Thanks for pointing that out. Missed that kind of accessory completely. That will help a lot for getting the backfocus correctly for some of my scopes.
I just ordered one of those! This is a must have accessory if you use a focal reducer and/or corrector as back focus becomes more critical and annoying. Thanks for the video and clear skies!
I don´t live in the US, so getting the right accesories for achieving backfocus was an actual issue (e.g. calculating distances, awaiting for the products to be delivered, no returns, etc etc). This is a perfect product; the ultimate backfocus adjuster. I don't have Askar equipment but a Takahashi APO (with weird backfocus distances), and it was exactly what I needed. No more nightmares! ........ BTW, we really need a CloudXTerminator ;) lol
I have one sitting here next to my chair to use on my 103, but haven't tried it yet. My 0.8x reducer is spot on, but I also have the 0.6x reducer to try and wanted to have the adjuster for that. It has a very high-quality feel.
I think this part is a must have for everyone who has a flattner/reducer that has a factory included extension ring with 16 - 18mm from where you need to reach 55mm backfocus. I think I will include the Backfocus Adjuster into my imaging train and remove all extension rings from the flattners/ reducers on my telescopes.
Very nice video! I actually purchased this unit to help me fine tune backfocus for my coma corrector on my F4 Newtonian. I was never able to adjust BF properly on this telescope given I also have noticeable sensor tilt. I was able to definitively confirm sensor tilt by running the Askar backfocus adjuster too close and too far away from the sensor and observing the results from Hocus Focus aberration inspector and how the pattern of elongated stars does not revolve around the center of the image but rather offset to one corner . That is of course in addition to what hocus focus reports on tilt. Really amazing adjuster to use with fast Newtonians and sensitive coma correctors.
Got this when I picked up my 103 but wasn’t sure where it went in the chain. I’ve been okay so far without it but I’ve always been wary of backfocus from past experience. Great video!
Have you had any issues with tilt using this? It looks pretty well made. Getting ready to buy the 103APO and will use it with a ZWO 2600MC Duo and will get the 54/54 version of the spacer to stay with 54mm all the way to the camera. Thanks for posting this video.
Agree thanks for posting this. Would also like to know if you are able to confirm 'no tilt', as this is likely the only risk of adding this. Thank you very much.
Great info as usual. Please correct me but I thought that when using the FRA 400mm without reducer one doesn’t need to worry about the 55mm back focus . I just received this scope and haven’t used it yet with my ZWO 2600mm. Please clarify!! Scott
If FRA400 is used without reducer, you're right: no backfocus problem as it is a Petzval design. If you use a reducer, then backfocus come into play again. In the video he talks about his cpc800 as a backfocus problem source, not FRA400
4:00 so 48mm connector becomes 54mm by magic? That's not clear. Thank you for presenting this adapter but I have difficulty understanding what you are doing and where it should go. Why do you waste so much screen space with that back drop when demonstrating something so small in your hands? Put it on a table and position the camera above real close so your audience can see better.
Look at it again starting 4:00 - I first screw of the protector and state that it is 48mm - then at 4:20 I screw of the spacer and the connector at end of the spacer is 54mm. Here you screw on the adjuster and so you are again at the exact point as before with the spacer - so no space wasted and it needs no magic 😉 But I agree, I could have recorded it better.....
Hi Sasha, would you know if this adjuster can be used with the FRA400 if the 0.7xF3.9 reducer is attached? If I am not mistaken, this reducer does not have the removable 18 mm part and has only 48 thread. Thank you.
Can - yes, if you add an M48 to M54 adapter to the reducer and do not have a lot in front of your camera.... 😉 The question I ask myself much more is if backfocus is really still an issue at 290mm ...... and I would guess rather not. So you do not really need this.
I had a similar issue but I followed your advice and got the adjuster and it worked with like charm .
Thanks for pointing that out. Missed that kind of accessory completely. That will help a lot for getting the backfocus correctly for some of my scopes.
I've been using it for a few months now on my Askar V and I absolutely love it, as you said, really useful when switching filters.
I just ordered one of those! This is a must have accessory if you use a focal reducer and/or corrector as back focus becomes more critical and annoying. Thanks for the video and clear skies!
I don´t live in the US, so getting the right accesories for achieving backfocus was an actual issue (e.g. calculating distances, awaiting for the products to be delivered, no returns, etc etc). This is a perfect product; the ultimate backfocus adjuster. I don't have Askar equipment but a Takahashi APO (with weird backfocus distances), and it was exactly what I needed. No more nightmares! ........ BTW, we really need a CloudXTerminator ;) lol
I have one sitting here next to my chair to use on my 103, but haven't tried it yet. My 0.8x reducer is spot on, but I also have the 0.6x reducer to try and wanted to have the adjuster for that. It has a very high-quality feel.
I think this part is a must have for everyone who has a flattner/reducer that has a factory included extension ring with 16 - 18mm from where you need to reach 55mm backfocus. I think I will include the Backfocus Adjuster into my imaging train and remove all extension rings from the flattners/ reducers on my telescopes.
Very nice video! I actually purchased this unit to help me fine tune backfocus for my coma corrector on my F4 Newtonian. I was never able to adjust BF properly on this telescope given I also have noticeable sensor tilt. I was able to definitively confirm sensor tilt by running the Askar backfocus adjuster too close and too far away from the sensor and observing the results from Hocus Focus aberration inspector and how the pattern of elongated stars does not revolve around the center of the image but rather offset to one corner . That is of course in addition to what hocus focus reports on tilt. Really amazing adjuster to use with fast Newtonians and sensitive coma correctors.
Got this when I picked up my 103 but wasn’t sure where it went in the chain. I’ve been okay so far without it but I’ve always been wary of backfocus from past experience. Great video!
You place it at the start of the train after you screwed in a reducer.
Been looking at picking this up; timely video and great insight!
Perfect for my esprit 120! thank you!
Have you had any issues with tilt using this? It looks pretty well made. Getting ready to buy the 103APO and will use it with a ZWO 2600MC Duo and will get the 54/54 version of the spacer to stay with 54mm all the way to the camera. Thanks for posting this video.
I was not able to test it yet - still constant cloud cover..... But from the way it is build I can not image that this would introduce any tilt.
Please tell me if it works! I just got my .6 reducer for the 103 and I am very disappointed. Especially with the duo
@@mreddick786 Could you elaborate a bit more what you are disappointed about?
Agree thanks for posting this. Would also like to know if you are able to confirm 'no tilt', as this is likely the only risk of adding this. Thank you very much.
@@thomasheatherington357 I can now confirm it - no tilt at all and very convenient to use!
Great info as usual. Please correct me but I thought that when using the FRA 400mm without reducer one doesn’t need to worry about the 55mm back focus . I just received this scope and haven’t used it yet with my ZWO 2600mm. Please clarify!!
Scott
If FRA400 is used without reducer, you're right: no backfocus problem as it is a Petzval design. If you use a reducer, then backfocus come into play again. In the video he talks about his cpc800 as a backfocus problem source, not FRA400
No, for the FRA400 without reducer you do not need to worry about backfocus, which I really enjoy about this scope. Have fun with it!
4:00 so 48mm connector becomes 54mm by magic? That's not clear. Thank you for presenting this adapter but I have difficulty understanding what you are doing and where it should go. Why do you waste so much screen space with that back drop when demonstrating something so small in your hands? Put it on a table and position the camera above real close so your audience can see better.
Look at it again starting 4:00 - I first screw of the protector and state that it is 48mm - then at 4:20 I screw of the spacer and the connector at end of the spacer is 54mm. Here you screw on the adjuster and so you are again at the exact point as before with the spacer - so no space wasted and it needs no magic 😉 But I agree, I could have recorded it better.....
Hi Sasha, would you know if this adjuster can be used with the FRA400 if the 0.7xF3.9 reducer is attached? If I am not mistaken, this reducer does not have the removable 18 mm part and has only 48 thread. Thank you.
Can - yes, if you add an M48 to M54 adapter to the reducer and do not have a lot in front of your camera.... 😉 The question I ask myself much more is if backfocus is really still an issue at 290mm ...... and I would guess rather not. So you do not really need this.