|
Post by ChrisV on Apr 6, 2017 10:38:27 GMT
Someone, somewhere else was asking about focal reducers for the ED80 F7.5. What would you all recommend. I think they are going to use some sort of sammie 1/3" camera. Hopefully they'll come over and have a look.
|
|
|
Post by davy on Apr 6, 2017 12:14:22 GMT
I tried the cheap o.5 from ebay,,you get what you pay for with these,, you get a £500 scope then put a £10 focal reducer on,. Like putting remould tyres on a Porsche... I personally saved up an bought the Skywatcher 0.85 matched focal reducer and flatner on,, Skywatcher has done all the research and testing,, so it's screw on and you know it works... The exception to this would be Ken's fit focal reducer,, if lens came out a broken decent pair of binoculars.. Only my outlook and approach
|
|
|
Post by Dragon Man on Apr 6, 2017 16:49:20 GMT
The good thing about the ED80 is that even using a 0.5x FR you have enough 'in' travel. And as davy said, the FR that I made from a Binocular lens works fantastic. It is about 0.58x, but different power Binoculars will give slightly different focal reduction amounts. Chris, the best way to help people wanting to know about this stuff is to send them here we we can help them directly instead of trying to pass along stuff by re-posting. We exist so people can come here and ask whatever they want Just passing info along in dribs and drabs as they keep asking you, and you ask us, and we tell you, then you tell them, doesn't help as much as them coming in and having conversation.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Apr 9, 2017 8:41:50 GMT
The good thing about the ED80 is that even using a 0.5x FR you have enough 'in' travel. And as davy said, the FR that I made from a Binocular lens works fantastic. It is about 0.58x, but different power Binoculars will give slightly different focal reduction amounts. Chris, the best way to help people wanting to know about this stuff is to send them here we we can help them directly instead of trying to pass along stuff by re-posting. We exist so people can come here and ask whatever they want Just passing info along in dribs and drabs as they keep asking you, and you ask us, and we tell you, then you tell them, doesn't help as much as them coming in and having conversation. That's interesting Ken. I just acquired a gold tube ED80 f7.5. It has been fitted with a very nice Bintel 10:1 Crayford focuser. I can't get enough in-focus with my home-made 0.8x reducer (used your contruction method of course ). I designed it for 0.8x and have tested it on another scope and it's very close. So it looks like I should replace the fancy one with the common garden variety perhaps....
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Apr 9, 2017 8:49:00 GMT
I tried the cheap o.5 from ebay,,you get what you pay for with these,, you get a £500 scope then put a £10 focal reducer on,. Like putting remould tyres on a Porsche... I personally saved up an bought the Skywatcher 0.85 matched focal reducer and flatner on,, Skywatcher has done all the research and testing,, so it's screw on and you know it works... The exception to this would be Ken's fit focal reducer,, if lens came out a broken decent pair of binoculars.. Only my outlook and approach Not sure about that. If you're talking about a reducer for a 1/3" sensor camera I think I'd be looking at the cheap option first....
|
|
|
Post by davy on Apr 9, 2017 9:41:16 GMT
Hi Robert,the focal reducer is also a flatner but yes on a Samsung CCTV converted camera it is an expensive option, But I plan my kit upgrades well in advance and my kit gives me a wide option for whatever direction in astronomy I fancy,at a given time,,, I do lots of stuff out with video astronomy and my kit has to cover this view of mine..
The ed80 with the 0.85 focal reducer is for dslr use,, Given the weather in Scotland and this being a long term hobby I have a bit of time on my hands to step back and look at what is going to happen in the future and don't jump on the "" oh it's new so I must buy it bandwagon"" I can't afford it.. But I have been buying kit bit by bit over the years and could kit out an observatory as ken says lol.
Rather than hijack this thread I will start a new Davy's kit and theory behind it and how it evolves
|
|
|
Post by Dragon Man on Apr 9, 2017 10:09:22 GMT
The good thing about the ED80 is that even using a 0.5x FR you have enough 'in' travel. And as davy said, the FR that I made from a Binocular lens works fantastic. It is about 0.58x, but different power Binoculars will give slightly different focal reduction amounts. Chris, the best way to help people wanting to know about this stuff is to send them here we we can help them directly instead of trying to pass along stuff by re-posting. We exist so people can come here and ask whatever they want Just passing info along in dribs and drabs as they keep asking you, and you ask us, and we tell you, then you tell them, doesn't help as much as them coming in and having conversation. That's interesting Ken. I just acquired a gold tube ED80 f7.5. It has been fitted with a very nice Bintel 10:1 Crayford focuser. I can't get enough in-focus with my home-made 0.8x reducer (used your contruction method of course ). I designed it for 0.8x and have tested it on another scope and it's very close. So it looks like I should replace the fancy one with the common garden variety perhaps.... That is really strange Robert. A 0.8x focal reducer will require less 'in' travel than a 0'5x focal reducer. Please try this for me: Point your ED80 with the focal reducer at a bright star. Wind your focuser in as far as it will go, and as it gets wound in does the out-of-focus star get larger or smaller? If it gets smaller, then you are going the right way but for some weird reason you aren't getting enough 'in' travel. Even with a 0.5x FR I still have spare 'in' travel. If it gets larger, then you will need to wind the focuser 'out' further. If you reach the end of focus travel outwards, you will need an extension tube (you can make one out of an un-needed Barlow by removing the Barlow lens and use just the tube). Please let me know what happens
|
|
|
Post by davy on Apr 9, 2017 11:39:05 GMT
Before I went down the route of focal reducer to get focus on my ed80 I bought a 2" 80mm focal tube to allow me to get focus with my dslr,, One of the more technical gifted could maybe explain how this equates to gunners of the scope.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Apr 9, 2017 23:18:08 GMT
Ken
I'll check it again, but I'm pretty sure it was short of in-focus - only by about a mm or two.
Robert
|
|
|
Post by Dragon Man on Apr 10, 2017 11:53:05 GMT
Robert, if you can't get enough 'In' travel I am wondering if the Bintel Crayford Focuser (which is a GSO Crayford Focuser) is longer than the standard Crayford focuser that comes with the ED80. ED80's are made by Synta and come with a Synta Crayford focuser factory fitted. Here's one: and here's the GSO Version: The GSO Crayford Focuser might be longer than the original Synta Focuser, and they often require an adaptor ring to make them fit certain telescopes, and that adaptor ring may add even more to the length of the focuser. The distance that could be longer on the GSO is from the end of the telescope tube to the end of the Focuser barrel when wound all the way in. If it is longer, that would give the GSO less 'In' travel distance than a Synta Focuser.
|
|