Brian:
My dealer, other dealers, and users have told me, or mentioned in forums, that it's necessary to optimize the scopes to get the best performance out of them and to eliminate certain issues.One issue that some, though not all, scopes have is that in cold temperatures, the lens cell or screws press against the glass, causing strange star shapes to appear. This is something that 'needs' to be fixed if you want an excellent scope.I'm not an expert; I can only share what the dealers and users are saying.I know that third-party reducers aren’t 100% compatible, but I need one if I want to achieve a maximum focal length of 400mm. With the flattener, the focal length is too long for my needs.
I'm not gonna boast that I have the coldest temps out there, but my season is during the winter when the temperatures are often around -20c, I have imaged closer to -30c over certain periods and let everything stay outside. No issues with pinched optics as far as I can tell. I know certain scopes struggle with this, the Sharpstar Z4 being one of them, someone I know had to return theirs due to excessive issues when it wasn't even that cold.
Jan, This is slightly off topic, but you have given me some hope that I might do some backyard AP work in the dead of winter.  Ian (central Canada)
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Ian Dixon:
Jan,
This is slightly off topic, but you have given me some hope that I might do some backyard AP work in the dead of winter.
Ian (central Canada) Worth a shot! That's when I get most of my opportunities, late spring till early autumn has no darkness around here (NO). But I have only good experiences so far. I keep the power on so the integral parts are not freezing, at least during the coldest periods. Then I cover everything up with an old jacket during the day.
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Tareq Abdulla:
I wish to buy high end scopes such as AP or Tak
in fact i wanted to buy Stellarvue, but they went with improved versions so they increased the prices since their old versions the old Access versions from Stellarvie rock. if you get one second hand you can save a fortune. I have an old second hand 80mm SV Access Doublet, and also a brand new SVX102T. that little 80mm Doublet has taken some very good shots, as anyone who frequents cloudy nights can confirm. Spaceman 56
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David Russell:
Tareq Abdulla:
I wish to buy high end scopes such as AP or Tak
in fact i wanted to buy Stellarvue, but they went with improved versions so they increased the prices since their old versions
the old Access versions from Stellarvie rock. if you get one second hand you can save a fortune.
I have an old second hand 80mm SV Access Doublet, and also a brand new SVX102T.
that little 80mm Doublet has taken some very good shots, as anyone who frequents cloudy nights can confirm.
Spaceman 56 I try to buy only a brand new as much i can regardless about the scopes quality, i have reasons, but it is too late now to think about Stellarvue scopes anyway because i bought many scopes already from another brands.
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Jan Erik Vallestad:
I'm not gonna boast that I have the coldest temps out there, but my season is during the winter when the temperatures are often around -20c, I have imaged closer to -30c over certain periods and let everything stay outside. No issues with pinched optics as far as I can tell. I know certain scopes struggle with this, the Sharpstar Z4 being one of them, someone I know had to return theirs due to excessive issues when it wasn't even that cold. This was very interesting to read. I have just drawn a 100+ hour project to a close due to the excessive diffraction problems I am seeing with my Z4. LRGB, all filters. It has definitely been much worse past 2 months with quite a few sub-zero nights here in the UK. Bigger / brighter stars with the scope have always been a little "wonky" even (as you stated) when it has not been that cold... but I always put it down to me and / or a problem with how I was capturing / processing. But the problem is clearly scope related. Of course it could be some protrusion in the scope (seal, baffle, spacer etc) but it has gotten so bad since late November, I am sure temp is a factor. I too am discussing with FLO right now... and have provided sample images / test shots etc etc. Hoping this is something that a skilled scope dude can tweak on their work bench. Really do not wish to lose the scope... small star detail, star count in general and picture detail is phenomenal... and it focuses like a dream. Fingers crossed!
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This was very interesting to read. I have just drawn a 100+ hour project to a close due to the excessive diffraction problems I am seeing with my Z4. LRGB, all filters. It has definitely been much worse past 2 months with quite a few sub-zero nights here in the UK.
Bigger / brighter stars with the scope have always been a little "wonky" even (as you stated) when it has not been that cold... but I always put it down to me and / or a problem with how I was capturing / processing. But the problem is clearly scope related.
Of course it could be some protrusion in the scope (seal, baffle, spacer etc) but it has gotten so bad since late November, I am sure temp is a factor. I too am discussing with FLO right now... and have provided sample images / test shots etc etc. Hoping this is something that a skilled scope dude can tweak on their work bench.
Really do not wish to lose the scope... small star detail, star count in general and picture detail is phenomenal... and it focuses like a dream. Fingers crossed! I hope they get it sorted for you! I've had nothing but good experiences with them overall. I was considering the Z4 for myself in 2023, but I wound up getting the Esprit 100ED in stead which I am very happy with! I'm sure I mentioned it in a post somewhere before (maybe here), but I always found it a bit werid that the Sharpstar website advertises this scope with fake spikes in the images unless they had something to hide.. https://www.sharpstar-optics.com/Products_1/26.html |
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Hey, I dont think you can get much better for under 400mm fl: https://www.astrosysteme.com/products/uwf300-f1-3/ |
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Jan Erik Vallestad:
I'm sure I mentioned it in a post somewhere before (maybe here), but I always found it a bit werid that the Sharpstar website advertises this scope with fake spikes in the images unless they had something to hide.. Yes, I saw that note from you also... that is a bit strange. Funnily enough, I never spotted that before so never questioned. Problem is quite easy to see below... as the stars become more prominent, so the issue becomes increasingly worse. (No post stretch star reduction has been performed) I am never fussed with surrounding star glow or halos even... in fact I like the bleed into the surrounding dust (I tend to do dusty pics lol). But the tattiness around the edges which increases to the diffraction does need the investigation. Pointless to try any processing technique of course as it is baked into the background.  FYI, the increased red is from use of Antlia R+ filter which offers enhanced IR. The irony here is that I think the small (even tiny) stars are fantastic hehe!
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SW Esprit line is currently under heavy discount. There might be something new on the horizon. I currently own FRA500 and I'm usually using it with reducer. There is CA on the edges so it's not perfect (APS-C) but I love it. I am also looking at what's available in that 300-400mm range and around f/4. There isn't much options. Couple of WO models and Tak with new reducer. Once I get my remote observatory ready I'll upgrade to something else.
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And i am trying to finalize my last 4th setup in my multiple setup i planned to have since like 3-4 years ago, i have two 90mm triplets already, and i have 106/700, i have three Touptek IMX571 cameras, so i need to add last scope and also 4th IMX571 camera, not sure which one it will be, i was thinking about a red or black color camera so i can use it with anything red, i prefer to match the color of the camera to the scope despite that it is unnecessary, so in my mind is FRA500 or another 106 or this discounted Esprit 100, WO is very expensive, and other brands 90 triplet is still a bit pricey, so i will wait and see what i can find with offers.
Also, for this forth IMX71 camera, i don't know if i should get it mono again or going with color, because nowadays even under light pollution skies, using a color with dual band filter is possible, and i don't need to think about having all scopes at once, it is just flexibility, and buying RASA 8" to have 400mm is an option as long i can accept the pros and cons, i do have Canon 300mm f2.8 which i can connect it with 1.4x to give me 420mm, so i have many ideas and plans for that 4th setup, i wanted to match my two 90mm f/6 + 0.8x which is giving me 432mm nicely, while with 106/700 if i can use 0.6x it will give me 420mm, same as if i use 300mm + 1.4x so that will save me a scope cost, but i have to decide which 4th imx571, a color or a mono, i already have two mono and one color.
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The new William Optics Cat 91 WIFD is amazing ... 2 micron spots to the edge of full frame. https://williamoptics.com/products/cat-91-wifdThe Askar SQA55 is also amazing ... 2 micron spots almost everywhere https://www.cloudynights.com/gallery/image/216692-spot-diagram-sqa55/https://www.youtube.com/watch?v=GzUmdZ708iAhttps://www.youtube.com/watch?v=SkLtO4A9t94https://www.youtube.com/watch?v=HDm-YrPS6UcThe Askar SQA85 is even better ... 1 micron spots almost everywhere https://www.cloudynights.com/gallery/image/225554-sqa85-sd/The Askar SQA106 is the Tak/Esprit killer ... 1 micron spots almost everywhere https://astronomyplus.com/products/askar-sqa106-f-4-8-quintuplet-apo-sqa106I'm thinking of selling my Esprit 100ED and getting the SQA106 ... it will sharper and supports full-frame.
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