Reducer/flattener + OTA compatibility

[rnobleeddy]

Have been a Newtonian user but in the expectation that I may be able to travel somewhere this year, I bought a 2nd hand 60mm refractor that should double as a widefield scope for use at home, and be portable enough (and just about wide enough) to use with a star adventurer. 

I then realized I know nothing about reducers/field flatteners. Are there good generic reducers or is it best to pair the OTA/reducer from the same brand? I've seen a few scopes that have matched reducers and so I guess these relate specifically to those optics, but is it the case that they'll work poorly on other OTAs, or just not as well?

Main reason for asking is I might get a 1x flattener to go with the 0.79x reducer the scope already has, but would like to know if I'm tied into a specific brand, or if I decide to get a bigger refractory later, if I'll be able to reuse.

 

[KP82]

It will be good if you could disclose the brand and model of your 60mm refractor.

AFAIK almost every refractor intended as an astrograph with a built-in reducer or petzval lens configuration already produces a flat field. There is no need of an additional flattener.

Generally speaking it will always be a good idea to get the dedicated flattener/reducer if there is one for the scope you have. It will make it a lot easier to get the correct backspacing. Otherwise go for a good general purpose FR/FF like the APM Riccardi, Hotech SCA and TS Optics 2"/3" 0.79x (I've got one of these).

Edited March 4, 2021 by KP82

[rnobleeddy]

10 hours ago, KP82 said:

It will be good if you could disclose the brand and model of your 60mm refractor.

AFAIK almost every refractor intended as an astrograph with a built-in reducer or petzval lens configuration already produces a flat field. There is no need of an additional flattener.

Generally speaking it will always be a good idea to get the dedicated flattener/reducer if there is one for the scope you have. It will make it a lot easier to get the correct backspacing. Otherwise go for a good general purpose FR/FF like the APM Riccardi, Hotech SCA and TS Optics 2"/3" 0.79x (I've got one of these).

The OTA is https://www.astroshop.eu/telescopes/ts-optics-apochromatic-refractor-ap-60-360-photoline-fpl53-red-ota/p,56055  - realize it's not going to be the best small OTA out there, but I didn't want to spend too much given how much use it'll get.

I'm getting one of https://www.teleskop-express.de/shop/product_info.php/language/en/info/p5965_TS-Optics-REFRACTOR-0-79x-2--ED-Reducer-Corrector-fuer-APO-und-ED.html with it.

So I guess I was thinking of getting something like https://www.teleskop-express.de/shop/product_info.php/language/en/info/p10090_TS-Optics-REFRAKTOR-1-0x-Flattener-fuer-ED---APO-mit-60-65-mm-Oeffnung.html as well, although in retrospect., I'll probably live with using the 0.79x flattener and just cropping the image. Reading the details for the 1.0x flattener, it appears to be pretty specific to small refractors, so wouldn't be helpful for much else.

I'd be using either an APS-C or 4/3" sized sensor.

Thanks!

[KP82]

41 minutes ago, rnobleeddy said:

The OTA is https://www.astroshop.eu/telescopes/ts-optics-apochromatic-refractor-ap-60-360-photoline-fpl53-red-ota/p,56055  - realize it's not going to be the best small OTA out there, but I didn't want to spend too much given how much use it'll get.

I'm getting one of https://www.teleskop-express.de/shop/product_info.php/language/en/info/p5965_TS-Optics-REFRACTOR-0-79x-2--ED-Reducer-Corrector-fuer-APO-und-ED.html with it.

So I guess I was thinking of getting something like https://www.teleskop-express.de/shop/product_info.php/language/en/info/p10090_TS-Optics-REFRAKTOR-1-0x-Flattener-fuer-ED---APO-mit-60-65-mm-Oeffnung.html as well, although in retrospect., I'll probably live with using the 0.79x flattener and just cropping the image. Reading the details for the 1.0x flattener, it appears to be pretty specific to small refractors, so wouldn't be helpful for much else.

I'd be using either an APS-C or 4/3" sized sensor.

Thanks!

That 60 f/6 doublet is a decent scope and I'm sure you will get excellent results from it. The only 60mm better than it are the Taks, FS60 and FOA60.

That's the same reducer I've got. It works very well with my 600D which has an APS-C sized sensor. Just one word of caution, the advertised backspacing on TS website are slightly shorter than the actual number. For example when I used it with my APM 107, the backspacing I've worked out is about 58 - 59mm rather than 57mm.

Edited March 4, 2021 by KP82