Starizona 2” sct6.3 iv reducer - Forums

Topic starter

Apr 27, 2023 · Edited: Apr 27, 2023

I was wondering how far back from the 2” sct threads can i place my reducer without introducing astigmatism or other issues when imaging? If i place a 10mm spacer on the incoming side of the reducer, is that too much? If i insert the reducer into a crayford focuser that is 60mm thick would that be to far?

wondering if anyone has played with this on any of the xlt line of celestron sct’s. Specifically an 8” xlt sct.

End goal would be to use a crayford focuser for imaging with the starizona sct6.3 iv reducer.

gfunkernator

Apr 28, 2023 · Edited: Apr 28, 2023

Well as long as the reducer's rear threads (camera side) are exactly 90.3mm from the camera's sensor, it shouldn't matter. I've never done that with my 8SE and SCT Corrector, since I use the celestron motor focuser.

RammaN

Topic starter

Apr 28, 2023 · Edited: Apr 28, 2023

Yes i realize backspacing in 90.3mm. I have heard that the edges of the corrector start having issues with star shapes the further you place the corrector away from the 2” thread visual back, regardless of backspacing. Was wondering if anyone has had this issue.

Mike H - Sky View Observatory

Jun 14, 2023

I'd like to know this as well. I use a Baader crayford on the back of my 8" SCT so the Starizona unit would be 105mm away from the SCT back (thread). Is this a problem? I think I'll call Starizona and ask.

Lynn K

Jun 14, 2023

I'm not sure of the exact mm spacing from the rear SCT threads. I use A Feather Touch 2" crayford focuser on C9.25. I push the reducer all the way in till it bottoms out on the rear of the focuser adapter. I then pull it back a couple of millimeters. I then set the focuser at haft it's focal tube distance and use the standard primary mirror focuser to bring to focus. The Feather Touch is a 1.5" tube. So, my guess is the reducer is about 1 to .8 inches from the rear threaded SCT threads.

I don't think the distance is crucial, unless you are at an extreme.

I just recently bought the IV. I have been using the III. I haven't done a total imaging session. I only did testing, using a Pegasus Falcon rotater. I was using Starlight Xpress Trius SX-814 which is not large chip but has 3.76nm pixels. The star looked round on center to me. A slite tilt in the train. I also did testing on my C11 to see if it captures higher resolution. I didn't notice any.

This set up is an experiment to see if I can image LRGB galaxies from Bortle 7 skies. I mostly do fast refractor Narrowband imaging.

Lynn K.

Mike H - Sky View Observatory

Jun 14, 2023 · Edited: Jun 14, 2023

Thanks for the reply Lynn. I asked Astro-Physics about the distance of their Telecompressor to the SCT threads and they said it wasn't an issue. Only the distance from the reducer to the camera chip was important. I'm waiting for a response from Starizona. Quite a bit of difference between your 25mm and my 105mm

If Starizona says it doesn't matter, all that's left is to buy it and try it.

Edit: all the reviews say the Starizona corrector is an great piece and the improvement is dramatic.

Lynn K

Jun 15, 2023

I think the AP reducers are not flatteners. I Know my AP TV27 wasn't. Varying the distance changed the reduction amount.

I never did a controlled comparison test of the Starizona SCT III to the IV version. I did often have blotted stars with the III. The stars were much smaller with the IV. However, I used 3 to 5 min subs with the III and only tested the IV using 1 to 2 min subs. I just compared and old 2016 image with the III to a recent one of M51 with the IV. The IV image is definitely sharper, but that may be due to focus. So, no conclusion. I am happy with the resolution I got with the IV. Can I eliminate the gradients from my Bortle 7 skies, is another matter.

Lynn K.

Jure Menart

Jun 15, 2023

I would also be interested in an answer from Starizona, as I think I will also need to buy external focuser in near future.

Mike H - Sky View Observatory

Jun 15, 2023

Lynn and Jure, thank you for your response. You are correct in that the AP unit is not a flattener but just a reducer.

Starizona said,"while the distance is not critical from the back of the SCT to the corrrector, it should be as short as you can make it so as not to effect the reduction amount. Since the barrell is two inches in diameter, the unit should be slid into the focuser as far as possible to minimize the distance." Baader also makes a "ClickLock" attachment for the Baader Steeltrack that I currently own to replace the standard three screw compression ring. This would minimize any tilt on the image train by a better alignment. It would also be a more secure attachment. I think this is the answer to my dilemma. Now I have to spend $500 more on my setup. Fortunately, I only spent $300 on the scope

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Jure Menart

Jun 15, 2023

Lynn and Jure, thank you for your response. You are correct in that the AP unit is not a flattener but just a reducer.

Starizona said,"while the distance is not critical from the back of the SCT to the corrrector, it should be as short as you can make it so as not to effect the reduction amount. Since the barrell is two inches in diameter, the unit should be slid into the focuser as far as possible to minimize the distance." Baader also makes a "ClickLock" attachment for the Baader Steeltrack that I currently own to replace the standard three screw compression ring. This would minimize any tilt on the image train by a better alignment. It would also be a more secure attachment. I think this is the answer to my dilemma. Now I have to spend $500 more on my setup. Fortunately, I only spent $300 on the scope

Mike thanks for update!

I just received my Starizona last week and bought Baader ClickLock to connect it to my SCT. I am quite happy with both. I can see much flatter stars in corners (in 2 corners on 1 side actually) while on the other side they are still fairly bad (but not as before with Celestron 0.63x reducer). I am waiting to receive tilt corrector and I will check if it's only tilt this time (it seems as elongated stars are only on 1 side).

I wanted to avoid additional cost of external focuser - but if I want to sleep at night I think I will need to invest into one. I can't get good results with stock focuser of my old C8 SCT.

Mike H - Sky View Observatory

Jun 15, 2023

Oh it's good to hear a positive report on the Starizona piece and the Clicklock. Thank you Jure. Bad stars only on one side does sound like a tilt problem. I'll be anxious to hear back if the tilt corrector takes care of it. I know the external focuser is an appreciable expense, especially the Baader piece. However, for me it make focusing so much easier. Once focus is near, the knob on the SCT never has to be touched. I've been using this old SCT for a few months now and haven't touched the SCT knob again. All the focusing comes from the Baader.

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Jure Menart

Jun 15, 2023

Some images with my initial issues and also after I got Starizona can be seen in this forum thread by the way:

https://www.astrobin.com/forum/c/astrophotography/deep-sky/tiltcollimationback-focus-issues/

I know they are not nice as I still have issues but it did improve my quite bad frames

Mike H - Sky View Observatory

Jun 15, 2023

That was a good read. Very educational. Everyone knows only so much can be expected out of an older C8. One guy told me to buy an Edge HD and be done with it and he may be right

. However, I'm not a "Pixel Peeper" so reasonable results is all I'm seeking out of a $300 telescope. I have a WO GT81 triplet and a 130mm triplet so higher expectations come from them. But neither are good for small galaxies and globular clusters. Image scale is so small. I like experimenting with this C8 and don't let frustration set in. Please keep posting your results. I'm following you so I'll get a notification when you post. Do you mind me asking where you're located? Just curious. I'm in southwest Florida.

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Jure Menart

Jun 15, 2023

That was a good read. Very educational. Everyone knows only so much can be expected out of an older C8. One guy told me to buy an Edge HD and be done with it and he may be right . However, I'm not a "Pixel Peeper" so reasonable results is all I'm seeking out of a $300 telescope. I have a WO GT81 triplet and a 130mm triplet so higher expectations come from them. But neither are good for small galaxies and globular clusters. Image scale is so small. I like experimenting with this C8 and don't let frustration set in. Please keep posting your results. I'm following you so I'll get a notification when you post. Do you mind me asking where you're located? Just curious. I'm in southwest Florida.

I am located near Zurich, Switzerland (Bortle 5 sky).

Yes, I am a little bit frustrated with my latest M13 - I plan to take time, collimate again, polar align again to have as good guiding as possible, focus manually and re-run it with shorter subs (I think 120s was too much, I think I'll go with 60s). But at the same time is part of learning curve right

Similar I still need to do for M27 - I want to reshoot RGB stars for that as stars are just horrible there

So hopefully this week nothing new, just reshooting nicer stars

Mike H - Sky View Observatory

Jun 15, 2023

Wow Zurich. That's interesting. Pretty much the same sky here at Bortle 5. I do have one advantage and that's a small observatory I built last year. So polar aligment is not an issue. Except for periodic checks it stays aligned. We're coming into the rainy season so hot, humid and rain until about September. With the permanent setup I can go out quickly if the skies are clear. When I used to have to setup and tear down every time I wouldn't image all summer. So I missed a lot of desirable targets.

Lynn K

Jun 15, 2023

I have owned a period 2000 C8 and now own Edge 8. The difference is the field flattener in the baffle tube. Celestron seems to do a better job on centering the secondary. They have to, because of the flattener. You can re- center the secondary yourself. I have done it on all the Celestron SCTs I have owned except a C5. I have owned the C8, I mentioned, a carbon fiber C9.25 and C11. Two C6. Because of the spherical primary and secondary design, accurate secondary centering is not essential for visual. Once you bring a reducer/flattener into the imaging train, it makes a big difference. It is essential for Hyperstar F 2 imaging, since the Hyperstar is a /flattener working of a F2 or F2.5 spherical primary. I do only visual with the Edge 8. It gives nice stars with Televue Delos eyepieces. I see no advantage of the Edge over a regular C8, C9.25 & C11 equipped with Starizona Flattener IV. There are limitations in back focus with the Edge. However, as mentioned, Celestron does a better job of centering the secondary, and the external corrector plate centering screws is a long needed application. Starzona has Tutorial on how to re- center the secondary.

Lynn K.

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Steve Spring

Jun 15, 2023

Hi RammaN,

Although I cna't answer your question fully I have some experience and am a little way along the process.
I have fitted an external focuser (2" Esatto). I'm lucky that this focuser doesn't add a great deal of distance at the back of the scope threads and it still leaves enough room to keep the Celestron Focus Motor fitted as well. It's a lovely focuser with zero backlash and can be connected to a phone for focusing when using the scope visually which I like to do with friends when the planets are high sometimes.

All that said, I'm not yet in hte position to recommend an external focuser as yet as I am still working through the set up and with such short nights (especially here in the UK) I don't think I will come back to it until the Autumn/Winter.

I have found that after making an autofocus run with the Celestron Focus Motor and my Esatto at half range, when I take a focus run with th e Esatto, it produces a lower FWHM reading and changes it's original position suggesting an improvement. However, it may be that both runs are within the Critical Focus Zone anyway. The differnence is not night and day. I'm always striving to improve each and every aspect of my set up with each iteration but really we have to expect dimishing return for what can be expensive endeavours so beware!

. I understand the wanting to try it to find out because that's where I am but I'm sorry to say I can't confirm yet.

I also have a Baader ClickLock. Just a note, I have read that these can still produce tilt and one tip was to attach your Optical Train with the scope pointing to the ground if you want a repeatable process when re-attaching it. Also, read a tip, be careful not to overtighten to make sure you don't pinch the reducer. A 2" focus lock ring is not a bad idea as well to ensure the reducer is inserted to the same distance each time it is removed and replaced. However, I would still advise leaving the optical train in place if possible once you are happy with your set up.

This is how I have things set up along with a tilt plate which I dont have set brilliantly yet but is mostly there except the bottom left of my images (I think - happy for crtitisism). I have followed Starizona advise of keeping it as close to the back of the scope as possible. I attach the train with the focuser set fully in, vertically down and then back this off to the middel of the focuser range ready for an auto focus run.

I have read a thread though where someone has described how to find the optimal position for the imaging train with regards to back focus. It it they describe taking a camera and setting it to Prime Focus optimal back focus.i.e as you would for planetary imaging without the FR attached. In this position you would then focus the scope using hte stock focuser. At this stage you would attach your FR and imaging train and insert the imaging train back and forth until you achive the distance with best focus. You would then lock your train at this distance. I am yet to try this or determine the effect of different distance would have on vignetting also.

https://www.cloudynights.com/topic/821192-starizona-063x-reducercorrector-iv-for-scts/

Now for the caveat. I really am not offering any advise so sorry about that but hope that sharing my experiences might in some way help

Certainly, using the Starizona Reducer over hte Celestron is better. Using say a 533 sensor over an APS-C will require little effort and for galaxies, most will fit within that foot print as well.

Remember that the C8 will suffer with mirror flop either side of the meridian to some degree also. The external focuser will help with mirror shift when focusing but that shouldn't be so much of an issue for DSO anyway.

Sorry I can't be more helpful and will be watching this thread keenly to see other users findings

CS

Steve

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