213 replies to this topic

[CHASLX200]

If anyone gets a chance, compare an f15 refractor to an f5 or f6 (achromats) and you'll see what dramatic difference means.

Just FC alone at F/5 kills it for me let alone color.

[bobhen]

I have a 6" f/15 and a 6" f/5 achromat. They're very fun to compare and contrast. But they also show how overstated CA is on most viewing. Planets? Sure, I'll take the f/15 every day. But widefield? The f/5 holds its own, even moderate power on an extended object; very nice. I can also use the 6" f/5 for H-alpha NV viewing of nebula, H-alpha viewing of the sun with a Quark, etc. Both things the f/15 would be inferior without modification.

The difference is more dramatic when the full spectrum is used, which is not the case with Ha solar or Ha NV observing, and when powers are above lowish to high.

 

Having said that, I have owned a 102mm F5 achromat for 20-years and use it for low power, deep sky, wide field observing visually or with a Ha filter and image intensifier for NV observing. For those uses, fast achromats are great.

 

Fast achromats can be had used at relatively low prices. They are a good bargain if you have the need for what they offer.

 

Bob 

[SandyHouTex]

A 7 inch Questar with all the trimmings for a mere $14,000:

 

https://astromart.co...are-accessories

 

I think I'd go with a 180c Mewlon ($2200) and a GM8 ($2700) for $5000.

[SandyHouTex]

And why would anyone "sand cast" a diagonal holder:

 

https://astromart.co...l-free-shipping

 

$225

[Kasmos]

And why would anyone "sand cast" a diagonal holder:

 

https://astromart.co...l-free-shipping

 

$225

Probably because they were'nt common and that's how Celestron made almost everything back then.

[Bomber Bob]

Potential Steal & Great Gift!!   Kenko KES-80 F15 EQ Kit IOB:   https://zenmarket.jp...ode=u1151302193

 

Near mint Beauty!  Pre-NES version with the Coke Can Axes.  Bet it would smoke my 1978 Tasco (T) 15K...

 

Another ZEN temptation I don't need...   1996 Takahashi MT-130 w/ Cradle + Reducer + Extender:   https://zenmarket.jp...ode=n1151029366

 

Minty Mirrors & Cosmetics, too.

Edited by Bomber Bob, 03 September 2024 - 03:59 PM.

[Mr Magoo]

Older Dynascope - $100 in Crawfordsville, IN

 

Yes, the scope is a steal for that price.  It is identical to the one I purchased a few months ago, but it didn't  have a mount.  I believe they were built from '57-59.

 

They have some very nice features.  Great optics!  Rotating rings, circular vane for the secondary, and the focuser has a draw tube with R&P.

 

If it was local for me, I would grab it.

Unfortunately it was a scam.

[CHASLX200]

A 7 inch Questar with all the trimmings for a mere $14,000:

 

https://astromart.co...are-accessories

 

I think I'd go with a 180c Mewlon ($2200) and a GM8 ($2700) for $5000.

OUCH!  I was never happy with mine and only kept it a few weeks when we had a cold winter and would never cool worth a hoot and 6k was a lot to me back then so out it went.

[Garyth64]

Unfortunately it was a scam.

Did you check it out?

 

https://www.facebook...386437751163263

[RichA]

And why would anyone "sand cast" a diagonal holder:

 

https://astromart.co...l-free-shipping

 

$225

High quality sand casting and machining PLUS it's collimatable.  Put in an Antares diagonal mirror and put it up against AP, TV, etc.

[Russell Smith]

High quality sand casting and machining PLUS it's collimatable.  Put in an Antares diagonal mirror and put it up against AP, TV, etc.

I'm in over my head but, if I need to upgrade the mirror...?

[SandyHouTex]

Probably because they were'nt common and that's how Celestron made almost everything back then.

Takahashi has their own foundry and the don't sand cast there diagonals, focusers, etc..

[SandyHouTex]

High quality sand casting and machining PLUS it's collimatable.  Put in an Antares diagonal mirror and put it up against AP, TV, etc.

As a mechanical engineer by trade, I would never do this.

[cavedweller]

And why would anyone "sand cast" a diagonal holder:

 

https://astromart.co...l-free-shipping

 

$225

They were provided with the sand cast OTA, so possibly to match the aesthetics.

[jgraham]

Go with what ya' know. Either that, or it doubled as counterweight for the rear cell. 😀

[Kitfox]

...

 

Another ZEN temptation I don't need...   1996 Takahashi MT-130 w/ Cradle + Reducer + Extender:   https://zenmarket.jp...ode=n1151029366

 

Minty Mirrors & Cosmetics, too.

You STILL don’t have an MT-130?  

[gianluca]

Noody would ... today.

But things were different 60 years ago...

Apply the same readoning, and It will be easy to criticise using a Schmidt corrector, syncro motors, spur gears, the Celestron focusing mechanism, till even the whole build of Galileo's telescope...

 

And, by the way: in truth Takahashi DOES sand cast its focusers...

 

G.

 

 

 

Takahashi has their own foundry and the don't sand cast there diagonals, focusers, etc..

[AstroKerr]

Takahashi has their own foundry and the don't sand cast there diagonals, focusers, etc..

Takahashi 1

 

Takahashi 2

 

and so on. 

 

I wouldn't put the gist of post #63 on your resume without good reason - it is limiting. Boeing may have a few openings.  

Edited by AstroKerr, 04 September 2024 - 01:59 AM.

[cavedweller]

And why would anyone "sand cast" a diagonal holder:

 

https://astromart.co...l-free-shipping

 

$225

Price reduced to $195.

 

Also, on CN Classifieds:

 

https://www.cloudyni...giant-diagonal/

Edited by cavedweller, 04 September 2024 - 07:45 AM.

[m0bius]

Sears 6344 76mm F15 refractor - $80 in Vacaville, CA

[Senex Bibax]

I haven't seen one of these before. Plenty of Polaroscope refractors, but here is a reflector. I sent a message to the seller for more info.
Toronto Kijiji, price not given:  https://www.kijiji.c...cope/1657067211

[SandyHouTex]

Noody would ... today.

But things were different 60 years ago...

Apply the same readoning, and It will be easy to criticise using a Schmidt corrector, syncro motors, spur gears, the Celestron focusing mechanism, till even the whole build of Galileo's telescope...

 

And, by the way: in truth Takahashi DOES sand cast its focusers...

 

G.

They sandcast the outer part of it, not the steel tube that focuses.

[SandyHouTex]

Takahashi 1

 

Takahashi 2

 

and so on. 

 

I wouldn't put the gist of post #63 on your resume without good reason - it is limiting. Boeing may have a few openings.  

See my previous post.  I already work for the government entity that uses Boeing stuff.  I helped design, test, manufacture, and launch package the solar arrays on space station.

 

And you?

Edited by SandyHouTex, 04 September 2024 - 12:11 PM.

[mdowns]

c80 and polaris mount,$215.00 on FB florida

[RichA]

I'm in over my head but, if I need to upgrade the mirror...?

That may not even be an issue, I only mention it because the diagonal mirror is a conventional oval like a Newtonian diagonal and if you actually wanted a 1/10th wave unit (neither of which AP or TV are) you can easily get it.