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HunterHarling

Best 60-90mm refractor for imaging?

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Regarding reducers and F ratios, it's important to remember that any reduction in exposure time is valid only for the entire and extended new field. If you forget this you'll end up believing Starizona's Hyperstar nonsense, such as, Exposures that take an hour at f/10 take mere seconds with the Hyperstar lens.    I am amazed that they have not been taken to court over this claim since it is patently mendacious. There is a clear implication in the claim that the exposures in question are the same exposures when, of course, they are not since the focal length has been reduced to one fifth of what it was with an equivalent reduction in resolution.

Hunter, you live in California: isn't it going to be a bit hot for an uncooled DSLR? You could obtain the same chip in a cooled CMOS camera which I would have thought would work far better.

Olly

 

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11 hours ago, ollypenrice said:

Tak claim 44mm for the FSQ85 and that certainly won't cover full frame as I know from two examples of the scope. I wouldn't buy anything from which I hadn't seen full frame images. You cannot trust the published claims.

Now 'fixed' by adding the 1.01x flattener (which is now is included when purchasing the new FSQ85 EDP). Although this won't work when using the reducer.

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Posted (edited)

It seems strange to go for a telescope costing thousands but spend little on an unsuitable camera.  Just my opinion of course.

Edited by Gina
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17 hours ago, HunterHarling said:

Also I forgot to mention, the scope needs to have a full frame corrected field, as I will use a Nikon d810a with it. Is the reccardi reducer available in the USA?

I get a bit confused here - you initially said that you would use an ASI1600 (much smaller chip). As others have said here: in California you probably do much better with a cooled camera (like the ASI)

I have an Esprit 100 which is a really great and fast little scope. I just bought a TS 3" 0.79x reducer for it:

https://www.teleskop-express.de/shop/product_info.php/info/p6085_TS-Optics-REFRACTOR-0-79x-Reducer-Corrector---full-sized-sensors---M68-connection.html

That brings the FL down to 430 mm.

The image circle of the Esprit 100 is claimed (by FLO) to be 40 mm, so with the reducer it would be 32 mm which would be plenty for the ASI1600 but not enough for a full frame DSLR.

The good thing with the TS reducer is that I only needed two adapters with it to screw it onto the Esprit (costed 75 + 19 Euro). Fitting the Riccardi reducer to the Esprit would mean that I need the following adapters according to an email from Marcus Ludes at APM telescopes (citing it directly):

ASI 1600 MM with 17.5 mm back focus at Esprit 100 need follow adapters ( 81 mm – 17.5 mm – 30 mm = 33.5 mm after Riccardi )
-          Adapter M74 x 1 ID-Thread  to M63 x 1 ID Thread, APM custom made Euro 60
-          Riccardi Reducer M63
-          Adapter TSO-M63a-M48a , 3 mm thick Euro 44
-          Adapter  ( 17-23 mm )  TSM48vvar Euro 32
-          Adapter TSVF208 , 8 mm Euro 29,00
-          Adapter TSM48i-T2a, 4 mm Euro 19
 

So you would end up with 5 adapters costing 184 Euro, so now you would have to add 50% of the cost of the actual reducer on a pile of metal rings......

And I would expect that the quality of the TS reducer is about the same as the Riccardi.

What I do have to admit is that I have not been able to test the 3" TS reducer yet since I have no astrodarkness up here now. However, I have previously used the 2" version of the TS reducer on my Esprit 150 and stars were perfect to the edge with my ASI1600.

 

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6 hours ago, ollypenrice said:

Hunter, you live in California: isn't it going to be a bit hot for an uncooled DSLR? You could obtain the same chip in a cooled CMOS camera which I would have thought would work far better.

I will mostly be using the refractor with the asi1600, but I was hoping to use the d810a as well. I actually hadn't thought about the heat issue...😟

However, at some point I want to move over to one of the large full frame ccd/cmos cameras. But that is still a long way off, and I may very well have a tak by then.

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31 minutes ago, gorann said:

I have an Esprit 100 which is a really great and fast little scope. I just bought a TS 3" 0.79x reducer for it:

Do you see any quality decrease with the reducer, like larger stars, less detail, or strange star shapes? Also, what is the difference between the 2in and 3in?

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2 hours ago, gorann said:

I get a bit confused here - you initially said that you would use an ASI1600 (much smaller chip). As others have said here: in California you probably do much better with a cooled camera (like the ASI)

I have an Esprit 100 which is a really great and fast little scope. I just bought a TS 3" 0.79x reducer for it:

https://www.teleskop-express.de/shop/product_info.php/info/p6085_TS-Optics-REFRACTOR-0-79x-Reducer-Corrector---full-sized-sensors---M68-connection.html

That brings the FL down to 430 mm.

The image circle of the Esprit 100 is claimed (by FLO) to be 40 mm, so with the reducer it would be 32 mm which would be plenty for the ASI1600 but not enough for a full frame DSLR.

The good thing with the TS reducer is that I only needed two adapters with it to screw it onto the Esprit (costed 75 + 19 Euro). Fitting the Riccardi reducer to the Esprit would mean that I need the following adapters according to an email from Marcus Ludes at APM telescopes (citing it directly):

ASI 1600 MM with 17.5 mm back focus at Esprit 100 need follow adapters ( 81 mm – 17.5 mm – 30 mm = 33.5 mm after Riccardi )
-          Adapter M74 x 1 ID-Thread  to M63 x 1 ID Thread, APM custom made Euro 60
-          Riccardi Reducer M63
-          Adapter TSO-M63a-M48a , 3 mm thick Euro 44
-          Adapter  ( 17-23 mm )  TSM48vvar Euro 32
-          Adapter TSVF208 , 8 mm Euro 29,00
-          Adapter TSM48i-T2a, 4 mm Euro 19
 

So you would end up with 5 adapters costing 184 Euro, so now you would have to add 50% of the cost of the actual reducer on a pile of metal rings......

And I would expect that the quality of the TS reducer is about the same as the Riccardi.

What I do have to admit is that I have not been able to test the 3" TS reducer yet since I have no astrodarkness up here now. However, I have previously used the 2" version of the TS reducer on my Esprit 150 and stars were perfect to the edge with my ASI1600.

 

Excellent reality check. I come back to my earlier point: don't put theory (or marketing claims) before practice and don't buy a system because somebody says it will work. Buy a system with images which prove it does work.

Olly

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4 hours ago, HunterHarling said:

Do you see any quality decrease with the reducer, like larger stars, less detail, or strange star shapes? Also, what is the difference between the 2in and 3in?

No quality decrease with the 2" TS reducer, a fine piece of optics, and the 3" has the same opics, just a bigger diameter, so I trust it will perform nicely. If you are going to use the ASI1600 the 2" reducer would work fine (cheaper) and you could just put it into the eye-piece holder of the scope so you do not need any adapter to attach it to the scope.

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I think I've settled on the Esprit 100. I'll be fine if it doesn't handle full frame, as I'll be using the ASI1600 and probably won't change cameras for a long time.

I'll definitely post my results when I get it.

 

Thanks everyone for your excellent help.

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On 28/05/2019 at 21:18, gorann said:

No quality decrease with the 2" TS reducer, a fine piece of optics, and the 3" has the same opics, just a bigger diameter, so I trust it will perform nicely. If you are going to use the ASI1600 the 2" reducer would work fine (cheaper) and you could just put it into the eye-piece holder of the scope so you do not need any adapter to attach it to the scope.

I've ordered the 3" TS 0.79 for my 100mm Altair Starwave. Glad to see some positive reviews. Fingers crossed for a flat field!

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On 01/06/2019 at 22:12, HunterHarling said:

I think I've settled on the Esprit 100. I'll be fine if it doesn't handle full frame, as I'll be using the ASI1600 and probably won't change cameras for a long time.

I'll definitely post my results when I get it.

 

Thanks everyone for your excellent help.

You will never regret it! If you are worried about QC you can order it from FLO and get it checked before shipment (for 75 GBP I think). I did that with both my Esprits.

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I would love to order from FLO but I'm in the US and shipping might be tricky.

Anyhow, the Esprit scopes seem to be back ordered at the moment, and I'll get it in about 10 days.

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On 26/05/2019 at 22:33, HunterHarling said:

What about William Optics telescopes?

I have a WO 72. I'm not impressed with its full field. I'm pretty sure mine has a bit of pinched or misaligned optics. I wouldn't buy a WO again. 

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Well, the Esprit won't be in for another month, so I put in an order for the fsq 106.

Yes it's expensive, but I was going to get it at some point, and I know I'll have it all my life. Also, there's no doubt about the quality or ability to cover full frame, so I know I'll have many incredible nights with it.😀

I'll be sure to post my first light results when I get it.

 

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