Which Refractor Is Best for $7000

[clive milne]

Originally Posted by gregbradley

Other scopes may vary with an AP most likely having the largest corrected circle in its class.

Greg.

AP 160ff, corrected field 76mm:
http://www.astro-physics.com/product..._acc/160ff.htm

TOA-150 with FL67 field flattener, 90mm
http://www.takahashi-europe.com/en/T...ifications.php

[Logieberra (Logan)]

Both Marcus and I have the older style focuser on the TOA. Some quote it as a 2.7" model, which is not correct. To my knowledge, it's 3.5". Depends where the focuser is measured, that is to say, 2.7" is not the same across manufacturers. Also, my 3.5" along with #67 flattener -- flat, unobstructed wide field on 6D full frame chip.

[gregbradley]

Originally Posted by clive milne

AP 160ff, corrected field 76mm:
http://www.astro-physics.com/product..._acc/160ff.htm

TOA-150 with FL67 field flattener, 90mm
http://www.takahashi-europe.com/en/T...ifications.php

Both of these are 4 inch focusers and corrected circle varies. In this case Tak is ahead (the old Tak versus AP competition eh?).

See the TOA FL35 only has a 40mm corrected circle - thats the 2.7 inch flattener that vignetted terribly on my FS152 and was unusable with an STL11 camera. It could be my data is limited here to only an older type scope as my TEC110 would handle an
STL11 and its about a 2.7 inch focuser.

Your TOA would be 4 inch if it handles the 67 flattener as it has a 90mm corrected circle so it must be quite large.

TOA scopes have a different optical configuration to the older FS doublets so it may be less of a problem with them (I did hear a report from someone who was using 2.7 inch focuser successfully with STL11). The point being you'd have to make sure before you spent $7000 on a refractor with a 2. inch focuser that it could handle a chip that large if that was your intended use. It would be an expensive mistake if it doesn't.

Greg.

[Logieberra (Logan)]

Tak eventually replaced to the TOA focuser with the new 'B' style, now 'TOA-150B'. Same 4" focuser as used on latest FSQ. I was quoted $1,000 to upgrade to 'B', but after advice from Marcus I too stuck with the original and went with RoboFocus.

You could also go FeatherTouch for complete focuser upgrade (a very popular discussion in the US and Tak forums) but by the time you purchase the FT focuser, adapters and FT motor to suit, looking at $1,200+ and whopping great lump of original focuser rendered useless and near impossible to sell!

Agree with Greg, focuser needs to be considered carfully in a 7k scope purchase!

[Logieberra (Logan)]

P.S. If I had the coin an FLI focuser would have been my next choice. On R&P focusers you still have that nice manual control for visual sessions, just operate the R&P like the FLI is not even there, whereas Robo and FT motors both need that constant 12v power to operate...

[Peter Ward]

Originally Posted by clive milne

AP 160ff, corrected field 76mm:
http://www.astro-physics.com/product..._acc/160ff.htm

TOA-150 with FL67 field flattener, 90mm
http://www.takahashi-europe.com/en/T...ifications.php

The AP 155F7 looks like it trumps contemporary offerings at 15-20 microns across a 4" field (100mm )

[Logieberra (Logan)]

Peter, is a used AP155 available in this 7k price range?

[gregbradley]

Used AP155 tend to go for closer to US$9000+. A 2.7 inch model may go for $8500. You can do a search on Astromart to see the history of sales but that's what I've seen.

There was a good one about 4 months ago. AP155, 4inch focuser and flattener for US$9500. That's low for that much scope.

By the time you add in shipping, insurance, GST, currency conversion its closer to $11,000.

Greg.

[Peter Ward]

Originally Posted by Logieberra

Peter, is a used AP155 available in this 7k price range?

Unless it's had a hard life, no....but at 20% more it would be a steal.

The other thing I'd note is the $A is long overdue for a correction/fall-off-cliff

I'm still smarting from when it was $US 0.48