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Revelation Astro 12" F4 imaging Newtonian - First Light

laser_jock99

By laser_jock99
in Member Equipment Reviews

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laser_jock99

laser_jock99

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Last night was the first clearish night for a couple of weeks so I gave my new Revelation Astro 12" F4 a quick go.

I'm reasonablly impressed with the scope it really is optically quite fast. This is the first time I have been able to see some of the DSO's I'm imaging actually through the camera eyepiece! Imagine my delight when I could clearly see M27 & M57 through the viewfinder.

The selection of photos below were taken from a semi-light polluted site (Milky Way just visible at zenith). All are full frame, single subs of 60 seconds with a Fuji IS Pro camera @ ISO800. No darks or flats applied, no coma corrector (yet) just prime focus & unguided.

M27 Vulpecula single 60s sub.

Dsir4453.jpg

M92 Hercules single 60s sub

M92_Dsir4458.jpg

M57 (centre crop) single 60s sub

M57_Dsir4467.jpg

M45 Pleiades- bit of interference from the moon nearby but gives an idea of the FOV. Single 60s sub.

M45_Dsir4503.jpg

M31 Andromeda- again very close to the half moon. Single 60s sub.

M31_Dsir4504.jpg

M11 Scutum, single 60s sub.

M11_Dsir4480.jpg

M13 Hercules, single 60s sub

Dsir4447.jpg

And finally the moon which caused me to give up for the night!

Dsir4511.jpg

So early results look promising. The scope needs to be well collimated and probably should have been re-checked mid session?

Shorter exposure times meant I could image a large number of objects (some I had never seen/imaged before) in a short session. A bit of tweaking and a coma corrector and this scope should have good potential for deep imaging.

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laser_jock99

laser_jock99

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That's impressive performance for a 20kg OTA, unguided, L_J. What mount was carrying this load?

As you say, with a slight bit of coma correction it should be superb.

Loaded onto an NEQ6 Pro tripod mounted, so polar alignment may not have been the best. Also found out that balance was critical with this kind of load. I have 4 x 5Kg Skywatcher counterweights but could usefully use another one as I don't like using the extension bar. When I get a guidescope on top it will definately need more weight. The drive appeared to be struggling at times but I put that mainly down to using an underated power supply. Skywatcher reccomend a 5A source whereas I only have a 2.5A power supply. The power drain was enough to crash the EQ6 when slewing at on point.

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  • 2 weeks later...
laser_jock99

laser_jock99

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I have now had a chance to use this scope visually now (it being to hazy for imaging tonight!). A couple of seconds was spent fine tuning the collimation before leaving the scope to cool down outside for an hour. The collimation seems to have held okay since last breaking down the scope and only required 1/8 turn on one screw to bring it back on. I didn't use the built in fan tonight- cool down time afer a hot day in a shed seems to be about 2+ hours at this time of year. Air tube current effect on an out of focus star were still just apparent at 1 am after 2 hours outside. The outside temp is 15 deg C still and I'm observing from a concrete patio, so how much of this is purely down to the scope I'm not sure.

I used a range of eyepieces and obtained pleasing views of M31 with a 50mm UWA, both satelite galaxies being nicely shown. Moving to the M13 globular in Hercules I started to up the eyepiece powers till I got to my 4.8mm Nagler. The sprinkling of stars at high power was a real treat. The EQ6 GOTO decided to throw aa wobbly so I had to find my next target via the finder scope- M57 ring nebula. Again moving up the eyepiece power clearly showed the ring structure. With the 4.8mm Nagler M57 occupied the whole FOV, it was pushing thigs a bit as I still had tube air currents at this point but I half fancied I could see the central with averted vision?

So my initial reaction is that visualy this scope seems reasonably capable. For critical high power planetary and lunar viewing I would definatley allow enough cool down time for this big mirror and probably suggest using the built in cooling fan.

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boabsta

boabsta

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Excellent pics. I'm basicly doing the same single exposures with my 200pds and heq5 and amazed at the results. Especialy when you read of multiple exposures and flats, bias and darks and proccesing and then they look almost the same!

The 1 thing I realy like about your images though is that you can clearly see the comma. Ive never realy seen it imaged before so that was good to see. Its funny how it looks like a slow zoom on a fast photo, all points facing the centre.

I look forward to seeing your next batch of images :D

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laser_jock99

laser_jock99

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Excellent pics. I'm basicly doing the same single exposures with my 200pds and heq5 and amazed at the results. Especialy when you read of multiple exposures and flats, bias and darks and proccesing and then they look almost the same!

The 1 thing I realy like about your images though is that you can clearly see the comma. Ive never realy seen it imaged before so that was good to see. Its funny how it looks like a slow zoom on a fast photo, all points facing the centre.

I look forward to seeing your next batch of images :D

Coma is unavoidable especially in these optically fast Newtonians so you will see it at the edge of frame. More important for me was to see that at least the centre looked good and that I was able to get reasonable collimation without too much grief. I should be getting a coma corrector / focal reducer soon which will hopefully deal with the edge of field coma effects.

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boabsta

boabsta

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Or you can just crop the pics down and save £100. Thats my plan for the moment anyway :)

Wasn't criticising for the coma, was actualy glad to see it as most pics you see are with correctors and then when you see coma on your own pics you can wonder what your doing wrong.

As I said, excellent pics and I genuinely am looking forward to the next captures :D

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  • 2 weeks later...
davies07

davies07

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Nice pictures. Promises of lots of things to explore here.

I too bought an F4 Newt, but a 10-inch, and have been loving the speed with which it captures photons and also the thrill of seeing these objects by eye. You will see even more with the 12-inch.

The coma quickly became an issue for me. Fainter stars, off the centre, are smudged out when viewing extended objects. You can fix coma with an MPCC for imaging and some EPs if you buy the add-on kit. But I made the 'mistake' of looking at a Televue Paracorr. I just had to buy it. Expensive, but it works very well for visual and imaging.

Thought I should mention it .... :smiley:

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laser_jock99

laser_jock99

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Nice pictures. Promises of lots of things to explore here.

I too bought an F4 Newt, but a 10-inch, and have been loving the speed with which it captures photons and also the thrill of seeing these objects by eye. You will see even more with the 12-inch.

The coma quickly became an issue for me. Fainter stars, off the centre, are smudged out when viewing extended objects. You can fix coma with an MPCC for imaging and some EPs if you buy the add-on kit. But I made the 'mistake' of looking at a Televue Paracorr. I just had to buy it. Expensive, but it works very well for visual and imaging.

Thought I should mention it .... :smiley:

Got my eye on one of these:

https://www.teleskop-express.de/shop/product_info.php/info/p4685_ASA-2--Newtonian-Corrector---Reducer-0-73x.html

It would cost more than scope itself though........

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Josh Wilson

Josh Wilson

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Wait!!! Don't buy that corrector just yet. Get Gimp! You can use a tool to fix the coma. I believe it's called 'Lens Distortion'. Might sound bad but if you do the exact opposite of what the telescope messes up, it can fix the coma. Give that a go before you purchase the corrector.

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laser_jock99

laser_jock99

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Wait!!! Don't buy that corrector just yet. Get Gimp! You can use a tool to fix the coma. I believe it's called 'Lens Distortion'. Might sound bad but if you do the exact opposite of what the telescope messes up, it can fix the coma. Give that a go before you purchase the corrector.

Too late- the corrector is on it's way! Also bear in mind the ASA Keller is a focal reducer too (I just hope I've got enough back focus to use it.....)

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  • 2 months later...
laser_jock99

laser_jock99

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Do you have a link to one of these bad boys? In this case - google is not my friend!

Cheers

Ian

The scope or the corrector/reducer?

Scope came from here:

http://www.telescope...Newtonians.html

Corrector/reducer from here:

http://www.teleskop-...ucer-0-73x.html

More recent test images

300s single sub Horsehead

DSIR6112_1024.jpg

600s single sub Rosette

DSIR6121_noels_1024.jpg

600s single sub Crescent nebula

DSIR6089_noels_1024.jpg

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laser_jock99

laser_jock99

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Wow! Loads of signal, especially the cresent.

Is the EQ6 now happy with the load?

The scope at 12" apperture and very short focal ratio acts like a photon Hoover! Seems to pick up the faint detail really quick- the 10 minute Cresent Nebula test shot being a good example- all that faint stuff in the background is starting to show nicely after minutes not hours.

The EQ6 doesn't moan & groan too much- I had to upgrade the the power supply to a true 5A unit and I had to get two more counter weights (20Kg total). As long as the EQ6 gets enough power and is well balanced it's fine.

I use this scope out in the open though so windy nights are out of the question. Anything this big will act like a giant sail!

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Chris

Chris

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Very impressive stuff indeed! LJ:) Theres a lot of mixed opinions about these fast Newts but I'm certainly coming round to them, and this thread is certainly adding to that. I'm trying to decide on a main scope for my obsy? something like an 8" Quattro would make a lot of sense when coupled with my old almost vintage HEQ5, I've got to grab as many photons as I can with my short subs:D

p.s. heres a question, would mounting a 12" on an NEQ6 equate to moutning a 10" on an HEQ5? Not that I would attempt to put a 10" on my old mount:D I'm just wondering?

Chris

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  • 3 weeks later...
whooshbang

whooshbang

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wow, beast of a newt. some great initial images there too. Also keeping my eye on 12" newtonian for an obsy project later next year for observing only but i'll be keeping an eye on your progress with this set up for sure. Thanks for the post.

I wonder how many more 12" newts on eq6 mounts there are on this forum?

Be good to hear how people get on with them.

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