TS states it can. Tele Vue made it for their Petzval types. A Petzval has got a group of lenses relatively far away from the front group, so there is some similarity in the design. There is an article by Baader Planetarium, only available in German where they tested the NPR1073 at the PlaneWave CDK 17 and CDK 12.5. https://www.baader-p...evue-am-cdk-17/
The latter proves the reducer can deal with flat fields other than by a Petzval so why should it refuse the quadruplet?
The reduction is 0.8 only. I am seriously thinking about it for my 65/420 but for now the relativly little reduction stopped me from buying it. Should I change my mind in the near future I will let you know. I tried the TS-CCD47 and it creates astigmatism everywhere (sample: https://astrob.in/355284/0/) The CCD47 is designed for slower systems without coorrector and naturally low curvature lke RCs.
For the time being I ordered the 2'' to 58mm adapter for astronomical filters on a camera lens. As soon as the weather permits I will try the Tamron 90mm Macro f/2.8 with 7nm Ha-filter to get Heart and Soul in one image.
So you think about converting the f/6.8 474mm to f/5,4 379mm?
During my research I listed a few options:
TS AP 80/480 = TLAPO804 + TSRED279 FPL-53 Triplet, 380mm f/4.7 Eur 800+235 = 1035 Eur
TSAPO71Q 347mm, FPL53-Tripl incl 1-lens. Fluorid corr, f/4,9 Eur 1300
WO 71/420 GT71 Triplet + WO Flat6A II 0.8x 336mm f/4,5 Eur 880+230=1110
WO 71/350 incl. Korrektor FPL-53 Triplet 350mm f/4.9 Eur 1390
TSAPO65Q 420mm f/6.5 FPL53-Triplet w. Flat. Eur 775, 688 at Astroshop.de (I first commented: too long but it finally won the contest)
TS AP 60/360 + TS-Photoline Flat 1x 360mm f/6 Eur 450+165 = 615
TS AP 72/432 + TSRED279 FPL-53-Duplet, 331mm f/4,7 Eur 430+235 = 665 (my first choice in the doublet list)
TS 60/330 ony at Astroshop, FPL53 Dublet, Flattener unknown 330mm f/5,5 Eur 615
TSAPO72, devidable tube, FLP53-Duplet, TSRED279 316mm f/4,4 Eur 600+335=935
TSAPO80F7 - Duplet w TSRED279 424mm, f/5,5 Eur 550+235=785
WO AP 61/360 + Flattener: FPL-53-Duplet, 360mm, f/5,9 Eur 490+190 = 680 wobbely L-shaped tripod connector
I spent some days browsing astro bin images taken with some of the scops and reading about doublet vs. triplet and I phoned TS hotline and astroshop hotline and put a few questions.....
Conlusions (my conclusions, not common wisdom!):
- some doublets proof to be as good a some triplets but this is always for longer focal lenghts
- some triplets seem to be worse than some dublets but a look at the price explains why
- FPL 53 is regarded better than FPL 51
- FCD1 glass seems to be similar to FPL 51 http://www.hoya-opti...sreference.html
- FCD 100 seems to be close but not quite the same as FPL 53 (they put in in paren in the list, whatever that means)
- As soon as you approach f/4 tilt plates are recommended or part of the scope (TSAPO81Q FPL-53-Triplet incl. 3-lens corr. 352mm, f/4,4 comes with a tilt plate)
- shorter focal lenths are more demanding when it comes to CA
- the faster the more critical the focus position
My decision then was to stay away from too fast a system and tilt plates and to go for an FPL53 triplet to avoid CA with the short FL. I also want to enjoy the comfort of an included flattener. AND I AM HAPPY with the little toy. Only the dew cap is too short. Hope it helps.