Setting up the E160-ED for Full Frame Imaging Takahashi Epsilon-160ED · Dark Matters Astrophotography · ... · 1655 · 60487 · 369

Kaptas Attila:
If i would go for mono what for filters would you recommened for Epsilon? My camera is defect and i have to send it back to Germany, maybe when they cant fixed it i am gonna ask for a change in. 
Thank you for any advices.
Best
Attila

I'm using astrodon NB and chroma LRGB. 

I am getting halos with Oiii on mag 2.5 stars.  I'm considering selling all of my astrodons and chromas to get astronomiks. I've asked Bill to do a gamma Cass test shot with his O3 maxfr filter for a comparison.

Happy to do the test.

When I shot Jellyfish, a few years back, I was using 5nm Astrodon OIII.

Tejat and Propus were both in the frame:

Tejat:


Propus:


Final image:
Jellyfish Nebula (rockstarbill) - Full resolution | AstroBin

This is actually what prompted me to get 3nm Chroma filters instead of the ADons. While I never tried photographing these two stars again, I never did run into any halo problems.

In testing the MaxFR filters I did take 5 min shots in all three filters of Caph (Mag 2) and did not find any halo effects at all. In my IC1396 image, Garnet Star is in the frame, and while not Mag 2.5 it is Mag 4, which is brighter than Propus at Mag 6 -- and there is no halo effect at all. I will do this test tonight and report back, but my guess is that I will not see any halo effect at all.

Thanks.  Much appreciated.

My halo is way more pronounced than either of those.  Its unfortunate as I otherwise like the filters a lot.  Fingers crossed your test is good... and I'll pickup a set.

Yeah, the Epsilon is much faster than my GTX at F4.5. The camera I used then was the FLI 16200 CCD chip which is far less sensitive than modern CMOS are. 

If you do get some, buy direct from Gerd's site, and use the Credit Card option to pay instead of PayPal as they give you a horrid currency conversion rate.

Bill,

Wow, just WOW!  I looked at your Ha Bubble image in detail at 10:1. The stars in the corners are superb.

One request. Since this is 6 nm bandwidth image and at the long end of the design bandpass it may be hiding some chromatic effects. Do you have a Blue filter image we could look at? The shorter wavelengths are harder for the optical designer when optimizing for the whole spectrum so usually a good test. And at some point an RGB image would be important for things like lateral chromatic aberration which might show up on bright stars at the edge of the field.

One question and some advice, please. It seems there are two variables when fine tuning the camera's position. One is the extension of the focuser tube for the correct back spacing (56.2 without filter and ~57.2 with 3 mm glass filters). The other is the backspacing itself. If the focuser isn't in the right place one might be optimizing camera spacing incorrectly.

I am still using the stock focuser with the telescope colimated best I can at a fixed position angle. So what I have been doing is to try to eliminate the focuser position variable by auto focusing on a DSLR mounted with the Tak wide mouth T-ring adapter. It would seem this puts the camera at the right backspacing and allows the optimum focuser position to be achieved. I then remove the DSLR and install the imaging train (in my case a 54->68 mm adapter, ZWO OAG L, ZWO EFW, Octopi base (3mm thick) and ZWO ASI6200MM). This barely achieves 57.2 mm BFD with the camera clamp ring set to 1.95 mm above the top of the Octopi base - not ideal.

With the focuser set to optimum extension (in my case the stock focuser tube extendds 9.62 mm above the to of the flange to the bottom of the knurled corrector ring) I then adjust only the camera's position using the Octopi. I have to watch the temperature and only have an couple of hours  or so to make adjustments. When I have reached the point of diminishing returns, I finally do an auto focus and check that the final position is within the CFZ of the DSLR focus setting. Of course the slop in the stock focuser adds some uncertainty to this.

Your advice: is this a reasonable way to adjust camera position?

Bill, you have established the gold standard for those of us trying to achieve the highest full frame image quality on the 160ED! What is most important in my view is that you have shown what is possible and what the rest of us can strive to achieve. Thank you and everyone participating in this thread.

Bob Fugate

I have blue data, but it was from before I fixed the field with the new setup and the Octopi, so star quality will not be the same as today. 

Iris Nebula (rockstarbill) - Full resolution | AstroBin

This was taken with the Epsilon QHY600 combo in those days, and I think the star color is quite nice. I probably could have done a better job in processing, but I think the scope is superb in terms of nice star colors.

As for back focus, you want the distance from the corrector to the chip to be accurate. This is a bit of a challenge however, as not all cameras are exactly as the manufacturer states in terms of the camera back focus so using some shims or other solutions to fine tune the backfocus is highly recommended. I have not noticed any difference in where the focuser lands when at best focus. I have shifted my Leo fully inward, which puts me at about 96k steps in-focus. I have been at varied positions previously: 16k, 18k, 30k and those changes did not have any effect I was able to notice.

I am not sure if what you explained is a good way to adjust it. What I have been doing is taking a series of photos around the CFZ (center single star focused) and watching to see what the corners do in terms of star quality. If the corners improve with focus moves in, the chip needs to move out, and vice versa. This is tedious, but if you really want to dial it in, this is what is needed. If you have achieved good focus across the field, and you still see chevron shaped stars near the corners, you will need to adjust the back focus, then try again. If individual corner pairs move in opposite directions, then you have tilt and can fix that with the Octopi.

I am glad this info has been helpful for people. I have been working on this scope and the field with the big chip now for about one year, and it has been a labor!

I am glad this info has been helpful for people. I have been working on this scope and the field with the big chip now for about one year, and it has been a labor!

Bill, it's a big understatement, believe me . What you have been testing and doing for weeks are way much than helpful, it's like a dynamic FAQ with everyday a new answer to a new question 

No Halo on Sadr. There is some interesting glow pattern, not really sure what to make of it, but no halo. 

This was 10 mins, MaxFR OIII, High Gain Mode 56/40. Sadr is offset to the same place Gamma Cas was in your previous image @Chris White.



Full Test Sub: https://www.dropbox.com/s/h7e2x0qc2mfti71/TestShot_20220908_204330.fit?dl=0

Sorry for the tree bits on the left. I need to move!

Looks good.  The scatter is just probably some atmosphere illumination.  Sadr combined with the nearby full moon...

I found Halos on my HA data this morning.  So yeah, time to order som Gerds.

Aygen:
@ Chris : further to the MaxFR filters, do you plan to order the DeepSky filters with the L2 ? I have a doubt about which one to get. I remember Bill thoroughly advised about it but I can't my notes anymore 

Yes I use the Deep Sky RGB with L2 Luminance and the 6nm MaxFR. All in 50mm round.

Aygen:
@ Chris : further to the MaxFR filters, do you plan to order the DeepSky filters with the L2 ? I have a doubt about which one to get. I remember Bill thoroughly advised about it but I can't my notes anymore 

Yes I use the Deep Sky RGB with L2 Luminance and the 6nm MaxFR. All in 50mm round.

Thank you my friend - let's order them ASAP.
Wish you all an excellent weekend.

Here is a stack of 100 x 5min HA frames:

https://www.dropbox.com/s/4spa3qify5aw4z7/HA.fit?dl=0

While there is always room for improvements, I think this is the best place this scope has been at in terms of the field.

Bill,

Wow, just WOW!  I looked at your Ha Bubble image in detail at 10:1. The stars in the corners are superb.

One request. Since this is 6 nm bandwidth image and at the long end of the design bandpass it may be hiding some chromatic effects. Do you have a Blue filter image we could look at? The shorter wavelengths are harder for the optical designer when optimizing for the whole spectrum so usually a good test. And at some point an RGB image would be important for things like lateral chromatic aberration which might show up on bright stars at the edge of the field.

One question and some advice, please. It seems there are two variables when fine tuning the camera's position. One is the extension of the focuser tube for the correct back spacing (56.2 without filter and ~57.2 with 3 mm glass filters). The other is the backspacing itself. If the focuser isn't in the right place one might be optimizing camera spacing incorrectly.

I am still using the stock focuser with the telescope colimated best I can at a fixed position angle. So what I have been doing is to try to eliminate the focuser position variable by auto focusing on a DSLR mounted with the Tak wide mouth T-ring adapter. It would seem this puts the camera at the right backspacing and allows the optimum focuser position to be achieved. I then remove the DSLR and install the imaging train (in my case a 54->68 mm adapter, ZWO OAG L, ZWO EFW, Octopi base (3mm thick) and ZWO ASI6200MM). This barely achieves 57.2 mm BFD with the camera clamp ring set to 1.95 mm above the top of the Octopi base - not ideal.

With the focuser set to optimum extension (in my case the stock focuser tube extendds 9.62 mm above the to of the flange to the bottom of the knurled corrector ring) I then adjust only the camera's position using the Octopi. I have to watch the temperature and only have an couple of hours  or so to make adjustments. When I have reached the point of diminishing returns, I finally do an auto focus and check that the final position is within the CFZ of the DSLR focus setting. Of course the slop in the stock focuser adds some uncertainty to this.

Your advice: is this a reasonable way to adjust camera position?

Bill, you have established the gold standard for those of us trying to achieve the highest full frame image quality on the 160ED! What is most important in my view is that you have shown what is possible and what the rest of us can strive to achieve. Thank you and everyone participating in this thread.

Bob Fugate

I have blue data, but it was from before I fixed the field with the new setup and the Octopi, so star quality will not be the same as today. 

Iris Nebula (rockstarbill) - Full resolution | AstroBin

This was taken with the Epsilon QHY600 combo in those days, and I think the star color is quite nice. I probably could have done a better job in processing, but I think the scope is superb in terms of nice star colors.

As for back focus, you want the distance from the corrector to the chip to be accurate. This is a bit of a challenge however, as not all cameras are exactly as the manufacturer states in terms of the camera back focus so using some shims or other solutions to fine tune the backfocus is highly recommended. I have not noticed any difference in where the focuser lands when at best focus. I have shifted my Leo fully inward, which puts me at about 96k steps in-focus. I have been at varied positions previously: 16k, 18k, 30k and those changes did not have any effect I was able to notice.

I am not sure if what you explained is a good way to adjust it. What I have been doing is taking a series of photos around the CFZ (center single star focused) and watching to see what the corners do in terms of star quality. If the corners improve with focus moves in, the chip needs to move out, and vice versa. This is tedious, but if you really want to dial it in, this is what is needed. If you have achieved good focus across the field, and you still see chevron shaped stars near the corners, you will need to adjust the back focus, then try again. If individual corner pairs move in opposite directions, then you have tilt and can fix that with the Octopi.

I am glad this info has been helpful for people. I have been working on this scope and the field with the big chip now for about one year, and it has been a labor!

Bill, thanks for these details. Makes sense and I will incorporate in my quest. Greatly appreciated. Bob

Here is a stack of 100 x 5min HA frames:

https://www.dropbox.com/s/4spa3qify5aw4z7/HA.fit?dl=0

While there is always room for improvements, I think this is the best place this scope has been at in terms of the field.

Incredible data, Bill. And nothing that I would bother regarding the upper left of your image. I am too very demanding but honestly speaking, that's just very very good.

PS : what are you waiting for publishing a crazy great image

Derailed for getting more data on Bubble Wide for the time being, due to fires here.

So, here is the processed HA: Bubble Wide Field - HA Only (rockstarbill) - Full resolution | AstroBin

Pretty impressive for 8 hours of data.

John Hayes:
Bill,
I can see just a little bit of elongation in the upper right corner but in my book it falls within the acceptable range.  Overall, I don't think that you'll get any better than that.  This is very impressive performance over such a hug field.  I'm impressed!

John

Thanks John! Yeah, I think there is a tiny amount as well, but it would probably be more harmful if I tried to do anything about it. I was quite pleased with the end result here. After a year or so of working on this combo I am finally at peace with the frame quality.

@Bill Long i know i already asked before, but are you using some secondary mirror heater or you are just using your fan at the back of the primary?

Best
Attila