Julian Shaw's sombrero - with a surprise!

[Thalestris24]

17 hours ago, Petergoodhew said:

Louise, I've tried a couple of times with my Altair Astro 115 ED/APO and a 2" ED Barlow - so far without success.  I had a very heavy QSI683wsg dangling off the end of the Barlow - and my whole setup just wasn't solid enough (and not helped by the thumbscrew attachment of the Barlow to the focuser).  I'm curently working on changing to a screw-thread attachment to the focuser, cannibalising by Planostar flattener, which should help - but I suspect I also need to find an approach like Julian has for screw-threading the Barlow too before I can succeed.  Focal lengths of 1600+ are pretty unforgiving!

Good luck! Do post about how you get on

Louise

[ollypenrice]

Thanks to all for the kind comments and to Vim and Mark regarding deconvolution and the mathematical aspects of the system.

In choosing a small pixel camera to try this kind of project with our TEC 140 I followed the received wisdom and went for the Atik 460, giving 0.92"PP. Perhaps I should have gone for the 490 and 0.75"PP. There is the Barlow possibility but I don't know if the extra length would fit in the TEC's observatory! It's already tight. And the TEC flattener, whch I presume one wouldn't use with the Advanced Barlow, has the side effect of improving the blue correction in the TEC (which is primarily corrected for visual.) I can't be sure this would apply with the Barlow.

Another small aside: I found Julian's 460 data to have precisely the same characteristics as ours, to the point of seeming slightly uncanny. The background sky is a little noisy in that it has irregular pixel values varying between, say, 15 and 23 after a basic stretch. (On our Kodaks the range would only be from about 20 to 23 and with more at 23.) I've posted this before, but compressing the histogram below 23 works nicely. The lowest of the four anchor points is at 23.

Olly

 

[MartinB]

It is a stunning image.  However...apart from the excellent execution and processing what it tells me is that the Sombrero is very bright!  The exquisite detail in the dust band is testament to the quality of an apo refractor working at F15.  Well done Julian for a very logical choice.  Now, what I'm wondering is...how well would this set up work on the Fireworks galaxy?

[Thommy]

Very interesting, indeed. It has been demonstrated before that object S/N is independent of f-ratio. However, aperture and exposure time are important. Perhaps that is the effect we see here.

Take a look at the argumentation here http://www.stanmooreastro.com/f_ratio_myth.htm

/Thommy

[ollypenrice]

On 18/08/2017 at 11:29, MartinB said:

It is a stunning image.  However...apart from the excellent execution and processing what it tells me is that the Sombrero is very bright!  The exquisite detail in the dust band is testament to the quality of an apo refractor working at F15.  Well done Julian for a very logical choice.  Now, what I'm wondering is...how well would this set up work on the Fireworks galaxy?

It is indeed bright and this is a factor. I dare say Julian will visit the Fireworks at some time. I hope so. A difficulty in that target is the dense and potentially overpowering starfield so the Barlow might help on that. There would also be the possibility of longer exposures.

Out of interest I do have it at native FL in our not dissimilar TEC 140. The colour comes from older data at 1.56"PP while the (new) luminance was at 0.91"PP

I used to find a metre FL something of a half way house but the arrival of a small pixel camera has opened up the galaxies even without Barlow.

Olly

[toxic]

just wow stunning image 

[Rodd]

There's my fast system!!!  Wow.  Beautiful

Rodd

[tony210]

Great image! -the receding disc dust lanes are excellent and make this a great galaxy - a bit low where I live though-Tony

[Rodd]

 

On ‎19‎/‎08‎/‎2017 at 09:03, ollypenrice said:

Out of interest I do have it at native FL in our not dissimilar TEC 140.

Wow--almost like the Hubbell image.  I'm commenting on the M104--you put this link into my thread--but I didn't see it when I commented on your post there--maybe it came in after you edited it?  makes me want to try the TOA 130 at F7.7 1000mm fl on M104 instead of the C11Edge.  I love refractors.  If changing scopes wasn't such a bother I would shoot it with one, then the other.  that is unlikely to happen though--noy with the num ber of clear nights I get.

[Helen]

A lovely image!  and I think gives an answer to my question in this thread ?  

 Worth a go!

Helen

[smr]

Amazing processing and image. It looks 3D. 

[gorann]

Really intrigued by this resurrected thread (started and nutured by @ollypenrice@Rodd@juliangeorgeshaw@MartinB@Thalestris24@Petergoodhew@wimvb and others). Has anyone done any more of this Barlow DSO imaging? Tempted to invest in a 2" Barlow / focal extender to turn my Esprit 150 into an f/14 galaxy hunter! Also not sure if I should go for the expensive Astro-Physics or Tele-Vue models or the more affordable Explore Scientific x2 Focal Extender. Maybe this approach only works on the bright Sombrero?

[wimvb]

19 minutes ago, gorann said:

Tempted to invest in a 2" Barlow / focal extender to turn my Esprit 150 into an f/14 galaxy hunter!

Carefull with this, Göran. As Olly wrote in the OP, the refractor used is a VERY good 6" refractor. A Barlow doesn't just magnify the nice stuff, but also the ugly. Any faults in the optics will be increased by 2 as well. So, even if the Esprit is a good 6" scope, it may not cope with a Barlow. And you will also need a good sky quality to benefit from the low "/pixel. Otherwise you may end up just oversampling.

[Helen]

Well when the weather next cooperates I am going to test with a WO 123 FLT scope and the AP Barlow.  I'm thinking of keeping the magnification as low as possible and seeing what happens.  It will certainly be a test of operating on non-ideal conditions (conditions are never ideal in suburban damp Wales!)

Helen

[gorann]

6 minutes ago, wimvb said:

Carefull with this, Göran. As Olly wrote in the OP, the refractor used is a VERY good 6" refractor. A Barlow doesn't just magnify the nice stuff, but also the ugly. Any faults in the optics will be increased by 2 as well. So, even if the Esprit is a good 6" scope, it may not cope with a Barlow. And you will also need a good sky quality to benefit from the low "/pixel. Otherwise you may end up just oversampling.

Not sure that the Esprit 150 is of any lower optical quality than the TMB LZOS 152 apo or TEC 140. Have not seen any tests saying that it would be, and there are plenty of reviews. Teleskop Service that sells all of these refractors says "We have been searching for a long time for the apropriate objective for a true high-end apochromat, and struck lucky with the Skywatcher ESPRIT 150. We have compared the image with other apochromats like TEC or LZOS and we have not found quality differences (https://www.teleskop-express.de/shop/product_info.php/info/p6463_TS-Optics-Photoline-150-mm-f-7-FPL53-Triplet---Starlight-3-5--Feather-Touch.html). In any case, whatever good quality apo refractor is used it would be interesting to see what people may find by using a Barlow.

[gorann]

15 minutes ago, Helen said:

Well when the weather next cooperates I am going to test with a WO 123 FLT scope and the AP Barlow.  I'm thinking of keeping the magnification as low as possible and seeing what happens.  It will certainly be a test of operating on non-ideal conditions (conditions are never ideal in suburban damp Wales!)

Helen

It will be really exciting to see what you find Helen, and maybe you could bring your scope to a darker site.

[wimvb]

30 minutes ago, gorann said:

Not sure that the Esprit 150 is of any lower optical quality than the TMB LZOS 152 apo or TEC 140. Have not seen any tests saying that it would be, and there are plenty of reviews. Teleskop Service that sells all of these refractors says "We have been searching for a long time for the apropriate objective for a true high-end apochromat, and struck lucky with the Skywatcher ESPRIT 150. We have compared the image with other apochromats like TEC or LZOS and we have not found quality differences (https://www.teleskop-express.de/shop/product_info.php/info/p6463_TS-Optics-Photoline-150-mm-f-7-FPL53-Triplet---Starlight-3-5--Feather-Touch.html). In any case, whatever good quality apo refractor is used it would be interesting to see what people may find by using a Barlow.

Hadn't read that. So the TS scope uses an Esprit lens cell? Anyway, it would be interesting to see an image taken with a barlow. That would make the Esprit a truly allround scope then.

[Rodd]

1 hour ago, gorann said:

Really intrigued by this resurrected thread (started and nutured by @ollypenrice@Rodd@juliangeorgeshaw@MartinB@Thalestris24@Petergoodhew@wimvb and others). Has anyone done any more of this Barlow DSO imaging? Tempted to invest in a 2" Barlow / focal extender to turn my Esprit 150 into an f/14 galaxy hunter! Also not sure if I should go for the expensive Astro-Physics or Tele-Vue models or the more affordable Explore Scientific x2 Focal Extender. Maybe this approach only works on the bright Sombrero?

I would go with a powermate over a barlow.   And I think you should try it--perfect optics or not.    No image is perfect.

Rodd

[gorann]

1 minute ago, wimvb said:

Hadn't read that. So the TS scope uses an Esprit lens cell? Anyway, it would be interesting to see an image taken with a barlow. That would make the Esprit a truly allround scope then.

Actually, I only think TS put a Feather Touch focuser on it. The transport case in their image is exactly the same as the one I got with my Esprit and why would they make their own aluminium tube? Regarding the TEC 140 and and APM LZOS 152, I would expect that the price differences (8295 Euro for the TEC and 8590 Euro for the APM and 5195 Euro for the Esprit) partly has to do with the focusers and mainly has to do with the land of production (Europe vs China). Still the standard Esprit focuser is a very good one in my oppinion - quite a step up from other SW focusers.

[wimvb]

10 minutes ago, Rodd said:

I would go with a powermate over a barlow.   And I think you should try it--perfect optics or not.    No image is perfect.

Rodd

What exactly is the difference between a Powermate and a Barlow? Price wise they seem about the same (comparing TV 2" Powermate to AP Barlow from the original image in this thread).

[gorann]

30 minutes ago, Rodd said:

I would go with a powermate over a barlow.   And I think you should try it--perfect optics or not.    No image is perfect.

Rodd

 

17 minutes ago, wimvb said:

What exactly is the difference between a Powermate and a Barlow? Price wise they seem about the same (comparing TV 2" Powermate to AP Barlow from the original image in this thread).

I just spent some time reading up on this. A Barlow in its original configuration is a simple two lens set with concave lenses or with three lenses in "apo" configuration (but some say that apo is of no use here), A Power Mate (as Tele Vue calls it) or Focal Extender (as Explore Scientific calls it) is a more advanced 4 lens construction that gives out a paralell light path so that magnification is independent of distance to chip (for a Barlow magnification increase with distance to chip). The Astro-Physics one is just a well made 2-lens Barlow but the Tele Vue and ES ones are of the more advanced 4-lens construction. The ES one may be as good as the TV one but at half the price. But what I have not figured out (but now asked FLO) is if the ES one can the screwed onto the camera or if a less desirable 2" "eyepiece"-barrel have to be attached to the camera (would make the image train less solid).

[Merlin66]

Note also that the Meade Series 5000 x3 Extender is very similar to the ES and is telecentric design.

 

[gorann]

3 minutes ago, Merlin66 said:

Note also that the Meade Series 5000 x3 Extender is very similar to the ES and is telecentric design.

 

Yes, forgot to mention that Power Mates and ES  Extender constuction is called telecentric, but 3x is a bit over the top - making my Esprit into a 3300 FL scope may be to push it.....

[wimvb]

12 minutes ago, gorann said:

making my Esprit into a 3300 FL scope may be to push it.....

At f/21, I would think so. 

But it's easier to swap barlow/powermate than telescope.

[Merlin66]

My rule of thumb for solar imaging is focal ratio =x5 pixel size.

Usually work around f25.