Recommend a refractor for imaging - around 500mm focal length

[tooth_dr]

I'm after a 4" triplet, something around 500mm/F5, with a good flat field and nice round stars.  Principally it will be used with a 28.4mm diagonal APS-C sensor, but would be nice if it delivered a wider flat field.

I was chatting to Jessen about the APM 105/650, with the 0.75x reducer, giving 487mm at F4.65, but unfortunately this scope is just out of my budget.

What would be your recommendation for a suitable scope?

 

Thanks in advance

Adam.

[david_taurus83]

Esprit?

[vlaiv]

Maybe this:

https://www.teleskop-express.de/shop/product_info.php/info/p12878_TS-Optics-CF-APO-102-mm-f-7-FPL55-Triplet-APO-Refractor-with-Certificate.html

together with this:

https://www.teleskop-express.de/shop/product_info.php/info/p11122_Riccardi-0-75x-APO-Reducer-and-Flattener-with-M63x1-Thread.html

Or maybe even M82 version of Riccardi flattener (larger and corrects for full frame if that is of use)

[scitmon]

https://www.firstlightoptics.com/askar-telescopes/askar-fra600-f56-108mm-quintuplet-apo-astrograph.html

 

might be worth looking at?

[tooth_dr]

6 minutes ago, scitmon said:

https://www.firstlightoptics.com/askar-telescopes/askar-fra600-f56-108mm-quintuplet-apo-astrograph.html

 

might be worth looking at?

Thanks for the link. I am for sending my current SharpStar back, don’t think I’ll buy another. 

[tooth_dr]

11 minutes ago, vlaiv said:

Maybe this:

https://www.teleskop-express.de/shop/product_info.php/info/p12878_TS-Optics-CF-APO-102-mm-f-7-FPL55-Triplet-APO-Refractor-with-Certificate.html

together with this:

https://www.teleskop-express.de/shop/product_info.php/info/p11122_Riccardi-0-75x-APO-Reducer-and-Flattener-with-M63x1-Thread.html

Or maybe even M82 version of Riccardi flattener (larger and corrects for full frame if that is of use)

The RIRED seems to be an excellent price on TS. Tempted to pick it up regardless. 
The M63 version has a slightly better spot diagram so likely just that one. 

Edited February 25, 2021 by tooth_dr

[tooth_dr]

31 minutes ago, david_taurus83 said:

Esprit?

It’s a very good option

[scitmon]

10 minutes ago, tooth_dr said:

Thanks for the link. I am for sending my current SharpStar back, don’t think I’ll buy another. 

Oh? What was wrong with it?

[tooth_dr]

What about this option, with the 0.75 reducer?

APM Telescopes Super ED APO Astrograph 107/700 Apochromatic Refractor Telescope with 3" APM Focuser (365astronomy.com)

APM Riccardi x0.75 Small Reducer (astrograph.net)

 

[vlaiv]

I can't tell anything except that I would consider it for myself if I had the need / funds for it.

Haven't read or heard of any experiences with that particular model, but it does look to be quite ok scope.

[Sp@ce_d]

+1 for Esprit 80. I've had two for a few years now I was so impressed. Currently put the recently acquired ASI2600MC on one, very early days but so far clouds & moon look good across the field of view 🤣

[tooth_dr]

2 minutes ago, Sp@ce_d said:

+1 for Esprit 80. I've had two for a few years now I was so impressed. Currently put the recently acquired ASI2600MC on one, very early days but so far clouds & moon look good across the field of view 🤣

Unfortunately too short a focal length for me at 400mm, plus i changed from an 80mm scope so looking a  bigger aperture. I’m looking 500mm or close to this to mate up when my other 500mm scope on a dual rig. 

Edited February 25, 2021 by tooth_dr

[vlaiv]

Hm, seen this?

 

[tooth_dr]

2 minutes ago, vlaiv said:

Hm, seen this?

I did, mentioned it in first post. I did look into that but it’s over budget. 

[vlaiv]

1 minute ago, tooth_dr said:

I did, mentioned it in first post. I did look into that but it’s over budget. 

Indeed, my bad ...

[Sp@ce_d]

TaK Baby Q at 450mm 😁.. won't illuminate a FF tho. or the FSQ106 at 530mm 🤣

I looked at Sharpstar before I found my Esprit 150. The reason I ended up with two Esprit 80's is because I tried alternatives and like you, sent them back. I guess there's a reason why certain scopes come up time and time again in recommendations. Whats the 500mm you already have? If you're happy with that why not get another?

[tooth_dr]

7 minutes ago, Sp@ce_d said:

Whats the 500mm you already have? If you're happy with that why not get another?

Takahashi Epsilon 180ed, one of them in enough for any mortal. 

[Sp@ce_d]

12 minutes ago, tooth_dr said:

Takahashi Epsilon 180ed, one of them in enough for any mortal. 

So its the FSQ106 then.. anything less and .. well .. life's too short 😆

[tooth_dr]

31 minutes ago, Sp@ce_d said:

So its the FSQ106 then.. anything less and .. well .. life's too short 😆

Holy Moly, those are dear!

[Laurin Dave]

Esprit100..  550mm  fl, 40mm diameter flat field ..  might be a bit heavy for a JTD saddle though ..  what happened with the Sharpstar? 

 

[Laurin Dave]

3 minutes ago, Laurin Dave said:

Esprit100..  550mm  fl, 40mm diameter flat field ..  might be a bit heavy for a JTD saddle though ..  what happened with the Sharpstar? 

 

Just read you’re sending it back 

[gorann]

17 minutes ago, Laurin Dave said:

Esprit100..  550mm  fl, 40mm diameter flat field ..  might be a bit heavy for a JTD saddle though ..  what happened with the Sharpstar? 

 

I have my Esprit 100 on a JTD saddle next to my Esprit 150 - no problem.

[gorann]

Actually, I just ordered a second JTD saddle for my upcoming double RASA 8 rig. Still, I wonder why this seems to be the only adjustable double-rig saddle made.

[Laurin Dave]

14 minutes ago, gorann said:

Actually, I just ordered a second JTD saddle for my upcoming double RASA 8 rig. Still, I wonder why this seems to be the only adjustable double-rig saddle made.

Mine’s piggybacked and uses shims for alignment..  but I have an OAG on the 150 otherwise there’s be nowhere for the guide scope 

[tooth_dr]

Any other considerations for a good short FOV refractor? Budget £2000-2300