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8SE Mount Advice

astrophotography imaging SCT eq dso dslr equipment cassegrain beginner
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#1 Jujubean

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Posted 08 April 2020 - 01:15 PM

Hey everyone,

 

I'm starting out basic astrophotography and I need some advice. I bought an 8SE SCT a few months ago, and I've enjoyed looking at the planets and taking basic astrophotography of bright DSOs such as the Orion, Swan, Lagoon, and Trifid Nebula. A few days ago I bought (hasn't arrived yet) a wedge for my scope hoping to up my exposure times. After looking through some forums and articles, I'm wondering if its really worth it.

 

I want to know how long of exposures the wedge allows me to take. I'm hoping for at least 1 or 2 minutes without guiding.

Am I better off returning it, selling the altaz mount, and buying an Advanced VX Mount?

 

Also, I'm pretty new to stacking. I'm currently using Deep Sky Stacker, but it's throwing away most of my frames. What software should I use?

 

Thanks smile.gif



#2 sandconp

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Posted 08 April 2020 - 04:02 PM

I personally would not bother with a wedge.  I have an ALT-Z Mount and can easily take 20 to 30 second exposures using a Hyperstar Lens.  I use Sharcap to track on the stars so no guiding is required but I do get field rotation and I just crop it off.

 

I have since migrated to a CGX equatorial mount for all my astrophotography.  The AVX Mount would be a better choice than a wedge but it does have a lower weight limit than the CGX which can hold up to 55 lbs.


Edited by sandconp, 08 April 2020 - 04:02 PM.

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#3 rnyboy

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Posted 08 April 2020 - 04:02 PM

Hello Jujubean,

 

I'm also quite new to EAA and astrophotography and purchased my 6SE last year.  The following is from what I've read on the various astronomy forums and my own personal experience with using reducers with a ZWO ASI385MC camera...

 

The general consensus is a wedge for an SE mount is a waste of money, not easy to use, and should be avoided.  I don't own one but I don't remember coming across any  "I like my SE on a wedge." responses compared to those that have tried one and threw their hands up in the air in defeat.  YMMV however.

 

The SE mounts are really only good for sub 30s exposures.  I try to keep mine at 15s max and very often livestack in SharpCap Pro.  I have also used Deep Sky Stacker for stacking my images and some processing of the stacked images.

 

I don't know what your are using for your imaging camera/sensor but instead of a wedge I would strongly recommend getting a Celestron f/6.3 reducer/corrector or equivalent for your 8SE.  It will get you about a 1.6x wider FOV and decrease exposures by about a factor of 3 at the suggested working distance of 105mm between the back of reducer and the front of the image sensor.  Using one f/6.3 reducer will let you use up to a 35mm size equivalent FOV sensor and reduce coma at the edges when using the correct working distance.

 

You can also stack two f/6.3 reducers to get f/4 and then get about a factor of six reduction in exposures with an even wider FOV by about 2.4x.  HOWEVER, you need to be using a small 1/3 or 1/2 size CMOS imager with the stacked reducers or you'll start to have very noticeable vignetting.   The working distance with the stacked reducers is ~85mm.

 

You need to be at the correct working distance or you won't get the proper reduction factor and you won't get the optimal field flattening and coma correction the reducer can provide.  Less separation reduces the f-ratio and increasing the separation increases the f-ratio.  There are limits as to how much you can vary from the recommended working distance and as you get further away from the proper distance you will most likely start to get more image distortions such as increased coma or excessive vignetting.

 

I've also used a cheaper 0.5x 1.25" reducer which gives a factor of 4 shorter exposures and a 2x wider FOV.  The working distance for my 0.5x is about 55mm.

 

I've also used a f/6.3 with a 0.5x reducer 55mm in front of the sensor trying for an f/3.3.  Exposures were fast but I was not all that successful and I had distortions around the image edges.  I think there is a more optimal working distance than 55mm for the 0,5x and I think I also used 105mm working distance for the f/6.3.  I think this was my second attempt at using multiple reducers in the optical train and I now know both working distances were not correct.  I strongly think this arrangement, even with proper spacing, will have pretty sever vignetting but I'd still like to see what this setup could do.  If anybody is reading this and has a suggestion for proper spacings using these two reducers please feel free to speak up.

 

A Hyperstar is also very good in that it gets you down near f/2 with a very wide FOV.  In your scope and mine as currently setup the internal baffle prevents us from getting a FOV wider than roughly 1.5o.  Hyperstar replaces your secondary mirror on the front of your scope and the baffle becomes a non-issue.  Hyperstar is the considerably pricer but better solution than the reducers.  BUT, if you put the price of the wedge towards Hyperstar in wouldn't be a terrible cost.  I think the main drawback is that you need to remove the secondary mirror and install the Hyperstar and then if you want to use your scope for something like planetary imaging you would have to remove the Hyperstar and replace AND recollimate the secondary mirror; kind of a PITA in my mind.  The reducers let you easily switch from a moderately wide FOV to a planetary scope by simply removing the reducers and perhaps using a 2x Barlow and go to f/20 for the bright objects like the moon and planets.  I will just mention that there are over- and under-sampling issues you need to think about when using digital imagers.  This is a good site for seeing what different reducers, Barlows, image sensor sizes will do with your 8SE will have in regards to sampling...

 

  http://astronomy.tools/

 

I have a 6SE and your 8SE has about the same FOVs as my 6SE when operating with the same optics.  It's really not meant to be a DSO scope and those reducers will push you much closer to it being a DSO suitable scope than using only a wedge.

 

If you go the reducer route I would suggest investing in some T2 and 1.25" spacer tubes of varying length and a T2 to 1.25" adapter ring or two.  They make it very easy to change working distances, and mounting of filters if you use them, when using different reducer configurations.

 

Your idea of selling the SE mount and buying an AVX seems like a good one to me.  I have thought about doing the same thing in the future.


Edited by rnyboy, 08 April 2020 - 04:38 PM.

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#4 Jujubean

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Posted 08 April 2020 - 04:44 PM

Thanks for the replies,

 

It seems the wedge isn't going to be much help to me. I guess I'll return it and get something else.

 

My camera is a Canon T3i DSLR.

 

So a reducer will allow me to get the quality of a 1.5 min exposure in a 30 second exposure? Would you recommend getting the celestron one or the other one you mentioned?

 

Do you think I should buy the reducer or the AVX mount first?

 

Thanks.


Edited by Jujubean, 08 April 2020 - 04:46 PM.


#5 rnyboy

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Posted 08 April 2020 - 05:50 PM

Not quite 1.5 min down to 30 secs.  The reduction is 2.52 actually and I rounded.  So a 1.5 min exposure would be down to 36 secs and with the 60% wider FOV. 

 

Buy a reducer first!  It's one of the cheapest improvements you can make for your scope.  Even visual viewing is more pleasing with the reducer in place.  Think of the reducer and AVX mount as two separate issues.  I don't think there is anybody that regrets buying a reducer for their SCT.

 

I have a Celestron and Astro-Tech f/6.3.  The Celestron is something like $120 and the A-T was more like $70.  Even though many say they are identical my Astro-Tech brings things to focus a bit sooner than the Celestron, so they aren't really "identical" but probably pretty close.

 

I purchased the Celestron first simply because I wanted a known quality brand.  Aside from the slightly shorter focus distance for the A-T, which would mean a slightly shorter working distance of something more like 100mm, and IF they are all the same shorter focus and this is not a result of poorer quality control, then I'd say you could go with the A-T; because optically it seems fine.

 

One nice thing is that your 8SE gathers almost 2x more light than my 6SE, so with all other things being equal, I'd have to collect around twice as many exposures to get a similar signal as you can but mine will almost certainly have more noise as well.

 

I don't use the star diagonal when imaging because it doesn't allow for using more than one f/6.3 reducer and I don't need it when using the 0.5x alone to reach the zenith.  However, when using just a single f/6.3 you could attach the f/6.3 to the back of the scope, the visual back to the reducer, the star diagonal to the visual back, then whatever you currently use to attach your DSLR to the visual back into the star diagonal.  The path length of the Celestron 1.25" prism star diagonal that comes with the scope is reported to be 66mm.  I strongly suspect your distance from the back of the reducer to the DSLR's sensor when using the star diagonal is going to be more than the recommended 105mm.  The change in reduction, and I'm guessing (hoping?) any increase in coma, isn't that terribly strong with working distance so go ahead and try it.  Your going to have somewhat more than the f/6.3 reduction (f/6 ??) and may have some noticeable vignetting that you can crop out if it's too bad.  Using the star diagonal should get you more in alt before hitting the mount than having everything in a straight line out the back of the scope.

 

With all the extra weight sticking off the back of the scope you are more than likely going to have to push the OTA pretty far forward in the mount dovetail as possible to have the OTA being better balanced and the best chance at not having the camera hit the mount and restricting the alt you can reach.  It would probably be a good idea to balance the whole OTA with everything attached on a pencil or other tube to find the new balance point and then mount the OTA assembly such that it is slightly back heavy if possible.  If not then slightly front heavy.  The main thing is to have some weight preloading the alt spur gear so the OTA can't do any see-sawing over the pivot point if too well balanced.

 

Also, if you haven't done so yet, adjust for the gear backlash.  I'm pretty much assuming that you have done that.  If by chance you haven't do a search on adjusting backlash and some very good information is contained in postings by a now deceased and very helpful person who went by the user name of "tel" or "Tel".

 

If you want to use your DSLR without the star diagonal then the good news is I think you only need the T2 extensions.  Since I don't use a DSLR there may be a better way to do this that I don't know about.  You'll still need the proper adapters for attaching your DSLR to the T2 and then a T2 to 1.25" adapter for mounting into the visual back; you likely already have those.  Having all this stick out the back of your scope is going to limit your altitude to roughly 60o when not using a diagonal and you'll still have to pay attention to the OTA balance.  I've found lots of things to image lower that 60o but it is rather annoying if something potentially interesting is above 60o and I can't get to it.

 

I purchased the set of T2s through Amazon...

 

(https://www.amazon.c...0?ie=UTF8&psc=1)

 

You can definitely get some nice images of the smaller/brighter DSOs with a single f/6.3 and the 8SE but you need to remember this is not a scope meant for DSOs.  Cancelling the wedge is a good idea and apply the money to something else.  The AVX idea is still a good one too.  But to be honest doing fast exposure lucky imaging can absolve the poorer SE mounts from a lot of sins.

 

As a final input I'd suggest thinking about doing EAA with a cmos imager dedicated for astroimaging/fast exposure photography and a laptop PC at the scope.  The DSLR route is cheaper for sure but I quickly became hooked on now being able to do everything but the initial setup and take down remotely from inside a warm house.  The 8SE can be a pretty capable EAA scope when setup properly.  I just wish Rochester wasn't so darn cloudy.  I can live with the light pollution.

 

Mike Swanson's "The Nexstar's Users Guide II" is a very good reference to have and not that expensive.  I very much recommend it since you have an 8SE.

 

Oh, and by the way, welcome to the great money pit called amateur astronomy.  lol.gif


Edited by rnyboy, 09 April 2020 - 08:32 AM.

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#6 rnyboy

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Posted 08 April 2020 - 07:37 PM

Jujubean…  I looked up your DSLR and I don't know how you currently use it for taking your DSO images?  I saw it can do up to 3.7 fps for 34 jpgs or 6 RAW images and 30 fps video at 1920x1080.  I'm curious how you're currently using that DSLR with your 8se?

 

Have you tried taking 34 jpgs with 15 secs exposure each (60 sec / 3.7 fps = 16.2 s max exposure per frame before transfer/storing overhead) to get an equivalent exposure of 510 secs and stack those 34 jpgs?  That's a whole lot better than a single 90 sec exposure.  If possible to do, take several of those 34 jpg sets and then you'd have quite a few images to stack.  Most of this depends on how well your scope tracks and keeps the object near center on your camera's sensor.

 

For the planets/moon they are plenty bright to use the 30 fps video, which is really good for lucky imaging, and then use the AVI file for stacking.  That's pretty straight forward to do compared to the DSO stuff.  Have you done any of that yet?

 

I guess my real question is how do you currently get a lot of useable frames on DSOs for stacking?


Edited by rnyboy, 09 April 2020 - 08:29 AM.


#7 GuitsBoy

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Posted 09 April 2020 - 09:26 AM

I'm brand new to all this, so take it with a HUGE grain of salt.  I currently have the 6se which is the same mount.  I'm running a DIY wedge, f6.3 reducer/corrector, and a DIY autoguider with a cheap 60mm guide scope and ar0130 chipped webcam and PHD2.  I'm imaging with a stock canon t6s. I'm still tracking down more sources of jitter and play in the mount, but about half of my 60-90 second subs are usable.  Setting the PHD2 algorithm to "south only" effectively removed declination backlash issues for me.  It will only correct in one direction, and if it overshoots, it simple waits for the natural drift to correct it.

 

Anyway, if you got a good deal on the wedge, no reason not to give it a shot.  Or return it and build your own wedge out of a few scraps of wood.  Then maybe use the money for a focal reducer, or save towards a future upgrade?.  With good polar alignment, I was able to gt 75% of my unguided 30 second subs usable, and probably 90% of my unguided 20 second subs. Stacking goes a long way. 

In my opinion, the focal reducer was probably most important, followed closely by the wedge, but the DIY wedge was effectively free. My autoguiding setup also helped considerably and only cost about $130 out of pocket.  The nice thing is that the focal reducer and guide setup can move to a better scope and mount when the time comes.  I enjoy the challenge of seeing what a cheap little scope can pick up.  Why not see what you can do with  the equipment you already have?



#8 Jujubean

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Posted 09 April 2020 - 11:59 AM

Thanks for the responses!

 

I'll see what I can do with the wedge when it arrives.

 

 

rnyboy - right now I'm taking 20-30 second exposures with the t3i, but I'll try your idea of 34x15s

 

I have taken some planet and moon images. The moon photos were great, but the planets not so much. Probably because of seeing conditions. I'll go for the planets on good conditions when I have a chance.

 

I've tried taking a few bright DSO's with a bunch of 20 second exposures and stacking them, but I have to throw out a lot of frames. A few nights ago I took around 20 decent frames on a target, but could only stack a few.

 

 

GuitsBoy - I'm not sure about making a DIY wedge... It seems a bit risky.

 

I have been able to take some nice shots with my stock scope! smile.gif



#9 GuitsBoy

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Posted 09 April 2020 - 12:54 PM

If the bulk of your 20 second exposures are not able to be stacked, its probably because the starts are not being recognized.  For me, this is usually because of field rotation (in alt-az), poor alignment, poor focus, or poor mount tracking.  The wedge will certainly help with with the field rotation.  The alignment and focus are up to you and how much time you spend dialing it in.  The poor mount tracking is the most difficult issue to address with the SE mount.  Improving balance may help, as well as setting backlash compensation (though guiding wants them removed).  With alt-az and the full f10 focal ratio, I definitely had to keep my exposures down to 15 seconds max.  With the focal reducer, you can probably get away with a touch more.  Adding the wedge, and you can go even longer, but you open yourself up to a much higher probability of random tracking problems affecting your shot.

 

As for the DIY wedge, lots of people have made them with excellent results.  Ill try to post mine.  Please pardon the mess, with the recent events we had to clear out some room to make space to work from home, and stuff is laying around everywhere.  Its basically just 3/4 plywood, a couple hinges, and a couple aluminum turnbuckles.  Cost me 7 bucks at the hardware store, since I had the wood scraps.  I'm sure there are plenty of ways to dress it up a little nicer, maybe stain it, round the edges, etc.  Since it's adjustable, getting the angle right is not terribly important.  I set the scope to be parallel with the fork arm, and use the OTA itself to polar align the mount using a lighted reticle eyepiece.   I adjust the alt with the wedge turnbuckles, and simply move the tripod to set the az.

 

wedge1.jpg

 

wedge2.jpg


Edited by GuitsBoy, 09 April 2020 - 01:16 PM.


#10 rnyboy

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Posted 09 April 2020 - 02:00 PM

Jujubean…

 

This link is from today and shows a comparison image using an C8 on a GEM mount, so not using the SE mount, without a f/6.3 reducer and unmodified camera and one using the F/6.3 and after the camera was modified.  It should give you some idea about how the FOV will increase.  The two images I think have both been cropped so their not exactly comparable for the change in FOV.

 

https://www.cloudyni...9#entry10101206

 

"modified" in the link means the IR-cut filter in front of the sensor was removed so it makes it more sensitive to the longer wavelength red and IR portion of the spectrum.  The IR part is invisible to us humans but removing the filter gives the imager more photons to capture and improve S/N.  Some think it gives the image an unnatural look because it's using light we can't see but probably most Hubble and other high-power instrument images tend to be made various types of false colors to create the final images they publish.  So far I've always used the IR-cut in front of my 385MC but I want to take the time to try it without it as well.  One problem I find with this hobby is that there are more things to try than there is available time with clear skies to try them.


Edited by rnyboy, 09 April 2020 - 02:10 PM.


#11 rnyboy

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Posted 09 April 2020 - 02:03 PM

Guitsboy…

 

Nice homemade wedge.  I've thought about building one too but I hear way more people complaining about a wedge than not.  Does the wedge do any harm as far as vibrations go?

 

Got any links to  photos taken with the wedge?  They'd be interesting to see.

 

I read somewhere in these forums that the SE makes a mount shift every 30s or so while tracking.  That and field rotation are why everybody keeps there exposures to less than 30s to avoid adding any image blur from field rotation and when the mount makes that little jog during tracking and perhaps(?) to allow a bit for the mount to settle completely after the position shift.


Edited by rnyboy, 09 April 2020 - 02:18 PM.


#12 Jujubean

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Posted 09 April 2020 - 02:54 PM

GuitsBoy

 

Looks very nice, I'll think about making one.



#13 Jujubean

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Posted 09 April 2020 - 02:59 PM

rny,

 

From those photos it seems like the reducer makes the results a lot better...

 

I'm going to try out the scope tonight on a few dso's and see what I can do with 15 second exposures. Hopefully I will be able to get some decent results. I'll try your 34x15s method.

 

Thanks again for these responses!



#14 rnyboy

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Posted 09 April 2020 - 03:10 PM

Yeah, for DSOs the reducer is probably the cheapest "best" addition you can do imho.  A lot of observers leave it pretty much on their scopes permanently because it keeps dust out of the OTA and does a nice job of flattening the field and I guess some contrast improvement from that.

 

Another thing to keep in mind is that many people incorrectly think a reducer is somehow collecting more photons, but that is simply not true.  The scopes aperture is fixed and the number of photons is entirely dependent on that aperture.  With the reducer your simply concentrating more of the available photons into a smaller area on the camera sensor and now making use of the photons that without the reducer would be impinging on an area outside the frame of your sensor.


Edited by rnyboy, 09 April 2020 - 03:25 PM.


#15 GuitsBoy

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Posted 09 April 2020 - 03:58 PM

GuitsBoy

 

Looks very nice, I'll think about making one.

I only mean to show how easy it is to make them, and that the money could be re-purposed elsewhere, even if that means saving for an equatorial mount in time.

 

Guitsboy…

 

Nice homemade wedge.  I've thought about building one too but I hear way more people complaining about a wedge than not.  Does the wedge do any harm as far as vibrations go?

 

Got any links to  photos taken with the wedge?  They'd be interesting to see.

 

I read somewhere in these forums that the SE makes a mount shift every 30s or so while tracking.  That and field rotation are why everybody keeps there exposures to less than 30s to avoid adding any image blur from field rotation and when the mount makes that little jog during tracking and perhaps(?) to allow a bit for the mount to settle completely after the position shift.

Thank you.  I haven't noticed any ill effects from vibration.  I'm using it primarily on asphalt, and the streets quiet down fairly well at night, especially now.  The fact that its cantilevered over by a few inches make it so the weight of the OTA should be roughly centered over the tripod.  I'm going to try running the telescope without the legs extended, and I might even try those vibration reduction disks.

 

I have a few images, but I'm a little embarrassed to post any.  I've only had the telescope for maybe 6 or 7 weeks now.  I'm still in my infancy as far as stacking and post processing images, not to mention still learning the equipment and toying with filters.  I'm in a bortle-6 area about 25 miles outside NYC.  And I haven't really had a good method of focusing, another area I need to improve on.  I dont remember the exact specs on the ones I attached, but figure in the area of 15"-20" and maybe 10-20 stacked subs.  M51 might have been my first time out with the guider, but I was still having issues with it.  I ironed out some bugs since then, but had overcast skies and didnt get anything usable.  But did get some proof of concept 60-90 second exposures with fairly sharp stars.  The stretched stars towards the edges of M51 were due to an incorrect working length behind the focal reducer.  Simply using the prism diagonal gets me much closer to the desired 105mm distance.

 

I haven't noticed any cyclic mount shift or adjustment every 30 seconds.  Perhaps thats an alt-az mode issue that goes away if you run it in eq-north mode?  In PHD2, I do get occasional excessive drift, but I think it may be extra sensitive to wind and cable rub, etc. since the its not the most precision of mounts out there.  But Ive seen plenty of five to ten minute spans of seemingly dead on tracking, at least as far as I can tell.  I could take a screen shot of the PHD2 drift / correction chart.  Its probably laughably bad by most peoples standards, but I think it might show against any cyclic adjustment inherent in the mount.  Another variable might be dithering if guiding.  I'm going to try APT next time out to synchronize subs with dithering adjustments.  Looks like its clearing up here after all that rain, if I can get out there tonight, do you want me to look for anything specific?

 

m81-m82_small1.jpg

 

2020-04-01_m51 (Medium).jpg

 

m42_20200321c (Medium).jpg


Edited by GuitsBoy, 09 April 2020 - 04:05 PM.

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#16 rnyboy

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Posted 09 April 2020 - 04:20 PM

Hey, GuitsBoy, those are excellent images I think!  I'm basically new to this too and my first images were in late January of the Trapezium in Orion.  I'm amazed you can get that much FOV onto a 1/3 sensor of the ar0130 chipped webcam using the f/6.3, it's way more than I would have expected out of a 6SE.  Also that the SE mount handles the weight of your rig.  The cigar and Bode's image is really nice for a 6" scope.

 

I don't think you'd "notice" the mount shift.  I think the forum article I saw said that the update signals for the SE mount to make a tracking correction are generated about every 30s, so the amount of the shift would depend on where in the sky the scope is tracking and the spur gears aren't delivering as fine of a movement as worm gears so there more like little jumps compared to the more continuous smooth movement with the worm gears.

 

So far I've only got images of the moon, Bode's, the Ghost of Jupiter, NGC2438, Sombrero, the spindle NGC3115, and the Trapezium.  I missed out on the planets and right now Venus is in the trees of my backyard.  I'm pretty much restricted to a wedge of sky to the south starting at about 20o in alt and another wedge to the north but that one has to be above about 40o in alt due to the house. 

 

With my 385MC and a $25 1.25" 0.5x reducer this is what I got of Bode's the last time I was out with my 6SE.  There's more detail on the exposures and stuff here:  https://www.cloudyni.../#entry10059329

 

NX0UC7M.png


Edited by rnyboy, 09 April 2020 - 05:35 PM.

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#17 GuitsBoy

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Posted 09 April 2020 - 04:36 PM

Your Bodes came out great IMO, especially at the FOV.  Honestly, its at least double the size I got without any focal reducer.   On the plus side youre probably not fighting as much vignetting with the 1/2 size sensor, right?  Can I ask how you were able to achieve focus with the 0.5 focal reducer?  I tried at roughly 65 or 70mm working distance (closest I can get), and all I could get was a perfect white donut (secondary mirror obstruction).

 

I was considering buying an older used t4 or t5 off ebay and modding it myself.  I cant risk destroying the current camera with two young kids in the house.  Photos of the kids growing up are far more important to me than some silly space dust.  I might eventually go down that route and buy something used or refurb, but I'm trying to do everything on a shoestring budget, so for now I'm just gonna work with the camera Ive already got.



#18 speedster

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Posted 09 April 2020 - 04:57 PM

I like my 8SE on a wedge.  In fact, I love it.  I found the whole thing quick, easy, and intuitive.  That being said, I only use it when traveling and use a CGX-L at home.   I still love my wedge and won't part with it but the SE mount is a little wiggly whether wedged or not.  30 secs without a wedge vs 45 secs with a wedge doesn't make much difference in the final result.  Due to my light pollution, 90 secs seems to be the sweet spot for dso and the CGX-L easily does that without guiding.  As usual, no "best" answer for all situations but there are plenty of happy people on wedges.



#19 rnyboy

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Posted 09 April 2020 - 05:10 PM

I start to see some vignetting with two stacked f/6.3s but I don't find it all that objectionable.  Bodes filled up the imager almost completely with the 0.5x.  I would have liked to have used the stacked f/6.3s but then I never would have been able to get high enough in alt to get to Bodes.  The field rotation was over 7o for the conditions I used so I cropped out as much of that as I could while still keeping as much of the spirals as possible.

 

Focus was not a problem at all.  I had a lot of focus left.  For this image the distance to the sensor was about 45mm because that's the most I could get and still clear the mount to hit the zenith.  I've seen a few different working distances given for these cheap 1.25" 0.5x reducers, between near 45mm to more often closer to 55mm, and I don't know if that's because the different brands of those reducers actually have different focus or if it's in some way related to the scope used.  The f-ratio of a SCT depends on the position of the primary mirror when at focus so and I don't have a clue on how sensitive the f-ratio is to that.

 

I have to say I feel better now, I thought you were using the 1/3 ar0130 webcam for your images and couldn't believe the FOV on that, but if your using the cam to take pics of your kids than it's probably a full frame DSLR given your FOVs.  I have been wondering how large a chunk of the sky the 6SE can realistically take and seeing the cigar and Bodes in the same frame made me very happy!


Edited by rnyboy, 09 April 2020 - 05:29 PM.


#20 rnyboy

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Posted 09 April 2020 - 05:13 PM

Well Jujubean, it looks like there are people that like a SE on a wedge afterall.  This appears to be a YMMV topic based on the input from others.  So give it a go and see what you think.  Be sure to let us know what you think about it if you do.

 

One thing I find really interesting is there are a pretty fair number of people who seem to have started rather recently with no or little knowledge about astronomy/telescopes to now doing rather sophisticated imaging in a matter of weeks to months.  I can't help but chuckle when I think what we're getting for images with a circa. low $1,000s setups compared to the literally circa many $1,000,000s observatory scopes not really all that long ago.

 

I find the idea of adding autoguiding to my 6SE interesting.  And maybe a wedge could be in my future as well.

 

I guess I'll just have to get the shovel and throw more money into that astronomy endless pit.


Edited by rnyboy, 09 April 2020 - 05:30 PM.


#21 GuitsBoy

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Posted 09 April 2020 - 05:49 PM

I guess I'll just have to get the shovel and throw more money into that astronomy endless pit.

My father told me many many years ago, astronomy is a hole in the sky you throw money into.   

 

(Yes, stolen from boats)


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#22 Jujubean

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Posted 09 April 2020 - 06:12 PM

Wow, great images rny and Gutis!

 

I'll be bringing out my scope tonight, and going for M81 and M82. I've done Bode's once before but it didn't turn out to well because of my stacking issues so I got very little exposure time.

 

I'll try doing 15 second exposures.



#23 Jujubean

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Posted 09 April 2020 - 06:34 PM

Well Jujubean, it looks like there are people that like a SE on a wedge afterall.  This appears to be a YMMV topic based on the input from others.  So give it a go and see what you think.  Be sure to let us know what you think about it if you do.

 

One thing I find really interesting is there are a pretty fair number of people who seem to have started rather recently with no or little knowledge about astronomy/telescopes to now doing rather sophisticated imaging in a matter of weeks to months.  I can't help but chuckle when I think what we're getting for images with a circa. low $1,000s setups compared to the literally circa many $1,000,000s observatory scopes not really all that long ago.

 

I find the idea of adding autoguiding to my 6SE interesting.  And maybe a wedge could be in my future as well.

 

I guess I'll just have to get the shovel and throw more money into that astronomy endless pit.

When it arrives, I'll test it out for a while to see if it improves my images. If yes, great! I'll keep it. If no, I will return it and get an AVX.

 

Thanks everyone for helping me with this. 



#24 Jujubean

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Posted 09 April 2020 - 07:58 PM

 here after all that rain, if I can get out there tonight, do you want me to look for anything specific?

If you can, can you try a few more galaxies or planetary nebula? Whatever you can do would be great!

 

I'm starting my session now... hopefully I get something good

 

Thanks! smile.gif



#25 rnyboy

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Posted 09 April 2020 - 08:13 PM

GuitsBoy…  You were asking about focus improvement.  I've found SharpCap's focus assist to be pretty good for helping to focus, especially with the use of the Celestron focus motor.  I also used SharpCap's focus assist when manually focusing too, before I had the focus motor, but it's tougher to do simply because of the vibrations.  For what it's worth, the focus motor works great for me with absolutely no visible vibrations while focusing.




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