100mm APO scope

[urbko]

Hi, 

i'm looking to buy this scope, but i'm not sure if it's any good for astrophotography, i was hoping if any of you guys had a chance to use it.
And/or if any one can recomend any other good APO scope around 100mm for under or around 1000€  

Scope

Thank you. 

Urban

[dannybgoode]

Depending on what camera you plan you use you may find the focal length a touch long and the field of view a bit narrow for larger targets. This is what hampered my choice of 4” fracs.

Nice scope though but bear in mind you’ll need to budget for a field flattener (which usually acts as a focal reducer also). 

I like my 105mm /f6.2 as it has a native focal length 650mm but with the FR this is reduced to 487mm. Coupled with me camera lenses all the way up to my 10” SCT I have all bases covered but as my frac is going to be my weapon of choice I wanted versatility. 

Only issue is my scope is above budget (it was well above mine too ?). 

[urbko]

I have an ZWO 1600ASI, i realy like the 500-700 focal lenght, as it fits many targets , yes the price is without FR, so i'm willing to go a little above that pice mark  

haha that hapens too often  

[Thalestris24]

Hi

TS scopes are good quality. I have a 115mm F6.96 APO + Photoline 0.79x ff with R+P . I also have an 80mm F6 with .8x Altair Astro Lightroom ff. Not the same as the one you're interested but the ones I have are very nice. You might lose some colour correction with an ED but it's probably ok. I think, for imaging, you'd want a reducer as F7 would be a little slow. Of course, you can try and see what it's like at F7.

Louise

 

[vlaiv]

1 hour ago, urbko said:

Hi, 

i'm looking to buy this scope, but i'm not sure if it's any good for astrophotography, i was hoping if any of you guys had a chance to use it.
And/or if any one can recomend any other good APO scope around 100mm for under or around 1000€  

Scope

Thank you. 

Urban

That one is not so good. It uses FPL-51 glass and has some purple fringing around bright stars.

If you want 100mm scope around 1000e, take a look at this one:

https://www.teleskop-express.de/shop/product_info.php/info/p9868_TS-Optics-PhotoLine-102mm-f-7-FPL-53-Doublet-Apo-with-2-5--Focuser.html

It should have much better correction. There is another scope that might suit you for ASI1600, but it's a bit more expensive (it's a triplet):

https://www.teleskop-express.de/shop/product_info.php/info/p3041_TS-Optics-PHOTOLINE-115-mm-f-6-96-Triplet-APO-with-2-5--RP-focuser-1-11.html

For any of those, I think this reducer / field flattener is going to be excellent (a bit on expensive side):

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

 

[Merlin66]

Vlaiv,

I use three ED80 scopes, I believe using FPL-51 glass.

I don't see purple fringing and I'm not sure what the FPL-53 adds other than smart marketing.

To achieve "APO" performance you need the corrections applied to three optical elements, a doublet can only be a compromise.

 

[John]

If we are talking of the Skywatcher / Synta ED80's, they do use an FPL-53 ed glass element in the objective. The CA levels on those is very low.

[vlaiv]

21 minutes ago, Merlin66 said:

Vlaiv,

I use three ED80 scopes, I believe using FPL-51 glass.

I don't see purple fringing and I'm not sure what the FPL-53 adds other than smart marketing.

To achieve "APO" performance you need the corrections applied to three optical elements, a doublet can only be a compromise.

 

There are reviews of said scope, this one for example (under Altair Astro branding - now discontinued in favor of new version with FPL-53, again I suspect the same optics as scope I recommended instead):

https://www.altairastro.com/public/reviews/Starwave-102ED-Review-Sky-at-Night-Magazine-Issue-86-4_stars.pdf

Quote from above article: "We also looked for signs of chromatic aberration, when colours are not brought to the same focus point, and we were pleased to see very little colour fringing."

Others have reported that it is not color free, and that some violet fringing can be seen on bright stars. I've seen couple of pics taken with this scope and indeed there is color around bright stars.

Photographic application is more demanding on color correction than visual.

Don't get me wrong, I think above scope is good scope for the money, but OP did ask for 100mm APO in 1000e bracket, and I believe that FPL-53 doublet with lanthanum element is better choice for this application. That scope is the same optics as Stellarvue Access 102 F/7 - scope that got very favorable reviews.

I'm also not against FPL-51, there are good scopes out there using this glass and I'm not one to advocate for FPL-53 just because it's "better" type of glass. Other scope that I mentioned is FPL-51 based triplet.

 

[Merlin66]

John,

My SW ED80's are the older "Champagne"  ED80 pro model. I think the newer "Black Diamond" versions us the Schott FPL 53 glass.

 

[Thalestris24]

Yeah, the FPL53 version will be better optically but... 400 Euros more then you need to add a flattener, if not a reducer. So budget is a consideration. Urban doesn't say whether he has an osc 1600 or a mono. I'd have thought that If he's imaging in mono then colour correction would be less of an issue.

Louis

[John]

55 minutes ago, Merlin66 said:

John,

My SW ED80's are the older "Champagne"  ED80 pro model. I think the newer "Black Diamond" versions us the Schott FPL 53 glass.

 

They have always used Japanese Ohara FPL-53 glass as the ED element and I believe a Schott glass type as the mating element. Later Synta / Skywatcher had a revised marketing agreement with Schott which resulted in the stickers going on the tubes but my understanding is that they have always used this combination of glasses.

My ED120 is one of the original "Champagne" versions and it's definitely got an FPL-53 element in the objective. Very little CA from that scope either.

Obviously there is more to a refractor than just the ED glass type used though and the mating element used, the figure and polish and coatings all contribute to the ultimate image quality.

 

[Merlin66]

John,

Thanks for that. Always good to be corrected!

Bang per buck I find it hard to go past a good ED doublet.....

[John]

12 minutes ago, Merlin66 said:

Bang per buck I find it hard to go past a good ED doublet.....

Me too !