Scope comparison on Tycho

[jetstream]

We were blessed with another great evening with vg seeing for about an hour after sunset. I had the SW120ED and the TSA 120 out and cooled for a long time. The temps were fairly stable and we not dropping rapidly tonight.

I chose Tycho as a test bed for both scopes because of its placement near the terminator and also because of the size variation of its features and sharp tiered edges.  I used a Zeiss 25.1-6.7mm zoom and VIP barlowed to 2x roughly. The Zeiss has a virtual field stop and I forget the exact virtual placement of it so the 2x effect is conservative but not too far off.

I really enjoy observing and do so a lot, but I dislike these types of comparisons because someone might feel let down when there is a clear winner.

Tycho in the TSA120 was extremely sharp and contrasted showing the craterlets on the variegated ledge toward the terminator. These were distinct, sharp and showed easily with a couple very fine ones showing, they were possibly just indents in there. Tychos floor showed some slight "waves" to it, really light structure but easily seen. On the right side opposite the sharply defined central hill there is an small outcrop of rock. On the other side of the central feature is a larger, small boulder like filled outcrop cascading just into the crater. The tiered edges were very very sharply and finely defined and lightly snaked along its edge on the side toward the terminator. All views were highly contrasted but the seeing Tychos floor with subtle but distinct features were a great sight.

The SW120ED did not show the mentioned features the same way. Had I not had the TSA120 the view would have been perceived as "great" and it was. The views were sharp but not in comparison to the Tak. The edge of the crater toward the terminator showed one tier very well defined but the others were "smoothed" out melding together somewhat, still there but not clearly defined. On that mentioned ledge toward the terminator, it showed much softer and the small very fine craterlets (possibly indents) did not show at all. The ledges structure was blurred together compared to the Tak. The central hill was sharply defined and very good, the mentioned boulders intruding on the right showed a bit, not sharply defined as the Tak. Over on the left side of the central hill same thing.

Tychos floor showed nothing in the SW120ED, just smooth.

So thats my comparison and anyone who knows me knows that I just report things as I see them, regardless if its popular or not or if its the in thing to say.

The SW120ED is a sharp scope and I chose Tycho because I knew it would reveal differences between the scopes. If you had the 120ED and observed with it you would see it as nicely sharp and on some features as sharp as the TSA120. Its only when directly compared to eachother, under excellent seeing and with a top tier eyepiece do the differences show easily. Lesser eyepieces will make the scopes look closer together as will poorer seeing.

Of course this observation was with my eyes, under my sky and with my equipment. Had the SW120ED been the winner I would have gladly reported it, no question. I could continue doing comparisons but I dont think I will - Im just going to observe.

Gerry

Edited March 31, 2023 by jetstream

[Deadlake]

Did you mange to use the HR or TMB EP's at all?

[jetstream]

5 hours ago, Deadlake said:

Did you mange to use the HR or TMB EP's at all?

No, just the Zeiss zoom. The results would be the same however.

[John]

Interesting report 🙂

Of course it was mostly confirmation or expectation bias that you were seeing, apparently 😜

[jetstream]

8 hours ago, John said:

Interesting report 🙂

Of course it was mostly confirmation or expectation bias that you were seeing, apparently 😜

Lol, I report it as I see it and dont care what others think. All this talk about bias is just a distraction from acknowlegement regarding differences in optical quality. I just laugh when I report about how good our H130 is and there is no mention of bias then- and it is a good, diffraction limited telescope.

Its hard to believe that some appear so fragile that an issue like optical quality could upset them.IMHO.

[davidc135]

A very interesting report, Gerry, showing the difference between a good and an excellent scope. If you ever test the two in DPAC and were able to attribute the difference to colour correction or smoothness of figure etc it would be worthwhile.

David

[Stu]

On 02/04/2023 at 02:34, jetstream said:

Lol, I report it as I see it and dont care what others think. All this talk about bias is just a distraction from acknowlegement regarding differences in optical quality. I just laugh when I report about how good our H130 is and there is no mention of bias then- and it is a good, diffraction limited telescope.

Its hard to believe that some appear so fragile that an issue like optical quality could upset them.IMHO.

Quite right Gerry! Similarly I reported my Vixen FL102S was soundly trounced by my Heritage 130P on Zeta Herc, yet apparently only bought my Tak because I was too swayed by others eulogising about them.

[jetstream]

11 hours ago, davidc135 said:

A very interesting report, Gerry, showing the difference between a good and an excellent scope. If you ever test the two in DPAC and were able to attribute the difference to colour correction or smoothness of figure etc it would be worthwhile.

David

Yes, I would love to do this.  The 120ED, now with the focuser aligned is putting up vg views and will take around 500x . The TSA120 takes endless mag and the snap focus is brutally fast with my top eyepieces, the Zeiss zoom included. I'm noticing some things in these comparisons including the VX10/TSA. I can say this- I'm looking for features or circumstances that show up differences in these scopes and I have the seeing to do it in the spring.

When the terminator adds a great amount of contrast from placement the VX10 shows more detail-not sure about the contrast differences in the individual features shown yet. Under very difficult circumstances ie weak contrast from terminator placement near the edge, the TSA120 soundly bested the VX10. Dimming the brightness with very low scatter eyepieces at very high mag 300x+ the TSA 120 really did show the VX10 up. The TSA120 bested the 10" on Gassendi the other night as well.

Not sure if many are interested in these comparisons as some of the findings go against the grain. Right now I'm looking at a bigger refractor to go with the TSA and dont want to spend a pile on a suitable DPAC flat and I do think its flatness is important and thank you for the help on this.

I look forward to comparing my scopes in DPAC and hope to find a cost effective but suitable flat.

Edited April 3, 2023 by jetstream

[jetstream]

5 hours ago, Stu said:

Quite right Gerry! Similarly I reported my Vixen FL102S was soundly trounced by my Heritage 130P on Zeta Herc, yet apparently only bought my Tak because I was too swayed by others eulogising about them.

Thanks Stu. I think having the right tool for the job applies in all this. I have recently started to dissect the moon with some scopes and the results are a bit surprising. Under very difficult circumstances some scopes excel it seems. In the end a person will know what to reach for based on the observing conditions.

 

[mikeDnight]

20 hours ago, jetstream said:

Right now I'm looking at a bigger refractor to go with the TSA....

 Just buy yourself a Maxbright II binoviewer Gerry. A 120mm TSA for each eye will be stunning on lunar and planetary, and at a fraction of the price of a bigger scope. I can honestly say I haven't noticed any dimming of the image compared to the mono view, and there's certainly no reduction in resolution of fine detail. In fact fine detail becomes much easier to discern in the binoviewer.  Food for thought!

[mikeDnight]

20 hours ago, jetstream said:

Yes, I would love to do this.  The 120ED, now with the focuser aligned is putting up vg views and will take around 500x . The TSA120 takes endless mag and the snap focus is brutally fast with my top eyepieces, the Zeiss zoom included. I'm noticing some things in these comparisons including the VX10/TSA. I can say this- I'm looking for features or circumstances that show up differences in these scopes and I have the seeing to do it in the spring.

When the terminator adds a great amount of contrast from placement the VX10 shows more detail-not sure about the contrast differences in the individual features shown yet. Under very difficult circumstances ie weak contrast from terminator placement near the edge, the TSA120 soundly bested the VX10. Dimming the brightness with very low scatter eyepieces at very high mag 300x+ the TSA 120 really did show the VX10 up. The TSA120 bested the 10" on Gassendi the other night as well.

Not sure if many are interested in these comparisons as some of the findings go against the grain. Right now I'm looking at a bigger refractor to go with the TSA and dont want to spend a pile on a suitable DPAC flat and I do think its flatness is important and thank you for the help on this.

I look forward to comparing my scopes in DPAC and hope to find a cost effective but suitable flat.

I'm certainly interested in these comparisons Gerry. They are really important, so please keep em coming! 

[jetstream]

3 hours ago, mikeDnight said:

 Just buy yourself a Maxbright II binoviewer Gerry. A 120mm TSA for each eye will be stunning on lunar and planetary, and at a fraction of the price of a bigger scope. I can honestly say I haven't noticed any dimming of the image compared to the mono view, and there's certainly no reduction in resolution of fine detail. In fact fine detail becomes much easier to discern in the binoviewer.  Food for thought!

Geez Mike, I've almost convinced the wife about a new refractor! She may have just read this as she's scowling about something !😟

                                                                                                     

Shes actually on board and were heading across to USA to do the banking on the DM6 today. I do have excellent Binotron 27's and now that mono has been so good in the you know what shhhh!!! a guy named paul might be reading... that I will try binoviewing in it. Thank you for the heads up on the potential, but not, fun cash saving!

Gerry

Edited April 4, 2023 by jetstream

[jetstream]

3 hours ago, mikeDnight said:

I'm certainly interested in these comparisons Gerry. They are really important, so please keep em coming! 

Thanks Mike, the results are very interesting and all this is leading down the path to further understanding optics and what scope to choose when. I might we'll see.