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Endolf

Telescope upgrade advice

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Relatively new to astrophotography, I'm currently using an old Orion Optics 150mm f5 newtonian reflector, unsurprisingly I'm having some issues around focus, I can get focus, but the barrel protrudes into the main optical tube. I've tried adding the lense from a barlow to the camera adapter which brings the focus point out, still achievable, but obviously reduces the fov. Probably ok for some of the smaller objects, not so good for the larger objects like M42. It's also only a 1.25" focuser.

I'd like to upgrade my scope. I've obviously drooled over some the top end equipment, but I'm not sure I can justify £4-5k on a telescope when it's something I've not been doing all that long.

I don't have a fixed budget in mind, I'm happy to save a little longer for something that is better, but £500 to £1k would feel comfortable. I've looked at the skywatcher quattro refractors, the wide aperture whilst still having a focal length of around 750mm seems nice, reducers could be used for wider field etc so it sits in the range of focal lengths for some of the targets I might like to shoot. I've not read great stories about the range though, seems that collimation is an issue and can need doing more than once a night?.

The Sky-Watcher Evostar 120ED is looking like an option, does anyone have any recommendations outside of the sky-watcher range?, or any opinions on the ED range that might put me off?

Thanks

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On 09/03/2020 at 14:51, Endolf said:

outside of the sky-watcher range?,

SW quattro equivalent with better build quality, aluminium tube and proper r&p focuser:

https://www.bresser.de/es/Astronom-a-bresser/Telescopios/BRESSER-Messier-Tubo-optico-NT203s-800.html

Don't stress about collimation; there's a lot of misinformation out there.

You'd need to add a 1:10 fine focus and a longer, wider dovetail. The latter would be recommended for to the SW too. Still well within your budget however.

Is that the sort of thing you're looking for?

Cheers

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On 09/03/2020 at 13:51, Endolf said:

Relatively new to astrophotography, I'm currently using an old Orion Optics 150mm f5 newtonian reflector, unsurprisingly I'm having some issues around focus, I can get focus, but the barrel protrudes into the main optical tube. I've tried adding the lense from a barlow to the camera adapter which brings the focus point out, still achievable, but obviously reduces the fov. Probably ok for some of the smaller objects, not so good for the larger objects like M42. It's also only a 1.25" focuser.

I'd like to upgrade my scope. I've obviously drooled over some the top end equipment, but I'm not sure I can justify £4-5k on a telescope when it's something I've not been doing all that long.

I don't have a fixed budget in mind, I'm happy to save a little longer for something that is better, but £500 to £1k would feel comfortable. I've looked at the skywatcher quattro refractors, the wide aperture whilst still having a focal length of around 750mm seems nice, reducers could be used for wider field etc so it sits in the range of focal lengths for some of the targets I might like to shoot. I've not read great stories about the range though, seems that collimation is an issue and can need doing more than once a night?.

The Sky-Watcher Evostar 120ED is looking like an option, does anyone have any recommendations outside of the sky-watcher range?, or any opinions on the ED range that might put me off?

Thanks

Skywatcher are bringing out their new evolux range soon, the 80mm might suit your needs for imaging.

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Posted (edited)

Thank you for the replies. Interesting to me that the aperture sizes for the suggestions on refactors is ~100 or less, which raises a question in my mind, is it better to spend the money on higher quality optics at a lower aperture, or slightly lower quality optics, but at a larger aperture, for example, the Evostar 120 v.s. the Esprit 80 at a similar price point, although in this case there is a big difference in focal length too.

The Bresser reflector looks interesting, well within budget, larger aperture. A reducer to bring the focal length down a little and a field flattener still leave it well within budget. I'm still not decided on the refractor v.s. reflector at this stage :)

I'll confess I'd forgotten about checking the second hand market, so thanks for reminding me.

More to think about :)

Thanks again.

Edited by Endolf

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There are so many choices out there that will suit any budget and no matter what you decide to spend you will aways want some other little extra to complement it.

I would try to decide on what you want to image and what camera you will be using and spec a scope starting with that. No matter which scope you get, there are reducers that you can use or barlows/powermates that you might need to change the FOV.

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The Quattro is a great scope, you'll only get a small doublet refractor for the same money. The reality is you'll want both a short focal length refractor for wide fields of view and a longer focal length newt for galaxies.

I'd go for a cheaper scope and then put the money into a better mount and camera - that will make a bigger difference than sinking thousands into a refractor. 

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You haven't mentioned the mount at all, what do you have, and do you plan to upgrade it? If new to AP then certainly the smaller, higher quality apo refractor option would seem to be the most sensible while you learn the ropes. Quattros can be tricky for collimation from what I have read.

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Posted (edited)

Invest in a good mount and get a cheaper scope for now @SamAndrew

Buying a good mount will dictate later on which scope you want to buy. Example something like an Skywatcher MN190. Fantastic 7" APO performance (my biggest regret of letting it go, even worse my condition dictates I cant have one now) the minimal mount would be an EQ6, s/h market approx. £600-700. Maybe even cheaper.

The ED scopes are of high quality and even cheaper on the 2nd hand market.

I too like the idea of a 120ED, but still how wildering the bulkiness is compared to my 100ED and the weight.

 

 

Edited by Skyline

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Thanks for the advice, the comment about a short focal length refractor plus a longer focal length reflector was interesting.

Mount wise I treated myself to an EQ6-R Pro about a month ago, hoping to use the other equipment I had, I've updated from my partners Canon 1000D to a second hand 600D off ebay (which I'm tempted to get full spectrum modded), and I've got Stellarmate setup to control the rig.

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If you're starting out, the usual advice is to start short,  i..e. wide-field. You will have challenges enough, and longer focal lengths will just exacerbate problems and impede your progress. Since optical design challenges pile up rapidly as you increase curvature, wider apertures mean longer focal lengths. Hence the time-honored 80mm refractor as a starting scope. 350 to 500mm F/L is long enough for a rich variety of great targets, yet short enough to fit big bright ones (Orion, Andromeda) and not drive you mad in the process. 

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At this stage I must admit I'm tempted with the skywatcher esprit 100, focal length of 550 is a little longer than I was looking for (not by much), but the images people manage to get out of it are stunning. I know I'm short on a lot of the other gear at the moment (dedicate astro camera, filters, guiding etc), but on paper, the esprit 100 should be a nice upgrade over my old newtonian.

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Been doing more reading, came across the William Optics Zenithstar 126 APO, it's only a doublet, but looking at some of the targets I've been trying recently, the 0.8 reducer/flattener gives a good set of focal lengths at 970 or 770 (with the .8 reducer). Any opinions on this scope?

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I decided not to do the upgrade right now. Instead I've put some money in to a guide scope/camera for some auto guiding, a light pollution filter for my DSLR and a cheshire collimation tool. Assuming I can improve the image on my existing scope, i'll probably look at a ~400mm focal length triplet in time for the winter nebula season :).

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45 minutes ago, Endolf said:

I decided not to do the upgrade right now. Instead I've put some money in to a guide scope/camera for some auto guiding, a light pollution filter for my DSLR and a cheshire collimation tool. Assuming I can improve the image on my existing scope, i'll probably look at a ~400mm focal length triplet in time for the winter nebula season :).

Sounds good. Let us know how you get on

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I couldn't help myself, been looking at scopes again 🤣, I'm thinking something like the Esprit 100 for the winter season for wide field, but for now, for galaxy season, something with a much longer FL is the order.

I came across the Omegon RC, either the 154/1370 or the 203/1624, I like the look of the FL for both of these. I've not read much about Omegon, I know Tim from AstroAddict has a couple of their APOs. I've done the maths as with a Canon 600D the pixel size is a little large, but binning should help that?.

Anyone got anything good or bad to say about Omegon and their RCs, or RCs in general?

Thanks

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I had never heard of Stellamira before buying a field-flatenner built by them, they've vastly improved my FOV overall-focus, so their triplet looks really intriguing to me now.

I think an Esprit Pro, if you can afford the outlay, would be a good investment, I'm looking at the 120mm as a future purchase.

 

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Doing more research again, this time looking at the focal length and pixel sizes (using https://astronomy.tools/calculators/ccd_suitability).

My skies are not always good seeing, and I can see from that tool that 0.67"/pixel is the minimum for good seeing, but 1.33"/pixel for poor seeing. So going back to the average of 1"/pixel, I end up with a maximum FL of just over 1000mm, the GSO RC 8 has a FL of 1624, so I'd need a reducer, which whilst giving me a reasonable pixel ratio, means I'd need longer exposures to gather the same number of photons at the camera. Looking at other ~1000mm scopes, the explorer 200pds with the baader corrector seems to fit the bill. I wonder how long this thought will last..... 🤣 

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I finally made a decisions, the skywatcher 200 pds, then skywatcher shutdown their uk warehouse. So I did some more digging and ended up ordering a TS Optics 200/1000 OTA. I've also ordered myself the baader MPCC mkIII and a bahtinov mask for it. Should all be here for Monday. My IDAS LP D2 EOS filter should arrive tomorrow too. I'm sure it will be cloudy for a few weeks now. Sorry.

Hopefully still be able to order the Esprit 100 for nebula season :)

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1 hour ago, Endolf said:

I finally made a decisions, the skywatcher 200 pds, then skywatcher shutdown their uk warehouse. So I did some more digging and ended up ordering a TS Optics 200/1000 OTA. I've also ordered myself the baader MPCC mkIII and a bahtinov mask for it. Should all be here for Monday. My IDAS LP D2 EOS filter should arrive tomorrow too. I'm sure it will be cloudy for a few weeks now. Sorry.

Hopefully still be able to order the Esprit 100 for nebula season :)

Oh I would never base my purchasing decision on availability...

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2 hours ago, Endolf said:

TS Optics

Good decision. A well made telescope with a proper focuser:)

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