APM ED152 APO F8 and Takahashi FC100-DF

[jetstream]

1 hour ago, DRT said:

WOW!!

 

Congrats for a fine viewing session with an excellent telescope!

[johnturley]

15 hours ago, DRT said:

 

 

One thing I did learn is that my APM EPs don't reach focus in the Tak with the 2" Baader Zeiss Prism  

More later...

I assume that the problem is due to a combination of limited focuser travel on the TAK, and the short light path of the Baader Zeiss Prism diagonal (102 mm I think), so that you have to rack the focusing mount out further, and with the above eyepieces beyond the limit of travel. How do you find the Zeiss Prism Diagonal compares to mirror diagonals, I thought about getting one, but besides price was put off by the short light path with my ES Refractor also suffering from lack of adequate focuser travel (only 45mm), so I opted for the Baader 2in Click Lock mirror diagonal, which has a longer light path of 110mm, and with a 47mm click lock extension tube can reach focus with all my eyepieces without having to insert any additional extension tubes.

The APM I think has a much more respectable 80 mm travel on the focusing mount, although this is still relatively small compared with around 5in on my original Astro Physics Refractor, and about 6in on my 1980's 102mm f10 Vixen Refractor. I don't know why some telescope manufacturers have to skimp so much when it comes to focuser travel.

Sounds like as I suspected, that the TAK refractor is behaving according to the laws of physics when it comes to showing fine lunar detail compared to the APM, rather than the laws of magic.

John

[DRT]

Yes, Tak focuser doesn't come out far enough with the Prism so need to throw in an extension tube.

[andrew s]

4 hours ago, johnturley said:

The APM I think has a much more respectable 80 mm travel on the focusing mount

 

1 hour ago, DRT said:

Yes, Tak focuser doesn't come out far enough

What happened to the good old draw tube that used to come standard with refractors. Maybe they could be an optional extra. ?

Mark you my last refractor had RAS thread and was 40 years ago.

Regards Andrew

 

[alan potts]

Sorry Derek I am somewhat late with congratulations, yes as John said up front, two very fine scopes, it's raining hard here for a change. Only 18 degrees today where as the norm is about 34, it was 10 the other morning.

Alan

[25585]

On 26 June 2018 at 01:46, jetstream said:

yep, some don't like clamshell tube holders much

Or more than 2 tube rings..

[Stu]

On 26/06/2018 at 15:04, andrew s said:

 

What happened to the good old draw tube that used to come standard with refractors. Maybe they could be an optional extra. ?

Mark you my last refractor had RAS thread and was 40 years ago.

Regards Andrew

 

This is what I ‘built’ for when I use the Tak Prism in the FC100DC.....

At the end of the day, I would rather have enough in focus for native binoviewer use and have to use an extension than not be able to easily use binoviewers.

The draw tube is something I’ve seen on some APM scopes and as long as there is no flex or misalignment in the setup then it seems like a good solution.

[johnturley]

14 hours ago, Stu said:

This is what I ‘built’ for when I use the Tak Prism in the FC100DC.....

At the end of the day, I would rather have enough in focus for native binoviewer use and have to use an extension than not be able to easily use binoviewers.

The draw tube is something I’ve seen on some APM scopes and as long as there is no flex or misalignment in the setup then it seems like a good solution.

 

I think that the tubes of most refractors are now sized to accomodate binoviewers, for me the tube length on my ES 127 Refractor is about 50mm too short, and because there is only 45mm of travel on the focusing mount, I need a 50mm extension tube to reach focus with a star diagonal, an additional extension tube to reach focus with a DSLR, and a longer extension tube still to reach focus without a star diagonal.  This contrasts with my 1980's vintage Vixen 4in Refractor which had sufficient travel on the focusing mount to reach visual focus with or without a star diagonal, and with a DSLR, without the need for any extension tubes, it probably did not however have sufficient in focus to use a bino viewer.

John

[25585]

On 25 June 2018 at 21:57, DRT said:

Chris, I still have the Altair Starwave 152 F5.9 Achro and have also owned two of the 102 F11s. I very briefly owned an Altair Lightwave 66ED but sold it before really getting any use out of it.

All of these are in a different league to what you are looking at so the only advice I can give you is that the Altair scopes are very well put together with solid construction, well figured lenses and excellent quality focusers. I have had a problem with the paint job on my 152 but that is being rectified by Altair.

@DRTis your 152 Altair the lovely red tubed one? 

I was under the impression they were anodised red tubes. 

[25585]

On 26 June 2018 at 13:36, DRT said:

Yes, Tak focuser doesn't come out far enough with the Prism so need to throw in an extension tube.

My DL which has the same focuser came with an extension tube, did your DF not have one included. 

[jetstream]

18 hours ago, 25585 said:

Or more than 2 tube rings..

I guess some respond when criticism is initiated? 

[DRT]

2 hours ago, 25585 said:

@DRTis your 152 Altair the lovely red tubed one? 

I was under the impression they were anodised red tubes. 

No, it's the white one.

2 hours ago, 25585 said:

My DL which has the same focuser came with an extension tube, did your DF not have one included. 

Yes, but that extension is probably twice as long as I need.

[dweller25]

@DRT

A very impressive pair of scopes :-

A big 6” for when you have time to set it up and cool it down and a 4” lightweight APO for grab and go

Nice ?