What Reducer to use with the Explore Scientific ED APO 127

Topic starter

Feb 2, 2024 · Edited: Feb 2, 2024

Hi folks,

yesterday, I bought my long wanted Explore Scientific ED APO 127 FCD100 with Hexafoc and carbon tube. It was 20% off and so I took the chance to buy it. It will arrive tomorrow and I'm looking forward to get some great images with it. Sadly, this means, the next two weeks will be cloudy…

Ah.. just kidding.

Anyway, I am interested in how you use this scope (or similar ones). Because I spent a lot of money so far, I am struggling to buy the ES 0,7x reducer as well. The resulting focal length is reduced to 666mm (from 952) and so it is nearly the same as my 115/805 TS APO with a 0,79x reducer (632mm). I plan to use the scope with my 1,0x flattener for now to be prepared for galaxy season. The 0,7x reducer will be added in the second half of this year, I guess. But I think it would be nice to use the scope maybe with a 0,8x reducer (I don't want to use the reducer thats mounted on my 115/805 APO, because this setup works great and is permanently set up with it). I was looking at the website of Telescope Service to maybe find a solution in the 0,8x range. But they all seem to be good for scopes up to 120mm diameter. So I wonder, what to look for to get a "right" reducer for this scope. I use two cameras with SONY IMX492 sensors and maybe will upgrade to an APS-C sized sensor someday (ASI2600 or similar). Larger sensors are a bit out of my reach.

The 127ED APO is the largest scope (focal length) that may make sense on my EQ6 mounts. So this is the holy cow for me. I am sure, that for fainter targets a reducer makes a lot of sense. But are there any astro photographers out there, that use the scope with its 7,5 f ratio? Or do you exclusively use reducers? Maybe you mix both variants?

Thank you for your suggestions of reducers I may look for.

CS

Christian

Rodrigo Roesch

Feb 2, 2024

Hi
I use both depending on the object. The ES reducer works very well as long as you use the ring adapter which screws to the focuser after removing the compression ring. so it goes from 3" to 2.5". If you use the adapter that goes from 3" to 2', the vignetting would be too much for the ASPC-S or 4/3 sensor. One down side of the ES reducer is the size and weight. It is really a big piece of glass and it may be too much weight for the focuser if you use a filter wheel and a heaving camera like the ASI 2600

Helpful

SavannahCarl

Feb 2, 2024

I use the ES .7 focal reducer/corrector SN: FR0700791. Don' t forget to get the adapter.

Richard H

Feb 2, 2024

Hi Cristian,

I changed my Helix Crawford focuser to a Starlight Instrument gear focuser and do not use a reducer. I use a Hotech field flattener only and get pin-point stars corner-to-corner. Here is a link to the AgenaAstro.com website.
https://agenaastro.com/hotech-2-sca-field-flattener.html

Note: I've tried using the ES reducer/corrector and found it to be of poor quality and Stars were not pin-point corner-to-corner. Might have been a defective piece but went with quality Starlight Instruments focuser.

CS
Richard

Helpful Concise

Paul Puntin

Feb 2, 2024

For full FL I use the Hotech flattener which works very well with this scope. I have the ES 0.7x reducer for shorter FL but haven’t used it in anger as it is close to other scopes I have. With the Hotech flattener it makes a great galaxy scope. Have a look at my Astrobin page for use at f7.5 or the previous posters pages.

CS Paul

Concise Supportive

Jack

Feb 3, 2024

I too use the ES .7 focal reducer/corrector SN: FR0700791. This massive chunk of glass does an excellent job for me in my optical train.

Well Written

Tom Zepf

Feb 3, 2024

Richard H:
Hi Cristian,

I changed my Helix Crawford focuser to a Starlight Instrument gear focuser and do not use a reducer. I use a Hotech field flattener only and get pin-point stars corner-to-corner. Here is a link to the AgenaAstro.com website.
https://agenaastro.com/hotech-2-sca-field-flattener.html

Note: I've tried using the ES reducer/corrector and found it to be of poor quality and Stars were not pin-point corner-to-corner. Might have been a defective piece but went with quality Starlight Instruments focuser.

CS
Richard

This matches my experience: it's big and heavy, it's expensive, and the star shapes are not great. On the other hand, the Hotech flattener is the opposite of all those things.

Well Written

Franz Grapke

Feb 3, 2024 · Edited: Feb 3, 2024

Ich verwende den 3" 0,7 Reducer von Explore Scientific. Siehe meine Aufnahme von den Plejaden.

Eddie Bagwell

Feb 3, 2024

I have the same telescope and use the Long Perng .8x Flattener/Reducer and also their 1x Flattener. Great results without having to spend a ton of money. I mainly use the .8x with the refractor but it's nice to have the option of both when needed. I have heard good things about the Hotech too. Also, since the ED127 is so long, you might want to consider getting the 8" SW Pier Extension for your EQ6-R mount so the telescope will not bang against the tripod at zenith. I did a review and full install with pics on CN. Here is the link:

Sky Watcher EQ6R Pier Extension - Mounts - Cloudy Nights

Helpful Concise Supportive

Christian Großmann

Topic starter

Feb 3, 2024

Thank you all for your replies so far. It seems, there are some guys out there that uses the scope without the reducer. I already own a 1x flattener from TS that I will try at the first session. If it doesn't fit well, a 0,8x reducer maybe is the best option to get a different focal length than my other setups. Eddies suggestion sounds nice so far and I wil have a look at it. It seems it fits the smaller sensors quite well. If my Flattener will not work, I will have a look for an alternative like the Hotech. It seems to be used quite often out there.

The telescope arrived with the mail today. If I finished this forum post, I will go unpacking the beast. I can't wait…

So CS

Christian

Jack

Feb 3, 2024

Congrats on the ES 127. I am happy with the lens cell on mine and have had no issues. I too use an extension on my tripod for the EQ6-R with the es127. It is a long beastie and demands a bit of care.

I have no flexure in mine but use screw-in connectors throughout my imaging train.

Cleaning my optics today (I am in Michigan, USA and suffer from Spring and Fall pollen! That sticky stuff demands a cleaning. It's an ES not an AP or Tak so I'm willing to do the job myself.

Helpful Respectful Engaging Supportive

Christian Großmann

Topic starter

Feb 3, 2024

The extension tube may be a good decision. But I'm planning to build two telesope piers when the weather is warmer again. I hope they are finished in early spring. So I am not planning to buy one. I hope, that packing all additional weight (Guide Scope. Electronics, etc.) as far back as possible will help to lift the scope as high as I can. I already thought through some subjects and found some that were quite low in the sky. So I'm planning to solve this issue as soon as possible.

But I admit, that I'm a bit concerned about this situation…

Georg N. Nyman

Feb 4, 2024

I recommend the original ES 0.7x reducer - I have used it a lot in the past and the quality is very good.
I have sold my 127 a while ago to reduce the number of OTAś - the reducer is still waiting for a new user, just in case, someone wants one…

But back to your question - the original one, that is my recommendation

CS
Georg

Christian Großmann

Topic starter

Feb 6, 2024

Hi,

thank you all for your replies. Yesterday evening, we had about 4 hours of clear sky before it gets really cloudy again. So I decided to took the chance to try some images with the ES ED APO 127, which I already set up on sunday. After some minor fixes on the setup, I was able to get some images with my ASI 183MM Pro. I know, this camera isn't the best option, but the other cameras were all used for other projects at the moment.

My target of choice was NGC2403, which I imaged with my RC8 and the same camera some weeks ago. The focal length with the 0.67x reducer was 1088mm. I had a lot of vignetting even with the small sensor of the 183MM. Then I saw the first light of the ES telescope and was blown away by the much better quality even at f7.5 (compered the the 5.36 of the RC setup). I never really liked my RC and now I know, why. As mentioned above, I used my TSFlat2 flattener and the stars in the corners are no problem at all at least with the 183MM (as far as I can already tell - the sky quality was quite poor yesterday). The QHY294M Pro or my ZWO ASI 294 MM Pro may be a different story, but I can't test them yet.

So I guess I will have no issues with the scope even without a reducer. That is what I was hoping for. But guess what? I could not resist and ordered the ES 0.7x reducer as well. But I'm sure, I will keep him dry until the next nebula season.

But I may still look for a matching 0.8x-ish reducer. This would be the last option that makes sense to me so far.

So thank you all for your help.

Clear skies

Christian

Helpful Insightful Respectful Engaging

Rodrigo Roesch

Feb 6, 2024

Christian Großmann:
Hi,

thank you all for your replies. Yesterday evening, we had about 4 hours of clear sky before it gets really cloudy again. So I decided to took the chance to try some images with the ES ED APO 127, which I already set up on sunday. After some minor fixes on the setup, I was able to get some images with my ASI 183MM Pro. I know, this camera isn't the best option, but the other cameras were all used for other projects at the moment.

My target of choice was NGC2403, which I imaged with my RC8 and the same camera some weeks ago. The focal length with the 0.67x reducer was 1088mm. I had a lot of vignetting even with the small sensor of the 183MM. Then I saw the first light of the ES telescope and was blown away by the much better quality even at f7.5 (compered the the 5.36 of the RC setup). I never really liked my RC and now I know, why. As mentioned above, I used my TSFlat2 flattener and the stars in the corners are no problem at all at least with the 183MM (as far as I can already tell - the sky quality was quite poor yesterday). The QHY294M Pro or my ZWO ASI 294 MM Pro may be a different story, but I can't test them yet.

So I guess I will have no issues with the scope even without a reducer. That is what I was hoping for. But guess what? I could not resist and ordered the ES 0.7x reducer as well. But I'm sure, I will keep him dry until the next nebula season.

But I may still look for a matching 0.8x-ish reducer. This would be the last option that makes sense to me so far.

So thank you all for your help.

Clear skies

Christian

In my experience the ES reducer performs very well. My stars are sharp corner to corner. it is just heavy. Just make sure you get the ring adaptor from 3" to 2.5'

Christian Großmann

Topic starter

Feb 6, 2024

Rodrigo Roesch:
In my experience the ES reducer performs very well. My stars are sharp corner to corner. it is just heavy. Just make sure you get the ring adaptor from 3" to 2.5'

It's ordered as well

Do you mainly use your f/7 or slower telescope with it's natural focal length or with a reducer?