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Viktiste

Decide between Esprit 80 ED or Evostar 80 ED + Zwo 1600mm pro or 183mm pro

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I have decided to pull the trigger on a 80mm refractor and a dedicated cooled astro camera. For photographing nebula's and galaxies.

The OTA options I consider are the SW Esprit 80 ED (at £1 599) or the SW Evostar 80 ED (at £ 399). Will the performance of the triplet be that much better than the doublet that the three times higher price is justified?

For camera I am trying to choose between the ZWO ASI 183MM pro or the ASI 1600MM pro. Is there any reason (other than price) to prefer one over the other with either scope above? I will also be buying a filter-wheel.

Equipment I already have are a HEQ5 Pro, a ZWO ASI 120MC-S (for guiding), a SW 200P (which is too heavy/cumbersome for AP), Canon 500D and a DYI MyfocuserPro.

I have plugged these scope/camera combinations into astronomy tools and are aware of the FOV's they give.  I think I prefer the smaller FOV. Resolution ranges from 0.97"/pixel to 2.30 "/pixel for these combinations (with a 0.85x reducer/flattener), so I guess that is ok?

I am struggling to make the decision's, any thoughts? 

 

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1 hour ago, Viktiste said:

I have decided to pull the trigger on a 80mm refractor and a dedicated cooled astro camera. For photographing nebula's and galaxies.

The OTA options I consider are the SW Esprit 80 ED (at £1 599) or the SW Evostar 80 ED (at £ 399). Will the performance of the triplet be that much better than the doublet that the three times higher price is justified?

For camera I am trying to choose between the ZWO ASI 183MM pro or the ASI 1600MM pro. Is there any reason (other than price) to prefer one over the other with either scope above? I will also be buying a filter-wheel.

Equipment I already have are a HEQ5 Pro, a ZWO ASI 120MC-S (for guiding), a SW 200P (which is too heavy/cumbersome for AP), Canon 500D and a DYI MyfocuserPro.

I have plugged these scope/camera combinations into astronomy tools and are aware of the FOV's they give.  I think I prefer the smaller FOV. Resolution ranges from 0.97"/pixel to 2.30 "/pixel for these combinations (with a 0.85x reducer/flattener), so I guess that is ok?

I am struggling to make the decision's, any thoughts? 

 

A law of diminishing returns sets in very soon in this game. The Esprit is a far better scope than than the ED80 but the ED80 is far too good for it to be possible for any scope to be three times better. In narrowband the difference will be very significantly less than in broadband, where the real differences will show.  This may be a consumer problem but it's a nice problem to have, maybe?

Why would you prefer a smaller field of view? Don't make the mistake of thinking this 'gets you closer to the object' or somehow 'zooms you in.' It absolutely doesn't. The extent to which you are 'zoomed in' or 'getting a larger image of a small object' or 'resolving more details' has nothing at all to do with the field of view. It depends on your imaging scale in arcseconds per pixel.

Olly

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I agree with Olly, it may be almost three times the price, but will maybe about 10-15% better, same as if you were deciding between the Espirit 80 and the FSQ 85mm Tak, which again, just over three times the cost of the Espirit 80, but also again maybe only 15% better...

:)

Edited by StarDodger

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51 minutes ago, StarDodger said:

I think the OP has the price mixed up with the Espirit 100 Ed... :)

 

Yes, I did. £1 059 is the right price, so not 3 times more expensive, but still...  I am biased towards saving some money and go for the Evostar. 

Edited by Viktiste

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1 hour ago, ollypenrice said:

Why would you prefer a smaller field of view? Don't make the mistake of thinking this 'gets you closer to the object' or somehow 'zooms you in.' It absolutely doesn't. The extent to which you are 'zoomed in' or 'getting a larger image of a small object' or 'resolving more details' has nothing at all to do with the field of view. It depends on your imaging scale in arcseconds per pixel.

That was my thinking, to be able to 'zoom in' on smaller objects. But yes you are of course right, arcsec per pixels will determine that.

So assuming the Evostar 80ED and a 0.85 reducer, then:

ASI1600mm will give 1.54"/pixel

ASI183 will give 0.97"/pixel 

The ASI 1600mm has a  4/3" sensor, the ASI 183 has a 1" sensor.

Im I correct in saying the smaller sensor gives better pixel resolution and smaller FOV and the larger sensor gives lower pixel resolution and larger FOV?

I have a 'feeling' the 1600mm is the better camera, but struggle to convince myself why. The price difference between these cameras is not that big so I can go for either one.

 

Edited by Viktiste

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41 minutes ago, Viktiste said:

That was my thinking, to be able to 'zoom in' on smaller objects. But yes you are of course right, arcsec per pixels will determine that.

So assuming the Evostar 80ED and a 0.85 reducer, then:

ASI1600mm will give 1.54"/pixel

ASI183 will give 0.97"/pixel 

The ASI 1600mm has a  4/3" sensor, the ASI 183 has a 1" sensor.

Im I correct in saying the smaller sensor gives better pixel resolution and smaller FOV and the larger sensor gives lower pixel resolution and larger FOV?

I have a 'feeling' the 1600mm is the better camera, but struggle to convince myself why. The price difference between these cameras is not that big so I can go for either one.

 

You are correct in difference between cameras in terms of pixel resolution and FOV, but there is important BUT there - resolving power of scope and atmospheric conditions.

80mm aperture simply won't be able to resolve 1"/px under almost any circumstances (real ones that you might encounter - meaning HEQ5 mount and regular, even pristine skies). Even going for 1.54"/px is going to be a stretch in most circumstances. With 80mm scope you should really aim for around 2"/px.

You can do 2"/px with ASI183 - just simply bin x2 your pixels and you will be there - question is, what would be the point? If you already have ASI1600 model and there is a scope that will give you 2"/px - I would go for that combination. In fact I have such combination :D and it works well.

With larger sensor, you'll probably want a flattener as well.

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Thanks Vlaiv.

So many things to consider :Envy:

Just to clarify - I don't already have the ASI1600. What camera to buy is also what I need to decide.

So do you think going for the Evostar 80ED + 0.85 reducer/flattener + ASI1600 (=1.54"/px)  will be a mistake considering my HEQ5 mount? 

Not quite sure which scope (in the similar price range as the Evostar) to pick to get in the  2"/px ballpark. 

 

Edited by Viktiste

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8 hours ago, Viktiste said:

So do you think going for the Evostar 80ED + 0.85 reducer/flattener + ASI1600 (=1.54"/px)  will be a mistake considering my HEQ5 mount? 

No, not a mistake. Many people that try (or have tried) such combination will find it works wonderfully.

With choosing camera scope combo - it's not like on/off switch - one combo will work, while other won't. There is continuous range of performance, and sometimes when we talk about optimal setup - difference between it and "next best thing" will be more in theoretical domain than in practical. You will be hard pressed to tell the difference in SNR of let's say 5-10% in your data. It will be there, but for intention of image rendering it will be minimal if noticeable at all.

80mm scope and 1.54"/px sampling will need something like following conditions in order not to oversample:

- 0.5" RMS guide error - rather difficult thing to achieve on HEQ5, it can be done but probably not consistently. It would involve modding the mount (belt, tripod/pier, saddle plate ....) and wind protection (or a calm night).

- 1.5" FWHM seeing. This is something that you can in principle get on some nights almost everywhere. Getting such figures most of the time requires very good location (in terms of seeing).

All this means that you will oversample a bit at 1.54"/px most of the time with 80mm scope on HEQ5, but like I said above, sampling rate is also not something that will either work or not work, it is continuum, meaning slight undersampling or slight oversampling will not be an issue that one will notice.

If you have budget large enough, then do look at triplet scopes of 80mm range. While 80ED is fine scope, there are scopes out there that are optically better, will produce tighter stars and will get you into more comfortable zone in terms of sampling rate.

For example Esprit 80, with 400mm FL and ASI1600 will give you 1.96"/px. There you go - probably better scope optically (and mechanically) and gives you about 2"/px.

 

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I don't have a budget as such but I am reluctant to spend silly amounts of money on this hobby (which is obviously totally possible to do). I have landed on the ASI1600MM+filterwheel. I have re-considered and think I will fork out for the Espirit and the belt mod for my HEQ5 . Thanks for the inputs Olly and Vlaiv, much appreciated. Regarding filters+filter wheel, there is an option to choose between 8 x 1.25" or 7x36mm. What should I choose here?

I assume I will need a flattener too?

 

Edited by Viktiste

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5 hours ago, Viktiste said:

I don't have a budget as such but I am reluctant to spend silly amounts of money on this hobby (which is obviously totally possible to do). I have landed on the ASI1600MM+filterwheel. I have re-considered and think I will fork out for the Espirit and the belt mod for my HEQ5 . Thanks for the inputs Olly and Vlaiv, much appreciated. Regarding filters+filter wheel, there is an option to choose between 8 x 1.25" or 7x36mm. What should I choose here?

I assume I will need a flattener too?

 

I can't really comment on filter wheel from experience - I use filter drawer with my setup. I do know however that ASI1600 can get away with 1.25" filters if mounted fairly close to the sensor and I would choose filter wheel not based on size of filters but rather mechanical quality. You want your filter wheel to be precise so you don't have to take flats every time. This means that it should repeat exact position every time. Any small shift in filter position will move dust shadows and you won't be able to get good calibration.

Flattener is something that you will need for larger sensors in order to have good stars all the way to the edge.

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Yes, you  need the flattener. I would also suggest that the 36mm filters will match the ASI1600mm better.

I can also vouch for the heq5/Esprit 80ED combo. My mount is not modded at all and I image at 2.8"pp: I was rejecting about 15 to 20% of my subs, as long as i avoided imaging around the point where the scope balance flips over (usually around, or just past, the meridian).

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3 minutes ago, vlaiv said:

I can't really comment on filter wheel from experience - I use filter drawer with my setup. I do know however that ASI1600 can get away with 1.25" filters if mounted fairly close to the sensor and I would choose filter wheel not based on size of filters but rather mechanical quality. You want your filter wheel to be precise so you don't have to take flats every time. This means that it should repeat exact position every time. Any small shift in filter position will move dust shadows and you won't be able to get good calibration.

Flattener is something that you will need for larger sensors in order to have good stars all the way to the edge.

I've never had a real problem with dust bunnies from the filters, it's usually somewhere else in the imaging train. In fact, like others on SGL, I usually just use the luminance flat to correct all my subs.

FWIW, i had the SX 7 position usb filter wheel. The biggest problem with that one is the janky usb connection diectly on the circuit board, but that's another story!

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Thanks Pompay.

6 hours ago, Pompey Monkey said:

I would also suggest that the 36mm filters will match the ASI1600mm better.

But on FLO's website it says "you can use 1.25" filters without vignetting up to f/5 or 31mm filters up to f/2"

So from that I guess the 1.25" is what i should select?

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As I understand it, 36mm filters have been produced to meet the demands of imagers using the very popular KAF 8300 chip based cameras. The 8300 is only 0.6mm bigger in the diagonal.

I guess it's down to how close you can get the filters to the chip...

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On 16/08/2019 at 20:32, Viktiste said:

I will also be buying a filter-wheel.

 

On 18/08/2019 at 12:49, vlaiv said:

I would choose filter wheel not based on size of filters but rather mechanical quality. You want your filter wheel to be precise so you don't have to take flats every time. This means that it should repeat exact position every time. Any small shift in filter position will move dust shadows and you won't be able to get good calibration

There have been reports, on this forum and zwo user forum, lately of zwo filter wheels not being mechanically precise. If you move from one filter to another and back, the filter won't return to its exact position. This is, in my opinion, totally unacceptable, but zwo seem to find it ok. I have also suspected this to be the case with my (zwo) filter wheel, because I've had trouble calibrating out dust bunnies lately. I'm not saying you should avoid zwo filter wheels, just do your homework before you give any manufacturer your hard earned money. 

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You have to consider a proper focuser for the SW80ED. The standard focuser won't cut imho. Thats something not to worry about with the Esprit model. For the price difference you could probably add a nice focuser which is more stiff/stable on the SW80ED. But  don't forget proper adapters to make it fit and you are fairly quick and several hundred Euros, or Pounds ;). 

I cannot give advice on the camera model or the doublet vs. triplet discussion. But I know that there are capable imagers out there doing wonderful images with there SW doublets.

 

regards

Michael

 

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If I got you right it seems like you have settled for the Esprit. I think that is the right decision since the price difference will be much less after you found that you had to replace the focuser on the SW80ED, and with the SW80ED you would always wonder if those not so perfect stars would have been perfect if you had gone for the Esprit.

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Also be aware of microlensing with the asi 1600. I get this with my ed80 but not with the 130pds. I would suggest making sure you have enough left over to belt mod you mount as this will really help you make the most of your kit. I have an older ed80 with the single speed focuser and have a asi1600, skywatcher ff and sx 7 filter wheel hanging off it with no issues. You may just need to file the focus tube so that it is nice and flat (really easy job).

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Thanks for the great inputs all. So this is what have decided on:

- Esprit 80 ED with field flattener.

- ASI16000mm pro kit (including EFW8, 1.25" LRGB & Ha/SII/OIII Filters)

- HEQ5 pro belt mod kit

- And a sheet of baader solar filter, since clear nights with no work the next morning are pretty rare

I realize now (I have read the threads on the zwo forum and here) that a few  people are unhappy about the ZWO EFW, but I think I will take my chances on that.  The belt mod has been on my wants list ever since I was first aware of it, mostly because of the noise the HEQ5pro  makes, but it will be better for guiding too.

I was tempted to throw in the ZWO OAG too, just because I think that looks like a pretty smooth setup, but decided against it.

So hopefully I end up with a setup I can enjoy for years to come.

Edited by Viktiste
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On 16/08/2019 at 19:32, Viktiste said:

I have decided to pull the trigger on a 80mm refractor and a dedicated cooled astro camera. For photographing nebula's and galaxies.

The OTA options I consider are the SW Esprit 80 ED (at £1 599) or the SW Evostar 80 ED (at £ 399). Will the performance of the triplet be that much better than the doublet that the three times higher price is justified?

For camera I am trying to choose between the ZWO ASI 183MM pro or the ASI 1600MM pro. Is there any reason (other than price) to prefer one over the other with either scope above? I will also be buying a filter-wheel.

Equipment I already have are a HEQ5 Pro, a ZWO ASI 120MC-S (for guiding), a SW 200P (which is too heavy/cumbersome for AP), Canon 500D and a DYI MyfocuserPro.

I have plugged these scope/camera combinations into astronomy tools and are aware of the FOV's they give.  I think I prefer the smaller FOV. Resolution ranges from 0.97"/pixel to 2.30 "/pixel for these combinations (with a 0.85x reducer/flattener), so I guess that is ok?

I am struggling to make the decision's, any thoughts? 

 

Well first things first an Esprit is not £1599 they have recently gone up on FLO to £1059 though. 

If its price to performance ratio you are looking for then you will never beat a SW 80 ED or 130PDS and a DSLR. Anything more than that and although performance increases your price to performance ratio will go down. So forgetting price to performance ratio I would say that the ESPRIT 80 is a significantly better scope than the SW80ED but you pay for it, hence if you have the cash grab the better scope, if you don't have the case then get the cheaper scope. The main difference between the two is F-ratio, color correction and the Esprit has a much nicer focuser. 

Either of the cameras are going to work with the Esprit at 400mm focal lenght. I would personally find the larger sensor of the ASI1600mm pro preferable if using the longer focal lenght ED80 though. You will want to look up micro lense diffration pattern in relation to the ASI1600mm pro before you make a purchase. 

Adam  

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On 18/08/2019 at 18:25, Viktiste said:

Thanks Pompay.

But on FLO's website it says "you can use 1.25" filters without vignetting up to f/5 or 31mm filters up to f/2"

So from that I guess the 1.25" is what i should select?

1.25 will be no problem at F5, but 31mm filters are virtually the same cost... 36mm filters are not required for a ASI1600mm pro. 

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Thanks Adam.

Newtonian+DSLR is not what I am looking for, I already have that.

This is what James at FLO answered regarding filter size. "You can get away with the 1.25" filters if they are mounted very close to the camera - you'd need the camera mounted next to the filterwheel. It's not a problem, but should you want to rearrange things and move the filters to a different part of the system you may find the 1.25" aren't enough"

Since 1.25" = 31.75mm I assume the 1.25" refers to the diameter of the mounting ring, not the actual filter size, otherwise there would be practically no difference. 

I have decided to go for the 31mm unmounted filters.

2 hours ago, Adam J said:

Well first things first an Esprit is not £1599 they have recently gone up on FLO to £1059 though. 

Correct,, I wrongly quoted the price for the 100 ED in the OP. 

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