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Stellarvue SVX080T-3SV w/ .74X Reducer-Flattener

astrophotography dslr refractor
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#251 zakry3323

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Posted 26 March 2020 - 05:13 PM

I was at 55.5mm last night and it's ok...still room for improvement. Unfortunately I'm working on trying to adjust tilt in the system and my Gerd Neumann CTU is a bit too thick. Right now the tilt is more annoying for me.

 Capture4.JPG
 


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#252 zakry3323

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Posted 27 March 2020 - 09:43 PM

I had a conversation with Alex at Stellarvue and he let me know that the reducer/flattener decouples with the differently-anodized extension, freeing up an additional 16mm of backspace and allowing enough room for the CTU with the use of a single M48 adjustable extension!

I didn't buy directly for Stellarvue, so I'm not sure if there's any documentation about the reducer/flattener. I didn't see much about it at the website  , but this a game changer for me, allowing me to use tilt adjustment along with my OAG and filter wheel. If anyone knows of any documentation floating around out in the Ether, would you please share it with me? 

IMG_20200327_220907.jpg

IMG_20200327_220935.jpg

I'm not sure if this is a single machined part, or if there's an M48 adapter threaded onto the thicker portion of the tube. I sure hope that it's two parts, but my hands are worn out from removing the extension. I'll stick it in the freezer and think about it tomorrow.

IMG_20200327_220953.jpg

 

 



#253 zakry3323

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Posted 28 March 2020 - 01:33 PM

I often tell people that astrophotography is more tedious than it is "hard". That being said, getting this apart was very hard. I'm going to invest in a good strap wrench and save my fingers next time :)

 

IMG_20200328_142636_resize_41.jpg


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#254 SebaAstro

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Posted 31 March 2020 - 08:56 PM

I often tell people that astrophotography is more tedious than it is "hard". That being said, getting this apart was very hard. I'm going to invest in a good strap wrench and save my fingers next time smile.gif

 

attachicon.gifIMG_20200328_142636_resize_41.jpg

I have the same reducer but after reading your post then I HAVE to try too since I have the OAG and filter well on my imaging train and I didn't realize that i needed to take that spacer off in order to reach 55 mm back focus.

 

I have only one concern: once the extender is removed and then you insert the flattener inside the focuser how to you plan to remove it? I don't see a way to hold it in order to unscrew it back out. 


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#255 zakry3323

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Posted 01 April 2020 - 10:18 AM

I have the same reducer but after reading your post then I HAVE to try too since I have the OAG and filter well on my imaging train and I didn't realize that i needed to take that spacer off in order to reach 55 mm back focus.

 

I have only one concern: once the extender is removed and then you insert the flattener inside the focuser how to you plan to remove it? I don't see a way to hold it in order to unscrew it back out. 

I haven't reassembled the imaging train completely yet, I'm waiting on an M48-T2 adapter to arrive in the mail sometime. 

 

IMG_20200401_105655.jpg

 

My plan is to go from Reducer-->Tilt Adjuster-->OAG-->FW-->Sensor, with an adjustable threaded extension between the OAG and the FW to get the focal distance dialed in. 

 

It's my understanding from my discussion with Alex that the backspace of 55mm is with the extension attached. Removing the 13mm extension gives you that much more space to use for additional or thicker accessories (like my tilt adjuster). I don't know what kind of OAG and filter wheel you're using, but it may not be necessary for you to remove the extension. 

 

To remove the reducer once installed, I'm just using the knurled ring that threads onto the reducer, seen in my photo above. It bottoms out counter-clockwise, so it should provide you a good grip to decouple from the drawtube.  



#256 zakry3323

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Posted 04 April 2020 - 06:28 PM

Update - I got my backspace handled but was still struggling with tilt last night. The tilt adjuster helped a lot until I changed the orientation of the scope....and found that the drawtube itself was sagging and causing some of its own tilt. 

So I'm shelving it for a bit. I need the imaging train parts for a much more straight-forward application with my new Edge HD. 



#257 GrafikDihzahyn

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Posted 15 April 2020 - 01:57 PM

Still having issues with my backfocus. And one night of stars every 2 weeks is NOT helping things.. 

 

Ive Ive t adding 2mm of spacers, in .3, .5, and 1mm increments. Then I started rrducing the spacing and I am now down to 52mm for any improvement on the corner stars.. something seems off.

 

Ive seen a few images of peeps rigs setup, and their field flatteners seem built differently. Not talking about the .74 reducer, but the flattener that came with the scope. Mine has the 13mm spacer on the camera side, while Im seeing others have this 13mm spacer in between the 2 larger pieces of the flattener. Does anyone else show this arrangement on theirs?



#258 GrafikDihzahyn

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Posted 05 May 2020 - 02:45 PM

Still no luck on the FF spacing , and just getting frustrated at this point. I downloaded the 30 day trial of CCDInspector to try and help, but Im not sure where to even start. I definitely looks flatter near 53 (removed the 13mm spacer and inserted a 10 instead). Does anyone have any tips on getting this scope working? Wish I had just gone with the 183 instead of the 1600 as the stars near the corners are showing bad coma. Not sure how this scope would even work with a full frame sensor.. is it possible Im just doing something wrong, or could I have a lemon of a flattener?



#259 Tim C

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Posted 05 May 2020 - 03:20 PM

Do you have a picture showing the connections between OTA and camera? Also, maybe an example frame via drop box to look at?

Tim

#260 GrafikDihzahyn

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Posted 05 May 2020 - 03:40 PM

Ill have to link the sample images when I get home from work, but attached is a caliper measurement of the spacing. I removed the filterwheel and tilt adapter to limit any issues until I get the spacing figured out. Ive tried the recommended s(ZWO) of 56mm, 55, 54, and 53mm. The coma is much worse at 56 than 53.

 

Just curious, there's not like some clear protective covering on the ZWO cameras that Im not aware of, or something similar thats thats causing me the problem?

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  • 20200416_084525-01.jpeg


#261 Tim C

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Posted 05 May 2020 - 03:47 PM

Do you have a filter in there somewhere and if so, how thick is it?

#262 Tim C

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Posted 05 May 2020 - 04:07 PM

There is no clear film that I’m aware of. I was wondering though if there is no filter in there you might be getting some bloat as I think a lum filter is needed to get sharp stars (something that blocks UV/IR). Spacing looks correct (for 55 mm). I’m using 55 as well (actually 56 but my 3mm thick filters effectively reduces that by 1mm de to the effect of filters). My stars aren’t absolutely perfect to the corners but good enough that I didn’t feel the need to tweak the spacing. I did spend a lot of time working on spacing for the reducer though.

#263 GrafikDihzahyn

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Posted 05 May 2020 - 04:29 PM

No filter was in this shot, as it was at 55mm. When I added the zwo filterwheel and filters (Astronomik - 1mm thick) it was at 56mm. I placed the filterwheel back on and am using the green filter instead of the Luminance or no filter at all, so that I'm dealing with just the green wavelength.

 

https://www.dropbox....yqGTQ8q3_a?dl=0

 

Here is a link with subs of 60 sec, 139 gain, green filter. 53, 54, 55, & 56 mm backspacing.

 

Side note, These are focused to make the corner stars the smallest they can be. Ive also heard to focus in the center, 50% of the frame, and corner of frame. Which is correct? Also downloaded the trial for CCDInspector last night, but not really sure what to look for quite yet.

 

I just feel a scope that claims to work with full frame is having this much difficulty with the smaller than APS-C chip. Then again, Im used to imaging with a DSLR, so I could be screwing something simple up without me knowing.


Edited by GrafikDihzahyn, 05 May 2020 - 04:49 PM.


#264 Tim C

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Posted 05 May 2020 - 05:33 PM

I didn't retain any single subs to compare to so had to look at stacks.  I think your results are on par with my own.   Looks to me like some corners are better than others (same as mine).  I have similarly shaped stars in some corners as you while other corners are better so probably some tilt there.  I've seen some full frame shots earlier in this thread that looked pretty good with the FF but the pixels were bigger I'm sure.  I think these small pixel cameras are pretty unforgiving.  My final pics with the FF were good enough by my standards so maybe stacking, meridian flips, and post processing help some at the end of the day?

 

 

 

 

 

No filter was in this shot, as it was at 55mm. When I added the zwo filterwheel and filters (Astronomik - 1mm thick) it was at 56mm. I placed the filterwheel back on and am using the green filter instead of the Luminance or no filter at all, so that I'm dealing with just the green wavelength.

 

https://www.dropbox....yqGTQ8q3_a?dl=0

 

Here is a link with subs of 60 sec, 139 gain, green filter. 53, 54, 55, & 56 mm backspacing.

 

Side note, These are focused to make the corner stars the smallest they can be. Ive also heard to focus in the center, 50% of the frame, and corner of frame. Which is correct? Also downloaded the trial for CCDInspector last night, but not really sure what to look for quite yet.

 

I just feel a scope that claims to work with full frame is having this much difficulty with the smaller than APS-C chip. Then again, Im used to imaging with a DSLR, so I could be screwing something simple up without me knowing.



#265 gundark

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Posted 05 May 2020 - 08:53 PM

I have the scope and the reducer/flattener but have not had the opportunity to use them yet—I have been using my SCT for galaxy season. I hope my results will be better than those being reported here but am not overly optimistic. There is probably a good reason that SV stopped making the reducer/flattener. 


Edited by gundark, 05 May 2020 - 08:55 PM.


#266 GrafikDihzahyn

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Posted 06 May 2020 - 11:01 AM

After last night and working with CCD Inspector I was able to ALMOST get ride of the coma completely. I am at 52.81mm of backfocus. A bit off from the 55 claimed, and 56 of ZWO adapters included with the 1600. Luckily I have a plethora of them! 

 

With CCD Inspector I was able to get my curvature down to 7, and just 1° of tilt. And that is with focusing in the center of the frame. When focusing on the edge of the frame it shows more tilt, so I may average a few more subs and see if I can get that lower. Should be easy enough to go back to where I'm at now as the tilt adapter hasnt hasn't been adjusted yet.

 

Received word my ASIAir Pro shipped and should receive on Friday. Ordered first week of Feb. Now to learn that software..


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