native mode + Canon T2i

The FSQ-106 System Chart tells us we need only spacers provided with the telescope and the Wide T-mount for EOS.

FSQ-106 + CR 0.73X Focal Reducer + Canon T2i

The FSQ-106 System Chart tells us we need only spacers provided with the telescope, TKA35201 and the Wide T-mount for EOS.

LIST of PARTS NOT INCLUDED with FSQ-106EDX4

This lists the adapters and spacers needed to supplement the parts provided with the FSQ-106. They are listed along with their: backfocus, manufacturer, vendor/part #, and price. Very possibly you can find alternative products and vendors, but I'm very happy with Agena and OPT.

    M54 (f) to M42 (m), 6.9mm, Blue Fireball, AgenaAstro/PAAR-BF-T-16, $25     

    M56(f) to M48(m), 12.1mm, Blue Fireball, AgenaAstro/ PAAR-BF-M-24, $43    

    12mm M42 spacer, 12mm, Celestron, OPT/CE-93618, $40 

 

    10mm M42 spacer, 10mm, source unknown        

    EOS to M42 (m) adapter, 10mm, QHY, AgenaAstro/PAAR-QH-20072, $35

    TKA35201, NA, Takahashi, OPT/TK-TKA35201, $82

    Wide T-mount for EOS, NA, Takahashi, OPT/TK-TMW0004, $167

    Thin M42 spacer rings, 0.1 to 1.0mm, Blue Fireball, AgenaAstro/PAAR-BF-S-SET7, $40

HELPFUL LINKS

https://agenaastro.com/

https://optcorp.com/ 

https://www.takahashiamerica.com/

https://astronomyplus.com/wp-content/uploads/2019/08/Takahashi-Adapter-Specifications.pdf

Finally, An Image!

 It's been three years since my last pretty image, not including the spectra. This is the first image taken with my transitional platform that's built around an AT65EDQ imaging scope, Losmandy G11G mount, and SBIG ST-8300M CCD. On the software side it uses APT, Stellarium, and PHD. 

I chose the Cocoon Nebula (IC 5146) and collected the following frames:

• Luminance: 12 frames @ 5 minutes each, unbinned, CCD cooled to -10C
• color filters: 12 frames each, 2.5 minutes, binned 2x2, -10C
• 24 dark frames at each bin/time/temperature combination used
  

I processed it using Images Plus and Photoshop.

Cocoon Nebula (minimal crop, scaled)

I'm really pleased with the performance of the G11G--the stars are nice and round. My processing left a lot to be desired, though. I clipped the dark end of the histogram and did not do a good job getting rid of the sky gradient; doubtless there are other shortcomings. But still, given that this was imaged through a white zone sky (Bortle 7.5) with only LRGB filters, I'm pleased.

Link to Astrobin page for this image

Next up is learning PixInsight, and with some luck the smoke will abate and I'll be able to travel to darker sites.

Smoke and the Nebraska Star Party

I registered and had purchased a park sticker. A few days before my planned departure to the Nebraska Star Party I assessed the smoke situation and decided not to attend. My personal judgement was that it wasn't worth the travel expense and hours of driving to seek out what would probably be mediocre sky.

Last night I was at a friend's house north of Minneapolis and the effect of the smoke was obvious. The limiting magnitude was around 4 instead of the usual 5.5. Extinction due to smoke was costing us somewhere around 1.5 magnitudes.  That translates as requiring exposure times to be 4 times their normal values.  

Looking at satellite loops suggests the smoke blanketed NSP the first three nights (Sunday, Monday and Tuesday nights). Wednesday night was probably the best of the event, but even then there were occasional clouds combined with smoke. Thursday night's forecast is for fewer clouds but more smoke. 

Considering the five nights from Sunday through Thursday, recent years have not been kind to NSP. In 2019 it rained four of those nights. If NSP 2020 had taken place it would have provided maybe five hours of good quality imaging, unfortunately coming as three hours one night and two another. This year's NSP 2021 may have been a complete loss for imaging unless you're willing to image through smoke.

I'm beginning to think I was spoiled by my first three NSP trips (2014, 15, and 16).

The question is if this is just a bad run of weather or an indication of some sort of "new normal" as the climate warms and wildfires become a regular feature of summer.

Time will tell. And while we wait, get fully vaccinated if you aren't already!

Get Vaccinated NOW.

Both my wife and I are now fully vaccinated: 2 jabs each and well past the time needed for them to take effect. It's very liberating after over a year of being in near-isolation! I can go to the hardware and grocery stores and shop -- no more curbside pickups. And it means when I'm ready I can hang out at the Club's dark-sky site and do some imaging.  My friends are all vaccinated so we don't have to worry about sharing the virus. In other words it's back to our pre-pandemic lives.

So if you're a vaccination holdout keep these little factoids in mind:

1. You're keeping health workers overworked because a certain percent of you will require hospitalization or you'll become long-haulers. Oh, funeral homes will also be busier because a small percentage of you will die.
   
2. You're already keeping the economy from returning to normal as fast as it might otherwise. This hurts everyone, including you. Have you been complaining about how "overreaction" to the virus has hurt the economy? That's what you're doing now.
   
3. You're placing at risk those who vaccination might not protect sufficiently. Remember, it's only 95% effective, and possibly less against variants. Know anyone with COPD or is on chemotherapy? Pass the virus to them and you will be responsible for the suffering they will endure.
   
4. Speaking of variants, you're doing the virus a favor by helping it hang around and create even more variants.
5. If you're holding out because you think there are "microchips" in the vaccine or it's some other kind of ludicrous plot against freedom or whatever...get some professional help because you've lost touch with reality.
6. What you're doing is following the very slow road to herd immunity for no reason. The people who will pay dearly for this are you holdouts and the few unlucky immunized people who you pass the virus to. The one thing you have going for you is that the crush of hospital admissions is now in the rear view mirror thanks to those of us who have gotten our jabs. You're welcome.
   

In other words, avoiding the jab is foolish and callous if not actually hypocritical and delusional. Good luck to you.

------------------

Some upgrades coming to my imaging system: I'm going solar! No more lugging two big heavy batteries around. Just one smaller one and a solar panel.  Even on a cloudy day it should be capable of replenishing the battery with enough power for another full night of imaging.

Also a new power junction box with a built-in dew controller.

On backorder and coming later this year is the big upgrade: an FSQ-106. Also a camera (ASI2600MM Pro) to replace my old SBIG ST-8300M. New filter wheel and OAG for it, too.

More about all this as it gets delivered and put to use!

Get Vaccinated!

I've now had my first jab of the Moderna vaccine. In fact, it was 20 days ago. The side effects were limited to a barely sore arm for about two days.  In eight days I get jab #2, and by April 20 I will be almost fully immune to COVID-19. I'm going to celebrate with a much-needed haircut.

After that I'll resume astrophotography from the club's Cherry Grove site and a friend's dark, relatively treeless back yard. And I'll be able to attend the Nebraska Star Party, too!

According to the WHO here are the people who shouldn't get a mRNA-based jab:

Individuals with a history of severe allergic reaction to any component of the vaccine should not take this or any other mRNA vaccine.

While vaccination is recommended for older persons due to the high risk of severe COVID-19 and death, very frail older persons with an anticipated life expectancy of less than 3 months should be individually assessed.

The vaccine should not be administered to persons younger than 18 years of age pending the results of further studies.

If you're not in one of those categories, then you have no reason to avoid the vaccine. 

Oh, you're not getting vaccinated because of something you've read on the internet? You've bought into the lies and bad science some people with political agendas are spreading? Fine, be a stooge. Chances are you'll only have mild symptoms if you get COVID.  Or maybe you'll have to spend a few days in a hospital bed, and then spend the next few years wondering if you're going to have chronic fatigue the rest of your life. No problem! At least you avoided the vaccine. Good luck to you and your loved ones.

---------------

Next time: I'm about to start a major upgrade of my imaging system: A new scope, camera, and processing software!

---------------

Follow-up: Our stimulus money didn't sit for more than a few hours in our bank account. Half went to Second Harvest, and half to St. Stephen's to help them assist the homeless. I hope you found a way to put your dollars to work for others, too. 

 

Donate Your Stimulus Checks

IF you are relatively untouched financially by the pandemic (and a large number of us have that good luck) you have a choice about what to do with your stimulus check(s). You could:

• Use the money to buy something for yourself, your family, or a friend.
• Save or invest the money
• Use the money to reduce your debt (mortgage, credit card, whatever)
• Donate the money
• Assist local businesses by buying their products or services
  

Those are certainly all good ways to dispose of the windfall and I'm not going to tell you one is better than the others; only you can make that decision.

I am going to encourage you to consider the last two options.

This pandemic has really hit the service sector hard, and particularly people whose earnings are lower. They've faced reduced hours, pay reductions, and complete loss of their jobs. In many cases they are trying to support a family. Eventually things will improve but while we wait for that they may be scrimping on food and medicines. One big way to help is to make sure they can find the food they need. 

Consider making a donation to your local food shelf. 

Further, there are those who are homeless, people who can't afford even the basic necessity of shelter during winter. Your donation can help provide them with a place of refuge. 

Consider making a donation to your local homeless shelter.

About that choice of patronizing local businesses? It's a good one, too. Many that serve the public have been forced to close in order to slow the spread of the pandemic. They've been asked to make a great sacrifice for the greater good. In other words, they're suffering financial hardship to keep you and your families healthy. At some point those of us they protected will want to show our appreciation, right? 

That appreciation can be in the form of our support for programs that will provide small businesses with relief. Yes, I know, that will mean raising our taxes, but don't small businesses deserve compensation for the sacrifices they're making on our behalf? I think it's safe to say keeping small businesses alive is a good thing. While we wait for those compensation programs to materialize:

Consider patronizing your local small businesses.

Sure, a new telescope or other piece of gear would be nice, but these are hard times for a lot of people. Pitch in and maybe more of us can make it to a better place together.