Refractor considerations

[Deadlake]

1 hour ago, Nikodemuzz said:

Exactly, I have read similar comments. And given that the light gathering difference is only about 15%, I wouldn't expect there to be a significant difference. Which further underscores my comment about the factors favoring the TSA-120 seem heavier.

I think you would get a difference for imaging if you went with a faster scope, but you are going for F7.5 scopes which are relatively slow. magic fluorite dose not help you there. 

By the way, both of those scope where on my shopping list but got crossed due to availability of faster scopes.

 

[Nikodemuzz]

1 hour ago, Deadlake said:

I think you would get a difference for imaging if you went with a faster scope, but you are going for F7.5 scopes which are relatively slow. magic fluorite dose not help you there. 

By the way, both of those scope where on my shopping list but got crossed due to availability of faster scopes.

 

This is true. Although with the reducer it will be F5.25 or thereabouts, but still. I have chosen to go that route because I wish that the scope would serve well as a visual instrument, too. However, there is an FSQ-106 in the Sales section at the moment that is making me question this approach...

May I ask what was your pick in the end?

[Deadlake]

4 hours ago, Nikodemuzz said:

This is true. Although with the reducer it will be F5.25 or thereabouts, but still. I have chosen to go that route because I wish that the scope would serve well as a visual instrument, too. However, there is an FSQ-106 in the Sales section at the moment that is making me question this approach...

May I ask what was your pick in the end?

I went with a LZOS 130mm/F6. This is for use with NV, where the aim is to get as close to F2 as possible. Televue makes a NV compressor that will get this scope to around 2.3. The only other option would of been a FSQ-130, which are no longer made and double the new price of the LZOS second hand. I did ask about compressors but that’s a hit on focus point and also expensive if you go Takahashi. The LZOS deals with temperature better, the only issue I can see is availablity on the 2nd hand market. 
I chose 130 mm as multi use due to the framing it will provide. I’ll end up get a 16” dob as well in the future, different light grasp and framing.

if you are happy with the image size you will get with fsq-106 and it’s the ED type then what’s not to like, for visual you can drop in a Q extender, (they apparently work in AP130GTX as well, so might try one in the LZOS). 

 

 

[Nikodemuzz]

8 hours ago, Deadlake said:

if you are happy with the image size you will get with fsq-106 and it’s the ED type then what’s not to like,

That is a good question, really. I had dismissed the FSQ because of its new price. The image size is not that different to the reduced TSA-120 (530mm vs 630mm). The visual use is a question for me even with the extender, but I have to be honest here. I enjoy visual observation, but I really don't enjoy prolonged stays in the cold. So imaging will be the dominant use case for sure. I dream of some day living in a warmer climate where I would be able observe more comfortably, but who knows when that will happen if ever?  

The FSQ would really probably be a very sensible choice for me. And here I was, finally arriving to a decision on the TSA. I really must seem hopeless, like a plastic bag in the wind! 😅

I did consider the APM LZOS as well, by the way. Other options seemed more tempting to me, and APM never sent me a quotation so they were chalked off the list.

Edited March 8, 2021 by Nikodemuzz
Typo

[Deadlake]

48 minutes ago, Nikodemuzz said:

That is a good question, really. I had dismissed the FSQ because of its new price. The image size is not that different to the reduced TSA-120 (530mm vs 630mm). The visual use is a question for me even with the extender, but I have to be honest here. I enjoy visual observation, but I really don't enjoy prolonged stays in the cold. So imaging will be the dominant use case for sure. I dream of some day living in a warmer climate where I would be able observe more comfortably, but who knows when that will happen if ever?  

The FSQ would really probably be a very sensible choice for me. And here I was, finally arriving to a decision on the TSA. I really must seem hopeless, like a plastic bag in the wind! 😅

I did consider the APM LZOS as well, by the way. Other options seemed more tempting to me, and APM never sent me a quotation so they were chalked off the list.

Surprised about APM, you could try rupert@astrograph.net. He usual get backs.

But the extra speed of the fsq-106 might be better for you, against the extra aperture as you've stated.
 

[Nikodemuzz]

The long considerations, comparisons and introspective use case studies have finally come to a close as the courier delivered this today.

 

[KP82]

34 minutes ago, Nikodemuzz said:

The long considerations, comparisons and introspective use case studies have finally come to a close as the courier delivered this today.

 

Congrats on acquiring one of the best 5" scopes in the world.

Are you going to keep it in an unheated obsy in order to minimise the cool down time?

[Nikodemuzz]

15 hours ago, KP82 said:

Congrats on acquiring one of the best 5" scopes in the world.

Are you going to keep it in an unheated obsy in order to minimise the cool down time?

Thanks KP82!

The plan is to have an observatory at some point, but it will take a while still. Now I'll have to settle for storing the scope in the cool but not quite ambient garage. I can usually set up well in advance in the backyard, but cool down times can become an issue anyway. My thinking with getting the TOA-130 was that a reasonably priced used scope can be sold again for minimal losses in the case it's not a good fit for my use case. And if it is, I'll be set for life.  

I can already tell that handling wise I worried too much about the weight. The scope is not light by any means, but is really not a problem at all.

Here are a few more pics:

 

[Neil27]

Gorgeous scope, never sell it is my advice. I regret selling mine around 9 years ago.

They are without doubt one of the best 5 inch refractors ever made.

Clear skies my friend 👍

[dweller25]

16 hours ago, Nikodemuzz said:

The long considerations, comparisons and introspective use case studies have finally come to a close as the courier delivered this today.

 

Nice glass 👍

[KP82]

3 hours ago, Nikodemuzz said:

Thanks KP82!

The plan is to have an observatory at some point, but it will take a while still. Now I'll have to settle for storing the scope in the cool but not quite ambient garage. I can usually set up well in advance in the backyard, but cool down times can become an issue anyway. My thinking with getting the TOA-130 was that a reasonably priced used scope can be sold again for minimal losses in the case it's not a good fit for my use case. And if it is, I'll be set for life.  

I can already tell that handling wise I worried too much about the weight. The scope is not light by any means, but is really not a problem at all.

Here are a few more pics:

 

Excellent plan. But I'm pretty sure you won't sell it. 😁

Have you thought about replacing the Tak cradle with a pair of tube rings? You can then attach a handle or another dovetail bar on the top to improve handling and prevent flexure in the ota.

[Deadlake]

1 minute ago, KP82 said:

Excellent plan. But I'm pretty sure you won't sell it. 😁

Have you thought about replacing the Tak cradle with a pair of tube rings? You can then attach a handle or another dovetail bar on the top to improve handling and prevent flexure in the ota.

I wondered how long it would take for the handle police to turn up. Must be an SGL thing. 🤣

I thought @JeremySor @johninderby would be first.

Edited March 25, 2021 by Deadlake

[Nikodemuzz]

1 hour ago, Deadlake said:

I wondered how long it would take for the handle police to turn up. Must be an SGL thing. 🤣

I thought @JeremySor @johninderby would be first.

Hah, that's funny! 

Although I must say that the idea about getting the rings has crossed my mind. I'll use the scope for a while as is to see how badly I really need them. No need to fix what ain't broken, especially as the rings aren't that cheap either. The handle would be nice, though. Still, I might prefer mounting the scope to the rings that are already attached to the saddle. To me sliding the dovetail into the saddle feels more awkward, even with handle. Without one it's almost a non-starter.

[Deadlake]

18 minutes ago, Nikodemuzz said:

Hah, that's funny! 

Although I must say that the idea about getting the rings has crossed my mind. I'll use the scope for a while as is to see how badly I really need them. No need to fix what ain't broken, especially as the rings aren't that cheap either. The handle would be nice, though. Still, I might prefer mounting the scope to the rings that are already attached to the saddle. To me sliding the dovetail into the saddle feels more awkward, even with handle. Without one it's almost a non-starter.

When I ordered the LZOS I discussed with Rupert having a handle fitted. Not surprisingly with the phenolic tube option (which apart from stopping dewing will stop my hands getting frozen to the tube) is not a standard option. In the end he had a spare APM handle and when the starlight rings where ordered the dovetail was sized to match the length of the standard APM handle. Trying to unattach the scope at the end of the night without a handle would be an expensive accident.