Stalla Mira .6 reducer/ flattener.

[alan potts]

Bought one of these 0.6 reducers from FLO about two months back and like a moron didn't read the advert correctly. Optimised for DSLR's I see it states with a back focus of 55mm.

I banged in the normal 16.5mm and 21mm spacers and then wasted 4 hours of wonderful sky, returning rather odd shaped stars in all the frames. Does anyone know if this can be used on my Zwo 071 or is it for the bin as I will not return things that are my fault.

Alan

[StevieDvd]

Not speaking from experience, but I have been looking for a new camera and reducer so interested in the issues.

The ZWO page here for a ZWO 071 has a diagram showing 55mm for the camera to focuser (using a 16.5mm & 21mm adapter) but leaves the 21mm out when connected to a reducer.  So may be worth trying a quick test without the 21mm adapter perhaps?

Steve

 

[symmetal]

Optimised for DSLR just means it has a 55mm backfocus distance. Any sensor, DSLR or not, placed 55mm from the FF would be fine.

Using the 16.5 and 21mm spaces along with the camera's 17.5mm backfocus should give the 55mm required. Are you using a filter between the FF and the camera? The ASI071 response graph extends significantly into the IR with a similar response for RG and B beyond 800nm. It doesn't show the response of the protect glass, so there is no UV-IR cut filter in the way, which could lead to out of focus IR giving star bloating in all three colours.

So a UV-IR cut filter is needed somewhere, possibly screwed into the rear of the FF. Note that if the filter is between the FF and the camera you need to increase the above 55mm spacing by 1/3 the thickness of all the glass in the way. The camera  protect glass should be included here as well, so 56 to 56.5mm spacing is a better figure to use.

Alan

[alan potts]

12 hours ago, symmetal said:

Optimised for DSLR just means it has a 55mm backfocus distance. Any sensor, DSLR or not, placed 55mm from the FF would be fine.

Using the 16.5 and 21mm spaces along with the camera's 17.5mm backfocus should give the 55mm required. Are you using a filter between the FF and the camera? The ASI071 response graph extends significantly into the IR with a similar response for RG and B beyond 800nm. It doesn't show the response of the protect glass, so there is no UV-IR cut filter in the way, which could lead to out of focus IR giving star bloating in all three colours.

So a UV-IR cut filter is needed somewhere, possibly screwed into the rear of the FF. Note that if the filter is between the FF and the camera you need to increase the above 55mm spacing by 1/3 the thickness of all the glass in the way. The camera  protect glass should be included here as well, so 56 to 56.5mm spacing is a better figure to use.

Alan

I have a UV/IR filter on the front of the reducer. The trouble with it is that the lenses that do the work are recessed into the housing. I must carefully try and measure it to see what it is. It may just be leave of the 16.5mm spacer, lets hope. I am not going to go to the trouble of finding other spacers, for what it cost I will just throw it in a draw and forget it, my fault for not reading it correctly.

Thanks for your input.

Alan

[Clarkey]

I have the non-reducing flattener which is 'optimised' for DSLR but I am using it with a 1600MM pro. The 55mm is from the shoulder of the M42 or M48 adaptor. In theory the standard spacers for ZWO 55mm backfocus should work. I did have to add a couple of additional spacers to add about 1.5mm additional distance on mine - but other than that it works well. (Depending how fussy you are, it is not perfect in the corners - but pretty good).

[alan potts]

5 hours ago, Clarkey said:

I have the non-reducing flattener which is 'optimised' for DSLR but I am using it with a 1600MM pro. The 55mm is from the shoulder of the M42 or M48 adaptor. In theory the standard spacers for ZWO 55mm backfocus should work. I did have to add a couple of additional spacers to add about 1.5mm additional distance on mine - but other than that it works well. (Depending how fussy you are, it is not perfect in the corners - but pretty good).

Really, if that is the case then I did exactly what you have done without any additional shims. The affect I get is s little like stars all around edges that look like those from a reflector with spider vanes, absolutely unuseable as an image. I have to say though from memory the centre was not bad. No one would accept what I got as even half decent, it was rubbish and I have since dumped all data. If anything I was wondering if it could be pinched optics as at a quick glance I didn't see the fault. I do have some thin shims I could try to add. I don't have any luck at all with reducers, no matter what they cost, OK the scope is an F 7 APO but decent optics at the top end of the spec but it should be better than what I am getting, miles better.

Alan   

[Clarkey]

Ok fair enough - could be a duff one? If is that bad I think you would be justified in sending it back.

[alan potts]

35 minutes ago, Clarkey said:

Ok fair enough - could be a duff one? If is that bad I think you would be justified in sending it back.

I'll try it again, though I have only had it a short while I haven't been able to use for weather firstly and then I dislocated two fingers on my right hand (still affected) which hampered me doing a great deal. FLO being what they are I am sure will be understanding in the face of this. I dare say these laws on sales, which I don't entirely agree with, do not take into account that if in the UK you could be unable to try anything for many weeks. We had a terrible April and though May has been great I haven't Just able to try it the once so far.

Thanks for your help.

Alan