11.02
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So you have it setup now to pull air from the ota and exhaust out? Yes, I decided on that since shooting bugs into my scope did not sound pleasant. When you get the Noctua just make sure it is mounted with the logo sticker facing out. |
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11.02
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Chris mentioned small offsets to the focus, which may slightly improve the field. I though this was an interesting experiment so I whipped up a quick DragScript in Voyager to test this later tonight: |
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11.02
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What a night of testing, and tweaking. After running the fan for 26 hours straight and covering the scope to shield it from the sun, there were a few tweaks I needed to make in NINA with the Octopi to get back to my ideal state of 3 micron or less correction. That is a horizon I have already overcome though and was not the pivotal point I wanted to dig into. After all of this work, and trust me, I have been on a long journey with this scope -- the last thing I wanted to figure out, with data in hand -- was the ultimate question! How do I focus, this system, in the best way possible. This is the new mission for me! For me and the system I use to run my telescopes (Voyager) there are three realistic options: 1. Single Star with Robofire 2. LocalField with Robofire 3. Single Star with Robofire + a small offset (suggested by Chris "The One Who Knocks" White). When I thought about this logically, I assumed Heisenberg (Chris) was wrong. I thought Local Field should offset as well, so why would I need to manually do so? Well, thoughts and assumptions are one thing, let's look at the data: Looks like the -125 offset, as the master of meth-like Vermont Maple Syrup suggested, seems to be quite good. A little better than local field focus (which did pretty well, IMO). But let's test this with less pressure on the CFZ (HA). Single star focus vs Single star with a -125-step offset: Remarkable difference. I visually inspected all of these deltas, and the -125 step data was better. It seems that Mr. White is not only good at making Maple Syrup (he is - buy this stuff: Organic Pure Vermont Maple Syrup- Glass Jug) he is also very good at figuring out ways to solve field issues.  I would be remiss if I just sat here and mumbled. Data here: https://www.dropbox.com/sh/s470zobje8ynrhw/AACYWTrZ1jSIov0XT-hAfr9ya?dl=0 Lots of it, so go through it yourself. Draw your own conclusions. For my next project I will try Maple White's suggestion and see what the project shows. Based on this testing, I think it will be optimal for this telescope. Cheers, Bill PS -- I made jokes and references to the television show "Breaking Bad" here. |
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11.02
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Some measurements for people that might not know to do so themselves: PI:  CCDI:   I would call this a wrap, gents. Strong emphasis on the seeing. Median of 1.5 pixels? Unheard of here and this system is up to the task (check the data)! Lets go!  |
20.43
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The problem in my opinion with field focus is precision and accuracy ( i.e predictable repeatability). You might get lucky and hit the sweet spot but not over and over again. With a 9 point v curve, field focus is prone to error. A bad sub, for example can throw off the focus estimate. Also the curve depends on only 4 points in either side of focus to establish slope. With single star in voyager about 40 points are analyzed then averaged with multiple v curves to establish a relative hfr baseline. Because focus is predictable you can rely on this comprehensive analysis to accurately and precisely achieve focus. Applying an offset is becomes academic and you can get the same precise and accurate result every time. In this case you can use focus to counter the effect of field curvature. It doesn't take much of an offset to impact off axis stars. For epsilon I have found that all you need is a 10 micron focus offset in the opposite direction of backspacing error. (All systems will have some level of backspacing error no matter how careful you dial it in) . Glad it helped Bill! |
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11.02
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| It was definitely useful. I'll be testing this setting on my next project to see how it does on a long integration. |
4.88
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Thank you all for having contributed to this article ! I am expecting to get my e-160ed by end of this year. Icing on cake, Tak Europe will install the Leo as well as the collimation directly. Very looking forward to it. Meanwhile, to be ready to fight any tilt issue, what would you recommend ? I have read many positive reviews with regards to the GERD CTU. I came to learn about the Octopi lastly. Anything. Thank you and all the best. |
1.51
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To Bill Long: Bill, could you provide a bit more detail on how you mounted the Noctura fan on the back of your 160ED? In particular did you use some sort of adapter between the hole pattern on the back of the telescope and the fan or any kind of vibration isolation material? Thanks, Bob Fugate |
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20.43
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Thank you all for having contributed to this article ! The Octopi is certainly easier to dial in than the Gerd. Having a screw for each corner makes using tools like Hocus Focus very easy. A half turn on the octopi screw corresponds to about 15microns of optical tilt adjustment. You just cant get that kind of precision with a coarser thread 3-point collimation system like the Gerd. That said, it really depends on what your camera is. If you are using a full frame camera and want perfect stars, Octopi. If you are using an APS-C camera or smaller then it will be easier to dial in and the much less expensive Gerd would work well. It is a very nice system afterall, and I have used it and have recommended it. Also, backspacing is important. If you have a mono camera with filter wheel you may or may not have the space for the Gerd. It takes up 17.3mm of spacing. The Octopi is only about 5.5mm depending on your camera. |
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4.88
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Thank you Chris for chiming in. I will most probably be using my asi 2600 mm pro (APS-C). My imaging train should be as follow : camera > EFW > CTU ? > fine tuning rings. It would be easier to keep it as it is (with OAG), but I don’t see much leeway left if I want to have have something ready to tackle any tilt issue. |
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11.02
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Thank you Chris for chiming in. With the Octopi you can fit an OAG rather easily. |
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4.88
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Thank you Chris for chiming in. Really ? So, I need to read a bit about it and discover how to fit it in my imaging train. |
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11.02
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To Bill Long: Hi Bob, I used this 3D Printed solution: https://www.thingiverse.com/thing:4734957 4 M4x30 mm screws are needed. I clipped off the motherboard connector and plugged the red and black wires into a 2.1x5.5mm barrel jack to power it from the Ultimate Powerbox. The yellow wire you can ignore. I just clipped it further down so it was out of the way. No vibration mitigation was needed. The Noctua fans have anti vibration measures built in. It comes with standoffs but those aren't needed. |
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20.43
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Thought I would share my Epsilon first light! I still have some tweaks to make on spacing, but overall this is extremely encouraging! I'm stoked about this scope. |
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4.88
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Thought I would share my Epsilon first light! I still have some tweaks to make on spacing, but overall this is extremely encouraging! I'm stoked about this scope. Yeahhhh, incredible scope. Gorgeous ! Looking forward to having it in a few months |
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11.02
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Thought I would share my Epsilon first light! I still have some tweaks to make on spacing, but overall this is extremely encouraging! I'm stoked about this scope. It really is an incredible scope. It's a perfect match to the Mach 2. |
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11.02
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Enjoying some Cygnus imaging tonight, with this excellent astrograph and my QHY600PH-M! Could not be happier right now.  |
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4.88
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Are you going to reiterate a 65h of integration time ? Joke aside, marvelous scope Bill. I can't wait for it even though I must admit that my TOA is giving me full "satisfaction" By the way, I have made up my mind > I will get the Octopi too even though I wont be able to fit my OAG (I am missing a few millimeters). The most recent version of the ASI interface takes up a minimum of 3.5 mm. The installation doesn't seem complicated (from what I have seen via videos). However, what about the fine tuning, anything to cautious about ? |
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11.02
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Are you going to reiterate a 65h of integration time Not going that deep this time, in fact I have had enough cloud interference tonight I will probably just salvage some of this HA, snap a bit more tomorrow and move on to SII and OII. I have a TOA150 here as well, and it is a very good scope, just not as fast as the banana is. How to tune and use the Octopi, I think Chris "Heisenberg" White can answer far better than me. |
1.20
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Thanks a lot for your feeback and all the tips, it is really helpfull. @Bill Long@Chris White you did good job  I own a 160ED since early June. My camera is the 2600MMP. My first picture was the seahorse : https://www.astrobin.com/nv9u8k/ I've done it real pain dealing on tilt issues EVERY night. // I'm using the GERD Neumann CTU. For the second picture (Cave Nebula : https://www.astrobin.com/full/51rfxn/0/) I bought the Moonlite focuser. The tilt didn't moove for all my shooting week. The stars were not perfect but friends of mine reminded me "le mieux est l'ennemi du bien" (the best is the enemy of the good). For my third image I want perfectly round stars  I started test with a DSLR (Cannon 500D) - the sensor is supposed to have no tilt. But one of the corner is ko. => I think I will start by remooving and reinstalling the saddle of the focuser I may need your help in the next weeks to analyse the images. Thanks a lot ! |
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4.88
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« Bon courage à toi cher Julien » I am sure that you will reach a point where you will have « perfect » stars all over. Don’t lose faith. That’s why I am ready to remove my OAG for perfectly well rounded and shaped stars ! I will most get the Octopi. PS: excellentes images |
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1.20
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Aygen: Thanks a lot Aygen ! Aygen: This could be the solution for me too but I don't know if there are shipments to France. I'll ask Keith. Frist the Saddle. Step by step  Have fun with your Epsilon frist lights ! |
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4.88
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Julien Dufour:Aygen: I hope they deliver to Europe. If not - I will have to find a plan "b" (ask someone from the US to have it first, and then dispatch it to me.... |
3.58
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I have my order placed for the Optec Leo and it is estimated to be delivered around the end of September. I bought the Gerd Neumann CTU and it was delivered last week. I noticed that it was mentioned the Octopi CTU was easier to use for full frame cameras. I'm planning on using my ASI2600MM with my 160. Do you think it is worthwhile to upgrade to the Octopi with an APS-C sensor (there may be an upgrade in the next year to full frame so i think i answered my own question)? I think i can still use the Gerd Neumann CTU with my iDK (much more back space available) so at least i can still use it. I also saw that you were using Hocus Focus in NINA for adjusting tilt. Is that better/easier than using ASTAP or CCDInspector? I use NINA but I haven't installed that plug-in yet. Thanks! |
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20.43
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Are you going to reiterate a 65h of integration time Ha... I doubt that. The main challenge with the Octopi when used with the e160ed is that because it is on top of the OTA you are fighting gravity when locking the "brake" screws. This creates a cantilever effect, or tilting of the entire unit which can cause inconsistent locking positions. The way to counter this (as Bill figured out) is to only loosen two of the four locking screws at a time. That way you always have some brakes engaged. So if you want to make an adjustment on the lower left corner, you would loosen the brake for the lower left and upper right. Make your adjustment and then snug both brakes back down. You want the brakes snug but not so tight that you cant get the plate to pivot inside. You'll get a feel for it after spend some time with it. The fine thread screws are very delicate. make sure you dont torque these. If you cant turn them, you need to loosen more brakes. You dont want to damage the screws. Definitely use NINA Hocus Focus. A little trial and error to see what happens will teach you more than you can learn by reading. Once you have started, if you run into trouble... post here and we can help! |
