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asi2600mm Duo (any practical experience?)

ZWO ASI2600MM DUO Duo-Narrowband Narrowband
Nick GrundyOscarBill Becher
•25 replies•1.2k views
Nick Grundy avatar
Nick Grundy avatar
Hi All, I was looking at this and though I love the idea of ditching my guidescope on my epsilon160, I'm trying to fathom how significant a change this would be. (since I already use an asi2600mm)

I've noted that wider narrowband filters would also be required (something in the 6-8+ nm bandpass). I'm also thinking that my image sequence might need to evolve. I usually do a sequence of 3-6 exposures with each filter cycling through. That doesn't require stopping/starting guiding, but with a camera like this behind the filter, maybe it would? 

Looking for any practical knowledge of using these DUO's. 

thanks and CS
Nick
Bill Becher avatar
Bill Becher avatar
I had difficulty tracking through RGB Optilong filters with the ASI2600 Duo Mono on a Celestron EdgeHD 11" and OAG.

I suspect that this would work best with a color camera at shorter focal lengths.
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Nick Grundy avatar
Nick Grundy avatar
Bill Becher:
and OAG.


thanks Bill, was the OAG unused but still in the optical train? 

assuming you were at the native F10, I could imagine that being difficult. I'm planning on 530mm FL, so hopefully that would be a sufficient amount of stars?
Bill Becher avatar
Bill Becher avatar
Nick Grundy:
Bill Becher:
and OAG.


"thanks Bill, was the OAG unused but still in the optical train? "

Oops no OGA, just a filter wheel.  I was using a .7 reducer so was at F7.7 Focal length was 1,975 mm.
Nick Grundy avatar
Nick Grundy avatar
I'm guessing there's a decent lumination fall off at the edge of the image cirlce under a filter (they cite a 42mm circle) combined with the focal length makes it very tough on guide star selection

In contrast, does the OAG perform well for you? (seems like it does most with the edge11)
Bill Becher avatar
Bill Becher avatar
Nick I have had better results with an OAG on the edge11.  I tried the Celestron OAG but the ZWO OAG L works better probably because it comes later in the optical train and gets more stars.

I am using the ZWO 174 guide cam as it has a larger sensor. Getting the backfocus right with the edge is the problem I ordered a custom adapter so that I can use the Askar backfocus adjuster to fine tune the backfocus.

I sold the Duo
Brian Puhl avatar
Brian Puhl avatar
I think it's fair to say the 'Duo' cameras were designed with one user in mind….   The RASA user. 

Beyond that, I can't comprehend why you'd ever want one.  It's not the greatest idea.
MaksPower avatar
MaksPower avatar
(deleted)
Nick Grundy avatar
Nick Grundy avatar
FYI, i bought one of these (despite Brian thinking its terrible idea) and am pleasantly surprised. In a situation where you don't have the backfocus for OAG, but want to keep the load lighter, it works well. 

a couple notes though
  • Ive tried mine with 3nm SHO filters and the guiding can be challenging. guide stars can still be found and work, but it's almost not working. 5-6nm SHO filters are probably better if you can tolerate that with your sky
  • If you want to shoot mono on a widefield setup, it's quite useful. (especially LRBG) It's nice to drop a scope, focusing that scope and the extra camera connections
  • If you are using an automated routing like NINA, you'll want to modify your sequence actions to stop guiding, switch filters, then restart guiding when you change filters for main camera imaging (something I had to adjust and takes extra time in your night)
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Jeremy Jackson avatar
Jeremy Jackson avatar
Brian Puhl:
I think it's fair to say the 'Duo' cameras were designed with one user in mind....   The RASA user. 

Beyond that, I can't comprehend why you'd ever want one.  It's not the greatest idea.

Paired with RedCat71 - it works well
Nick Grundy avatar
Nick Grundy avatar
Jeremy Jackson:
Paired with RedCat71 - it works well


definitely! I actually had mine on my redcat51
Oscar avatar
Oscar avatar
Nick Grundy:
FYI, i bought one of these (despite Brian thinking its terrible idea) and am pleasantly surprised. In a situation where you don't have the backfocus for OAG, but want to keep the load lighter, it works well.

I have a question that is a tiny bit off-topic

I've always wanted a Blue Fireball rotator on my newt, to frame my objects better

but my backfocus doesn't support it, because I have a 17.5mm backfocus camere, an OAG and filter drawer, all of which takes up the whole 55mm backfocus

I have three options:

1. remove the filter drawer and attach my filters to the outside-facing filter thread on the coma corrector
2. get a Rowe coma corrector and keep the OAG and filter drawer
3. keep the current coma corrector and the filter drawer, remove the OAG and use a 2600mc duo instead

all three options would give me enough backfocus to use the rotator

which would you (or anybody else) choose?
Nick Grundy avatar
Nick Grundy avatar
17.5mm backfocus camere,


which camera are you using? I know you can remove the tilt plate from the ZWO cameras, which gets you another 5mm. (though I don't know how the filter drawer attach then) 

I was already in the market to get another 2600mm, so the DUO made sense for me. Buying the camera just to deal with the backspace, seems like an expensive solution.
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Alex Nicholas avatar
Alex Nicholas avatar
I've seen reviews where people have guided perfectly fine through 6nm narrowband filters with the duo. The question is, how does your mount like to perform? I can happily use 3sec guide exposures, because the periodic error of my mount is low frequency and very low amplitude… I know that harmonic mounts suffer from eratic, high frequency and reasonably/very high amplitude periodic error, so people typically require 0.5~1s guide exposures to tame them nicely. Not sure you'd be able to run a 0.5s guide exposure from behind a 3nm Ha filter (unless your optics are REALLLY fast) 

I'm considering a 2600MM Duo for my rig, but again, I can run 60s unguided exposures with less than 1 arc sec of drift, so I can run 5 sec guide exposures, or stack multiple 2sec guide exposures and maintain a perfectly acceptable level of precision..
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Oscar avatar
Oscar avatar
Nick Grundy:
17.5mm backfocus camere,


which camera are you using? I know you can remove the tilt plate from the ZWO cameras, which gets you another 5mm. (though I don't know how the filter drawer attach then) 

I was already in the market to get another 2600mm, so the DUO made sense for me. Buying the camera just to deal with the backspace, seems like an expensive solution.

asi533mc pro

it's actually 6.5mm in the camera itself

but with the 11mm ring that comes with the camera, it's 17.5

the rotator takes up 13.5mm
Brian Puhl avatar
Brian Puhl avatar
Nick Grundy:
FYI, i bought one of these (despite Brian thinking its terrible idea) and am pleasantly surprised. In a situation where you don't have the backfocus for OAG, but want to keep the load lighter, it works well. 

a couple notes though
  • Ive tried mine with 3nm SHO filters and the guiding can be challenging. guide stars can still be found and work, but it's almost not working. 5-6nm SHO filters are probably better if you can tolerate that with your sky



You pretty much noted right here why I think it's a terrible idea       Unless you have a high end mount, you need reasonably fast updates to account for periodic error.   Especially this day and age with all the harmonic mounts being the craze.   Portable or not, they have some of the worst periodic error of any mounts on the market and require high speed updates.
Beat Wirthmueller avatar
Beat Wirthmueller avatar
Hi Nick - I'm using the ZWO 2600MC duo for almost a year now. First with a RedCat 51 on a StarAdventurer Gti followed by the ASKAR 103 Apo on the ZWO AM5 Mount with harmonic drive. With both settings the 2600MC duo is controlled by the ZWO AsiAir Pro and I'm very pleased with the guiding. I'm also using filters like the Optolong L-Extreme and with some fine tuning get excellent results from my point of view.
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Nick Grundy avatar
Nick Grundy avatar
Brian Puhl:
require high speed updates.


I think that's probably the most notable caveat. Don't use the DUO with tight narrowband filters if you also need short exposures in PHD2 for guiding. 

I tested 2s guide exposures last night with the DUO with Optolong SHO 3nm filters. Ha was definitely problematic depending on where in the sky i was tracking. On the HEM44EC (which is only half strain wave in RA) I bumped to 3.5s exposures and didn't struggle with guide star selection. 

So if you do DUO, just keep that in mind. Otherwise, it seems like a viable path if you don't have the backfocus for OAG
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Eric Willis avatar
Eric Willis avatar
My duo works great with a redcat 71, AM5, and 3 nm Optolong L-ultimate filters. I have to use a guide camera setting of 350 gain (with dark library) and 2 second exposures, but still manage to guide around 0.75" on an average clear night.  On a great night, I've seen guiding down to 0.3" to 0.4"
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James McHugh avatar
James McHugh avatar
I will add my opinion in case someone reading this considering purchasing this camera.
I use this camera with a 12" f/4 Newtonian and a TOA-130NS with Baader 6.5nm SHO filters. I tend to use about 4 sec exposures, so I am not chasing the seeing. Shorter exposures would also be fine. I have never had any problem finding guide stars. I previously use a SBIG STL which is also self-guiding and finding even a single guide star could be challenging at times, but there is no comparison - the ZWO is light years ahead. I image at -10C while previously on the SBIG I would go to -20C but the ZWO can't do that and -10C is enough for the CMOS chip.
The only glitch I have found is the native ZWO drivers for the guider in PHD2 have some issues  - sometimes the image is noisy?  I use the ASCOM drivers and it works fine.
I highly recommend this camera to anyone considering it.
The filter in this link will show you the images I have taken with this camera: https://deepspaceplace.com/images.php?sort=&filter=ASI2600MM
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Tony Gondola avatar
Tony Gondola avatar
Just remember that if something in the unit fails you loose both an imaging camera and your ability to guide. Think VCR/TV combos…
John Stone avatar
John Stone avatar
Oscar:
Nick Grundy:
FYI, i bought one of these (despite Brian thinking its terrible idea) and am pleasantly surprised. In a situation where you don't have the backfocus for OAG, but want to keep the load lighter, it works well.

I have a question that is a tiny bit off-topic

I've always wanted a Blue Fireball rotator on my newt, to frame my objects better

but my backfocus doesn't support it, because I have a 17.5mm backfocus camere, an OAG and filter drawer, all of which takes up the whole 55mm backfocus

I have three options:

1. remove the filter drawer and attach my filters to the outside-facing filter thread on the coma corrector
2. get a Rowe coma corrector and keep the OAG and filter drawer
3. keep the current coma corrector and the filter drawer, remove the OAG and use a 2600mc duo instead

all three options would give me enough backfocus to use the rotator

which would you (or anybody else) choose?

Have you considered getting a large rotator, like M68, and then placing it between the coma corrector and the focuser drawtube?   The large size would allow the coma corrector to be inserted through the rotator.

I believe you'd only need the rotator's thickness in draw-tube in-focus for this to work.
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MaksPower avatar
MaksPower avatar
well…
#1with a mono camera will be painful when you want to change filters.
#2 could work, but why keep the OAG if using the DUO camera ?
#3 means going OSC (as I do).
Oscar avatar
Oscar avatar
John Stone:
Oscar:
Nick Grundy:
FYI, i bought one of these (despite Brian thinking its terrible idea) and am pleasantly surprised. In a situation where you don't have the backfocus for OAG, but want to keep the load lighter, it works well.

I have a question that is a tiny bit off-topic

I've always wanted a Blue Fireball rotator on my newt, to frame my objects better

but my backfocus doesn't support it, because I have a 17.5mm backfocus camere, an OAG and filter drawer, all of which takes up the whole 55mm backfocus

I have three options:

1. remove the filter drawer and attach my filters to the outside-facing filter thread on the coma corrector
2. get a Rowe coma corrector and keep the OAG and filter drawer
3. keep the current coma corrector and the filter drawer, remove the OAG and use a 2600mc duo instead

all three options would give me enough backfocus to use the rotator

which would you (or anybody else) choose?

Have you considered getting a large rotator, like M68, and then placing it between the coma corrector and the focuser drawtube?   The large size would allow the coma corrector to be inserted through the rotator.

I believe you'd only need the rotator's thickness in draw-tube in-focus for this to work.

I have thought about that; I guess I would need to do some DIY work for the coma corrector to attach to a rotator that way, or maybe not, if I remove the stopper ring on the coma corrector and use an M48 female to M68 male ring adapter, or something like that

note that since my last post here, I have abandoned the newt; but I'll get a better one later, thx for the idea.
Oscar avatar
Oscar avatar
MaksPower:
#2 could work, but why keep the OAG if using the DUO camera ?


I believe I meant with a non-Duo camera, because I never had one

my post is an old one and I have since taken another route, but still might get another newt later, thx anyway