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I just read about the Altair 1600 with interest. 100 pounds less that the ASI. It has a heated window, which ASI 1600 does not have, but on the other hand I have so far never had any dew problems with my ASI1600. Another difference is that the chip appears to be further into the Altair camera (17.5 mm "from flat end of T2 / M42x0.75x female adapter") while it is 6.5 mm into the ASI 1600. That could possibly be a problem for the Altair if you want to fit in both a filter wheel and an OAG between the camera and flattener/reducer.

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Not a cloud in the sky at the moment, they're waiting on the other side of the hill for a new camera to arrive

The math is quite easy: Required filter diameter = ((Total distance from Filter to sensor / F-ratio) + (Sensor Diagonal / 2)) x 2 Remember that the sensor distance has to include the distanc

As @pete_l, I'm a bit baffled by the HUUUGE memory in the Altair. A 4GB memory buffer for a 20 Mpix camera just doesn't make sense. You could save a whole nights imaging data in that camera, and still

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3 hours ago, Anthonyexmouth said:

It may just be that 4GB modules are the cheapest option to buy now. Factories will be pumping out that kinda size for millions of mobile phones so sourcing them would be easier and probably cheaper rather than actually needing all that memory

Could be! I'm not sure how the (Hypercam) 183 might store frames or whether it can read them as fast as storing them. But maybe the 4GB makes it better for continuous shooting? But I know little about such things as I'm really dso only (ok, occasionally do some white light solar).
Anyway, my qhy183m with it's mere 128MB frame buffer arrived earlier - not unpacked it yet... I'll probably need some fittings in order to attach it but might be able to just put it directly in place of the minicam5s on the ts 80mm :). I might have to pay more attention to the fr spacing though it's still quite small sensor.

Louise

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50 minutes ago, gorann said:

I just read about the Altair 1600 with interest. 100 pounds less that the ASI. It has a heated window, which ASI 1600 does not have, but on the other hand I have so far never had any dew problems with my ASI1600. Another difference is that the chip appears to be further into the Altair camera (17.5 mm "from flat end of T2 / M42x0.75x female adapter") while it is 6.5 mm into the ASI 1600. That could possibly be a problem for the Altair if you want to fit in both a filter wheel and an OAG between the camera and flattener/reducer.

So with the ASI front adapter removed to give the 6.5mm what's left to attach anything to? 

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5 hours ago, Anthonyexmouth said:

So with the ASI front adapter removed to give the 6.5mm what's left to attach anything to? 

Once you take the black collar off then your left with a male T2 thread that gives the 6.5mm backfocus that threads directly into the ZWO filter wheel I use. 

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On 27/03/2019 at 11:32, Anthonyexmouth said:

... if the Altair is the same camera ...

It is not the same.

ZWO does not make cameras for Altair Astro.

A Chinese company called ToupTek make Altair Astro's cameras.

HTH, 

Steve 

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19 hours ago, andyboy1970 said:

I believe the 4Gb buffer is to allow for slower computers on USB2 and prevent dropped frames/subs.

Yes, but since a buffer only needs to hold one image at a time, 4 GB is seriously overdimensioned. Normal memory size for a buffer is 128 or 256 MB. But the earlier remark that 4 GB modules may actually be cheaper than 256 MB is a valid one.

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How is 17.5mm backfocus friendly with 31mm filters?

or 36mm and larger needed?

Win £100 on the cam price, - loose £200 or even more  on filters, does not sound a very good deal

Edited by RolandKol
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1 hour ago, wimvb said:

Yes, but since a buffer only needs to hold one image at a time, 4 GB is seriously overdimensioned. Normal memory size for a buffer is 128 or 256 MB. But the earlier remark that 4 GB modules may actually be cheaper than 256 MB is a valid one.

I think that maybe only true with single subs rather than video though I know nothing really!

Louise

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1 hour ago, Thalestris24 said:

I think that maybe only true with single subs rather than video though I know nothing really!

Louise

I actually wondered the same, but I read in some ad blurb that a buffer memory isn't as critical in a sequence capture. Not that I know either.

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4 hours ago, RolandKol said:

How is 17.5mm backfocus friendly with 31mm filters?

or 36mm and larger needed?

Win £100 on the cam price, - loose £200 or even more  on filters, does not sound a very good deal

Are you saying 31mm filters are too small for that amount of back focus?

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On 29/03/2019 at 19:02, Anthonyexmouth said:

Are you saying 31mm filters are too small for that amount of back focus?

The math is quite easy:

Required filter diameter = ((Total distance from Filter to sensor / F-ratio) + (Sensor Diagonal / 2)) x 2

Remember that the sensor distance has to include the distance to the filter within the filter wheel (~6mm for zwo wheel).

So total distance from sensor to filter = 23.5mm for Altair Camera.

Altair 1600 TEC + ZWO filter wheel (This assumes the camera has a male connection if not then the back focus will further increase so you may have to add another 1-2mm).

F4 = ((23.5 / 4) + (21.9 / 2)) x 2 = 33.7 mm

F5 = ((23.5 / 5) + (21.9 / 2)) x 2 = 31.3 mm

F6 = ((23.5 / 6) + (21.9 / 2)) x 2 = 29.7 mm

F7 = ((23.5 / 7) + (21.9 / 2)) x 2 = 28.6 mm

So if you want no vignetting with 31mm filters its F6 or slower, if you accept moderate but correctable vignetting its F5 or slower and by the time you get to F4 you are going to be losing quite allot of signal in the corners of the image. That all assumes your optics are perfectly collimated because if not things will be worse.

So you can get away with 31mm filters, but I would not use them faster than F6 if it was me. To get to F5 I would want 36mm filters. 

In terms of 1.25 inch filter (clear aperture = 25mm -> 26mm then you might just get away with it at F6.4 dependent on filter mounting but you will be seeing some significant vignetting.

Compare that to the ASI1600mm pro ZWO filter wheel.

F4 = ((12.5 / 4) + 21.9 / 2)) x 2 = 28.2 mm

F5 = ((12.5 / 5) + 21.9 / 2)) x 2 = 26.9 mm

F6 = ((12.5 / 6) + 21.9 / 2)) x 2 = 26.1 mm

F7 = ((12.5 / 7) + 21.9 / 2)) x 2 = 25.5 mm

So you can use it with 31mm down to F4 or even faster, and you can reasonably use it 1.25 inch filter down to F5 or even F4 if you are willing to accept some moderate vignetting.

Hope this makes everything clear.

Adam

 

Edited by Adam J
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Finally decided on a 183 based colour cooled camera. The Altair has a built in ir cut filter and the zwo doesn't. Is there any benefit to not having it built in on the zwo or is the Altair better because it automatically protects the sensor

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Only benefit I can see for no IR filter is the fact you can have the choice of which filter to buy ? some are pretty expensive ... Unless you have a large wallet or a need for a filter other than IR then the Altair is fine . Are you going Tec cooled or the fan version ?

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Just now, knobby said:

Only benefit I can see for no IR filter is the fact you can have the choice of which filter to buy ? some are pretty expensive ... Unless you have a large wallet or a need for a filter other than IR then the Altair is fine . Are you going Tec cooled or the fan version ?

Tec cooled. Wonder what the quality of the AA filter is. 

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Indeed, I'm sure it's ok but as I said, that's the advantage of the ZWO, you decide the quality / price.

The ZWO just has a clear anti reflective glass so the sensor is still protected.

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24 minutes ago, Anthonyexmouth said:

The zwo is probably the right choice, gutted Flo are out of stock at the moment. I hate waiting for stuff when I want it. 

You know FLO is first rate and you never have problems with them. I have just ordered, a while back as it happened , some objects which were out of stock. They kept me informed every step of the way. I am sure FLO will get them back in soon and you too will be kept in the light, sometimes things are worth waiting for.

I can't say I understood all of the replies before this post but read them anyway as FLO delivered clouds and alot of rain this time, I do love the way people rally round to spend your money:).

Good Luck I want maybe a 071 myself soon.

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25 minutes ago, Anthonyexmouth said:

Flo is just a push bike ride away for me. Trying my hardest to wait, but it's really frustrating. Worried I might change my mind if I've got too long to think about it

I actually facny the 183MC as well as the 071, I will most likely buy both given time or similar. If you go with FLO please ask them to pack it without cloud and rain, judging by the amount I have over here they will out of stock too.

Alan

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16 hours ago, Anthonyexmouth said:

The zwo is probably the right choice, gutted Flo are out of stock at the moment. I hate waiting for stuff when I want it. 

Things were delayed a little while ZWO attended NEAF in the US but it might be closer than you think. I’ll check when at my desk tomorrow. 

HTH, 

Steve 

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4 minutes ago, FLO said:

Things were delayed a little while ZWO attended NEAF in the US but it might Ben closer than you think. I’ll check when at my desk tomorrow. 

HTH, 

Steve 

Cool, thank you. Is there anything on the immediate ZWO horizon that's going to replace or better the 183mc pro. 

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8 minutes ago, alan potts said:

I actually facny the 183MC as well as the 071, I will most likely buy both given time or similar. If you go with FLO please ask them to pack it without cloud and rain, judging by the amount I have over here they will out of stock too.

Alan

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Not a cloud in the sky at the moment, they're waiting on the other side of the hill for a new camera to arrive

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