Tele Vue TRF-2008 Field flattener

Calculating whether I can insert a filter wheel between my QHY10 camera and TRF-2008 field flattener

I would like to use a light pollution filter with my QHY10 camera for nebulae as my location is badly light polluted and the situation is getting constantly worse due to new estates and industrial units being built around Lichfield. However such filters are not always ideal for all targets such as galaxies and I would therefore like to be able to move the filter in and out of the front of the camera without affecting the orientation of camera and telescope/field flattener. Doing this would mean that I can take series of flat frames with filter and without filter and then rotate it in or out as needed.

In my previous post, I have attached the instruction manual for the Tele Vue TRF-2008 field flattener that I use with the QHY10 camera.

Here it is again (PDF):

Tele Vue TRF-2008 Instruction Manual

This manual states that the optimal distance from flattener to camera sensor is 56mm.

Teleskop Service do a manual filter wheel for 2 inch filters.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p9358_TS-Optics-manuelles-Filterrad-fuer-5x-2–Filter.html

The specifications of the filter wheel are as follows:

These show that the filter wheel requires just under 30mm from M48 thread to M48 thread.

However this now means I would need 2 x M48 to T2 adapters, one each side of the filter wheel.

First Light Optics sell such adapters:

So if I used the First Light Optics adapters above then I would add 2 x 10mm into the optical path giving a total of 30mm for filter wheel and 20mm for adapters = 50mm.

Although this appears to be small enough to fit within the optimal 56mm distance from field flattener to camera of 56mm, the page reproduced from the QHY10 camera instruction manual below shows that the QHY10 adds a back-focus requirement of 20mm meaning that the total back-focus requirement would be 70mm when optimal distance is 56mm.

QHY10 camera instruction manual PDF version accessed October 2019

However, if I can find a filter wheel with similar front-back width as the one above buy with T2 threads rather than M48 ones so that I don’t need adapters then it should work OK.

Andy

Improving connection between field flattener and focuser on Sky Watcher Equinox Pro 80mm OTA so that QHY10 camera is not loose/does not fall out

I was very concerned that only one thumb screw on focuser tube for Sky Watcher Equinox Pro 80mm OTA- my QHY10 and field flattener kept becoming loose risking it would all fall out and affecting focus and flats. I was going to drill and tap extra holes for more thumb screws then noticed this hole directly opposite the thumb screw, virtually invisible because it has a grub screw in it. I replaced that with a more robust bolt and now have a very secure connection for my camera that i don’t think will loosen….Just need to take another set of flats now!

Andy

 

Sky Watcher Equinox Pro 80mm OTA + Tele Vue TRF-2008 field flattener + QHY10 camera & William Optics 66mm OTQ with T7C guide camera + TS OAG/flip mirror on HEQ5 Pro & focus points on both scopes with these cameras 20/9/2019

Sky Watcher Equinox Pro 80mm OTA + Tele Vue TRF-2008 field flattener + QHY10 camera & William Optics 66mm OTQ with T7C guide camera + TS OAG/flip mirror on HEQ5 Pro & focus points on both scopes with these cameras 20/9/2019:

     

Focusing QHY10 with Tele Vue TRF-2008 Reducer-flattener in situ for first time during day on Sky Watcher Equinox Pro 80mm OTA

I added my Tele Vue TRF-2008 Reducer-flattener into the imaging train for my QHY10 camera on my Sky Watcher Equinox Pro 80mm telescope today. As first step, I decided to try focusing it during the day. This needed me to reduce the aperture by 70% with aperture mask as well using minimum 1/10000 second exposure setting in Nebulosity 4 for the camera and also aim as the darkest part of the daytime garden.

Following image shows bottom garden in focus with QHY10 only attached to telescope:

In the following image, I added in my Tele Vue TRF-2008 Reducer-flattener and TS Optics off axis guider/flip mirror together into the imaging train – as you can see I could not obtain focus even when the focuser was fully racked in as far as it would go (needed to go in not out – could see focus improve as I did so):

Finally, in this image, you can see that I obtained focus with the Tele Vue TRF-2008 Reducer-flattener and QHY10 but without the TS Optics off axis guider/flip mirror, so sadly I won’t be able to use the TS OAG/FM with the TRF-2008 and my QHY10:

Focus was achieved at the end of the garden with QHY10 and Tele Vue TRF-2008 Reducer-flattener with a setting of 17mm on the focus tube of the Equinox 80mm OTA. Note 35mm of T2-adapters were used as spacer between the TRF-2008 and QHY10 as advised in the TRF-2008 manual.

Next step is to try focusing at night and find alternative way of finding my objects than the TS OAG/FM as I am keen to use the TRF-2008.

Andy